[cfe-commits] r69687 - /cfe/trunk/lib/CodeGen/CodeGenFunction.cpp

[Chris Lattner]

Author: lattner
Date: Tue Apr 21 12:59:23 2009
New Revision: 69687

URL: http://llvm.org/viewvc/llvm-project?rev=69687&view=rev
Log:
don't bother emitting a zero byte memset at all.  We used to get them
in cases like this:

typedef struct {
  short instance;
  char name[0];
} ATTR_LIST_ENTRY2;

void test() {
  ATTR_LIST_ENTRY2 X = (ATTR_LIST_ENTRY2) { .instance = 7, };
}  

While it is safe to emit them, it is pretty silly.


Modified:
    cfe/trunk/lib/CodeGen/CodeGenFunction.cpp

Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.cpp?rev=69687&r1=69686&r2=69687&view=diff

==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.cpp Tue Apr 21 12:59:23 2009
@@ -396,8 +396,7 @@
   return LabelIDs.insert(std::make_pair(L, LabelIDs.size())).first->second;
 }
 
-void CodeGenFunction::EmitMemSetToZero(llvm::Value *DestPtr, QualType Ty)
-{
+void CodeGenFunction::EmitMemSetToZero(llvm::Value *DestPtr, QualType Ty) {
   const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
   if (DestPtr->getType() != BP)
     DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
@@ -405,6 +404,10 @@
   // Get size and alignment info for this aggregate.
   std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
 
+  // Don't bother emitting a zero-byte memset.
+  if (TypeInfo.first == 0)
+    return;
+  
   // FIXME: Handle variable sized types.
   const llvm::Type *IntPtr = llvm::IntegerType::get(LLVMPointerWidth);