+This is a rough history of garbage collector bugs and versions.
+
+This has been maintained with varying diligence over the years.
+
+I made an attempt to include recent contributors here. I apologize for any
+omissions.
+
+RECENT UPDATES ARE RECORDED IN ../ChangeLog FILE INSTEAD TO CONFORM TO
+MORE COMMON CONVENTIONS.
+
+-------------------------
+
+ Version 1.3 and immediately preceding versions contained spurious
+assembly language assignments to TMP_SP. Only the assignment in the PC/RT
+code is necessary. On other machines, with certain compiler options,
+the assignments can lead to an unsaved register being overwritten.
+Known to cause problems under SunOS 3.5 WITHOUT the -O option. (With
+-O the compiler recognizes it as dead code. It probably shouldn't,
+but that's another story.)
+
+ Version 1.4 and earlier versions used compile time determined values
+for the stack base. This no longer works on Sun 3s, since Sun 3/80s use
+a different stack base. We now use a straightforward heuristic on all
+machines on which it is known to work (incl. Sun 3s) and compile-time
+determined values for the rest. There should really be library calls
+to determine such values.
+
+ Version 1.5 and earlier did not ensure 8 byte alignment for objects
+allocated on a sparc based machine.
+
+ Version 1.8 added ULTRIX support in gc_private.h.
+
+ Version 1.9 fixed a major bug in gc_realloc.
+
+ Version 2.0 introduced a consistent naming convention for collector
+routines and added support for registering dynamic library data segments
+in the standard mark_roots.c. Most of the data structures were revamped.
+The treatment of interior pointers was completely changed. Finalization
+was added. Support for locking was added. Object kinds were added.
+We added a black listing facility to avoid allocating at addresses known
+to occur as integers somewhere in the address space. Much of this
+was accomplished by adapting ideas and code from the PCR collector.
+The test program was changed and expanded.
+
+ Version 2.1 was the first stable version since 1.9, and added support
+for PPCR.
+
+ Version 2.2 added debugging allocation, and fixed various bugs. Among them:
+- GC_realloc could fail to extend the size of the object for certain large object sizes.
+- A blatant subscript range error in GC_printf, which unfortunately
+ wasn't exercised on machines with sufficient stack alignment constraints.
+- GC_register_displacement did the wrong thing if it was called after
+ any allocation had taken place.
+- The leak finding code would eventually break after 2048 byte
+ byte objects leaked.
+- interface.c didn't compile.
+- The heap size remained much too small for large stacks.
+- The stack clearing code behaved badly for large stacks, and perhaps
+ on HP/PA machines.
+
+ Version 2.3 added ALL_INTERIOR_POINTERS and fixed the following bugs:
+- Missing declaration of etext in the A/UX version.
+- Some PCR root-finding problems.
+- Blacklisting was not 100% effective, because the plausible future
+ heap bounds were being miscalculated.
+- GC_realloc didn't handle out-of-memory correctly.
+- GC_base could return a nonzero value for addresses inside free blocks.
+- test.c wasn't really thread safe, and could erroneously report failure
+ in a multithreaded environment. (The locking primitives need to be
+ replaced for other threads packages.)
+- GC_CONS was thoroughly broken.
+- On a SPARC with dynamic linking, signals stayed diabled while the
+ client code was running.
+ (Thanks to Manuel Serrano at INRIA for reporting the last two.)
+
+ Version 2.4 added GC_free_space_divisor as a tuning knob, added
+ support for OS/2 and linux, and fixed the following bugs:
+- On machines with unaligned pointers (e.g. Sun 3), every 128th word could
+ fail to be considered for marking.
+- Dynamic_load.c erroneously added 4 bytes to the length of the data and
+ bss sections of the dynamic library. This could result in a bad memory
+ reference if the actual length was a multiple of a page. (Observed on
+ Sun 3. Can probably also happen on a Sun 4.)
+ (Thanks to Robert Brazile for pointing out that the Sun 3 version
+ was broken. Dynamic library handling is still broken on Sun 3s
+ under 4.1.1U1, but apparently not 4.1.1. If you have such a machine,
+ use -Bstatic.)
+
+ Version 2.5 fixed the following bugs:
+- Removed an explicit call to exit(1)
+- Fixed calls to GC_printf and GC_err_printf, so the correct number of
+ arguments are always supplied. The OS/2 C compiler gets confused if
+ the number of actuals and the number of formals differ. (ANSI C
+ doesn't require this to work. The ANSI sanctioned way of doing things
+ causes too many compatibility problems.)
+
+ Version 3.0 added generational/incremental collection and stubborn
+ objects.
+
+ Version 3.1 added the following features:
+- A workaround for a SunOS 4.X SPARC C compiler
+ misfeature that caused problems when the collector was turned into
+ a dynamic library.
+- A fix for a bug in GC_base that could result in a memory fault.
+- A fix for a performance bug (and several other misfeatures) pointed
+ out by Dave Detlefs and Al Dosser.
+- Use of dirty bit information for static data under Solaris 2.X.
+- DEC Alpha/OSF1 support (thanks to Al Dosser).
+- Incremental collection on more platforms.
+- A more refined heap expansion policy. Less space usage by default.
+- Various minor enhancements to reduce space usage, and to reduce
+ the amount of memory scanned by the collector.
+- Uncollectable allocation without per object overhead.
+- More conscientious handling of out-of-memory conditions.
+- Fixed a bug in debugging stubborn allocation.
+- Fixed a bug that resulted in occasional erroneous reporting of smashed
+ objects with debugging allocation.
+- Fixed bogus leak reports of size 4096 blocks with FIND_LEAK.
+
+ Version 3.2 fixed a serious and not entirely repeatable bug in
+ the incremental collector. It appeared only when dirty bit info
+ on the roots was available, which is normally only under Solaris.
+ It also added GC_general_register_disappearing_link, and some
+ testing code. Interface.c disappeared.
+
+ Version 3.3 fixes several bugs and adds new ports:
+- PCR-specific bugs.
+- Missing locking in GC_free, redundant FASTUNLOCK
+ in GC_malloc_stubborn, and 2 bugs in
+ GC_unregister_disappearing_link.
+ All of the above were pointed out by Neil Sharman
+ (neil@cs.mu.oz.au).
+- Common symbols allocated by the SunOS4.X dynamic loader
+ were not included in the root set.
+- Bug in GC_finalize (reported by Brian Beuning and Al Dosser)
+- Merged Amiga port from Jesper Peterson (untested)
+- Merged NeXT port from Thomas Funke (significantly
+ modified and untested)
+
+ Version 3.4:
+- Fixed a performance bug in GC_realloc.
+- Updated the amiga port.
+- Added NetBSD and 386BSD ports.
+- Added cord library.
+- Added trivial performance enhancement for
+ ALL_INTERIOR_POINTERS. (Don't scan last word.)
+
+ Version 3.5
+- Minor collections now mark from roots only once, if that
+ doesn't cause an excessive pause.
+- The stack clearing heuristic was refined to prevent anomalies
+ with very heavily recursive programs and sparse stacks.
+- Fixed a bug that prevented mark stack growth in some cases.
+ GC_objects_are_marked should be set to TRUE after a call
+ to GC_push_roots and as part of GC_push_marked, since
+ both can now set mark bits. I think this is only a performance
+ bug, but I wouldn't bet on it. It's certainly very hard to argue
+ that the old version was correct.
+- Fixed an incremental collection bug that prevented it from
+ working at all when HBLKSIZE != getpagesize()
+- Changed dynamic_loading.c to include gc_priv.h before testing
+ DYNAMIC_LOADING. SunOS dynamic library scanning
+ must have been broken in 3.4.
+- Object size rounding now adapts to program behavior.
+- Added a workaround (provided by Manuel Serrano and
+ colleagues) to a long-standing SunOS 4.X (and 3.X?) ld bug
+ that I had incorrectly assumed to have been squished.
+ The collector was broken if the text segment size was within
+ 32 bytes of a multiple of 8K bytes, and if the beginning of
+ the data segment contained interesting roots. The workaround
+ assumes a demand-loadable executable. The original may have
+ have "worked" in some other cases.
+- Added dynamic library support under IRIX5.
+- Added support for EMX under OS/2 (thanks to Ari Huttunen).
+
+Version 3.6:
+- fixed a bug in the mark stack growth code that was introduced
+ in 3.4.
+- fixed Makefile to work around DEC AXP compiler tail recursion
+ bug.
+
+Version 3.7:
+- Added a workaround for an HP/UX compiler bug.
+- Fixed another stack clearing performance bug. Reworked
+ that code once more.
+
+Version 4.0:
+- Added support for Solaris threads (which was possible
+ only by reimplementing some fraction of Solaris threads,
+ since Sun doesn't currently make the thread debugging
+ interface available).
+- Added non-threads win32 and win32S support.
+- (Grudgingly, with suitable muttering of obscenities) renamed
+ files so that the collector distribution could live on a FAT
+ file system. Files that are guaranteed to be useless on
+ a PC still have long names. Gc_inline.h and gc_private.h
+ still exist, but now just include gc_inl.h and gc_priv.h.
+- Fixed a really obscure bug in finalization that could cause
+ undetected mark stack overflows. (I would be surprised if
+ any real code ever tickled this one.)
+- Changed finalization code to dynamically resize the hash
+ tables it maintains. (This probably does not matter for well-
+ -written code. It no doubt does for C++ code that overuses
+ destructors.)
+- Added typed allocation primitives. Rewrote the marker to
+ accommodate them with more reasonable efficiency. This
+ change should also speed up marking for GC_malloc allocated
+ objects a little. See gc_typed.h for new primitives.
+- Improved debugging facilities slightly. Allocation time
+ stack traces are now kept by default on SPARC/SUNOS4.
+ (Thanks to Scott Schwartz.)
+- Added better support for small heap applications.
+- Significantly extended cord package. Fixed a bug in the
+ implementation of lazily read files. Printf and friends now
+ have cord variants. Cord traversals are a bit faster.
+- Made ALL_INTERIOR_POINTERS recognition the default.
+- Fixed de so that it can run in constant space, independent
+ of file size. Added simple string searching to cords and de.
+- Added the Hull-Ellis C++ interface.
+- Added dynamic library support for OSF/1.
+ (Thanks to Al Dosser and Tim Bingham at DEC.)
+- Changed argument to GC_expand_hp to be expressed
+ in units of bytes instead of heap blocks. (Necessary
+ since the heap block size now varies depending on
+ configuration. The old version was never very clean.)
+- Added GC_get_heap_size(). The previous "equivalent"
+ was broken.
+- Restructured the Makefile a bit.
+
+Since version 4.0:
+- Changed finalization implementation to guarantee that
+ finalization procedures are called outside of the allocation
+ lock, making direct use of the interface a little less dangerous.
+ MAY BREAK EXISTING CLIENTS that assume finalizers
+ are protected by a lock. Since there seem to be few multithreaded
+ clients that use finalization, this is hopefully not much of
+ a problem.
+- Fixed a gross bug in CORD_prev.
+- Fixed a bug in blacklst.c that could result in unbounded
+ heap growth during startup on machines that do not clear
+ memory obtained from the OS (e.g. win32S).
+- Ported de editor to win32/win32S. (This is now the only
+ version with a mouse-sensitive UI.)
+- Added GC_malloc_ignore_off_page to allocate large arrays
+ in the presence of ALL_INTERIOR_POINTERS.
+- Changed GC_call_with_alloc_lock to not disable signals in
+ the single-threaded case.
+- Reduced retry count in GC_collect_or_expand for garbage
+ collecting when out of memory.
+- Made uncollectable allocations bypass black-listing, as they
+ should.
+- Fixed a bug in typed_test in test.c that could cause (legitimate)
+ GC crashes.
+- Fixed some potential synchronization problems in finalize.c
+- Fixed a real locking problem in typd_mlc.c.
+- Worked around an AIX 3.2 compiler feature that results in
+ out of bounds memory references.
+- Partially worked around an IRIX5.2 beta problem (which may
+ or may not persist to the final release).
+- Fixed a bug in the heap integrity checking code that could
+ result in explicitly deallocated objects being identified as
+ smashed. Fixed a bug in the dbg_mlc stack saving code
+ that caused old argument pointers to be considered live.
+- Fixed a bug in CORD_ncmp (and hence CORD_str).
+- Repaired the OS2 port, which had suffered from bit rot
+ in 4.0. Worked around what appears to be CSet/2 V1.0
+ optimizer bug.
+- Fixed a Makefile bug for target "c++".
+
+Since version 4.1:
+- Multiple bug fixes/workarounds in the Solaris threads version.
+ (It occasionally failed to locate some register contents for
+ marking. It also turns out that thr_suspend and friends are
+ unreliable in Solaris 2.3. Dirty bit reads appear
+ to be unreliable under some weird
+ circumstances. My stack marking code
+ contained a serious performance bug. The new code is
+ extremely defensive, and has not failed in several cpu
+ hours of testing. But no guarantees ...)
+- Added MacOS support (thanks to Patrick Beard.)
+- Fixed several syntactic bugs in gc_c++.h and friends. (These
+ didn't bother g++, but did bother most other compilers.)
+ Fixed gc_c++.h finalization interface. (It didn't.)
+- 64 bit alignment for allocated objects was not guaranteed in a
+ few cases in which it should have been.
+- Added GC_malloc_atomic_ignore_off_page.
+- Added GC_collect_a_little.
+- Added some prototypes to gc.h.
+- Some other minor bug fixes (notably in Makefile).
+- Fixed OS/2 / EMX port (thanks to Ari Huttunen).
+- Fixed AmigaDOS port. (thanks to Michel Schinz).
+- Fixed the DATASTART definition under Solaris. There
+ was a 1 in 16K chance of the collector missing the first
+ 64K of static data (and thus crashing).
+- Fixed some blatant anachronisms in the README file.
+- Fixed PCR-Makefile for upcoming PPCR release.
+
+Since version 4.2:
+- Fixed SPARC alignment problem with GC_DEBUG.
+- Fixed Solaris threads /proc workaround. The real
+ problem was an interaction with mprotect.
+- Incorporated fix from Patrick Beard for gc_c++.h (now gc_cpp.h).
+- Slightly improved allocator space utilization by
+ fixing the GC_size_map mechanism.
+- Integrated some Sony News and MIPS RISCos 4.51
+ patches. (Thanks to Nobuyuki Hikichi of
+ Software Research Associates, Inc. Japan)
+- Fixed HP_PA alignment problem. (Thanks to
+ xjam@cork.cs.berkeley.edu.)
+- Added GC_same_obj and friends. Changed GC_base
+ to return 0 for pointers past the end of large objects.
+ Improved GC_base performance with ALL_INTERIOR_POINTERS
+ on machines with a slow integer mod operation.
+ Added GC_PTR_ADD, GC_PTR_STORE, etc. to prepare
+ for preprocessor.
+- changed the default on most UNIX machines to be that
+ signals are not disabled during critical GC operations.
+ This is still ANSI-conforming, though somewhat dangerous
+ in the presence of signal handlers. But the performance
+ cost of the alternative is sometimes problematic.
+ Can be changed back with a minor Makefile edit.
+- renamed IS_STRING in gc.h, to CORD_IS_STRING, thus
+ following my own naming convention. Added the function
+ CORD_to_const_char_star.
+- Fixed a gross bug in GC_finalize. Symptom: occasional
+ address faults in that function. (Thanks to Anselm
+ Baird-Smith (Anselm.BairdSmith@inria.fr)
+- Added port to ICL DRS6000 running DRS/NX. Restructured
+ things a bit to factor out common code, and remove obsolete
+ code. Collector should now run under SUNOS5 with either
+ mprotect or /proc dirty bits. (Thanks to Douglas Steel
+ (doug@wg.icl.co.uk)).
+- More bug fixes and workarounds for Solaris 2.X. (These were
+ mostly related to putting the collector in a dynamic library,
+ which didn't really work before. Also SOLARIS_THREADS
+ didn't interact well with dl_open.) Thanks to btlewis@eng.sun.com.
+- Fixed a serious performance bug on the DEC Alpha. The text
+ segment was getting registered as part of the root set.
+ (Amazingly, the result was still fast enough that the bug
+ was not conspicuous.) The fix works on OSF/1, version 1.3.
+ Hopefully it also works on other versions of OSF/1 ...
+- Fixed a bug in GC_clear_roots.
+- Fixed a bug in GC_generic_malloc_words_small that broke
+ gc_inl.h. (Reported by Antoine de Maricourt. I broke it
+ in trying to tweak the Mac port.)
+- Fixed some problems with cord/de under Linux.
+- Fixed some cord problems, notably with CORD_riter4.
+- Added DG/UX port.
+ Thanks to Ben A. Mesander (ben@piglet.cr.usgs.gov)
+- Added finalization registration routines with weaker ordering
+ constraints. (This is necessary for C++ finalization with
+ multiple inheritance, since the compiler often adds self-cycles.)
+- Filled the holes in the SCO port. (Thanks to Michael Arnoldus
+ <chime@proinf.dk>.)
+- John Ellis' additions to the C++ support: From John:
+
+* I completely rewrote the documentation in the interface gc_c++.h
+(later renamed gc_cpp.h). I've tried to make it both clearer and more
+precise.
+
+* The definition of accessibility now ignores pointers from an
+finalizable object (an object with a clean-up function) to itself.
+This allows objects with virtual base classes to be finalizable by the
+collector. Compilers typically implement virtual base classes using
+pointers from an object to itself, which under the old definition of
+accessibility prevented objects with virtual base classes from ever
+being collected or finalized.
+
+* gc_cleanup now includes gc as a virtual base. This was enabled by
+the change in the definition of accessibility.
+
+* I added support for operator new[]. Since most (all?) compilers
+don't yet support operator new[], it is conditionalized on
+-DOPERATOR_NEW_ARRAY. The code is untested, but its trivial and looks
+correct.
+
+* The test program test_gc_c++ (later renamed test_cpp.cc)
+tries to test for the C++-specific functionality not tested by the
+other programs.
+- Added <unistd.h> include to misc.c. (Needed for ppcr.)
+- Added PowerMac port. (Thanks to Patrick Beard again.)
+- Fixed "srcdir"-related Makefile problems. Changed things so
+ that all externally visible include files always appear in the
+ include subdirectory of the source. Made gc.h directly
+ includable from C++ code. (These were at Per
+ Bothner's suggestion.)
