Merge pull request #5714 from alexischr/update_bockbuild

[mono.git] / docs / mini-doc.txt

diff --git a/docs/mini-doc.txt b/docs/mini-doc.txt
index 30d9b4442b7ad5cc8c24bb5c2f67e04f5ab88008..ba19c1031f112256c83295ebe53f2ecf6dfb8680 100644 (file)
--- a/docs/mini-doc.txt
+++ b/docs/mini-doc.txt
@@ -4,7 +4,15 @@
           Miguel de Icaza (miguel@{ximian.com,gnome.org}),
           Paolo Molaro (lupus@{ximian.com,debian.org})
 
-  
+       This documents overall design of the Mono JIT up to version
+       2.0.   After Mono 2.0 the JIT engine was upgraded from
+       a tree-based intermediate representation to a linear
+       intermediate representation.
+
+       The Linear IL is documented here:
+
+           http://www.mono-project.com/Linear_IL
+
 * Abstract
 
        Mini is a new compilation engine for the Mono runtime.  The
@@ -70,6 +78,24 @@
        CIL code on the fly to marshal parameters, and then this
        code is in turned processed by the JIT engine.
 
+       Mono has now gone through three different JIT engines, these
+       are:
+
+       * Original JIT engine: 2002, hard to port, hard to
+         implement optimizations.
+
+       * Second JIT engine, used up until Mono 2.0, very
+          portable, many new optimizations.
+
+       * Third JIT engine, replaced the code generation layer from
+         being based on a tree representation to be based on a linear
+         representation.
+
+        For more information on the code generation changes, see our
+       web site for the details on the Linear IL:
+
+           http://www.mono-project.com/Linear_IL
+
 * Previous Experiences
 
        Mono has built a JIT engine, which has been used to bootstrap
@@ -162,7 +188,7 @@
        application domains, or generate code that will not be shared
        across application domains.
 
-* Objectives of the new JIT engine.
+* Second Generation JIT engine.
 
        We wanted to support a number of features that were missing:
 
@@ -206,7 +232,7 @@
             necessary that the JIT engine works in most of today's
             commercial hardware platforms. 
 
-* Features of the new JIT engine.
+* Features of the Second JIT engine.
 
        The new JIT engine was architected by Dietmar Maurer and Paolo
        Molaro, based on the new objectives.
@@ -375,13 +401,14 @@
        variables to registers.  The linear scan pass uses the
        information that was previously gathered by the loop nesting
        and loop structure computation to favor variables in inner
-       loops. 
+       loops.   This process updates the basic block `nesting' field
+       which is later used during liveness analysis.
 
        Stack space is then reserved for the local variables and any
        temporary variables generated during the various
        optimizations.
 
-** Instruction selection 
+** Instruction selection: Only used up until Mono 2.0
 
        At this point, the BURS instruction selector is invoked to
        transform the tree-based representation into a list of
@@ -489,7 +516,9 @@
        operations if possible.
 
        The rest of the code generation is fairly simple: a switch
-       statement is used to generate code for each of the MonoInsts
+       statement is used to generate code for each of the MonoInsts,
+       in the mono/mini/mini-ARCH.c files, the method is called
+       "mono_arch_output_basic_block".
 
        We always try to allocate code in sequence, instead of just using
        malloc. This way we increase spatial locality which gives a massive
@@ -606,7 +635,7 @@
        registers, fixed registers and clobbered registers by each
        operation.
 
-* BURG Code Generator Generator
+* BURG Code Generator Generator: Only used up to Mono 2.0
 
        monoburg was written by Dietmar Maurer. It is based on the
        papers from Christopher W. Fraser, Robert R. Henry and Todd
@@ -765,4 +794,4 @@
        processors, and some of the framework exists today in our
        register allocator and the instruction selector to cope with
        this, but has not been finished.  The instruction selection
-       would happen at the same time as local register allocation. <
\ No newline at end of file
+       would happen at the same time as local register allocation. <