Repository : ssh://g...@git.haskell.org/ghc
On branch : master
Link :
http://ghc.haskell.org/trac/ghc/changeset/56084d76eb1b57ad96a9e1c55f3d3e2d134f98d5/ghc
>---------------------------------------------------------------
commit 56084d76eb1b57ad96a9e1c55f3d3e2d134f98d5
Author: Simon Marlow <marlo...@gmail.com>
Date: Tue Sep 17 21:42:54 2013 +0100
Expand the commentary in Note [syntax of cmm files]
>---------------------------------------------------------------
56084d76eb1b57ad96a9e1c55f3d3e2d134f98d5
compiler/cmm/CmmParse.y | 33 +++++++++++++++++++++++++++++----
1 file changed, 29 insertions(+), 4 deletions(-)
diff --git a/compiler/cmm/CmmParse.y b/compiler/cmm/CmmParse.y
index 8367f7a..dee5c7d 100644
--- a/compiler/cmm/CmmParse.y
+++ b/compiler/cmm/CmmParse.y
@@ -104,15 +104,40 @@ Both high-level and low-level code can use a raw
tail-call:
jump stg_fun [R1,R2]
-This always transfers control to a low-level Cmm function, but the
-call can be made from high-level code. Arguments must be passed
-explicitly in R/F/D/L registers.
-
NB. you *must* specify the list of GlobalRegs that are passed via a
jump, otherwise the register allocator will assume that all the
GlobalRegs are dead at the jump.
+Calling Conventions
+-------------------
+
+High-level procedures use the NativeNode calling convention, or the
+NativeReturn convention if the 'return' keyword is used (see Stack
+Frames below).
+
+Low-level procedures implement their own calling convention, so it can
+be anything at all.
+
+If a low-level procedure implements the NativeNode calling convention,
+then it can be called by high-level code using an ordinary function
+call. In general this is hard to arrange because the calling
+convention depends on the number of physical register available for
+parameter passing, but there are two cases where the calling
+convention is platform-independnt:
+
+ - Zero arguments.
+
+ - One argument of pointer or non-pointer word type; this is always
+ passed in R1 according to the NativeNode convention.
+
+ - Returning a single value; these conventions are fixed and platform
+ independent.
+
+
+Stack Frames
+------------
+
A stack frame is written like this:
INFO_TABLE_RET ( label, FRAME_TYPE, info_ptr, field1, ..., fieldN )
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