[llvm-commits] [llvm-gcc-4.2] r52058 - in /llvm-gcc-4.2/trunk/gcc: config/i386/llvm-i386.cpp llvm-abi.h

[Dale Johannesen]

Author: johannes
Date: Fri Jun  6 14:56:41 2008
New Revision: 52058

URL: http://llvm.org/viewvc/llvm-project?rev=52058&view=rev
Log:
X86-64 ABI:  add handling for zero-length structs in C++.
These are padded to 1 byte, but are not passed the same
as normal 1-byte structs, nor as C zero-length structs.


Modified:
    llvm-gcc-4.2/trunk/gcc/config/i386/llvm-i386.cpp
    llvm-gcc-4.2/trunk/gcc/llvm-abi.h

Modified: llvm-gcc-4.2/trunk/gcc/config/i386/llvm-i386.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/config/i386/llvm-i386.cpp?rev=52058&r1=52057&r2=52058&view=diff

==============================================================================
--- llvm-gcc-4.2/trunk/gcc/config/i386/llvm-i386.cpp (original)
+++ llvm-gcc-4.2/trunk/gcc/config/i386/llvm-i386.cpp Fri Jun  6 14:56:41 2008
@@ -554,7 +554,12 @@
                                                         enum machine_mode Mode){
   int IntRegs, SSERegs;
   /* If ix86_HowToPassArgument return 0, then it's passed byval in memory.*/
-  return !ix86_HowToPassArgument(Mode, TreeType, 0, &IntRegs, &SSERegs);
+  int ret = ix86_HowToPassArgument(Mode, TreeType, 0, &IntRegs, &SSERegs);
+  if (ret==0)
+    return true;
+  if (ret==1 && IntRegs==0 && SSERegs==0)   // zero-sized struct
+    return true;
+  return false;
 }
 
 /* Returns true if all elements of the type are integer types. */

Modified: llvm-gcc-4.2/trunk/gcc/llvm-abi.h
URL: http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/llvm-abi.h?rev=52058&r1=52057&r2=52058&view=diff

==============================================================================
--- llvm-gcc-4.2/trunk/gcc/llvm-abi.h (original)
+++ llvm-gcc-4.2/trunk/gcc/llvm-abi.h Fri Jun  6 14:56:41 2008
@@ -449,12 +449,22 @@
     } else if (TREE_CODE(type) == RECORD_TYPE) {
       for (tree Field = TYPE_FIELDS(type); Field; Field = TREE_CHAIN(Field))
         if (TREE_CODE(Field) == FIELD_DECL) {
+          const tree Ftype = getDeclaredType(Field);
+          const Type *FTy = ConvertType(Ftype);
           unsigned FNo = GetFieldIndex(Field);
           assert(FNo != ~0U && "Case not handled yet!");
-          
-          C.EnterField(FNo, Ty);
-          HandleArgument(getDeclaredType(Field), ScalarElts);
-          C.ExitField();
+
+          // Currently, a bvyal type inside a non-byval struct is a zero-length
+          // object inside a bigger object on x86-64.  This type should be
+          // skipped (but only when it is inside a bigger object).
+          // (We know there currently are no other such cases active because
+          // they would hit the assert in FunctionPrologArgumentConversion::
+          // HandleByValArgument.)
+          if (!LLVM_SHOULD_PASS_AGGREGATE_USING_BYVAL_ATTR(Ftype, FTy)) {
+            C.EnterField(FNo, Ty);
+            HandleArgument(getDeclaredType(Field), ScalarElts);
+            C.ExitField();
+          }
         }
     } else if (TREE_CODE(type) == COMPLEX_TYPE) {
       C.EnterField(0, Ty);