+- Changed Intel code to also mark from ebp (Kevin Warne's
+ suggestion).
+- Renamed C++ related files so they could live in a FAT
+ file system. (Charles Fiterman's suggestion.)
+- Changed Windows NT Makefile to include C++ support in
+ gc.lib. Added C++ test as Makefile target.
+
+Since version 4.3:
+ - ASM_CLEAR_CODE was erroneously defined for HP
+ PA machines, resulting in a compile error.
+ - Fixed OS/2 Makefile to create a library. (Thanks to
+ Mark Boulter (mboulter@vnet.ibm.com)).
+ - Gc_cleanup objects didn't work if they were created on
+ the stack. Fixed.
+ - One copy of Gc_cpp.h in the distribution was out of
+ synch, and failed to document some known compiler
+ problems with explicit destructor invocation. Partially
+ fixed. There are probably other compilers on which
+ gc_cleanup is miscompiled.
+ - Fixed Makefile to pass C compiler flags to C++ compiler.
+ - Added Mac fixes.
+ - Fixed os_dep.c to work around what appears to be
+ a new and different VirtualQuery bug under newer
+ versions of win32S.
+ - GC_non_gc_bytes was not correctly maintained by
+ GC_free. Fixed. Thanks to James Clark (jjc@jclark.com).
+ - Added GC_set_max_heap_size.
+ - Changed allocation code to ignore blacklisting if it is preventing
+ use of a very large block of memory. This has the advantage
+ that naive code allocating very large objects is much more
+ likely to work. The downside is you might no
+ longer find out that such code should really use
+ GC_malloc_ignore_off_page.
+ - Changed GC_printf under win32 to close and reopen the file
+ between calls. FAT file systems otherwise make the log file
+ useless for debugging.
+ - Added GC_try_to_collect and GC_get_bytes_since_gc. These
+ allow starting an abortable collection during idle times.
+ This facility does not require special OS support. (Thanks to
+ Michael Spertus of Geodesic Systems for suggesting this. It was
+ actually an easy addition. Kumar Srikantan previously added a similar
+ facility to a now ancient version of the collector. At the time
+ this was much harder, and the result was less convincing.)
+ - Added some support for the Borland development environment. (Thanks
+ to John Ellis and Michael Spertus.)
+ - Removed a misfeature from checksums.c that caused unexpected
+ heap growth. (Thanks to Scott Schwartz.)
+ - Changed finalize.c to call WARN if it encounters a finalization cycle.
+ WARN is defined in gc_priv.h to write a message, usually to stdout.
+ In many environments, this may be inappropriate.
+ - Renamed NO_PARAMS in gc.h to GC_NO_PARAMS, thus adhering to my own
+ naming convention.
+ - Added GC_set_warn_proc to intercept warnings.
+ - Fixed Amiga port. (Thanks to Michel Schinz (schinz@alphanet.ch).)
+ - Fixed a bug in mark.c that could result in an access to unmapped
+ memory from GC_mark_from_mark_stack on machines with unaligned
+ pointers.
+ - Fixed a win32 specific performance bug that could result in scanning of
+ objects allocated with the system malloc.
+ - Added REDIRECT_MALLOC.
+
+Since version 4.4:
+ - Fixed many minor and one major README bugs. (Thanks to Franklin Chen
+ (chen@adi.com) for pointing out many of them.)
+ - Fixed ALPHA/OSF/1 dynamic library support. (Thanks to Jonathan Bachrach
+ (jonathan@harlequin.com)).
+ - Added incremental GC support (MPROTECT_VDB) for Linux (with some
+ help from Bruno Haible).
+ - Altered SPARC recognition tests in gc.h and config.h (mostly as
+ suggested by Fergus Henderson).
+ - Added basic incremental GC support for win32, as implemented by
+ Windows NT and Windows 95. GC_enable_incremental is a noop
+ under win32s, which doesn't implement enough of the VM interface.
+ - Added -DLARGE_CONFIG.
+ - Fixed GC_..._ignore_off_page to also function without
+ -DALL_INTERIOR_POINTERS.
+ - (Hopefully) fixed RS/6000 port. (Only the test was broken.)
+ - Fixed a performance bug in the nonincremental collector running
+ on machines supporting incremental collection with MPROTECT_VDB
+ (e.g. SunOS 4, DEC AXP). This turned into a correctness bug under
+ win32s with win32 incremental collection. (Not all memory protection
+ was disabled.)
+ - Fixed some ppcr related bit rot.
+ - Caused dynamic libraries to be unregistered before reregistering.
+ The old way turned out to be a performance bug on some machines.
+ - GC_root_size was not properly maintained under MSWIN32.
+ - Added -DNO_DEBUGGING and GC_dump.
+ - Fixed a couple of bugs arising with SOLARIS_THREADS +
+ REDIRECT_MALLOC.
+ - Added NetBSD/M68K port. (Thanks to Peter Seebach
+ <seebs@taniemarie.solon.com>.)
+ - Fixed a serious realloc bug. For certain object sizes, the collector
+ wouldn't scan the expanded part of the object. (Thanks to Clay Spence
+ (cds@peanut.sarnoff.com) for noticing the problem, and helping me to
+ track it down.)
+
+Since version 4.5:
+ - Added Linux ELF support. (Thanks to Arrigo Triulzi <arrigo@ic.ac.uk>.)
+ - GC_base crashed if it was called before any other GC_ routines.
+ This could happen if a gc_cleanup object was allocated outside the heap
+ before any heap allocation.
+ - The heap expansion heuristic was not stable if all objects had finalization
+ enabled. Fixed finalize.c to count memory in finalization queue and
+ avoid explicit deallocation. Changed alloc.c to also consider this count.
+ (This is still not recommended. It's expensive if nothing else.) Thanks
+ to John Ellis for pointing this out.
+ - GC_malloc_uncollectable(0) was broken. Thanks to Phong Vo for pointing
+ this out.
+ - The collector didn't compile under Linux 1.3.X. (Thanks to Fred Gilham for
+ pointing this out.) The current workaround is ugly, but expected to be
+ temporary.
+ - Fixed a formatting problem for SPARC stack traces.
+ - Fixed some '=='s in os_dep.c that should have been assignments.
+ Fortunately these were in code that should never be executed anyway.
+ (Thanks to Fergus Henderson.)
+ - Fixed the heap block allocator to only drop blacklisted blocks in small
+ chunks. Made BL_LIMIT self adjusting. (Both of these were in response
+ to heap growth observed by Paul Graham.)
+ - Fixed the Metrowerks/68K Mac code to also mark from a6. (Thanks
+ to Patrick Beard.)
+ - Significantly updated README.debugging.
+ - Fixed some problems with longjmps out of signal handlers, especially under
+ Solaris. Added a workaround for the fact that siglongjmp doesn't appear to
+ do the right thing with -lthread under Solaris.
+ - Added MSDOS/djgpp port. (Thanks to Mitch Harris (maharri@uiuc.edu).)
+ - Added "make reserved_namespace" and "make user_namespace". The
+ first renames ALL "GC_xxx" identifiers as "_GC_xxx". The second is the
+ inverse transformation. Note that doing this is guaranteed to break all
+ clients written for the other names.
+ - descriptor field for kind NORMAL in GC_obj_kinds with ADD_BYTE_AT_END
+ defined should be -ALIGNMENT not WORDS_TO_BYTES(-1). This is
+ a serious bug on machines with pointer alignment of less than a word.
+ - GC_ignore_self_finalize_mark_proc didn't handle pointers to very near the
+ end of the object correctly. Caused failures of the C++ test on a DEC Alpha
+ with g++.
+ - gc_inl.h still had problems. Partially fixed. Added warnings at the
+ beginning to hopefully specify the remaining dangers.
+ - Added DATAEND definition to config.h.
+ - Fixed some of the .h file organization. Fixed "make floppy".
+
+Since version 4.6:
+ - Fixed some compilation problems with -DCHECKSUMS (thanks to Ian Searle)
+ - Updated some Mac specific files to synchronize with Patrick Beard.
+ - Fixed a serious bug for machines with non-word-aligned pointers.
+ (Thanks to Patrick Beard for pointing out the problem. The collector
+ should fail almost any conceivable test immediately on such machines.)
+
+Since version 4.7:
+ - Changed a "comment" in a MacOS specific part of mach-dep.c that caused
+ gcc to fail on other platforms.
+
+Since version 4.8
+ - More README.debugging fixes.
+ - Objects ready for finalization, but not finalized in the same GC
+ cycle, could be prematurely collected. This occasionally happened
+ in test_cpp.
+ - Too little memory was obtained from the system for very large
+ objects. That could cause a heap explosion if these objects were
+ not contiguous (e.g. under PCR), and too much of them was blacklisted.
+ - Due to an improper initialization, the collector was too hesitant to
+ allocate blacklisted objects immediately after system startup.
+ - Moved GC_arrays from the data into the bss segment by not explicitly
+ initializing it to zero. This significantly
+ reduces the size of executables, and probably avoids some disk accesses
+ on program startup. It's conceivable that it might break a port that I
+ didn't test.
+ - Fixed EMX_MAKEFILE to reflect the gc_c++.h to gc_cpp.h renaming which
+ occurred a while ago.
+
+Since 4.9:
+ - Fixed a typo around a call to GC_collect_or_expand in alloc.c. It broke
+ handling of out of memory. (Thanks to Patrick Beard for noticing.)
+
+Since 4.10:
+ - Rationalized (hopefully) GC_try_to_collect in an incremental collection
+ environment. It appeared to not handle a call while a collection was in
+ progress, and was otherwise too conservative.
+ - Merged GC_reclaim_or_delete_all into GC_reclaim_all to get rid of some
+ code.
+ - Added Patrick Beard's Mac fixes, with substantial completely untested
+ modifications.
+ - Fixed the MPROTECT_VDB code to deal with large pages and imprecise
+ fault addresses (as on an UltraSPARC running Solaris 2.5). Note that this
+ was not a problem in the default configuration, which uses PROC_VDB.
+ - The DEC Alpha assembly code needed to restore $gp between calls.
+ Thanks to Fergus Henderson for tracking this down and supplying a
+ patch.
+ - The write command for "de" was completely broken for large files.
+ I used the easiest portable fix, which involved changing the semantics
+ so that f.new is written instead of overwriting f. That's safer anyway.
+ - Added README.solaris2 with a discussion of the possible problems of
+ mixing the collector's sbrk allocation with malloc/realloc.
+ - Changed the data segment starting address for SGI machines. The
+ old code failed under IRIX6.
+ - Required double word alignment for MIPS.
+ - Various minor fixes to remove warnings.
+ - Attempted to fix some Solaris threads problems reported by Zhiying Chen.
+ In particular, the collector could try to fork a thread with the
+ world stopped as part of GC_thr_init. It also failed to deal with
+ the case in which the original thread terminated before the whole
+ process did.
+ - Added -DNO_EXECUTE_PERMISSION. This has a major performance impact
+ on the incremental collector under Irix, and perhaps under other
+ operating systems.
+ - Added some code to support allocating the heap with mmap. This may
+ be preferable under some circumstances.
+ - Integrated dynamic library support for HP.
+ (Thanks to Knut Tvedten <knuttv@ifi.uio.no>.)
+ - Integrated James Clark's win32 threads support, and made a number
+ of changes to it, many of which were suggested by Pontus Rydin.
+ This is still not 100% solid.
+ - Integrated Alistair Crooks' support for UTS4 running on an Amdahl
+ 370-class machine.
+ - Fixed a serious bug in explicitly typed allocation. Objects requiring
+ large descriptors where handled in a way that usually resulted in
+ a segmentation fault in the marker. (Thanks to Jeremy Fitzhardinge
+ for helping to track this down.)
+ - Added partial support for GNU win32 development. (Thanks to Fergus
+ Henderson.)
+ - Added optional support for Java-style finalization semantics. (Thanks
+ to Patrick Bridges.) This is recommended only for Java implementations.
+ - GC_malloc_uncollectable faulted instead of returning 0 when out of
+ memory. (Thanks to dan@math.uiuc.edu for noticing.)
+ - Calls to GC_base before the collector was initialized failed on a
+ DEC Alpha. (Thanks to Matthew Flatt.)
+ - Added base pointer checking to GC_REGISTER_FINALIZER in debugging
+ mode, at the suggestion of Jeremy Fitzhardinge.
+ - GC_debug_realloc failed for uncollectable objects. (Thanks to
+ Jeremy Fitzhardinge.)
+ - Explicitly typed allocation could crash if it ran out of memory.
+ (Thanks to Jeremy Fitzhardinge.)
+ - Added minimal support for a DEC Alpha running Linux.
+ - Fixed a problem with allocation of objects whose size overflowed
+ ptrdiff_t. (This now fails unconditionally, as it should.)
+ - Added the beginning of Irix pthread support.
+ - Integrated Xiaokun Zhu's fixes for djgpp 2.01.
+ - Added SGI-style STL allocator support (gc_alloc.h).
+ - Fixed a serious bug in README.solaris2. Multithreaded programs must include
+ gc.h with SOLARIS_THREADS defined.
+ - Changed GC_free so it actually deallocates uncollectable objects.
+ (Thanks to Peter Chubb for pointing out the problem.)
+ - Added Linux ELF support for dynamic libararies. (Thanks again to
+ Patrick Bridges.)
+ - Changed the Borland cc configuration so that the assembler is not
+ required.
+ - Fixed a bug in the C++ test that caused it to fail in 64-bit
+ environments.
+
+Since 4.11:
+ - Fixed ElfW definition in dyn_load.c. (Thanks to Fergus Henderson.)
+ This prevented the dynamic library support from compiling on some
+ older ELF Linux systems.
+ - Fixed UTS4 port (which I apparently mangled during the integration)
+ (Thanks to again to Alistair Crooks.)
+ - "Make C++" failed on Suns with SC4.0, due to a problem with "bool".
+ Fixed in gc_priv.h.
+ - Added more pieces for GNU win32. (Thanks to Timothy N. Newsham.)
+ The current state of things should suffice for at least some
+ applications.
+ - Changed the out of memory retry count handling as suggested by
+ Kenjiro Taura. (This matters only if GC_max_retries > 0, which
+ is no longer the default.)
+ - If a /proc read failed repeatedly, GC_written_pages was not updated
+ correctly. (Thanks to Peter Chubb for diagnosing this.)
+ - Under unlikely circumstances, the allocator could infinite loop in
+ an out of memory situation. (Thanks again to Kenjiro Taura for
+ identifying the problem and supplying a fix.)
+ - Fixed a syntactic error in the DJGPP code. (Thanks to Fergus
+ Henderson for finding this by inspection.) Also fixed a test program
+ problem with DJGPP (Thanks to Peter Monks.)
+ - Atomic uncollectable objects were not treated correctly by the
+ incremental collector. This resulted in weird log statistics and
+ occasional performance problems. (Thanks to Peter Chubb for pointing
+ this out.)
+ - Fixed some problems resulting from compilers that dont define
+ __STDC__. In this case void * and char * were used inconsistently
+ in some cases. (Void * should not have been used at all. If
+ you have an ANSI superset compiler that does not define __STDC__,
+ please compile with -D__STDC__=0. Thanks to Manuel Serrano and others
+ for pointing out the problem.)
+ - Fixed a compilation problem on Irix with -n32 and -DIRIX_THREADS.
+ Also fixed some other IRIX_THREADS problems which may or may not have
+ had observable symptoms.
+ - Fixed an HP PA compilation problem in dyn_load.c. (Thanks to
+ Philippe Queinnec.)
+ - SEGV fault handlers sometimes did not get reset correctly. (Thanks
+ to David Pickens.)
+ - Added a fix for SOLARIS_THREADS on Intel. (Thanks again to David
+ Pickens.) This probably needs more work to become functional.
+ - Fixed struct sigcontext_struct in os_dep.c for compilation under
+ Linux 2.1.X. (Thanks to Fergus Henderson.)
+ - Changed the DJGPP STACKBOTTOM and DATASTART values to those suggested
+ by Kristian Kristensen. These may still not be right, but it is
+ it is likely to work more often than what was there before. They may
+ even be exactly right.
+ - Added a #include <string.h> to test_cpp.cc. This appears to help
+ with HP/UX and gcc. (Thanks to assar@sics.se.)
+ - Version 4.11 failed to run in incremental mode on recent 64-bit Irix
+ kernels. This was a problem related to page unaligned heap segments.
+ Changed the code to page align heap sections on all platforms.
+ (I had mistakenly identified this as a kernel problem earlier.
+ It was not.)
+ - Version 4.11 did not make allocated storage executable, except on
+ one or two platforms, due to a bug in a #if test. (Thanks to Dave
+ Grove for pointing this out.)
+ - Added sparc_sunos4_mach_dep.s to support Sun's compilers under SunOS4.
+ - Added GC_exclude_static_roots.
+ - Fixed the object size mapping algorithm. This shouldn't matter,
+ but the old code was ugly.
+ - Heap checking code could die if one of the allocated objects was
+ larger than its base address. (Unsigned underflow problem. Thanks
+ to Clay Spence for isolating the problem.)
+ - Added RS6000 (AIX) dynamic library support and fixed STACK_BOTTOM.
+ (Thanks to Fred Stearns.)
+ - Added Fergus Henderson's patches for improved robustness with large
+ heaps and lots of blacklisting.
+ - Added Peter Chubb's changes to support Solaris Pthreads, to support
+ MMAP allocation in Solaris, to allow Solaris to find dynamic libraries
+ through /proc, to add malloc_typed_ignore_off_page, and a few other
+ minor features and bug fixes.
+ - The Solaris 2 port should not use sbrk. I received confirmation from
+ Sun that the use of sbrk and malloc in the same program is not
+ supported. The collector now defines USE_MMAP by default on Solaris.
+ - Replaced the djgpp makefile with Gary Leavens' version.
+ - Fixed MSWIN32 detection test.
+ - Added Fergus Henderson's patches to allow putting the collector into
+ a DLL under GNU win32.
+ - Added Ivan V. Demakov's port to Watcom C on X86.
+ - Added Ian Piumarta's Linux/PowerPC port.
+ - On Brian Burton's suggestion added PointerFreeGC to the placement
+ options in gc_cpp.h. This is of course unsafe, and may be controversial.
