Revert suppression of __builtin_{read,write}_reversed for x86 and ARM,

for compatibility with earlier CompCert versions.
But don't use them in PackedStructs.


git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2216 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e

3 files changed, 38 insertions, 3 deletions

diff --git a/ia32/CBuiltins.ml b/ia32/CBuiltins.ml
index 4a3dde5..cbd5998 100644
--- a/ia32/CBuiltins.ml
+++ b/ia32/CBuiltins.ml
@@ -33,6 +33,15 @@ let builtins = {
     "__builtin_fmax",
       (TFloat(FDouble, []), [TFloat(FDouble, []); TFloat(FDouble, [])], false);
     "__builtin_fmin",
-      (TFloat(FDouble, []), [TFloat(FDouble, []); TFloat(FDouble, [])], false)
+      (TFloat(FDouble, []), [TFloat(FDouble, []); TFloat(FDouble, [])], false);
+    (* Memory accesses *)
+    "__builtin_read16_reversed",
+      (TInt(IUShort, []), [TPtr(TInt(IUShort, [AConst]), [])], false);
+    "__builtin_read32_reversed",
+      (TInt(IUInt, []), [TPtr(TInt(IUInt, [AConst]), [])], false);
+    "__builtin_write16_reversed",
+      (TVoid [], [TPtr(TInt(IUShort, []), []); TInt(IUShort, [])], false);
+    "__builtin_write32_reversed",
+      (TVoid [], [TPtr(TInt(IUInt, []), []); TInt(IUInt, [])], false);
   ]
 }
diff --git a/ia32/Machregs.v b/ia32/Machregs.v
index a2f3c3e..31ea8ee 100644
--- a/ia32/Machregs.v
+++ b/ia32/Machregs.v
@@ -101,6 +101,11 @@ Definition destroyed_by_cond (cond: condition): list mreg :=
 Definition destroyed_by_jumptable: list mreg :=
   nil.
 
+Local Open Scope string_scope.
+
+Definition builtin_write16_reversed := ident_of_string "__builtin_write16_reversed".
+Definition builtin_write32_reversed := ident_of_string "__builtin_write32_reversed".
+
 Definition destroyed_by_builtin (ef: external_function): list mreg :=
   match ef with
   | EF_memcpy sz al =>
@@ -109,6 +114,10 @@ Definition destroyed_by_builtin (ef: external_function): list mreg :=
   | EF_vstore Mfloat32 => X7 :: nil
   | EF_vstore_global (Mint8unsigned|Mint8signed) _ _ => AX :: nil
   | EF_vstore_global Mfloat32 _ _ => X7 :: nil
+  | EF_builtin id sg =>
+      if ident_eq id builtin_write16_reversed
+      || ident_eq id builtin_write32_reversed
+      then CX :: DX :: nil else nil
   | _ => nil
   end.
 
@@ -131,8 +140,6 @@ Definition mregs_for_operation (op: operation): list (option mreg) * option mreg
   | _ => (nil, None)
   end.
 
-Local Open Scope string_scope.
-
 Definition builtin_negl := ident_of_string "__builtin_negl".
 Definition builtin_addl := ident_of_string "__builtin_addl".
 Definition builtin_subl := ident_of_string "__builtin_subl".
diff --git a/ia32/PrintAsm.ml b/ia32/PrintAsm.ml
index 0878371..2d676d1 100644
--- a/ia32/PrintAsm.ml
+++ b/ia32/PrintAsm.ml
@@ -442,6 +442,25 @@ let print_builtin_inline oc name args res =
   | "__builtin_mull", [IR a; IR b], [IR rh; IR rl] ->
       assert (a = EAX && b = EDX && rh = EDX && rl = EAX);
       fprintf oc "	mull    %a\n" ireg EDX
+  (* Memory accesses *)
+  | "__builtin_read16_reversed", [IR a1], [IR res] ->
+      fprintf oc "	movzwl	0(%a), %a\n" ireg a1 ireg res;
+      fprintf oc "	rolw	$8, %a\n" ireg16 res
+  | "__builtin_read32_reversed", [IR a1], [IR res] ->
+      fprintf oc "	movl	0(%a), %a\n" ireg a1 ireg res;
+      fprintf oc "	bswap	%a\n" ireg res
+  | "__builtin_write16_reversed", [IR a1; IR a2], _ ->
+      let tmp = if a1 = ECX then EDX else ECX in
+      if a2 <> tmp then
+        fprintf oc "	movl	%a, %a\n" ireg a2 ireg tmp;
+      fprintf oc "	xchg	%a, %a\n" ireg8 tmp high_ireg8 tmp;
+      fprintf oc "	movw	%a, 0(%a)\n" ireg16 tmp ireg a1
+  | "__builtin_write32_reversed", [IR a1; IR a2], _ ->
+      let tmp = if a1 = ECX then EDX else ECX in
+      if a2 <> tmp then
+        fprintf oc "	movl	%a, %a\n" ireg a2 ireg tmp;
+      fprintf oc "	bswap	%a\n" ireg tmp;
+      fprintf oc "	movl	%a, 0(%a)\n" ireg tmp ireg a1
   (* Catch-all *)  
   | _ ->
       invalid_arg ("unrecognized builtin " ^ name)