+/*
+ * Copyright (c) 1999-2005 Hewlett-Packard Development Company, L.P.
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose, provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ */
+
+#ifndef GC_TINY_FL_H
+#define GC_TINY_FL_H
+/*
+ * Constants and data structures for "tiny" free lists.
+ * These are used for thread-local allocation or in-lined allocators.
+ * Each global free list also essentially starts with one of these.
+ * However, global free lists are known to the GC. "Tiny" free lists
+ * are basically private to the client. Their contents are viewed as
+ * "in use" and marked accordingly by the core of the GC.
+ *
+ * Note that inlined code might know about the layout of these and the constants
+ * involved. Thus any change here may invalidate clients, and such changes should
+ * be avoided. Hence we keep this as simple as possible.
+ */
+
+/*
+ * We always set GC_GRANULE_BYTES to twice the length of a pointer.
+ * This means that all allocation requests are rounded up to the next
+ * multiple of 16 on 64-bit architectures or 8 on 32-bit architectures.
+ * This appears to be a reasonable compromise between fragmentation overhead
+ * and space usage for mark bits (usually mark bytes).
+ * On many 64-bit architectures some memory references require 16-byte
+ * alignment, making this necessary anyway.
+ * For a few 32-bit architecture (e.g. x86), we may also need 16-byte alignment
+ * for certain memory references. But currently that does not seem to be the
+ * default for all conventional malloc implementations, so we ignore that
+ * problem.
+ * It would always be safe, and often useful, to be able to allocate very
+ * small objects with smaller alignment. But that would cost us mark bit
+ * space, so we no longer do so.
+ */
+#ifndef GC_GRANULE_BYTES
+ /* GC_GRANULE_BYTES should not be overridden in any instances of the GC */
+ /* library that may be shared between applications, since it affects */
+ /* the binary interface to the library. */
+# if defined(__LP64__) || defined (_LP64) || defined(_WIN64) \
+ || defined(__s390x__) \
+ || (defined(__x86_64__) && !defined(__ILP32__)) \
+ || defined(__alpha__) || defined(__powerpc64__) \
+ || defined(__arch64__)
+# define GC_GRANULE_BYTES 16
+# define GC_GRANULE_WORDS 2
+# else
+# define GC_GRANULE_BYTES 8
+# define GC_GRANULE_WORDS 2
+# endif
+#endif /* !GC_GRANULE_BYTES */
+
+#if GC_GRANULE_WORDS == 2
+# define GC_WORDS_TO_GRANULES(n) ((n)>>1)
+#else
+# define GC_WORDS_TO_GRANULES(n) ((n)*sizeof(void *)/GC_GRANULE_BYTES)
+#endif
+
+/* A "tiny" free list header contains TINY_FREELISTS pointers to */
+/* singly linked lists of objects of different sizes, the ith one */
+/* containing objects i granules in size. Note that there is a list */
+/* of size zero objects. */
+#ifndef GC_TINY_FREELISTS
+# if GC_GRANULE_BYTES == 16
+# define GC_TINY_FREELISTS 25
+# else
+# define GC_TINY_FREELISTS 33 /* Up to and including 256 bytes */
+# endif
+#endif /* !GC_TINY_FREELISTS */
+
+/* The ith free list corresponds to size i*GC_GRANULE_BYTES */
+/* Internally to the collector, the index can be computed with */
+/* ROUNDED_UP_GRANULES. Externally, we don't know whether */
+/* DONT_ADD_BYTE_AT_END is set, but the client should know. */
+
+/* Convert a free list index to the actual size of objects */
+/* on that list, including extra space we added. Not an */
+/* inverse of the above. */
+#define GC_RAW_BYTES_FROM_INDEX(i) ((i) * GC_GRANULE_BYTES)
+
+#endif /* GC_TINY_FL_H */
projects / hs-boehmgc.git / blobdiff