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Fix a bug in GVN that Duncan noticed, where we potentially need to insert a

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pointer bitcast when performing return slot optimization.

llvm-svn: 48343
This commit is contained in:
Owen Anderson 2008-03-13 22:07:10 +00:00
parent 795aaef9d1
commit 6c2454d9d1
2 changed files with 24 additions and 1 deletions
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6
lib/Transforms/Scalar/GVN.cpp
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@ -1171,8 +1171,12 @@ bool GVN::performCallSlotOptzn(MemCpyInst* cpy, CallInst* C,
// All the checks have passed, so do the transformation.
for (unsigned i = 0; i < CS.arg_size(); ++i)
if (CS.getArgument(i) == cpySrc)
if (CS.getArgument(i) == cpySrc) {
if (cpySrc->getType() != cpyDest->getType())
cpyDest = CastInst::createPointerCast(cpyDest, cpySrc->getType(),
cpyDest->getName(), C);
CS.setArgument(i, cpyDest);
}
// Drop any cached information about the call, because we may have changed
// its dependence information by changing its parameter.

19
test/Transforms/GVN/2008-03-13-ReturnSlotBitcast.ll Normal file
View File

@ -0,0 +1,19 @@
; RUN: llvm-as < %s | opt -gvn | llvm-dis | not grep {call.*memcpy.}
%a = type { i32 }
%b = type { float }
declare void @llvm.memcpy.i32(i8*, i8*, i32, i32) nounwind
declare void @g(%a*)
define float @f() {
entry:
%a_var = alloca %a
%b_var = alloca %b
call void @g(%a *%a_var)
%a_i8 = bitcast %a* %a_var to i8*
%b_i8 = bitcast %b* %b_var to i8*
call void @llvm.memcpy.i32(i8* %b_i8, i8* %a_i8, i32 4, i32 4)
%tmp1 = getelementptr %b* %b_var, i32 0, i32 0
%tmp2 = load float* %tmp1
ret float %tmp2
}