+ On the other hand, it seems to be needed often enough that it's worth
+ adding as a standard facility.
+
+Since 4.12:
+ - Fixed a crucial bug in the Watcom port. There was a redundant decl
+ of GC_push_one in gc_priv.h.
+ - Added FINALIZE_ON_DEMAND.
+ - Fixed some pre-ANSI cc problems in test.c.
+ - Removed getpagesize() use for Solaris. It seems to be missing in one
+ or two versions.
+ - Fixed bool handling for SPARCCompiler version 4.2.
+ - Fixed some files in include that had gotten unlinked from the main
+ copy.
+ - Some RS/6000 fixes (missing casts). Thanks to Toralf Foerster.
+ - Fixed several problems in GC_debug_realloc, affecting mostly the
+ FIND_LEAK case.
+ - GC_exclude_static_roots contained a buggy unsigned comparison to
+ terminate a loop. (Thanks to Wilson Ho.)
+ - CORD_str failed if the substring occurred at the last possible position.
+ (Only affects cord users.)
+ - Fixed Linux code to deal with RedHat 5.0 and integrated Peter Bigot's
+ os_dep.c code for dealing with various Linux versions.
+ - Added workaround for Irix pthreads sigaction bug and possible signal
+ misdirection problems.
+Since alpha1:
+ - Changed RS6000 STACKBOTTOM.
+ - Integrated Patrick Beard's Mac changes.
+ - Alpha1 didn't compile on Irix m.n, m < 6.
+ - Replaced Makefile.dj with a new one from Gary Leavens.
+ - Added Andrew Stitcher's changes to support SCO OpenServer.
+ - Added PRINT_BLACK_LIST, to allow debugging of high densities of false
+ pointers.
+ - Added code to debug allocator to keep track of return address
+ in GC_malloc caller, thus giving a bit more context.
+ - Changed default behavior of large block allocator to more
+ aggressively avoid fragmentation. This is likely to slow down the
+ collector when it succeeds at reducing space cost.
+ - Integrated Fergus Henderson's CYGWIN32 changes. They are untested,
+ but needed for newer versions.
+ - USE_MMAP had some serious bugs. This caused the collector to fail
+ consistently on Solaris with -DSMALL_CONFIG.
+ - Added Linux threads support, thanks largely to Fergus Henderson.
+Since alpha2:
+ - Fixed more Linux threads problems.
+ - Changed default GC_free_space_divisor to 3 with new large block allocation.
+ (Thanks to Matthew Flatt for some measurements that suggest the old
+ value sometimes favors space too much over time.)
+ - More CYGWIN32 fixes.
+ - Integrated Tyson-Dowd's Linux-M68K port.
+ - Minor HP PA and DEC UNIX fixes from Fergus Henderson.
+ - Integrated Christoffe Raffali's Linux-SPARC changes.
+ - Allowed for one more GC fixup iteration after a full GC in incremental
+ mode. Some quick measurements suggested that this significantly
+ reduces pause times even with smaller GC_RATE values.
+ - Moved some more GC data structures into GC_arrays. This decreases
+ pause times and GC overhead, but makes debugging slightly less convenient.
+ - Fixed namespace pollution problem ("excl_table").
+ - Made GC_incremental a constant for -DSMALL_CONFIG, hopefully shrinking
+ that slightly.
+ - Added some win32 threads fixes.
+ - Integrated Ivan Demakov and David Stes' Watcom fixes.
+ - Various other minor fixes contributed by many people.
+ - Renamed config.h to gcconfig.h, since config.h tends to be used for
+ many other things.
+ - Integrated Matthew Flatt's support for 68K MacOS "far globals".
+ - Fixed up some of the dynamic library Makefile targets for consistency
+ across platforms.
+ - Fixed a USE_MMAP typo that caused out-of-memory handling to fail
+ on Solaris.
+ - Added code to test.c to test thread creation a bit more.
+ - Integrated GC_win32_free_heap, as suggested by Ivan Demakov.
+ - Fixed Solaris 2.7 stack base finding problem. (This may actually
+ have been done in an earlier alpha release.)
+Since alpha3:
+ - Fixed MSWIN32 recognition test, which interfered with cygwin.
+ - Removed unnecessary gc_watcom.asm from distribution. Removed
+ some obsolete README.win32 text.
+ - Added Alpha Linux incremental GC support. (Thanks to Philipp Tomsich
+ for code for retrieving the fault address in a signal handler.)
+ Changed Linux signal handler context argument to be a pointer.
+ - Took care of some new warnings generated by the 7.3 SGI compiler.
+ - Integrated Phillip Musumeci's FreeBSD/ELF fixes.
+ - -DIRIX_THREADS was broken with the -o32 ABI (typo in gc_priv.h>
+
+Since 4.13:
+ - Fixed GC_print_source_ptr to not use a prototype.
+ - generalized CYGWIN test.
+ - gc::new did the wrong thing with PointerFreeGC placement.
+ (Thanks to Rauli Ruohonen.)
+ - In the ALL_INTERIOR_POINTERS (default) case, some callee-save register
+ values could fail to be scanned if the register was saved and
+ reused in a GC frame. This showed up in verbose mode with gctest
+ compiled with an unreleased SGI compiler. I vaguely recall an old
+ bug report that may have been related. The bug was probably quite old.
+ (The problem was that the stack scanning could be deferred until
+ after the relevant frame was overwritten, and the new save location
+ might be outside the scanned area. Fixed by more eager stack scanning.)
+ - PRINT_BLACK_LIST had some problems. A few source addresses were garbage.
+ - Replaced Makefile.dj and added -I flags to cord make targets.
+ (Thanks to Gary Leavens.)
+ - GC_try_to_collect was broken with the nonincremental collector.
+ - gc_cleanup destructors could pass the wrong address to
+ GC_register_finalizer_ignore_self in the presence of multiple
+ inheritance. (Thanks to Darrell Schiebel.)
+ - Changed PowerPC Linux stack finding code.
+
+Since 4.14alpha1
+ - -DSMALL_CONFIG did not work reliably with large (> 4K) pages.
+ Recycling the mark stack during expansion could result in a size
+ zero heap segment, which confused things. (This was probably also an
+ issue with the normal config and huge pages.)
+ - Did more work to make sure that callee-save registers were scanned
+ completely, even with the setjmp-based code. Added USE_GENERIC_PUSH_REGS
+ macro to facilitate testing on machines I have access to.
+ - Added code to explicitly push register contents for win32 threads.
+ This seems to be necessary. (Thanks to Pierre de Rop.)
+
+Since 4.14alpha2
+ - changed STACKBOTTOM for DJGPP (Thanks to Salvador Eduardo Tropea).
+
+Since 4.14
+ - Reworked large block allocator. Now uses multiple doubly linked free
+ lists to approximate best fit.
+ - Changed heap expansion heuristic. Entirely free blocks are no longer
+ counted towards the heap size. This seems to have a major impact on
+ heap size stability; the old version could expand the heap way too
+ much in the presence of large block fragmentation.
+ - added -DGC_ASSERTIONS and some simple assertions inside the collector.
+ This is mainlyt for collector debugging.
+ - added -DUSE_MUNMAP to allow the heap to shrink. Suupported on only
+ a few UNIX-like platforms for now.
+ - added GC_dump_regions() for debugging of fragmentation issues.
+ - Changed PowerPC pointer alignment under Linux to 4. (This needs
+ checking by someone who has one. The suggestions came to me via a
+ rather circuitous path.)
+ - Changed the Linux/Alpha port to walk the data segment backwards until
+ it encounters a SIGSEGV. The old way to find the start of the data
+ segment broke with a recent release.
+ - cordxtra.c needed to call GC_REGISTER_FINALIZER instead of
+ GC_register_finalizer, so that it would continue to work with GC_DEBUG.
+ - allochblk sometimes cleared the wrong block for debugging purposes
+ when it dropped blacklisted blocks. This could result in spurious
+ error reports with GC_DEBUG.
+ - added MACOS X Server support. (Thanks to Andrew Stone.)
+ - Changed the Solaris threads code to ignore stack limits > 8 MB with
+ a warning. Empirically, it is not safe to access arbitrary pages
+ in such large stacks. And the dirty bit implementation does not
+ guarantee that none of them will be accessed.
+ - Integrated Martin Tauchmann's Amiga changes.
+ - Integrated James Dominy's OpenBSD/SPARC port.
+
+Since 5.0alpha1
+ - Fixed bugs introduced in alpha1 (OpenBSD & large block initialization).
+ - Added -DKEEP_BACK_PTRS and backptr.h interface. (The implementation
+ idea came from Al Demers.)
+
+Since 5.0alpha2
+ - Added some highly incomplete code to support a copied young generation.
+ Comments on nursery.h are appreciated.
+ - Changed -DFIND_LEAK, -DJAVA_FINALIZATION, and -DFINALIZE_ON_DEMAND,
+ so the same effect could be obtained with a runtime switch. This is
+ a step towards standardizing on a single dynamic GC library.
+ - Significantly changed the way leak detection is handled, as a consequence
+ of the above.
+
+Since 5.0 alpha3
+ - Added protection fault handling patch for Linux/M68K from Fergus
+ Henderson and Roman Hodek.
+ - Removed the tests for SGI_SOURCE in new_gc_alloc.h. This was causing that
+ interface to fail on nonSGI platforms.
+ - Changed the Linux stack finding code to use /proc, after changing it
+ to use HEURISTIC1. (Thanks to David Mossberger for pointing out the
+ /proc hook.)
+ - Added HP/UX incremental GC support and HP/UX 11 thread support.
+ Thread support is currently still flakey.
+ - Added basic Linux/IA64 support.
+ - Integrated Anthony Green's PicoJava support.
+ - Integrated Scott Ananian's StrongARM/NetBSD support.
+ - Fixed some fairly serious performance bugs in the incremental
+ collector. These have probably been there essentially forever.
+ (Mark bits were sometimes set before scanning dirty pages.
+ The reclaim phase unnecessarily dirtied full small object pages.)
+ - Changed the reclaim phase to ignore nearly full pages to avoid
+ touching them.
+ - Limited GC_black_list_spacing to roughly the heap growth increment.
+ - Changed full collection triggering heuristic to decrease full GC
+ frequency by default, but to explicitly trigger full GCs during
+ heap growth. This doesn't always improve things, but on average it's
+ probably a win.
+ - GC_debug_free(0, ...) failed. Thanks to Fergus Henderson for the
+ bug report and fix.
+
+Since 5.0 alpha4
+ - GC_malloc_explicitly_typed and friends sometimes failed to
+ initialize first word.
+ - Added allocation routines and support in the marker for mark descriptors
+ in a type structure referenced by the first word of an object. This was
+ introduced to support gcj, but hopefully in a way that makes it
+ generically useful.
+ - Added GC_requested_heapsize, and inhibited collections in nonincremental
+ mode if the actual used heap size is less than what was explicitly
+ requested.
+ - The Solaris pthreads version of GC_pthread_create didn't handle a NULL
+ attribute pointer. Solaris thread support used the wrong default thread
+ stack size. (Thanks to Melissa O'Neill for the patch.)
+ - Changed PUSH_CONTENTS macro to no longer modify first parameter.
+ This usually doesn't matter, but it was certainly an accident waiting
+ to happen ...
+ - Added GC_register_finalizer_no_order and friends to gc.h. They're
+ needed by Java implementations.
+ - Integrated a fix for a win32 deadlock resulting from clock() calling
+ malloc. (Thanks to Chris Dodd.)
+ - Integrated Hiroshi Kawashima's port to Linux/MIPS. This was designed
+ for a handheld platform, and may or may not be sufficient for other
+ machines.
+ - Fixed a va_arg problem with the %c specifier in cordprnt.c. It appears
+ that this was always broken, but recent versions of gcc are the first to
+ report the (statically detectable) bug.
+ - Added an attempt at a more general solution to dlopen races/deadlocks.
+ GC_dlopen now temporarily disables collection. Still not ideal, but ...
+ - Added -DUSE_I686_PREFETCH, -DUSE_3DNOW_PREFETCH, and support for IA64
+ prefetch instructions. May improve performance measurably, but I'm not
+ sure the code will run correctly on processors that don't support the
+ instruction. Won't build except with very recent gcc.
+ - Added caching for header lookups in the marker. This seems to result
+ in a barely measurable performance gain. Added support for interleaved
+ lookups of two pointers, but unconfigured that since the performance
+ gain is currently near zero, and it adds to code size.
+ - Changed Linux DATA_START definition to check both data_start and
+ __data_start, since nothing else seems to be portable.
+ - Added -DUSE_LD_WRAP to optionally take advantage of the GNU ld function
+ wrapping mechanism. Probably currently useful only on Linux.
+ - Moved some variables for the scratch allocator into GC_arrays, on
+ Martin Hirzel's suggestion.
+ - Fixed a win32 threads bug that caused the collector to not look for
+ interior pointers from one of the thread stacks without
+ ALL_INTERIOR_POINTERS. (Thanks to Jeff Sturm.)
+ - Added Mingw32 support. (Thanks again to Jeff Sturm for the patch.)
+ - Changed the alpha port to use the generic register scanning code instead
+ of alpha_mach_dep.s. Alpha_mach_dep.s doesn't look for pointers in fp
+ registers, but gcc sometimes spills pointers there. (Thanks to Manuel
+ Serrano for helping me debug this by email.) Changed the IA64 code to
+ do something similar for similar reasons.
+
+[5.0alpha5 doesn't really exist, but it may have escaped.]
+
+Since 5.0alpha6:
+ - -DREDIRECT_MALLOC was broken in alpha6. Fixed.
+ - Cleaned up gc_ccp.h slightly, thus also causing the HP C++ compiler to
+ accept it.
+ - Removed accidental reference to dbg_mlc.c, which caused dbg_mlc.o to be
+ linked into every executable.
+ - Added PREFETCH to bitmap marker. Changed it to use the header cache.
+ - GC_push_marked sometimes pushed one object too many, resulting in a
+ segmentation fault in GC_mark_from_mark_stack. This was probably an old
+ bug. It finally showed up in gctest on win32.
+ - Gc_priv.h erroneously #defined GC_incremental to be TRUE instead of FALSE
+ when SMALL_CONFIG was defined. This was no doubt a major performance bug for
+ the default win32 configuration.
+ - Removed -DSMALL_CONFIG from NT_MAKEFILE. It seemed like an anchronism now
+ that the average PC has 64MB or so.
+ - Integrated Bryce McKinley's patches for linux threads and dynamic loading
+ from the libgcj tree. Turned on dynamic loading support for Linux/PPC.
+ - Changed the stack finding code to use environ on HP/UX. (Thanks
+ to Gustavo Rodriguez-Rivera for the suggestion.) This should probably
+ be done on other platforms, too. Since I can't test those, that'll
+ wait until after 5.0.
+
+Since 5.0alpha7:
+ - Fixed threadlibs.c for linux threads. -DUSE_LD_WRAP was broken and
+ -ldl was omitted. Fixed Linux stack finding code to handle
+ -DUSE_LD_WRAP correctly.
+ - Added MSWIN32 exception handler around marker, so that the collector
+ can recover from root segments that are unmapped during the collection.
+ This caused occasional failures under Windows 98, and may also be
+ an issue under Windows NT/2000.
+
+Since 5.0
+ - Fixed a gc.h header bug which showed up under Irix. (Thanks to
+ Dan Sullivan.)
+ - Fixed a typo in GC_double_descr in typd_mlc.c.
+ This probably could result in objects described by array descriptors not
+ getting traced correctly. (Thanks to Ben Hutchings for pointing this out.)
+ - The block nearly full tests in reclaim.c were not correct for 64 bit
+ environments. This could result in unnecessary heap growth under unlikely
+ conditions.
+
+Since 5.1
+ - dyn_load.c declared GC_scratch_last_end_ptr as an extern even if it
+ was defined as a macro. This prevented the collector from building on
+ Irix.
+ - We quietly assumed that indirect mark descriptors were never 0.
+ Our own typed allocation interface violated that. This could result
+ in segmentation faults in the marker with typed allocation.
+ - Fixed a _DUSE_MUNMAP bug in the heap block allocation code.
+ (Thanks to Ben Hutchings for the patch.)
+ - Taught the collector about VC++ handling array operator new.
+ (Thanks again to Ben Hutchings for the patch.)
+ - The two copies of gc_hdrs.h had diverged. Made one a link to the other
+ again.
+
+Since 5.2 (A few 5.2 patches are not in 6.0alpha1)
+ - Fixed _end declaration for OSF1.
+ - There were lots of spurious leak reports in leak detection mode, caused
+ by the fact that some pages were not being swept, and hence unmarked
+ objects weren't making it onto free lists. (This bug dated back to 5.0.)
+ - Fixed a typo in the liblinuxgc.so Makefile rule.
+ - Added the GetExitCodeThread to Win32 GC_stop_world to (mostly) work
+ around a Windows 95 GetOpenFileName problem. (Thanks to Jacob Navia.)
+
+Since 5.3
+ - Fixed a typo that prevented compilation with -DUSE_3DNOW_PREFETCH.
+ (Thanks to Shawn Wagner for actually testing this.)
+ - Fixed GC_is_thread_stack in solaris_threads.c. It forgot to return a value
+ in the common case. I wonder why nobody noticed?
+ - Fixed another silly syntax problem in GC_double_descr. (Thanks to
+ Fergus Henderson for finding it.)
+ - Fixed a GC_gcj_malloc bug: It tended to release the allocator lock twice.
+
+Since 5.4 (A few 5.3 patches are not in 6.0alpha2)
+ - Added HP/PA prefetch support.
+ - Added -DDBG_HDRS_ALL and -DSHORT_DBG_HDRS to reduce the cost and improve
+ the reliability of generating pointer backtrace information, e.g. in
+ the Bigloo environment.
+ - Added parallel marking support (-DPARALLEL_MARK). This currently
+ works only under IA32 and IA64 Linux, but it shouldn't be hard to adapt
+ to other platforms. This is intended to be a lighter-weight (less
+ new code, probably not as scalable) solution than the work by Toshio Endo
+ et al, at the University of Tokyo. A number of their ideas were
+ reused, though the code wasn't, and the underlying data structure
+ is significantly different. In particular, we keep the global mark
+ stack as a single shared data structure, but most of the work is done
+ on smaller thread-local mark stacks.
