Introduce register pairs to describe calling conventions more precisely

This commit changes the loc_arguments and loc_result functions that describe calling conventions so that each argument/result can be mapped either to a single location or (in the case of a 64-bit integer) to a pair of two 32-bit locations.

In the current CompCert, all arguments/results of type Tlong are systematically split in two 32-bit halves.  We will need to change this in the future to support 64-bit processors.  The alternative approach implemented by this commit enables the loc_arguments and loc_result functions to describe precisely which arguments need splitting.  Eventually, the remainder of CompCert should not assume anything about splitting 64-bit types in two halves.

Summary of changes:
- AST: introduce the type "rpair A" of register pairs
- Conventions1, Conventions: use it when describing calling conventions
- LTL, Linear, Mach, Asm: honor the new calling conventions when observing external calls
- Events: suppress external_call', no longer useful
- All passes from Allocation to Asmgen: adapt accordingly.

1 files changed, 1 insertions, 1 deletions

diff --git a/configure b/configure
index 2dc60d28..6b0b4da8 100755
--- a/configure
+++ b/configure
@@ -314,7 +314,7 @@ else
   ocaml_opt_comp=false
 fi
 
-MENHIR_REQUIRED=20160303
+MENHIR_REQUIRED=20151112
 echo "Testing Menhir... " | tr -d '\n'
 menhir_ver=`menhir --version 2>/dev/null | sed -n -e 's/^.*version \([0-9]*\).*$/\1/p'`
 case "$menhir_ver" in