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When looking for dependencies on the src pointer, scan the src pointer. Scanning

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on the memcpy call will pull up other unrelated stuff. Fixes PR11142.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142150 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2011-10-16 20:13:32 +00:00
parent ea6578b72a
commit 36c7e6c36c
2 changed files with 36 additions and 13 deletions
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29
lib/Transforms/Scalar/MemCpyOptimizer.cpp
View File

@ -806,21 +806,26 @@ bool MemCpyOpt::processMemCpy(MemCpyInst *M) {
// a) memcpy-memcpy xform which exposes redundance for DSE.
// b) call-memcpy xform for return slot optimization.
MemDepResult DepInfo = MD->getDependency(M);
if (!DepInfo.isClobber())
return false;
if (MemCpyInst *MDep = dyn_cast<MemCpyInst>(DepInfo.getInst()))
return processMemCpyMemCpyDependence(M, MDep, CopySize->getZExtValue());
if (CallInst *C = dyn_cast<CallInst>(DepInfo.getInst())) {
if (performCallSlotOptzn(M, M->getDest(), M->getSource(),
CopySize->getZExtValue(), C)) {
MD->removeInstruction(M);
M->eraseFromParent();
return true;
if (DepInfo.isClobber()) {
if (CallInst *C = dyn_cast<CallInst>(DepInfo.getInst())) {
if (performCallSlotOptzn(M, M->getDest(), M->getSource(),
CopySize->getZExtValue(), C)) {
MD->removeInstruction(M);
M->eraseFromParent();
return true;
}
}
}
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
AliasAnalysis::Location SrcLoc = AA.getLocationForSource(M);
MemDepResult SrcDepInfo = MD->getPointerDependencyFrom(SrcLoc, true,
M, M->getParent());
if (SrcDepInfo.isClobber()) {
if (MemCpyInst *MDep = dyn_cast<MemCpyInst>(SrcDepInfo.getInst()))
return processMemCpyMemCpyDependence(M, MDep, CopySize->getZExtValue());
}
return false;
}

20
test/Transforms/MemCpyOpt/memcpy.ll
View File

@ -59,7 +59,7 @@ define void @test3(%0* noalias sret %agg.result) nounwind {
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %agg.result2, i8* %x.01, i32 32, i32 16, i1 false)
ret void
; CHECK: @test3
; CHECK-NEXT: %agg.result2 = bitcast
; CHECK-NEXT: %agg.result1 = bitcast
; CHECK-NEXT: call void @llvm.memcpy
; CHECK-NEXT: ret void
}
@ -130,3 +130,21 @@ declare i32 @g(%struct.p* byval align 8)
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
; PR11142 - When looking for a memcpy-memcpy dependency, don't get stuck on
; instructions between the memcpy's that only affect the destination pointer.
@test8.str = internal constant [7 x i8] c"ABCDEF\00"
define void @test8() {
; CHECK: test8
%A = tail call i8* @malloc(i32 10)
%B = getelementptr inbounds i8* %A, i64 2
tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %B, i8* getelementptr inbounds ([7 x i8]* @test8.str, i64 0, i64 0), i32 7, i32 1, i1 false)
; CHECK: tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %D, i8* getelementptr
%C = tail call i8* @malloc(i32 10)
%D = getelementptr inbounds i8* %C, i64 2
tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %D, i8* %B, i32 7, i32 1, i1 false)
; CHECK: tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %D, i8* getelementptr
ret void
}
declare noalias i8* @malloc(i32)