+ - Changed GC_malloc_many to be cheaper, and to require less mutual exclusion
+ with -DPARALLEL_MARK.
+ - Added full support for thread local allocation under Linux
+ (-DTHREAD_LOCAL_ALLOC). This is a thin veneer on GC_malloc_many, and
+ should be easily portable to other platforms, especially those that
+ support pthreads.
+ - CLEAR_DOUBLE was not always getting invoked when it should have been.
+ - GC_gcj_malloc and friends used different out of memory handling than
+ everything else, probably because I forgot about one when I implemented
+ the other. They now both call GC_oom_fn(), not GC_oom_action().
+ - Integrated Jakub Jelinek's fixes for Linux/SPARC.
+ - Moved GC_objfreelist, GC_aobjfreelist, and GC_words_allocd out of
+ GC_arrays, and separately registered the first two as excluded roots.
+ This makes code compiled with gc_inl.h less dependent on the
+ collector version. (It would be nice to remove the inclusion of
+ gc_priv.h by gc_inl.h completely, but we're not there yet. The
+ locking definitions in gc_priv.h are still referenced.)
+ This change was later coniditoned on SEPARATE_GLOBALS, which
+ is not defined by default, since it involves a performance hit.
+ - Register GC_obj_kinds separately as an excluded root region. The
+ attempt to register it with GC_arrays was usually failing. (This wasn't
+ serious, but seemed to generate some confusion.)
+ - Moved backptr.h to gc_backptr.h.
+
+Since 6.0alpha1
+ - Added USE_MARK_BYTES to reduce the need for compare-and-swap on platforms
+ for which that's expensive.
+ - Fixed a locking bug ib GC_gcj_malloc and some locking assertion problems.
+ - Added a missing volatile to OR_WORD and renamed the parameter to
+ GC_compare_and_swap so it's not a C++ reserved word. (Thanks to
+ Toshio Endo for pointing out both of those.)
+ - Changed Linux dynamic library registration code to look at /proc/self/maps
+ instead of the rld data structures when REDIRECT_MALLOC is defined.
+ Otherwise some of the rld data data structures may be prematurely garbage
+ collected. (Thanks to Eric Benson for helping to track this down.)
+ - Fixed USE_LD_WRAP a bit more, so it should now work without threads.
+ - Renamed XXX_THREADS macros to GC_XXX_THREADS for namespace correctness.
+ Tomporarily added some backward compatibility definitions. Renamed
+ USE_LD_WRAP to GC_USE_LD_WRAP.
+ - Many MACOSX POWERPC changes, some additions to the gctest output, and
+ a few minor generic bug fixes. (Thanks to Dietmar Planitzer.)
+
+Since 6.0 alpha2
+ - Fixed the /proc/self/maps code to not seek, since that apparently is not
+ reliable across all interesting kernels.
+ - Fixed some compilation problems in the absence of PARALLEL_MARK
+ (introduced in alpha2).
+ - Fixed an algorithmic problem with PARALLEL_MARK. If work needs to
+ be given back to the main mark "stack", the BOTTOM entries of the local
+ stack should be given away, not the top ones. This has substantial
+ performance impact, especially for > 2 processors, from what I can tell.
+ - Extracted gc_lock.h from gc_priv.h. This should eventually make it a
+ bit easier to avoid including gc_priv.h in clients.
+ - Moved all include files to include/ and removed duplicate links to the
+ same file. The old scheme was a bad idea because it was too easy to get the
+ copies out of sync, and many systems don't support hard links.
+ Unfortunately, it's likely that I broke some of the non-Unix Makefiles in
+ the process, although I tried to update them appropriately.
+ - Removed the partial support for a copied nursery. It's not clear that
+ this would be a tremendous win, since we don't consistently lose to
+ generational copying collectors. And it would significantly complicate
+ many things. May be reintroduced if/when it really turns out to win.
+ - Removed references to IRIX_JDK_THREADS, since I believe there never
+ were and never will be any clients.
+ - Added some code to linux_threads.c to possibly support HPUX threads
+ using the Linux code. Unfortunately, it doesn't work yet, and is
+ currently disabled.
+ - Added support under Linux/X86 for saving the call chain, both in (debug)
+ objects for client debugging, and in GC_arrays._last_stack for GC
+ debugging. This was previously supported only under Solaris. It is
+ not enabled by default under X86, since it requires that code be compiled
+ to explicitly dave frame pointers on the call stack. (With gcc this
+ currently happens by default, but is often turned off explicitly.)
+ To turn it on, define SAVE_CALL_CHAIN.
+
+Since 6.0 alpha3
+ - Moved up the detection of mostly full blocks to the initiatiation of the
+ sweep phase. This eliminates some lock conention in the PARALLEL_MARK case,
+ as multiple threads try to look at mostly full blocks concurrently.
+ - Restored the code in GC_malloc_many that grabs a prefix of the global
+ free list. This avoids the case in which every GC_malloc_many call
+ tries and fails to allocate a new heap block, and the returns a single
+ object from the global free list.
+ - Some minor fixes in new_hblk.c. (Attempted to build free lists in order
+ of increasing addresses instead of decreasing addresses for cache performance
+ reasons. But this seems to be only a very minor gain with -DEAGER_SWEEP,
+ and a loss in other cases. So the change was backed out.)
+ - Fixed some of the documentation. (Thanks in large part to Fergus
+ Henderson.)
+ - Fixed the Linux USE_PROC_FOR_LIBRARIES code to deal with apps that perform
+ large numbers of mmaps. (Thanks to Eric Benson.) Also fixed that code to
+ deal with short reads.
+ - Added GC_get_total_bytes().
+ - Fixed leak detection mode to avoid spurious messages under linuxthreads.
+ (This should also now be easy for the other supported threads packages.
+ But the code is tricky enough that I'm hesitant to do it without being able
+ to test. Everything allocated in the GC thread support itself should be
+ explicitly deallocated.)
+ - Made it possible (with luck) to redirect malloc to GC_local_malloc.
+
+Since 6.0 alpha4
+ - Changed the definition of GC_pause in linux_threads.c to use a volatile
+ asm. Some versions of gcc apparently optimize away writes to local volatile
+ variables. This caused poor locking behaviour starting at about
+ 4 processors.
+ - Added GC_start_blocking(), GC_end_blocking() calls and wrapper for sleep
+ to linux_threads.c.
+ The first two calls could be used to generally avoid sending GC signals to
+ blocked threads, avoiding both premature wakeups and unnecessary overhead.
+ - Fixed a serious bug in thread-local allocation. At thread termination,
+ GC_free could get called on small integers. Changed the code for thread
+ termination to more efficiently return left-over free-lists.
+ - Integrated Kjetil Matheussen's BeOS support.
+ - Rearranged the directory structure to create the doc and tests
+ subdirectories.
+ - Sort of integrated Eric Benson's patch for OSF1. This provided basic
+ OSF1 thread support by suitably extending hpux_irix_threads.c. Based
+ on earlier email conversations with David Butenhof, I suspect that it
+ will be more reliable in the long run to base this on linux_threads.c
+ instead. Thus I attempted to patch up linux_threads.c based on Eric's code.
+ The result is almost certainly broken, but hopefully close enough that
+ someone with access to a machine can pick it up.
+ - Integrated lots of minor changes from the NetBSD distribution. (These
+ were supplied by David Brownlee. I'm not sure about the original
+ authors.)
+ - Hacked a bit more on the HP/UX thread-support in linux_threads.c. It
+ now appears to work in the absence of incremental collection. Renamed
+ hpux_irix_threads.c back to irix_threads.c, and removed the attempt to
+ support HPUX there.
+ - Changed gc.h to define _REENTRANT in cases in which it should already
+ have been defined. It is still safer to also define it on the command
+ line.
+
+Since 6.0alpha5:
+ - Changed the definition of DATASTART on ALPHA and IA64, where data_start
+ and __data_start are not defined by earlier versions of glibc. This might
+ need to be fixed on other platforms as well.
+ - Changed the way the stack base and backing store base are found on IA64.
+ This should now remain reliable on future kernels. But since it relies
+ on /proc, it will no longer work in the simulated NUE environment.
+ - Made the call to random() in dbg_mlc.c with -DKEEP_BACK_PTRS dependent
+ on the OS. On non-Unix systems, rand() should be used instead. Handled
+ small RAND_MAX. (Thanks to Peter Ross for pointing this out.)
+ - Fixed the cord make rules to create the cord subdirectory, if necessary.
+ (Thanks to Doug Moen.)
+ - Changed fo_object_size calculation in finalize.c. Turned finalization
+ of nonheap object into a no-op. Removed anachronism from GC_size()
+ implementation.
+ - Changed GC_push_dirty call in solaris_threads.c to GC_push_selected.
+ It was missed in a previous renaming. (Thanks to Vladimir Tsichevski
+ for pointing this out.)
+ - Arranged to not not mask SIGABRT in linux_threads.c. (Thanks to Bryce
+ McKinlay.)
+ - Added GC_no_dls hook for applications that want to register their own
+ roots.
+ - Integrated Kjetil Matheussen's Amiga changes.
+ - Added FREEBSD_STACKBOTTOM. Changed the X86/FreeBSD port to use it.
+ (Thanks to Matthew Flatt.)
+ - Added pthread_detach interception for platforms supported by linux_threads.c
+ and irix_threads.c. Should also be added for Solaris?
+ - Changed the USE_MMAP code to check for the case in which we got the
+ high end of the address space, i.e. mem_ptr + mem_sz == 0. It appears
+ that this can happen under Solaris 7. It seems to be allowed by what
+ I would claim is an oversight in the mmap specification. (Thanks to Toshio
+ Endo for pointing out the problem.)
+ - Cleanup of linux_threads.c. Some code was originally cloned from
+ irix_threads.c and now unnecessary. Some comments were obviously wrong.
+ - (Mostly) fixed a longstanding problem with setting of dirty bits from
+ a signal handler. In the presence of threads, dirty bits could get lost,
+ since the etting of a bit in the bit vector was not atomic with respect
+ to other updates. The fix is 100% correct only for platforms for which
+ GC_test_and_set is defined. The goal is to make that all platforms with
+ thread support. Matters only if incremental GC and threads are both
+ enabled.
+ - made GC_all_interior_pointers (a.k.a. ALL_INTERIOR_POINTERS) an
+ initialization time, instead of build-time option. This is a
+ nontrivial, high risk change. It should slow down the code measurably
+ only if MERGE_SIZES is not defined, which is a very nonstandard
+ configuration.
+ - Added doc/README.environment, and implemented what it describes. This
+ allows a number of additional configuration options to be set through
+ the environment. It documents a few previously undocumented options.
+ - Integrated Eric Benson's leak testing improvements.
+ - Removed the option to throw away the beginning of each page (DISCARD_WORDS).
+ This became less and less useful as processors enforce stricter alignment.
+ And it hadn't been tested in ages, and was thus probably broken anyway.
+
+Since 6.0alpha6:
+ - Added GC_finalizer_notifier. Fixed GC_finalize_on_demand. (The variable
+ actually wasn't being tested at the right points. The build-time flag
+ was.)
+ - Added Tom Tromey's S390 Linux patch.
+ - Added code to push GC_finalize_now in GC_push_finalizer_structures.
+ (Thanks to Matthew Flatt.)
+ - Added GC_push_gc_structures() to push all GC internal roots.
+ - Integrated some FreeBSD changes from Matthew Flatt.
+ - It looks like USRSTACK is not always correctly defined under Solaris.
+ Hacked gcconfig.h to attempt to work around the problem. The result
+ is not well tested. (Thanks again to Matthew Flatt for pointing this
+ out. The gross hack is mine. - HB)
+ - Added Ji-Yong Chung's win32 threads and C++ fixes.
+ - Arranged for hpux_test_and_clear.s to no longer be needed or built.
+ It was causing build problems with gas, and it's not clear this is
+ better than the pthreads alternative on this platform.
+ - Some MINGW32 fixes from Hubert Garavel.
+ - Added Initial Hitachi SH4 port from Kaz Kojima.
+ - Ported thread-local allocation and parallel mark code to HP/UX on PA_RISC.
+ - Made include/gc_mark.h more public and separated out the really private
+ pieces. This is probably still not quite sufficient for clients that
+ want to supply their own kind of type information. But it's a start.
+ This involved lots of identifier renaming to make it namespace clean.
+ - Added GC_dont_precollect for clients that need complete control over
+ the root set.
+ - GC_is_visible didn't do the right thing with gcj objects. (Not that
+ many people are likely to care, but ...)
+ - Don't redefine read with GC_USE_LD_WRAP.
+ - Initial port to LINUX/HP_PA. Incremental collection and threads are not
+ yet supported. (Incremental collection should work if you have the
+ right kernel. Threads may work with a sufficiently patched pthread
+ library.)
+ - Changed gcconfig.h to recognize __i386__ as an alternative to i386 in
+ many places. (Thanks to Benjamin Lerman.)
+ - Made win32_threads.c more tolerant of detaching a thread that it didn't
+ know about. (Thanks to Paul Nash.)
+ - Added Makefile.am and configure.in from gcc to the distribution, with
+ minimal changes. For the moment, those are just placeholders. In the
+ future, we're planning to switch to a GNU-style build environment for
+ Un*x-like systems, though the old Makefile will remain as a backup.
+ - Turned off STUBBORN_ALLOC by default, and added it back as a Makefile
+ option.
+ - Redistributed some functions between malloc.c and mallocx.c, so that
+ simple statically linked apps no longer pull in mallocx.o.
+ - Changed large object allocation to clear the first and last few words
+ of each block before releassing the lock. Otherwise the marker could see
+ objects with nonsensical type descriptors.
+ - Fixed a couple of subtle problems that could result in not recognizing
+ interior pointers from the stack. (I believe these were introduced
+ in 6.0alpha6.)
+ - GC_debug_free_inner called GC_free, which tried to reacquire the
+ allocator lock, and hence deadlocked. (DBG_HDRS_ALL probably never worked
+ with threads?)
+ - Fixed several problems with back traces. Accidental references to a free
+ list could cause the free list pointer to be overwritten by a back pointer.
+ There seemed to be some problems with the encoding of root and finalizer
+ references.
+
+Since 6.0alpha7:
+ - Changed GC_debug_malloc_replacement and GC_debug_realloc_replacement
+ so that they compile under Irix. (Thanks to Dave Love.)
+ - Updated powerpc_macosx_mach_dep.s so that it works if the collector
+ is in a dynamic library. (Thanks to Andrew Begel.)
+ - Transformed README.debugging into debugging.html, updating and
+ expanding it in the process. Added gcdescr.html and tree.html
+ from the web site to the GC distribution.
+ - Fixed several problems related to PRINT_BLACK_LIST. This involved
+ restructuring some of the marker macros.
+ - Fixed some problems with the sizing of objects with debug information.
+ Finalization was broken KEEP_BACK_PTRS or PRINT_BLACK_LIST. Reduced the
+ object size with SHORT_DEBUG_HDRS by another word.
+ - The "Needed to allocate blacklisted ..." warning had inadvertently
+ been turned off by default, due to a buggy test in allchblk.c. Turned
+ it back on.
+ - Removed the marker macros to deal with 2 pointers in interleaved fashion.
+ They were messy and the performance improvement seemed minimal. We'll
+ leave such scheduling issues to the compiler.
+ - Changed Linux/PowerPC test to also check for __powerpc__ in response
+ to a discussion on the gcc mailing list.
+ - On Matthew Flatt's suggestion removed the "static" from the jmp_buf
+ declaration in GC_generic_push_regs. This was causing problems in
+ systems that register all of their own roots. It looks far more correct
+ to me without the "static" anyway.
+ - Fixed several problems with thread local allocation of pointerfree or
+ typed objects. The collector was reclaiming thread-local free lists, since
+ it wasn't following the link fields.
+ - There was apparently a long-standing race condition related to multithreaded
+ incremental collection. A collection could be started and a thread stopped
+ between the memory unprotect system call and the setting of the
+ corresponding dirt bit. I believe this did not affect Solaris or PCR, which
+ use a different dirty-bit implementation. Fixed this by installing
+ signal handlers with sigaction instead of signal, and disabling the thread
+ suspend signal while in the write-protect handler. (It is unclear
+ whether this scenario ever actually occurred. I found it while tracking
+ down the following:)
+ - Incremental collection did not cooperate correctly with the PARALLEL_MARK
+ implementation of GC_malloc_many or the local_malloc primitves. It still
+ doesn't work well, but it shouldn't lose memory anymore.
+ - Integrated some changes from the gcc source tree that I had previously
+ missed. (Thanks to Bryce McKinley for the reminder/diff.)
+ - Added Makefile.direct as a copy of the default Makefile, which would
+ normally be overwritten if configure is run.
+ - Changed the gc.tar target in Makefile.direct to embed the version number
+ in the gc directory name. This will affect future tar file distributions.
+ - Changed the Irix dynamic library finding code to no longer try to
+ eliminate writable text segments under Irix6.x, since that is probably no
+ longer necessary, and can apparently be unsafe on occasion. (Thanks to
+ Shiro Kawai for pointing this out.)
+ - GC_cleanup with GC_DEBUG enabled passed a real object base address to
+ GC_debug_register_finalizer_ignore_self, which expected a pointer past the
+ debug header. Call GC_register_finalizer_ignore_self instead, even with
+ debugging enabled. (Thanks to Jean-Daniel Fekete for catching this.)
+ - The collector didn't build with call chain saving enabled but NARGS=0.
+ (Thanks to Maarten Thibaut.)
+ - Fixed up the GNU-style build files enough so that they work in some
+ obvious cases.
+ - Added initial port to Digital Mars compiler for win32. (Thanks to Walter
+ Bright.)
+
+Since 6.0alpha8:
+ - added README.macros.
+ - Made gc.mak a symbolic link to work around winzip's tendency to ignore
+ hard links.
+ - Simplified the setting of NEED_FIND_LIMIT in os_dep.c, possibly breaking
+ it on untested platforms.
+ - Integrated initial GNU HURD port. (Thanks to Chris Lingard and Igor
+ Khavkine.)
+ - A few more fixes for Digital Mars compiler (Walter Bright).
+ - Fixed gcc version recognition. Renamed OPERATOR_NEW_ARRAY to
+ GC_OPERATOR_NEW_ARRAY. Changed GC_OPERATOR_NEW_ARRAY to be the default.
