Support for 64-bit architectures: x86 in 64-bit mode

This commit enriches the IA32 port so that it supports x86 processors in 64-bit mode as well as in 32-bit mode, depending on the value of Archi.ptr64, which itself is set from the configuration model.

To activate x86-64 bit support, configure with "x86_64-linux".

Main steps:
- Enrich Op.v and Asm.v with 64-bit operations
- SelectLong: in 64-bit mode, use 64-bit operations directly; in 32-bit mode, fall back on the old implementation based on pairs of 32-bit integers
- Conventions1: support x86-64 ABI in addition to the 32-bit ABI.
- Add support for the new 64-bit operations everywhere.
- runtime/x86_64: implementation of the supporting library appropriate for x86 in 64-bit mode

To do:
- More optimizations are possible on 64-bit integer arithmetic operations.
- Could add new chunks to load, say, an unsigned byte into a 64-bit long
  (currently we load as a 32-bit int then zero-extend).
- Implements the wrong ABI for struct passing.

1 files changed, 6 insertions, 3 deletions

diff --git a/ia32/CBuiltins.ml b/ia32/CBuiltins.ml
index 79a839f3..1fe3b200 100644
--- a/ia32/CBuiltins.ml
+++ b/ia32/CBuiltins.ml
@@ -19,12 +19,15 @@ open C
 
 let builtins = {
   Builtins.typedefs = [
-    "__builtin_va_list", TPtr(TVoid [], [])
+    (* Actually a struct passed by reference; equivalent to 3 64-bit words *)
+    "__builtin_va_list", TArray(TInt(IULong, []), Some 3L, [])
   ];
   Builtins.functions = [
     (* Integer arithmetic *)
     "__builtin_bswap",
       (TInt(IUInt, []), [TInt(IUInt, [])], false);
+    "__builtin_bswap64",
+      (TInt(IULongLong, []), [TInt(IULongLong, [])], false);
     "__builtin_bswap32",
       (TInt(IUInt, []), [TInt(IUInt, [])], false);
     "__builtin_bswap16",
@@ -79,8 +82,8 @@ let builtins = {
   ]
 }
 
-let size_va_list = 4
-let va_list_scalar = true
+let size_va_list = 3*8
+let va_list_scalar = false
 
 (* Expand memory references inside extended asm statements.  Used in C2C. *)