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Fix bug in x86 memcpy / memset lowering. If there are trailing bytes not handled by rep instructions, a new memcpy / memset is introduced for them. However, since source / destination addresses are already adjusted, their offsets should be zero.

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llvm-svn: 50239
This commit is contained in:
Evan Cheng 2008-04-25 00:26:43 +00:00
parent 247bdc8ec7
commit 484060ba4a
2 changed files with 20 additions and 11 deletions
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19
lib/Target/X86/X86ISelLowering.cpp
View File

@ -4822,7 +4822,7 @@ X86TargetLowering::EmitTargetCodeForMemset(SelectionDAG &DAG,
DAG.getConstant(Offset, AddrVT)),
Src,
DAG.getConstant(BytesLeft, SizeVT),
Align, DstSV, Offset);
Align, DstSV, 0);
}
// TODO: Use a Tokenfactor, as in memcpy, instead of a single chain.
@ -4847,8 +4847,6 @@ X86TargetLowering::EmitTargetCodeForMemcpy(SelectionDAG &DAG,
if (!AlwaysInline && SizeVal > getSubtarget()->getMaxInlineSizeThreshold())
return SDOperand();
SmallVector<SDOperand, 4> Results;
MVT::ValueType AVT;
unsigned BytesLeft = 0;
if (Align >= 8 && Subtarget->is64Bit())
@ -4881,25 +4879,24 @@ X86TargetLowering::EmitTargetCodeForMemcpy(SelectionDAG &DAG,
Ops.push_back(Chain);
Ops.push_back(DAG.getValueType(AVT));
Ops.push_back(InFlag);
Results.push_back(DAG.getNode(X86ISD::REP_MOVS, Tys, &Ops[0], Ops.size()));
SDOperand RepMovs = DAG.getNode(X86ISD::REP_MOVS, Tys, &Ops[0], Ops.size());
SmallVector<SDOperand, 4> Results;
Results.push_back(RepMovs);
if (BytesLeft) {
// Handle the last 1 - 7 bytes.
unsigned Offset = SizeVal - BytesLeft;
MVT::ValueType DstVT = Dst.getValueType();
MVT::ValueType SrcVT = Src.getValueType();
MVT::ValueType SizeVT = Size.getValueType();
Results.push_back(DAG.getMemcpy(Chain,
Results.push_back(DAG.getMemcpy(Chain,
DAG.getNode(ISD::ADD, DstVT, Dst,
DAG.getConstant(Offset,
DstVT)),
DAG.getConstant(Offset, DstVT)),
DAG.getNode(ISD::ADD, SrcVT, Src,
DAG.getConstant(Offset,
SrcVT)),
DAG.getConstant(Offset, SrcVT)),
DAG.getConstant(BytesLeft, SizeVT),
Align, AlwaysInline,
DstSV, Offset, SrcSV, Offset));
DstSV, 0, SrcSV, 0));
}
return DAG.getNode(ISD::TokenFactor, MVT::Other, &Results[0], Results.size());

12
test/CodeGen/X86/2008-04-24-MemCpyBug.ll Normal file
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@ -0,0 +1,12 @@
; RUN: llvm-as < %s | llc -march=x86 | not grep 120
; Don't accidentally add the offset twice for trailing bytes.
%struct.S63 = type { [63 x i8] }
@g1s63 = external global %struct.S63 ; <%struct.S63*> [#uses=1]
declare void @test63(%struct.S63* byval align 4 ) nounwind
define void @testit63_entry_2E_ce() nounwind {
tail call void @test63( %struct.S63* byval align 4 @g1s63 ) nounwind
ret void
}