+ It can be overridden with -DGC_NO_OPERATOR_NEW_ARRAY. (Thanks to
+ Cesar Eduardo Barros.)
+ - Changed the byte size to free-list mapping in thread local allocation
+ so that size 0 allocations are handled correctly.
+ - Fixed Linux/MIPS stackbottom for new toolchain. (Thanks to Ryan Murray.)
+ - Changed finalization registration to invoke GC_oom_fn when it runs out
+ of memory.
+ - Removed lvalue cast in finalize.c. This caused some debug configurations
+ not to build with some non-gcc compilers.
+
+Since 6.0alpha9:
+ - Two more bug fixes for KEEP_BACK_PTRS and DBG_HDRS_ALL.
+ - Fixed a stack clearing problem that resulted in SIGILL with a
+ misaligned stack pointer for multithreaded SPARC builds.
+ - Integrated another HURD patch (thanks to Igor Khavkine).
+
+Since 6.0:
+ - Non-debug, atomic allocations could result in bogus smashed object
+ reports with debugging on. (Thanks to Patrick Doyle for the small
+ test case.)
+ - Fixed GC_get_register_stack_base (Itanium only) to work around a glibc
+ 2.2.4 bug.
+ - Initial port to HP/UX on Itanium. Thread support and both 32 and 64
+ bit ABIs appear to work. Parallel mark support doesn't yet, due to
+ some inline assembly code issues. Thread local allocation does appear
+ to work.
+ - ifdef'ed out glibc2.1/Itanium workaround. I suspect nobody is using
+ that combination anymore.
+ - Added a patch to make new_gc_alloc.h usable with gcc3.0. (Thanks to
+ Dimitris Vyzovitis for the patch.)
+ - Debugged 64-bit support on HP/UX PA-RISC.
+ - Turned on dynamic loading support for FreeBSD/ELF. (Thanks to Peter
+ Housel.)
+ - Unregistering of finalizers with debugging allocation was broken.
+ (Thanks to Jani Kajala for the test case.)
+ - Old finalizers were not returned correctly from GC_debug_register_finalizer.
+ - Disabled MPROTECT_VDB for Linux/M68K based on a report that it doesn't work.
+ - Cleaned up some statistics gathering code in reclaim.c (Thanks to Walter
+ Bright.)
+ - Added some support for OpenBSD/ELF/Linux. (Thanks to Suzuki Toshiya.)
+ - Added Jakub Jelinek's patch to use dl_iterate_phdr for dynamic library
+ traversal to dyn_load.c. Changed it to weakly reference dl_iterate_phdr,
+ so that the old code is stilll used with old versions of glibc.
+ - Cleaned up feature test macros for various threads packages and
+ integrated (partially functional) FreeBSD threads code from Loren Rittle.
+ It's likely that the cleanup broke something, since it touched lots of
+ code. It's also likelly that it fixed some unreported bugs in the
+ less common thread implementations, since some of the original code
+ didn't stand up to close scrutiny. Support for the next pthreads
+ implementation should be easier to add.
+
+Since 6.1alpha1:
+ - No longer wrap read by default in multithreaded applications. It was
+ pointed out on the libgcj list that this holds the allocation lock for
+ way too long if the read blocks. For now, reads into the heap are
+ broken with incremental collection. It's possible to turn this back on
+ if you make sure that read calls don't block (e.g. by calling select
+ first).
+ - Fix ifdef in Solaris_threads.h to refer to GC_SOLARIS_THREADS.
+ - Added check for environment variable GC_IGNORE_GCJ_INFO.
+ - Added printing of stop-the-world GC times if GC_PRINT_STATS environment
+ variable is set.
+ - The calloc definition in leak_detector.h was missing parentheses, and
+ realloc was missing a second argument to GC_REALLOC.
+ (Thanks to Elrond (elrond<at>samba-tng.org).)
+ - Added GC_PRINT_BACK_HEIGHT environment variable and associated
+ code, mostly in the new file backgraph.c. See doc/README.environment.
+ - Added -DUSE_GLOBAL_ALLOC to work around a Windows NT issue. (Thanks to
+ Jonathan Clark.)
+ - Integrated port to NEC EWS4800 (MIPS-based workstation, with somewhat
+ different address-space layout). This may help for other machines with
+ holes in the data segment. (Thanks to Hironori Sakamoto.)
+ - Changed the order in which GC_push_roots and friends push things onto
+ the mark stack. GC_push_all calls need to come first, since we can't
+ necessarily recovere if those overflow the mark stack. (Thanks to
+ Matthew Flatt for tracking down the problem.)
+ - Some minor cleanups to mostly support the Intel compiler on Linux/IA64.
+
+Since 6.1 alpha2:
+ - Minor cleanup on the gcconfig.h section for SPARC.
+ - Minor fix to support Intel compiler for I386/Linux. (Thanks to Sven
+ Hartrumpf.)
+ - Added SPARC V9 (64-bit) support. (Thanks to Jeff Sturm.)
+ - Restructured the way in which we determine whether or not to keep
+ call stacks for debug allocation. By default SAVE_CALL_COUNT is
+ now zero on all platforms. Added SAVE_CALL_NARGS parameters.
+ If possible, use execinfo.h to capture call stack. (This should
+ add support for a number of new platforms, though often at
+ considerable runtime expense.)
+ - Try to print symbolic information for call stacks. On Linux, we
+ do this with a combination of execinfo.h and running addr2line in
+ a separate process. This is both much more expensive and much more
+ useful. Amazingly, it seems to be fast enough for most purposes.
+ - Redefined strdup if -DREDIRECT_MALLOC is given.
+ - Changed incremental collector and MPROTECT_VDB implementation so that,
+ under favorable conditions, pointerfree objects are not protected.
+ Added GC_incremental_protection_needs() to determine ahead of time whether
+ pointerfree objects may be protected. Replaced GC_write_hint() with
+ GC_remove_protection().
+ - Added test for GC_ENABLE_INCREMENTAL environment variable.
+ - Made GC_time_limit runtime configurable. Added GC_PAUSE_TIME_TARGET
+ environment variable.
+ - Eliminated GC_page_sz, a duplicate of GC_page_size.
+ - Caused the Solaris and Irix thread creation primitives to call
+ GC_init_inner().
+
+Since 6.1alpha3:
+ - Fixed typo in sparc_mach_dep.S, preventing the 64-bit version from
+ building. Increased 64-bit heap size limit in test.c slightly, since
+ a functional SPARC collector seems to slightly exceed the old limits.
+ (Thanks again to Jeff Sturm.)
+ - Use NPRGREG in solaris_threads.c, thus printing all registers if things
+ go wrong.
+ - Added GC_MARKERS environment variable to allow use of a single marker
+ thread on an MP without confusing the lock implementation.
+ - Collect much less aggressively in incremental mode with GC_TIME_UNLIMITED.
+ This is really a purely generational mode, and we can afford to
+ postpone the collection until the heap is (nearly) full.
+ - Remove read() wrapper for MPROTECT_VDB. It was causing more harm than
+ good. It is often no longer needed if system calls avoid writing to
+ pointerfull heap objects.
+ - Fix MACOSX test in gcconfig.h. (Thanks to John Clements.)
+ - Change GC_test_and_set so that it consistently has one argument.
+ Add spaces to ::: in powerpc assembly code in gc_locks.h.
+ (Thanks to Ryan Murray.)
+ - Fixed a formatting error in dbg_mlc.c. Added prototype to GC_abort()
+ declaration. (Thanks to Michael Smith.)
+ - Removed "source" argument to GC_find_start(). Eliminate GC_FIND_START().
+ - Added win32 recognition code in configure.in. Changed some of the
+ dllimport/export defines in gc.h. (Thanks to Adam Megacz.)
+ - GC_malloc_many didn't set hb_last_reclaimed when it called
+ GC_reclaim_generic. (I'm not sure this matters much, but ...)
+ - Allocating uncollectable objects with debug information sometimes
+ allocated objects that were one byte too small, since uncollectable
+ objects don't have the extra byte added at the end. (Thanks to
+ Wink Saville for pointing this out.)
+ - Added a bit more assertion checking to make sure that gcj objects
+ on free lists never have a nonzero second word.
+ - Replaced BCC_MAKEFILE with an up-to-date one. (Thanks to
+ Andre Leiradella.)
+ - Upgraded libtool, cinfigure.in and some related files to hopefully
+ support NetBSD/SPARC. (Thanks to Adrian Bunk.) Unfortunately,
+ libtool 1.4.2 seemed to be buggy due to missing quotes in several
+ "test" invocations. Fixed those in the ltmain.sh script.
+ - Some win32-specific patches, including the introduction of
+ GC_CreateThread. (Thanks to Adam Megacz.)
+ - Merged in gcj changes from Anthony Green to support embedded systems.
+ - Tried to consistently rename preprocessed assembly files with a capital
+ .S extension.
+ - Use alpha_mach_dep.S on ALPHA again. It doesn't really matter, but this
+ makes our distribution consistent with the gcc one, avoiding future merge
+ problems.
+ - Move GET_MEM definition into gcconfig.h. Include gcconfig.h slightly
+ later in gc_priv.h to avoid forward references to ptr_t.
+ - Add some testing of local allocation to test.c.
+ - Change definition of INVALID_QTID in specific.h. The -1 value was used
+ inconsistently, and too likely to collide with a valid stack address.
+ Some general clean-up of specific.[ch]. Added assertions. (Thanks
+ to Michael Smith for tracking down an intermittent bug to this
+ general area. I'm not sure it has been squashed yet, however.)
+ - On Pthread systems it was not safe to call GC_malloc() between fork()
+ and exec(). According to the applicable standards, it doesn't appear
+ to be safe to call malloc() or many other libc functions either, thus
+ it's not clear this is fixable. Added experimental support for
+ -DHANDLE_FORK in linux_threads.c which tries to support it. It may
+ succeed if libc does the right thing. I'm not sure whether it does.
+ (Thanks to Kenneth Schalk for pointing out this issue.)
+ - Documented thread local allocation primitives to require an
+ explicit GC_init call. GC_init_parallel is no longer declared to
+ be a constructor function, since that isn't portable and often
+ seems to lead to initialization order problems.
+ - Changed gc_cpp.cc and gc_cpp.h in one more attempt to make them
+ compatible with Visual C++ 6. (Thanks to Wink Saville for the
+ patch.)
+ - Some more patches for Linux on HP PA-RISC.
+ - Added include/gc_allocator.h. It implements (hopefully) standard
+ conforming (as opposed to SGI-style) allocators that allocate
+ collectable (gc_allocator) or GC-traceable, but not collectable
+ (traceable_allocator) objects. This borrows heavily from libstc++,
+ which borrows heavily from the SGI implementation, this part of
+ which was written by Matt Austern. Changed test_cpp.cc to very
+ minimally test this.
+ - On Linux/X86, retry mmap with a different start argument. That should
+ allow the collector to use more (closer to 3GB) of the address space.
+ (Thanks to Jeffrey Mark Siskind for tracking this down.)
+ - Force 64 bit alignment with GCJ support. (Reflects Bryce McKinley's
+ patch to the gcc tree.)
+ - Refined the choice of sa_handler vs. sa_sigaction in GC_dirty_init
+ to accomodate some glibc5 systems. (Thanks to Dan Fandrich for the
+ patch.)
+ - Compensated for the fact that current versions of glibc set
+ __libc_stack_end incorrectly on Linux/IA64 while initialization code
+ is running. This could cause the collector to miss 16 bytes of
+ the memory stack if GC_malloc or friends where called before main().
+ - Mostly integrated Takis Psarogiannakopoulos' port to DG/UX Inix 86.
+ This will probably take another iteration to work, since his
+ patch conflicted with the libtool upgrade.
+ - Added README.arm.cross containing some information about cross-
+ compiling to an ARM processor from Margaret Fleck.
+
+Since 6.1alpha4:
+ - Added GC_finalizer_mem_freed, and changed some of the code that
+ decided on heap expansion to look at it. Memory explicitly
+ deallocated by finalizers essentially needs to be counted as reclaimed
+ by the GC. Otherwise there are cases in which the heap can grow
+ unboundedly. (Thanks to Mark Reichert for the test case.)
+ - Integrated Adam Megacz patches to not scan dynamic libraries if
+ we are compiling with gcc on win32. Otherwise we need structured
+ exception handling to deal with asynchronously unmapped root
+ segments, and gcc doesn't directly support that.
+ - Integrated Anthony Green's patch to support Wine.
+ - GC_OPERATOR_NEW_ARRAY was misspelled OPERATOR_NEW_ARRAY in several
+ places, including gc_cpp.cc. (Thanks to Wink Saville for pointing
+ this out.)
+ - Integrated Loren James Rittle's Alpha FreeBSD patches. In
+ response to Richard Henderson's suggestion, these also
+ changed the declarations of symbols like _end on many platforms to
+ that they wouldn't mistakenly be declared as short data symbols.
+ - Integrated changes from the Debian distribution. (Thanks to Ryan Murray
+ for pointing these out.) Fix C++ comments in POWERPC port. Add ARM32
+ incremental GC support. Get rid of USE_GENERIC_PUSH_REGS for alpha/Linux,
+ this time for real. Use va_copy to get rid of cord printf problems
+ (finally).
+ - Close file descriptor used to count cpus. Thanks to Jeff Sturm for
+ pointing out the omission.
+ - Don't just drop gcj free lists in GC_start_reclaim, since that can
+ eventually cause the marker to see a bogus mark descriptor in the
+ dropped objects. The usual symptom was a very intermittent segmentation
+ fault in the marker. This mattered only if one of the GC_gcj_malloc
+ variants was used. (Thanks to Michael Smith, Jeff Sturm, Bryce
+ McKinley and Tom Tromey for helping to track this down.)
+ - Fixed Linux and Solaris/64 SPARC configuration. (Thanks to David Miller,
+ Jeff Sturm, Tom Tromey, and Christian Joensson.)
+ - Fixed a typo in strdup definition. (Thanks to Gerard A Allan.)
+ - Changed Makefile.direct to invoke $(CC) to assemble alpha_mach_dep.S.
+ This is needed on Linux. I'm not sure whether it's better or worse
+ on Tru64.
+ - Changed gc_cpp.h once more to declare operator new and friends only in
+ a Microsoft environment. This may need further fine tuning. (Thanks to
+ Johannes Schmidt for pointing out that the older code breaks on gcc3.0.4.)
+ - Don't ever override strdup if it's already macro defined. (Thanks to
+ Adnan Ali for pointing out the problem.)
+ - Changed gc_cpp.h yet again to also overload placement new. Due to the
+ C++ overloading rules, the other overloaded new operations otherwise hide
+ placement new, which causes many STL uses to break. (Thanks to Reza
+ Shahidi for reporting this, and to Matt Austern for proposing a fix.)
+ - Integrated cygwin pthreads support from Dan Bonachea.
+ - Turn on DYNAMIC_LOADING for NetBSD. (Thanks to Krister Walfridsson.)
+ - Changed printing code to print more complete GC times.
+ - Applied Mark Mitchell's Irix patch to correct some bitrot.
+ - Clarified which object-printing routines in dbg_mlc.c should hold
+ the allocation lock. Restructured the code to allow reasonable object
+ printing with -DREDIRECT_MALLOC.
+ - Fix the Linux mmap code to always start with 0x1000 as the initial hint.
+ Minor patches for 64-bit AIX, particularly to STACKBOTTOM.
+ (Thanks again to Jeffrey Mark Siskind.)
+ - Renamed "SUSPENDED" flag for Solaris threads support to avoid a conflict
+ with a system header. (Thanks to Philp Brown.)
+ - Cause win32_threads.c to handle an out of range stack pointer correctly,
+ though currently with a warning. (Thanks to Jonathan Clark for
+ observing that win32 applications may temporarily use the stack
+ pointer for other purposes, and suggesting a fix. Unfortunately, it's
+ not clear that there is a complete solution to this problem.)
+
+Since 6.1alpha5:
+ - Added GC_MAXIMUM_HEAP_SIZE environment variable.
+ - Fix configure.in for MIPS/LINUX. (Thanks to H.J. Lu.)
+ - Double page hash table size for -DLARGE_CONFIG.
+ - Integrated Bo Thorsen's X86-64 support.
+ - STACKBOTTOM definition for LINUX/MIPS was partially changed back.
+ (Thanks to H.J. Lu and Hiroshi Kawashima for resolving this.)
+ - Replaced all occurrences of LINUX_DATA_START in gcconfig.h with
+ SEARCH_FOR_DATA_START. It doesn't hurt to falll back to a search.
+ And __data_start doesn't seem to get defined correctly of the GC
+ library is loaded with LD_PRELOAD, e.g. for leak detection.
+ - If the GC_find_leak environment variable is set, do a
+ atexit(GC_gcollect) to give us at least one chance to detect leaks.
+ This may report some very benign leaks, but ...
+ - Addeded REDIRECT_FREE. It's necessary if we want leak detection with
+ LD_PRELOAD.
+ - Defer printing of leaked objects, as for smashed objects.
+ - Fixed process and descriptor leak in GC_print_callers. Try for
+ line number even if we got function name.)
+ - Ported parallel GC support and thread local allocation to Alpha.
+ Not yet well-tested.
+ - Added GC_DUMP_REGULARLY and added finalization statistics to GC_dump().
+ - Fixed Makefile.am to mention alpha_mach_dep.S instead of the defunct
+ alpha_mach_dep.s. (Thanks to Fergus Henderson.)
+ - Incorporated a change to new_gc_alloc.h, suggested by Johannes Schmidt,
+ which should make it work with gcc3.1. (I would still like to encourage
+ use of gc_allocator.h instead.)
+ - Use alpha_mach_dep.S only on Linux. (It's not clear that this is
+ optimal, but it otherwise didn't build on Tru64. Thanks to Fergus
+ Henderson.)
+ - Added ifdef to guard free() in os_dep.c. Otherwise we get a
+ compilation error on Irix. (Thanks to Dai Sato.)
+ - Added an experimental version of GC_memalign to mallocx.c. This can't
+ always work, since we don't handle alignment requests in the hblk-level
+ allocator, and we can't handle arbitrary pointer displacements unless
+ GC_all_interior_pointers is enabled. But it should work for alignment
+ requests up to HBLKSIZE. This is not yet documented in the standard
+ places.
+ - Finally debugged the OSF1/Tru64 thread support. This needs more testing,
+ since I needed to add a somewhat unconvincing workaround for signal
+ delivery issues that I don't yet completely understand. But it does
+ pass my tests, even in parallel GC mode. Incremental GC support is
+ disabled if thread support is enabled, due to the signal issues.
+ - Eliminated name-space-incorrect definition of _cdecl from gc_cpp.h.
+ - Added GC_debug_malloc_replacement and GC_debug_realloc_replacement
+ declarations to gc.h. On IA64, this is required for REDIRECT_MALLOC
+ to work correctly with these.
+ - Fixed Linux USE_PROC_FOR_LIBRARIES to work with a 64-bit /proc format.
+
+Since 6.1:
+ - Guard the test for GC_DUMP_REGULARLY in misc.c with
+ "#ifndef NO_DEBUGGING". Otherwise it fails to build with NO_DEBUGGING
+ defined. (Thanks to Manuel Serrano.)
+ - Message about retrying suspend signals was incorrectly generated even when
+ flag was not set.
+ - Cleaned up MACOSX/NEXT root registration code. There was apparently a
+ separate ifdef case in GC_register_data_segments() for no reason.
+ - Removed MPROTECT_VDB for MACOSX port, based on one negative report.
+ - Arrange for gc.h and friends to be correctly installed with GNU-style
+ "make install".
+ - Enable the GNU-style build facility include C++ support in the library
+ with --enable-cplusplus. (Thanks to Thomas Maier for some of the patch.)
+ - Mark from GC_thread_key in linux_threads.c, in case that's allocated
+ from the garbage collected heap, as it is with our own thread-specific
+ storage implementation. (Thanks to Jeff Sturm.)
+ - Mark all free list header blocks if they are heap allocated. This avoids
+ some unnecessary tracing. And it remains correct if we clear the
+ root set. (Thanks to Jeff Sturm for identifying the bug.)
+ - Improved S390/Linux support. Add S390/Linux 64-bit support. (Thanks
+ to Ulrich Weigand.)
+ - Corrected the spelling of GC_{M,C}ALLOC_EXPLICTLY_TYPED to
+ GC_{M,C}ALLOC_EXPLICITLY_TYPED in gc_typed.h. This is technically
+ an interface change. Based on the fact that nobody reported this,
+ I suspect/hope there were no clients.
+ - Cleaned up gc_typed.h so that (1) it adds an extern "C" declaration
+ when appropriate, (2) doesn't generate references to undefined internal
+ macros, and (3) allows easier manual construction of descriptors.
+ - Close the file descriptor used by GC_print_address_map().
+ - Set the "close-on-exec" bit for various file descriptors maintained
+ for the collector's internal use.
+ - Added a hack to find memory segments owned by the system allocator
+ under win32. Based on my tests, this tends to eventually find all
+ segments, though it may take a while. There appear to be cleaner,
+ but slower solutions under NT/XP. But they rely on an API that's
+ unsupported under 9X.
+ - Changed Linux PowerPC stack finding to LINUX_STACKBOTTOM. (Thanks
+ to Akira Tagoh for pointing out that HEURISTIC1 doesn't work on
+ 64-bit kernels.)
+ - Added GC_set_free_space_divisor to avoid some Windows dll issues.
+ - Added FIXUP_POINTER, POINTER_SHIFT, POINTER_MASK to allow preprocessing
+ of candidate pointers for tagging, etc.
+ - Always lock around GC_notify_full_gc(). Simplified code for
+ invoking GC_notify_full_gc().
+ - Changed the way DATASTART is defined on FreeBSD to be robust against
+ an unmapped page after etext. (Thanks to Hironori Sakamoto for
+ tracking down the intermittent failure.)
+ - Made GC_enable() and GC_disable() official. Deprecated direct update
+ of GC_dont_gc. Changed GC_gcollect to be a noop when garbage collection
+ is disabled.
+ - Call GC_register_dynamic_libraries before stopping the world on Linux,
+ in order to avoid a potential deadlock due to the dl_iterate_phdr lock.
+ - Introduced a more general mechanism for platform-dependent code to
+ decide whether the main data segment should be handled separately
+ from dynamic libraries, or registered by GC_register_dynamic_libraries.
+ The latter is more reliable and easier on Linux with dl_iterate_phdr.
+
+Since 6.2alpha1:
+ - Fixed the completely broken FreeBSD code in 6.2alpha1. (Thanks to
+ Hironori Sakamoto for the patch.)
+ - Changed IRIX reference in dbg_mlc.c to IRIX5. (Thanks to Marcus Herbert.)
+ - Attempted to work around the problems with .S filenames and the SGI
+ compiler. (Reported by several people. Untested.)
+ - Worked around an HP/UX make issue with the GNU-style build process.
+ - Fixed the --enable-cplusplus build machinery to allow builds without
+ a C++ compiler. (That was always the intent ...)
+ - Changed the debugging allocation macros to explicitly pass the return
+ address for Linux and XXXBSD on hardware for which we can't get stack
+ traces. Use __builtin_return_address(0) to generate it when possible.
+ Some of the configuration work was cleaned up (good) and moved to gc.h
+ (bad, but necessary). This should make leak detection more useful
+ on a number of platforms. (Thanks to Fabian Thylman for the suggestion.)
+ - Fixed compilation problems in dbg_mlc.c with GC_ADD_CALLER.
+ - Bumped revision number for dynamic library.
+
+Since 6.2alpha2:
+ - Don't include execinfo.h in os_dep.c when it's not needed, and may not exist.
+
+Since 6.2alpha3:
+ - Use LINUX_STACKBOTTOM for >= glibc2.2 on Linux/MIPS. (See Debian bug
+ # 177204)
+ - Integrated Jeff Sturm and Jesse Rosenstock's MACOSX threads patches.
+ - Integrated Grzegorz Jakacki's substantial GNU build patch. "Make dist"
+ should now work for the GNU build process. Documentation files
+ are installed under share/gc.
+ - Tweaked gc_cpp.h to again support the Borland compiler. (Thanks to
+ Rene Girard for pointing out the problems.)
+ - Updated BCC_MAKEFILE (thanks to Rene Girard).
+ - Added GC_ASSERT check for minimum thread stack size.
+ - Added --enable-gc-assertions.
+ - Added some web documentation to the distribution. Updated it in the
+ process.
+ - Separate gc_conf_macros.h from gc.h.
+ - Added generic GC_THREADS client-defined macro to set the appropriate
+ GC_XXX_THREADS internal macro. (gc_config_macros.h.)
+ - Add debugging versions of _ignore_off_page allocation primitves.
+ - Moved declarations of GC_make_closure and GC_debug_invoke_finalizer
+ from gc.h to gc_priv.h.
+ - Reset GC_fail_count even if only a small allocation succeeds.
+ - Integrated Brian Alliet's patch for dynamic library support on Darwin.
+ - gc_cpp.h's gc_cleanup destructor called GC_REGISTER_FINALIZER_IGNORE_SELF
+ when it should have called the lower case version, since it was
+ explicitly computing a base pointer.
+
+Since 6.2alpha4:
+ - GC_invoke_finalizers could, under rare conditions, set
+ GC_finalizer_mem_freed to an essentially random value. This could
+ possibly cause unbounded heap growth for long-running applications
+ under some conditions. (The bug was introduced in 6.1alpha5, and
+ is not in gcc3.3. Thanks to Ben Hutchings for finding it.)
+ - Attempted to sanitize the various DLL macros. GC_USE_DLL disappeared.
+ GC_DLL is used instead. All internal tests are now on GC_DLL.
+ README.macros is now more precise about the intended meaning.
+ - Include DllMain in the multithreaded win32 version only if the
+ collector is actually built as a dll. (Thanks to Mohan Embar for
+ a version of the patch.)
+ - Hide the cygwin threadAttach/Detach functions. They were violating our
+ namespace rules.
+ - Fixed an assertion in GC_check_heap_proc. Added GC_STATIC_ASSERT.
+ (Thanks again to Ben Hutchings.)
+ - Removed some obsolete definitions for Linux/PowerPC in gcconfig.h.
+ - CORD_cat was not rebalancing unbalanced trees in some cases, violating
+ a CORD invariant. Also tweaked the rebalancing rule for
+ CORD_cat_char_star. (Thanks to Alexandr Petrosian for the bug report
+ and patch.)
+ - Added hand-coded structured exception handling support to mark.c.
+ This should enable support of dynamic libraries under win32 with
+ gcc-compiled code. (Thanks to Ranjit Mathew for the patch.)
+ Turned on dynamic library scanning for win32/gcc.
+ - Removed some remnants of read wrapping. (Thanks to Kenneth Schalk.)
+ GC_USE_LD_WRAP ws probably broken in recent versions.
+ - The build could fail on some platforms since gcconfig.h could include
+ declarations mentioning ptr_t, which was not defined, e.g. when if_mach
+ was built. (Thanks to Yann Dirson for pointing this out.) Also
+ cleaned up tests for GC_PRIVATE_H in gcconfig.h a bit.
+ - The GC_LOOP_ON_ABORT environment variable interfered with incremental
+ collection, since the write fault handler was erroneously overridden.
+ Handlers are now set up in the correct order.
+ - It used to be possible to call GC_mark_thread_local_free_lists() while
+ the world was not stopped during an incremental GC. This was not safe.
+ Fortunately, it was also unnecessary. Added GC_world_stopped flag
+ to avoid it. (This caused occasional crashes in GC_set_fl_marks
+ with thread local allocation and incremental GC. This probably happened
+ primarily on old, slow multiprocessors.)
+ - Allowed overriding of MAX_THREADS in win32_threads.c from the build
+ command line. (Patch from Yannis Bres.)
+ - Taught the IA64/linux code to determine the register backing store base from
+ /proc/self/maps after checking the __libc symbol, but before guessing.
+ (__libc symbols are on the endangered list, and the guess is likely to not
+ always be right for 2.6 kernels.) Restructured the code to read and parse
+ /proc/self/maps so it only exists in one place (all platforms).
+ - The -DUSE_PROC_FOR_LIBRARIES code was broken on Linux. It claimed that it
+ also registered the main data segment, but didn't actually do so. (I don't
+ think anyone actually uses this configuration, but ...)
+ - Made another attempt to get --enablecplusplus to do the right thing.
+ Since there are unavoidable problems with C programs linking against a
+ dynamic library that includes C++ code, I separated out the c++ code into
+ libgccpp.
+
+Since 6.2alpha5:
+ - There was an extra underscore in the name of GC_save_registers_in_stack
+ for NetBSD/SPARC. (Thanks to Jaap Boender for the patch.)
+ - Integrated Brian Alliet's patch for Darwin. This restructured the
+ linuxthreads/pthreads support to separate generic pthreads support
+ from more the system-dependent thread-stopping code. I believe this
+ should make it easier to eliminate the code duplication between
+ pthreads platforms in the future. The patch included some other
+ code cleanups.
+ - Integrated Dan Bonachea's patch to support AIX threads. This required
+ substantial manual integration, mostly due to conflicts with other
+ recent threads changes. It may take another iteration to
+ get it to work.
+ - Removed HPUX/PA-RISC support from aix_irix_threads.c. It wasn't used
+ anyway and it cluttered up the code. And anything we can do to migrate
+ towards generic pthreads support is a good thing.
+ - Added a more explicit test for tracing of function arguments to test.c.
+ (Thanks to Dan Grayson.)
+ - Added Akira Tagoh's PowerPC64 patch.
+ - Fixed some bit rot in the Cygwin port. (Thanks to Dan Bonachea for
+ pointing it out.) Gc.h now includes just windows.h, not winbase.h.
+ - Declared GC_save_regs_in_stack() in gc_priv.h. Remove other declarations.
+ - Changed --enable-cplusplus to use automake consitionals. The old way
+ confused libtool. "Make install" didn't work correctly for the old version.
+ Previously --enable-cplusplus was broken on cygwin.
+ - Changed the C version of GC_push_regs to fail at compile time if it is
+ generated with an empty body. This seems to have been the cause of one
+ or two subtle failures on unusual platforms. Those failures should
+ now occur at build time and be easily fixable.
+
+Since 6.2alpha6:
+ - Integrated a second round of Irix/AIX patches from Dan Bonachea.
+ Renamed mips_sgi_mach_dep.S back to mips_sgi_mach_dep.s, since it requires
+ the Irix assembler to do the C preprocessing; gcc -E doesn't work.
+ - Fixed Makefile.direct for DARWIN. (Thanks to Manuel Serrano.)
+ - There was a race between GC_pthread_detach and thread exit that could
+ result in a thread structure being deallocated by GC_pthread_detach
+ eventhough it was still needed by the thread exit code. (Thanks to
+ Dick Porter for the small test case that allowed this to be debugged.)
+ - Fixed version parsing for non-alpha versions in acinclude.m4 and
+ version checking in version.h.
+
+Since 6.2:
+ - Integrated some NetBSD patches forwarded to me by Marc Recht. These
+ were already in the NetBSD package.
+ - GC_pthread_create waited for the semaphore even if pthread_create failed.
+ Thanks to Dick Porter for the pthread_support.c patch. Applied the
+ analogous fix for aix_irix_threads.c.
+ - Added Rainer Orth's Tru64 fixes.
+ - The check for exceeding the thread table size in win32 threadDetach
+ was incorrect. (Thanks to Alexandr Petrosian for the patch.)
+ - Applied Andrew Begel's patch to correct some reentrancy issues
+ with dynamic loading on Darwin.
+ - GC_CreateThread() was neglecting to duplicate the thread handle in
+ the table. (Thanks to Tum Nguyen for the patch.)
+ - Pass +ESdbgasm only on PA-RISC machines with vendor compiler.
+ (Thanks to Roger Sayle for the patch.)
+ - Applied more AIX threads patches from Scott Ananian.
+
+Since 6.3alpha1:
+ - Reenabled I_HOLD_LOCK assertion in aix_irix_threads.h.
+ - Put back the WINABI qualifier for GC_CreateThread. (Thanks to
+ Danny Smith for the patch. 6.3alpha1 had the qualifier in one place
+ but not elsewhere, which was clearly wrong.)
+ - Sometimes explicitly define __private_extern__ before DARWIN dyld.h
+ include. (Thanks to Andreas Tobker for postting the patch.)
+ - Included signal.h from pthread_support.c. Removed GC_looping_handler,
+ which was dead code.
+ - GC_find_start was misdeclared by gc_pmark.h if PRINT_BLACK_LIST was
+ defined. (Thanks to Glauco Masotti for testing and reporting this.)
+ Changed GC_find_start to never just return 0. According to its
+ comment it doesn't, and it's unclear that's correct.
+ - GC_alloc_large had several largely compensating bugs in the
+ computation of GC_words_wasted. (It was confused about bytes vs.
+ words in two places.)
+ - Integrated Slava Sysoltev's patch to support more recent versions of
+ the Intel compiler on IA64/Linux.
+ - Changed win32 spinlock initialization to conditionally set a spin count.
+ (Emmanual Stumpf pointed out that enabling this makes a large performance
+ difference on win32 multiprocessors.) Also cleaned up the win32 spinlock
+ initialization code a bit.
+ - Fixed thread support for HP/UX/IA64. The register backing store base for
+ the main thread was sometimes not set correctly. (Thanks to Laurent
+ Morichetti.)
+ - Added -DEMPTY_GETENV_RESULTS flag to work around Wine problem.
+ - Declare GC_stack_alloc and GC_stack_free in solaris_threads.h to
+ avoid 64-bit size mismatches. (Thanks to Bernie Solomon.)
+ - Fixed GC_generic_push_regs to avoid a potential and very unfortunate
+ tail call optimization. This could lead to prematurely reclaimed
+ objects on configurations that used the generic routine and the new
+ build infrastructure (which potentially optimizes mach_dep.c).
+ This was a serious bug, but it's unclear whether it has resulted in
+ any real failures.
+ - Fixed CORD_str to deal with signed characters. (Thanks to Alexandr
+ Petrosian for noticing the problem and supplying the patch.)
+ - Merged a couple of NOSYS/ECOS tests into os_dep.c from gcj. (Thanks
+ to Anthony Green.)
+ - Partially merged a win32 patch from Ben Hutchings, and substantially
+ revised other parts of win32_threads.c. It had several problems.
+ Under MinGW with a statically linked library, the main thread was
+ not registered. Cygwin detached threads leaked thread descriptors.
+ There were several race conditions. For now, unfortunately the
+ static threads limit remains, though we increased it, and made table
+ traversal cost depend on the actual thread count.
+ There is also still some code duplication with pthread_support.c.
+ (Thread descriptors did become much smaller, since Ben Hutchings
+ removed the thread context from them.)
+ - Integrated a Solaris configure.in patch from Rainer Orth.
+ - Added GC_IGNORE_FB and associated warning to very partially address
+ the issue of the collector treating a mapped frame buffer as part
+ of the root set. (Thanks to David Peroutka for providing some
+ insight. More would be helpful. Is there anything that can be used
+ to at least partially identify such memory segments?)
+
+Since 6.3alpha2:
+ - Removed -DSMALL_CONFIG from BCC_MAKEFILE.
+ - Changed macros to test for an ARM processor (Patch from Richard Earnshaw.)
+ - Mostly applied a DJGPP patch from Doug Kaufman. Especially Makefile.dj
+ had suffered from serious bit rot.
+ - Rewrote GC_apply_to_maps, eliminating an off-by-one subscript error,
+ and a call to alloca (for lcc compatibility).
+ - Changed USE_MUNMAP behavior on posixy platforms to immediately remap
+ the memory with PROT_NONE instead of unmapping it. The latter risks
+ an intervening mmap grabbing the address space out from underneath us.
+ Updated this code to reflect a cleaner patch from Ulrich Drepper.
+ - Replaced _T with _Tp in new_gc_alloc.h to avoid a MACOS X conflict.
+ (Patch from Andrew Begel.)
+ - Dynamically choose whether or not lock should spin on win32. (Thanks
+ to Maurizio Vairani for the patch.) This may be a significant performance
+ improvement for win32.
+ - Fix Makefile.direct to actually include NT_STATIC_THREADS_MAKEFILE
+ in the distribution. (Again thanks to Maurizio Vairani.)
+ - Maybe_install_looping_handler() was accidentally exported, violating
+ our name space convention.
+ - Made os_dep.c use sigsetjmp and SA_NODEFER for NetBSD. (Thanks to
+ Christian Limpach.) (I generalized the patch to use sigsetjmp on all
+ UNIX_LIKE platforms, admittedly a slightly risky move. But it may avoid
+ similar problems on some other platforms. I also cleaned up the defn
+ of UNIX_LIKE a bit. - Hans)
+ - Integrated Andrew Begel's Darwin threads patch, adjusted according to
+ some of Fergus Hendersons's comments. (Patch didn't apply cleanly,
+ errors are possible.)
+ - Added another test or two for the Intel 8.0 compiler to avoid
+ confusing it with gcc. The single-threaded collector should now build
+ with icc, at least on ia64.
+
+Since 6.3alpha3:
+ - USE_MMAP was broken by confusion in the code dealing with USE_MMAP_ANON.
+ (This was pointed out, and fixes were suggested by several other people.)
+ - Darwin supprt was broken in alpha3 as a result of my misintegration of
+ Andrew Begel's patches. Fixed with another patch from Andrew Begel.
+ - A new sanity check in pthread_stop_world.c:GC_push_all_stacks() was
+ overly aggressive. We may collect from an unregistered thread during
+ thread creation. Fixed by explicitly checking for that case. (Added
+ GC_in_thread_creation.)
+
+Since 6.3alpha4:
+ - Fix & vs && typo in GC_generic_malloc and
+ GC_generic_malloc_ignore_off_page. (Propagated from the gcc tree.)
+ - Removed SA_NODEFER hack from NetBSD and Solaris write-protect handler.
+ (According to Christian Limpach, the NetBSD problem is fixed.
+ Presumably so is the Solaris 2.3 problem.)
+ - Removed placement delete from gc_cpp.h for the SGI compiler.
+ (Thanks to Simon Gornall for the patch.)
+ - Changed semantics of the GC_IGNORE_FB environment variable, based
+ on experimentation by Nicolas Cannasse pointing out that the old
+ interpretation was useless. We still need help in identifying win32
+ graphics memory mappings. The current "solution" is a hack.
+ - Removed "MAKEOVERRIDES =" from Makefile.am and thus Makefile.in.
+ It probably made more sense in the gcc context.
+ - Explicitly ensure that NEED_FIND_LIMIT is defined for {Open,Net}BSD/ELF.
+ - Replaced USE_HPUX_TLS macro by USE_COMPILER_TLS, since gcc often
+ supports the same extension on various platforms.
+ - Added some basic (completely untested) defines for win64, in support
+ of future work.
+ - Declared GC_jmp_buf in os_dep.s as JMP_BUF instead of jmp_buf, fixing
+ a memory overwrite bug on Solaris and perhaps other platforms.
+ - Added 0 != __libc_stack_end test to GC_linux_stack_base. (Thanks to Jakub
+ Jelinek, both for the patch, and for explaining the problem to me.)
+ Otherwise "prelink"ing could cause the collector to fail.
+ - Changed default thread local storage implementation to USE_PTHREAD_SPECIFIC
+ for HP/UX with gcc. The compiler-based implementation appears to work
+ only with the vendor compiler.
+ - Export GC_debug_header_size and GC_USR_PTR_FROM_BASE from gc_mark.h,
+ making client mark code cleaner and less dependent on GC version.
+ - Export several new procedures and GC_generic_malloc from gc_mark.h
+ to support user-defined kinds. Use the new procedures to replace existing
+ code in gcj_mlc.c and typd_mlc.c.
+ - Added support for GC_BACKTRACES.
+ - Fixed a remaining problem in CORD_str with signed characters. (Thanks
+ to Alexandr Petrosian for the patch.)
+ - Removed supposedly redundant, but very buggy, definitions of finalizer
+ macros from javaxfc.h. Fortunately this file probably has no users.
+ The correct declarations were already in gc.h.
+ - Also need to set GC_in_thread_creation while waiting for GC during
+ thread termination, since it is also possible to collect from an
+ unregistered thread in that case.
+ - Define NO_GETENV for Windows CE, since getenv doesn't appear to exist.
+ + some other minor WinCE fixes. (Thanks to Alain Novak.)
+ - Added GC_register_describe_type_fn.
+ - Arrange for debugging finalizer registration to ignore non-heap
+ registrations, since the regular version of the routine also behaves
+ that way.
+ - GC_gcj_malloc and friends need to check for finalizers waiting to be run.
+ One of the more obscure allocation routines with missing a LOCK() call.
+ - Fixed cvtres invocations in NT_MAKEFILE and NT_STATIC_THREADS_MAKEFILE
+ to work with VS.NET.
+ - Cleaned up GC_INIT calls in test. Updated gc.man to encourage GC_INIT
+ use in portable code.
+ - Taught the GC to use libunwind if --enable-full-debug is specified on
+ IA64 and libunwind is present.
+ - The USE_MUNMAP code could get confused about the age of a block and
+ prematurely unmap it. GC_unmap_old had a bug related to wrapping of
+ GC_gc_no. GC_freehblk and GC_merge_unmapped didn't maintain
+ hb_last_reclaimed reasonably when blocks were merged. The code was
+ fixed to reflect original intent, but that may not always be an
+ improvement. See todo list item.
+
+Since 6.3alpha5:
+ - Define USE_GENERIC_PUSH_REGS for NetBSD/M68K.
+ - Fixed the X86_64 PREFETCH macros to correctly handle ia32e (which uses
+ different prefetch instructions from AMD64). (Thanks to H.J. Lu.)
+ - GC_config_macros.h did not correctly define GC_WIN32_THREADS from
+ GC_THREADS.
+ - Added simple_example.html.
+ - Merged Andrew Gray's patch to correctly restore signal handlers on
+ FreeBSD.
+ - Merged a patch from Andreas Jaeger to deal with prefetch-related warnings
+ on x86-64. Added some other casts so that the PREFETCH macros
+ always get a ptr_t argument. Removed some casts inthe PREFETCH
+ implementations.
+ - At Jesse Jones suggestion: Added a header guard for gc_allocator.h
+ and changed GC_debug_free to clobber contents of deallocated object.
+ - The signal masking code in pthread_stop_world.c contained some errors.
+ In particular SIGSEGV was masked in the handler, in spite of the fact that
+ it wrote to the heap. This could lead to an uncaught SIGSEGV, which
+ apparently became much more likely in Linux 2.6. Also fixed some
+ typos, and reduced code duplication in the same area.
+ - Remove ltconfig, clean up configure messages for DGUX (thanks to
+ Adrian Bunk for the patches).
+ - Integrated NetBSD/OpenBSD patches from Marc Recht and Matthias Drochner.
+
+Since 6.3alpha6:
+ - Compile test_cpp.cc with CXXCOMPILE instead of COMPILE.
+ - Very large allocations could cause a collector hang. Correct
+ calculation of GC_collect_at_heapsize.
+ - GC_print_hblkfreelist printed some bogus results if USE_MUNMAP
+ was defined.
+ - Include gc_config_macros.h in threadlibs.c.
+ - Correct MacOSX thread stop code. (Thanks to Dick Porter.)
+ - SMALL_OBJ definition was off by one. This could cause crashes
+ at startup. (Thanks to Zoltan Varga for narrowing this down to
+ a trivial test case.)
+ - Integrate Paolo Molara's patch to deal with a race in the Darwin
+ thread stopping code.
+ - Changed X86_64 implementation to use SA_SIGINFO in the MPROTECT_VDB
+ implementation. The old approach appears to have been broken by
+ recent kernels.
+ - Added GC_ATTR_UNUSED to eliminate a warning in gc_allocator.h (Thanks
+ to Andrew Begel.)
+ - Fix GC_task_self declaration in os_dep.c. (Thanks to Andrew Pinski.)
+ - Increase INITIAL_BUF_SZ in os_dep.c for Solaris /proc reads.
+
+Since gc6.3:
+ - Merge gcconfig.h changes from gcc tree.
+ - Unconditionally include gc_priv.h in solaris_pthreads.c, win32_threads.h,
+ aix_irix_threads.c, and solaris_threads.c to get thread definitions.
+ - Start marker threads in GC_thr_init, so that they get started even
+ if no other threads are ever started. (Oddly enough, the parallel
+ collector worked correctly, though not well, with no helper threads.)
+ - Go ahead and split large blocks in GC_allochblk_nth if GC_dont_gc
+ is set. (Thanks to Alexander Petrossian.)
+ - GC_PRINT_BACK_HEIGHT would deadlock with thread support.
+ - Let in_progress_space in backgraph.s grow dynamically.
+ - Fix README.solaris2. The GC_thr_init() hack doesn't work anymore.
+ - Convert GC_finalizer_mem_freed to bytes in allchblk.c.
+ - Add missing declaration for GC_generic_malloc_words_small_inner.
+ Without it, s390x breaks. (Thanks to Ulrich Weigand.)
+ - Applied several MacOSX patches to support older tool chains.
+ (Thanks to Stefan Ring.)
+ - Bug fix for NetBSD/amd64. (Thanks to Marc Recht.) Add NetBSD/sh3
+ support. (Thanks to Uchiyama Yasushi.)
+ - Fixed an uninitialized variable in cordprnt.c. (Thanks to gcc for
+ providing the warning.)
+ - Eliminated some, but not all, gcc -Wall warnings.
+ - Changed some old style casts to reinterpret_cast in new_gc_alloc.h.
+ (Thanks to Dan Grayson.)
+ - GC_extend_size_map shouldn't adjust for GC_all_interior_pointers if
+ GC_DONT_ADD_BYTE_AT_END is set.
+ - Changed some (long) casts to (word) in preparation for win64.
+ (Thanks to Peter Colson.)
+ - Changed "int stack_size" declaration in pthread_support.c to use
+ size_t. (Only mattered with GC_ASSERTIONS enabled.)
+ - Added CRIS (etrax) support. (Thanks to Simon Posnjak and
+ Hans-Peter Nilsson.)
+ - Removed GC_IGNORE_FB frame buffer recognition, and replaced
+ it with a check that the mapping type is MEM_IMAGE.
+ In theory, this should work much better, but it is a high
+ risk change for win32. (Thanks to Ashley Bone for the crucial
+ experimental data behind this, and to Rutger Ovidus for
+ some further experiments.)
+ - GC_allochblk_nth incremented GC_words_wasted by bytes rather than
+ words.
+ - Consider GC_words_wasted in GC_adj_words_allocd only if it is within
+ reason. (A hack to avoid some extremely unlikely scenarios in which
+ we manage to allocate only "wasted" space. 7.0 has a better fix.)
+ - Changed PowerPC GC_clear implementation to use lwsync instead of
+ eieio, since the documentation recommends against eieio, and
+ it seems to be incorrect if the preceding memory op is a load.
+ - Fixed print_block_list to print the correct kind number for
+ STUBBORN. (Thanks to Rutger Ovidus.)
+ - Have configure.in generate an error if it is asked to support
+ pthreads, but doesn't know how to.
+ - Added Kazuhiro Inaoka's patch for Renesas M32R support.
+ - Have the GNU build mechanism link with -ldl. Rename THREADLIBS
+ to THREADDLLIBS to reflect this. (Thanks to Sven Verdoolaege.)
+ - Added Hannes Mehnert's patch for FreeBSD/SPARC support.
+ - Merged some FreeBSD specific patches to threadlibs.c and dyn_load.c.
+ (Thanks tp John Merryweather Cooper.)
+ - Define MPROTECT_VDB on MACOSX only if threads are being used, since the
+ dirty page tracking mechanism uses threads. (This avoids an undefined
+ reference to _GC_darwin_register_mach_handler_thread.)
+ - By popular demand, use __libc symbols only if we are built with
+ USE_LIBC_PRIVATES, which is off by default, and not otherwise documented.
+ - Ignore GC_enable_incremental() requests when KEEP_BACK_PTRS is set.
+ The GC itself will dirty lots of pages in this cases, probably making
+ it counterproductive on all platforms. And the DARWIN port crashes.
+
+Since gc6.4:
+ - Integrated Paolo Molaro's patch to deal with EINTR in sem_wait.
+ - Make GC_approx_sp() write to dummy location to ensure that stack
+ is grown here, when sp looks reasonable, rather than later, when
+ it might look like a bad memory reference. (Problem was never
+ observed that I know of. But on rereading the code it seemed
+ dubious.)
+ - Separate out GC_with_callee_saves_pushed and sometimes call
+ it from GC_suspend_handler in pthread_stop_world.c. Callee-save
+ register values sometimes failed to get traced under HP/UX on
+ PA-RISC. Linux/IA64 had the same problem, though non-stacked
+ callee-save registers seem to be so rarely used there that nobody
+ ever noticed.
+ - Integrated an ancient Darwin powerpc_darwin_machine_dep.s patch
+ from Andreas Tobler, which I had lost.
+ - Fix compare_and_exchange implementation for gcc/IA64 to deal with
+ pickier compiler versions.
+ - Fixed Itanium 32-bit ABI support (HP/UX). In particular, the
+ compare_and_exchange implementation didn't consider that possibility.
+ - Undefine GC_pthread_detach in win32_threads.c. (Thanks to
+ Tagliapietra Tommaso.)
+ - Fixed inclusion of frame.h for NETBSD in os_dep.c.
+ - Applied Dan Bonachea's patch to use mmap on AIX.
+ - Several fixes to resurrect the Irix port on recent OS versions.
+ - Change ALPHA to use LINUX_STACKBOTTOM.
+ - Change SPARC64/LINUX to also use LINUX_STACKBOTTOM. Deal with potential
+ bad values of __libc_stack_end on that platform. (Thanks to David Miller.)
+ - Relax gctest to allow larger heap if ALIGN_DOUBLE isn't set.
+ (Unnecessary in 7.0)
+ - Force a define of __STDC__=0 for the IBM compiler on AIX, so that
+ we get prototypes. (Unnecessary in 7.0)
+ - GC_INIT definition for AIX and CYGWIN referred to DATASTART and DATAEND
+ which are only defined in private include files.
+ - Integrated some small gcconfig.h patches from Dan Bonachea. Also
+ relaxed assertion about FreeBSD stack size in pthread_support.c.
+ - Integrated Andrew Begel's darwin_stop_world.c patch for 64-bit
+ support. This may need additional work.
+ - Avoided potentially infinite recursion in GC_save_callers if
+ the system backtrace calls malloc. The workaround currently requires
+ __thread support if this code is used with threads.
+ - Avoided another similar infinite recursion by conditionally
+ invoking GC_save_callers in alloc.c. (Thanks to Matthias Andree
+ for helping to track down both of these.)
+ - Removed all traces of aix_irix_threads.c. AIX and Irix now use
+ pthread_support.c and pthread_stop_world.c. The old code appeared
+ to be unreliable for AIX, and was not regularly maintained.
+ - On Irix, ignore segments with MA_FETCHOP or MA_NOTCACHED attributed;
+ they're not always safe to read.
+ - Fixed a previously vacuous assertion (diagnosed by the SGI compiler)
+ in GC_remove_from_fl.
+ - Fix stack_size assertion in GC_pthread_create.
+ - Fix assertion in GC_steal_mark_stack.
+
+Since gc6.5:
+ - Fix CPU count detection for Irix and FreeBSD. (Thanks to Dan Bonachea.)
+ - Integrate Dan Bonachea's patch for the IBM XLC compiler on Darwin.
+ - Integrated Andreas Tobler's FreeBSD/PowerPC patch.
+ - Don't access the GC thread structure from the restart handler. It's
+ unsafe, since the handler may run too late. (Thanks to Ben Maurer for
+ tracking this down.)
+ - Applied Christian Thalinger's patch to change comment syntax in
+ alpha_mach_dep.S.
+ - Added test for GC_no_dls in GC_dyld_image_add for DARWIN. (Thanks to
+ Juan Jose Garcia Ripoli).
+ - Use LINUX_STACKBOTTOM for Linux/SH and LINUX/ARM. (Thanks to Sugioka
+ Toshinobu and Christian Thalinger.)
+ - Rewrote GC_parse_map_entry. This assumed a fixed column layout of
+ /proc/self/maps on Linux. This ceased to be true about 2 years ago.
+ The old code is probably quite problemetic with -DREDIRECT_MALLOC. It
+ is also used by default for IA64, though I haven't seen actual failures
+ there.
+ - More consistently define HBLKSIZE to 4096 on 64 bit architectures with
+ 4K pages. (Thanks to Andrew Haley.)
+ - With win32 threads, GC_stop_world needs to acquire GC_write_cs. (Thanks
+ to Ben Hutchings for the observation and patch.)
+ - Move up struct callinfo declaration to make gcc 4.0.2. happy.
+
+Since 6.6:
+ - Add "int" to Solaris "end" and "etext" declaration in gc.h. Declared
+ the symbols with underscores and as arrays, since that's what's actually
+ used. Perhaps this could all just be removed? (Thanks to John Bowman.)
+ - Fixed ARM GC_test_and_set code. (Thanks to Kazu Hirata and Paul Brook.)
+ - Added casts for assignments to hb_last_reclaimed, which truncate the
+ value. Added a cast to GC_adj_words_allocd. Use GetModuleHandleA
+ when retrieving a handle to kernel32.dll under win32. (Thanks to the
+ Visual Prolog developers.)
+ - Added Tandem S-Series support. (Thanks to Craig McDaniel. A modified
+ version of his patch was applied, and hence breakage is probably not
+ his fault.)
+ - Remove spurious gc:: qualifier for operator delete[] in gc_cpp.h.
+ (Thanks to Hanno Boeck.)
+ - Changed a test for LINUX in config_macros.h to one for __linux__.
+ - Add prototypes for GC_finalizer_notifier and GC_thr_init. (Thanks to
+ David Ayers.)
+ - Use ld instead of nonexitent ldz instruction in Darwin FindTopOfStack.
+ (Thanks to Andreas Tobler.)
+ - Add support for Darwin/X86. (Thanks to Geoff Norton and the Mono
+ developers.)
+ - Merge in some recent gcc fixes. Add ppc64 asm code. (Thanks to Bryce
+ McKinley and other gcj developers.)
+ - Scan MEM_PRIVATE sections under Windows ME and predecessors.
+ - Interior pointers with some largish offsets into large objects could
+ be ignored, if GC_all_interior_pointers was set. (Oddly this worked
+ correctly for stack references if it was not set. Otherwise it failed
+ for both stack and heap references.) Thanks to Andrew McKinlay for the
+ critical test case.
+ - Integrated Tatsuya Bizenn's NETBSD threads support, with some
+ untested changes.
+ - Added GC_strdup and friends to make leak detection work correctly
+ for strdup clients. (Thanks to Jon Moore.) Fixed the existing strdup
+ with malloc redirection to handle a null malloc return correctly.
+
+Since gc6.7:
+ - Added some support for Dragonfly BSD. (Thanks to Joerg Sonnenberger and
+ Thomas Klausner.)
+ - Improvements to the HP/UX section of configure.in/configure.ac.
+ (Thanks to Andreas Tobler)
+ - GC_unix_get_mem could neglect to release the malloc lock on Irix, under
+ extremely unlikely circumstances. Thanks to Jean-Baptiste Nivois for
+ some careful code reading.
+ - Added support for kFreeBSD + glibc (Thanks to Petr Salinger)
+ - Fix more MacOS threads memory leaks (Thanks to Allan Hsu)
+ - Added initial Solaris/X86-64 support (Thanks to Rainer Orth)
+
+Since gc6.8:
+ - Fix typo in PREFETCH implementation for X86_64. (Thanks to Peter Wang.)
+ - Fix M68K LINUX port. (Thanks to Debian packagers.)
+ - __GNUC__ was misspelled as __GNUC in new_gc_alloc.h. (Thanks to Peter Wang.)
+ - Integrated Allan Hsu's patch for OS X VM deallocation problems.
+ - Applied FreeBSD/X86_64 patch.
+
+Since gc6.9:
+ - Remove GC_PROTO, VOLATILE, GC_PTR, and GC_CONST. Assume ANSI C compiler
+ and use ANSI constructs unconditionally.
+ - Introduce #elif and #error in some of the appropriate places.
+ - Remove GC_printf cruft. Use stdargs.
+ - Remove separate Solaris threads support. Use the more generic Posix
+ implementation.
+ - Use atomic_ops for atomic operations and memory barriers.
+ - Clean up MPROTECT_VDB implementation. Use SA_SIGINFO wherever
+ possible.
+ - Remove broken SIGNALS stuff.
+ - Use size_t instead of word, where appropriate.
+ - Add .S.o rule to Makefile.am.
+ - Officially unsupport SunOS4, several old flavors of M68K (SunOS4,
+ A/UX, HP), IBM PC/RTs and RISCOS/Irix4. (I doubt the old code worked.
+ If anyone cares, these should be easy to resurrect.)
+ - Add EXPECT() in some critical places.
+ - Redefined hb_sz and hb_body to deal with bytes rather than words.
+ This affected a great deal of code. I would like to consistently use
+ byte offsets and sizes where there's not a convincing reason to do
+ otherwise.
+ - Redefined several other variables (GC_mem_found, GC_words_allocd)
+ etc. to use units of bytes. Most of these were also renamed to
+ reflect that fact.
+ - Killed as many "register" declarations as possible.
+ - Partially replaced stubborn allocation with manual write barrier.
+ It's currently broken.
+ - Restructured mark code, to allow mark bits to be kept either on
+ a per allocation granule or per object basis. The emphasis is
+ now on the -DUSE_MARK_BYTES option, since individual bits perform
+ quite badly on hyperthreaded P4s, and are probably suboptimal on
+ other architectures. -DUSE_MARK_BITS is currently broken, and may
+ be resurrected only for the single-threaded case. This significantly
+ reduced the cache footprint required by auxiliary GC data structures.
+ It also reduces space overhead for small heaps. It probably slows
+ things down slightly if interior pointers are very common.
+ - As part of the above, we now maintain an approximate count of set
+ mark bits in each heap block.
+ - As part of the above, the semantics of hb_map changed drastically.
+ For MARK_BIT_PER_OBJ, it doesn't exist. For MARK_BIT_PER_GRANULE,
+ it is purely a way to replace a mod instruction with a table lookup.
+ (Somewhat to my surprise, this still wins on modern hardware.)
+ - Removed PRINTSTATS, GATHERSTATS, and SILENT macros. Everything is
+ now controlled by GC_print_stats variable and GC_PRINT_STATS
+ and new GC_PRINT_VERBOSE_STATS environment variables.
+ - Add GC_log_printf and use it consistently for logging output.
+ - Unconditionally count the objects we reclaim in the sweep phase.
+ For thread local allocation, we need that anyway, and we expect
+ that's increasingly the only case that matters. And it simplifies
+ the code. In general expect minor performance hacks that benefit
+ only the single-threaded case to disappear.
+ - Remove GC_quiet from gc.h and elsewhere.
+ - Changed the heap expansion heuristic, and the definition of
+ GC_free_space_divisor, to refer to live data size, instead of total
+ heap size. I believe this is much more robust. It wasn't previously
+ possible, because we didn't have access to live data size.
+ - Thread local allocation added the extra byte in twice: Once in
+ thread_local_alloc, and once in malloc_many.
+ - Removed GC_malloc_words_small and GC_gcj_fast_malloc. A new
+ mechanism based on the thread local allocation data structures
+ is expected to be added instead. This should allow inlined code
+ that is both fast and doesn't rely on collector internals.
+ - Changed both free lists and reclaim lists to be indexed by granules
+ instead of words, norming halving their size.
+ - MERGE_SIZE is now the only option, and the macro was removed.
+ (Without it, we need a memory reference to GC_all_interior_pointers
+ anyway. Thus it costs us nothing.)
+ - Change GC_size_map to map to granules instead of words. Make sure
+ that every possible size up to TINY_FREELISTS is present.
+ - Split of macros need for fast inline allocation into gc_tiny_fl.h
+ in anticipation of a new inline allocator that doesn't rely on GC
+ internals.
+ - Changed thread local allocation to use GRANULE_BYTES and TINY_FREELISTS
+ in anticipation of a merge with the inline allocation code.
+ - Removed ALIGN_DOUBLE. This is mostly handled by GRANULE_BYTES.
+ - Make locking on most platforms conditional on GC_need_to_lock.
+
+Since gc7.0alpha1:
+ - GC_bytes_allocd was incremented by a possibly uninitialized variable
+ in GC_generic_malloc_inner. (Bug introduced in gc7.0alpha1. Thanks
+ to Ben Hutchings for tracking it down.)
+ - Win32 fixes. (Thanks to Ben Hutchings and Maurizio Vairani.)
+ - Integrated Ben Hutchings' GetWriteWatch-based virtual dirty bit
+ implementation for win32.
+ - Removed pc_gc.tar and floppy targets in Makefile.direct. Removed
+ pc_excludes file.
+ - No longer include GC_bytes_wasted when evaluating allocation progress.
+ Since we are now counting live memory, it no longer makes sense.
+ - Applied Davide Angelocola's configury patch. There are now separate
+ Makefile.am's in the cord and tests subdirectory, more tests, etc.
+ - Renamed configure.in to configure.ac.
+ - Merged a very small number of Nathanael Nerode's configure.ac
+ cleanups from the gcc tree. Unfortunately, that file is a bit
+ different from ours.
+ - Changed EINTR handling in sem_wait slightly.
+ - Restructure the root marking code. Remove all traces of
+ USE_GENERIC_PUSH_REGS, and effectively make it the default.
+ Make it easier to pass a context pointer to the mark routine, in
+ case we ever want to do precise stack marking.
+ - Replace GC_start_blocking() and GC_end_blocking() with GC_do_blocking().
+ This remains undocumented, and only implemented for pthreads. But it
+ removes an otherwise unavoidable race with stores of callee-save
+ registers.
+ - Fix GC_n_mark_bits for the default MARK_BIT_PER_GRANULE case. This
+ resulted in bogus complaints in heap dumps.
+ - Upgrade to libatomic_ops-1.0, and update build structure to match.
+ - Remove SRC_M3 support. Clean up lock initialization code in misc.c.
+ - Removed gc_local_alloc.h. If THREAD_LOCAL_ALLOC is defined, the
+ thread local allocation routines are now called automatically.
+ - Renamed gc_inl.h back to gc_inline.h. Changed the interface appreciably
+ since locking has turned into a dominant issue, and in-line allocation
+ only makes sense if it's no worse than thread-local allocation.
+ Gc_inline.h is now also used to implement thread-local allocation.
+ - Finished replacing stubborn allocation with manual write barrier.
+ Untested.
+ - Use thread-local allocation code by default.
+ - Added GC_register_my_thread and friends for Posix and win32.
+ - Patch for GWW_VDB from Ben Hutchings.
+ - Removed explicit THREAD_LOCAL_ALLOC tests, since that now always
+ redefines GC_malloc.
+ - Removed now unused AIX memory allocation code.
+ - Various minor fixes for bugs introduced in 7.0alpha1.
+
+Since gc7.0alpha2
+ - Added support for dlopen-based interception of pthread functions.
+ This is only half done. The gc.h redefinitions currently interfere.
+ - Integrated major automake overhaul from Petter Urkedal.
+
+Since gc7.0alpha3
+ (various 6.5, 6.6 changes)
+ - Removed GC_brief_async_signal_safe_sleep and used atomic_ops instead.
+ (Thanks to Ben Maurer.)
+ - Integrated build patches from David Angelocola and Petter Urkedal.
+ - Fix dynamic-linker-based pthread call redirection.
+ - Renamed RS6000 to POWERPC/AIX.
+ - Allow recovery from SIGSEGV in marker on Linux. This works around
+ a race in thread stack marking if /proc is used to find roots. We do
+ that by default with malloc redirection and threads. This involved
+ moving some GC_find_limit and SETJMP related declarations to gc_priv.h.
+ - Added doc/porting.html file.
+ - Added ADD_HEAP_GUARD_PAGES for sbrk/*nix platforms to debug extreme
+ memory overwrite errors.
+ - Added trivial NO_INCREMENTAL flag to facilitate debugging.
+ - Added GC_getattr_np-based GC_get_stack_base (untested).
+ - Separated thread local allocation into a separate file and added the
+ beginning of win32 support for that.
+
+Since gc7.0alpha4
+ (more 6.6, 6.7 changes)
+ - Some Solaris fixes, including some more general changes in how
+ the assembly pieces of mach_dep.c are handled.
+ - Removed a lot of SOLARIS_THREADS-specific code that was only
+ needed with the old implementation. This included many (mostly no-op)
+ versions of GC_is_fresh.
+ - Don't use atomic_ops in gc_locks.h unless we need threads.
+ - Fixed USE_MARK_BITS, which is once againthe default without PARALLEL_MARK.
+ - Removed Solaris GC_INIT hack. It's a workaround for a long dead bug,
+ and it seemed to be wrong anyway.
+ - Changed win32_threads.c to require preprocessor-based interception
+ of thread routines by default. A client call to GC_use_DllMain is
+ now required to get the old behavior in which DllMain is used to implicitly
+ register threads. This was doen for uniformity with other platforms, and
+ because the DllMain solution seemed to require very tricky code which,
+ at least in the past, imposed hard bounds onthe number of threads.
+ - Many small changes to make thread support work again on Cygwin.
+ - Moved definition of allocator lock etc. to pthread_support.c and
+ win32_threads.c for those two cases.
+ - Got rid of the FASTLOCK() machinery. It doesn't seem useful on modern
+ platforms.
+ - Cleaned up the uncollectable allocation routines, speeding up the
+ slower paths. The code did enough unnecessary work off the critical path
+ that the underlying logic was getting hard to extract.
+ - No longer turn off THREAD_LOCAL_ALLOC with DBG_HDRS_ALL. Indications
+ are it just works, and I think the reasons for it not working disappeared
+ a while ago.
+ - Fixed bugs in hb_n_marks calculation and assertion.
+ - Don't use __builtin_expect for pre-3.0 gcc.
+ - Define GWW_VDB only for recent Microsoft tool chains.
+ - Add overview.html to doc directory.
+ - Fix NT_STATIC_THREADS_MAKEFILE, various compiler warnings.
+ - Made thread local allocation sort of work with Cygwin. The code should
+ be there to deal with other Windows variants, But non-Cygwin Windows
+ threads need more bug fixes.
+
+Since gc7.0alpha5
+ (more 6.7 changes)
+ - Declare GC_dump() in gc.h.
+ - Add --enable-large-config, which just defines the LARGE_CONFIG macro.
+ - Make GlobalAlloc address alignment a bit more intuitive. (Thanks to
+ Charles Mills.)
+ - Use #elif in the definitions of GET_MEM.
+ - Overhaul porting.html. Remove corresponding text from README.
+ - Fix typo in DARWIN section of gcconfig.h.
+ - Fix Darwin thread memory leak. (Thanks to Bruce Mitchener.)
+ - Update x86 AO_test_and_set implementation to use "=q".
+ - Add $(EXEEXT) to many tests in tests/tests.am. (Corresponds to a
+ 6.7 fix, which no longer applied.)
+ - Fix Darwin/PPC port.
+ - Fix Cygwin/threads port.
+ - Fix gcj malloc support.
+ - For GNU-style make, don't build libatomic_ops unless threads are requested.
+ This should allow single-threaded builds on platforms which do not
+ currently support libatomic_ops.
+ - Clean up and hopefully fix the CFLAGS calculation for GNU build.
+ (Substantially improves things on HP/UX.)
+ - Integrated Andrei Polushin's Visual C++ patches. These provide for
+ stack traces, better C++ debug support, and better log file handling.
+ Note that these change the location of the log file to a the path of the
+ executable with a .log extension. To get the old behavior back, define
+ OLD_WIN32_LOG_FILE. For the time being, I'm checking his project
+ files and the like into a windows-untested subdirectory. They
+ are almost certainly already out of date, but better than what we had
+ before.
+ - Fixed some win32 threads bugs, and added support for _beginthreadex.
+ - Fix zero size thread local allocation so that explicit deallocation
+ works correctly.
+ - Removed serious bug in GC_malloc_uncollectable(large size).
+ - Do not try to do thread-local gcj allocation in incremental mode. There
+ are races in setting up the descriptor.
+ - Add GC_INIT() to middle.c, fix some more GC_printfn calls.
+ - Some assertions erroneously used I_HOLD_LOCK() negatively, eventhough
+ it can now spuriously return TRUE.
+ - Rename SUNOS5 macro and OS name to SOLARIS and SUNOS5DL to SOLARISDL.
+ - On Linux and some Un*x variants, allocate memory by first trying sbrk,
+ and then switching to mmap if that fails.
+ - Fixed /proc/x/maps reading to deal with asynchronous deletions.
+ - Fix REDIRECT_MALLOC with threads on Linux. It now usually seems to work
+ with ugly hacks that include having calloc behave differently when it is
+ called from ld.so or the pthreads library. A reasonable amount of
+ infrastructure was added to support some of this. Thanks to Roland McGrath
+ for ideas and information.
+ - Import various updated build scripts.
+ - Add GC_register_has_static_roots_callback. (Thanks to Andrew Haley.)
+ - Fix serious bugs in GC_malloc_atomic_uncollectable().
+ - Return GC_SUCCESS form GC_get_stack_base().
+ - Fix several atomic_ops problems on IA64 with HP Compiler.
+ - Update to atomic_ops-1.2.
+ - Fix hb_n_marks description and reclaim.c assertion.
+ - Various additional win32 threads fixes.
+ - Enable GC_ASSERTIONS for Debug build with NT_THREADS_MAKEFILE.
+
+[gc7.0alpha7 was released and version bumped to gc7.0alpha8]
+
+Since first gc7.0alpha8 version:
+ [ Some gc6.9 changes ]
+ - Change FindTopOfStack decl in darwin_stop_world.c.
+ - Move some static tests from misc.c to gcconfig.h. Use #error.
+ - Add GC_print_free_list() function. (Thanks to Bruce Hoult.)
+ - Add GC_GNU_THREADS support on HURD. (Thanks to Aleksey Demakov,
+ Barry DeFreese, and possibly other Debian maintainers.)
+ - __GNUC__ was misspelled as __GNUC in thread_local_alloc.h.
+ (Thanks to Peter Wang.)
+ - Integrated various MacOSX patches and tried to reconcile them.
+ Thanks to Allan Hsu, several contributers at Apple, and probably
+ others.
+ - Added some casts to powerpc.h in libatomic_ops to silence warnings.
+
+FOR FURTHER UPDATES SEE ../ChangeLog FILE.
+
+To do:
+ - REDIRECT_MALLOC and threads combination should work on more platforms,
+ and needs more testing on Linux.
+ - Clone marker inner loop to support arch-dependent prefetching,
+ and counting of objects marked for finalization.
+ - The USE_MUNMAP code should really use a separate data structure
+ indexed by physical page to keep track of time since last use of
+ a page. Using hblk headers means we lose track of ages when
+ blocks are merged, and we can't unmap pages that have been allocated and
+ dropped by the blacklisting code. I suspect both of these matter.
+ - A dynamic libgc.so references dlopen unconditionally, but doesn't link
+ against libdl.
+ - GC_proc_fd for Solaris is not correctly updated in response to a
+ fork() call. Thus incremental collection in the child won't work
+ correctly. (Thanks to Ben Cottrell for pointing this out.)
+ - --enable-redirect-malloc is mostly untested and known not to work
+ on some platforms.
+ - There seem to be outstanding issues on Solaris/X86, possibly with
+ finding the data segment starting address. Information/patches would
+ be appreciated.
+ - Very large root set sizes (> 16 MB or so) could cause the collector
+ to abort with an unexpected mark stack overflow. (Thanks again to
+ Peter Chubb.) NOT YET FIXED. Workaround is to increase the initial
+ size.
+ - The SGI version of the collector marks from mmapped pages, even
+ if they are not part of dynamic library static data areas. This
+ causes performance problems with some SGI libraries that use mmap
+ as a bitmap allocator. NOT YET FIXED. It may be possible to turn
+ off DYNAMIC_LOADING in the collector as a workaround. It may also
+ be possible to conditionally intercept mmap and use GC_exclude_static_roots.
+ The real fix is to walk rld data structures, which looks possible.
+ - Incremental collector should handle large objects better. Currently,
+ it looks like the whole object is treated as dirty if any part of it
+ is.
+
+FOR FURTHER UPDATES SEE ../ChangeLog FILE.
projects / hs-boehmgc.git / blobdiff