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[MemCpyOpt] Account for case that MemInsertPoint == BI. 

In that case, the new MemoryDef needs to be inserted *before*
MemInsertPoint.
This commit is contained in:
Florian Hahn 2020-09-04 13:58:59 +01:00
parent 4d536c6da5
commit 6bc5e866bd
2 changed files with 33 additions and 2 deletions
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8
llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
View File

@ -423,8 +423,12 @@ Instruction *MemCpyOptPass::tryMergingIntoMemset(Instruction *StartInst,
if (MSSAU) {
assert(LastMemDef && MemInsertPoint &&
"Both LastMemDef and MemInsertPoint need to be set");
auto *NewDef = cast<MemoryDef>(
MSSAU->createMemoryAccessAfter(AMemSet, LastMemDef, MemInsertPoint));
auto *NewDef =
cast<MemoryDef>(MemInsertPoint->getMemoryInst() == &*BI
? MSSAU->createMemoryAccessBefore(
AMemSet, LastMemDef, MemInsertPoint)
: MSSAU->createMemoryAccessAfter(
AMemSet, LastMemDef, MemInsertPoint));
MSSAU->insertDef(NewDef, /*RenameUses=*/true);
LastMemDef = NewDef;
MemInsertPoint = NewDef;

27
llvm/test/Transforms/MemCpyOpt/preserve-memssa.ll
View File

@ -123,6 +123,33 @@ entry:
ret i8 %0
}
define void @test7([4 x i32]* %ptr) {
; CHECK-LABEL: @test7(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds [4 x i32], [4 x i32]* [[PTR:%.*]], i64 0, i32 0
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds [4 x i32], [4 x i32]* [[PTR]], i64 0, i32 1
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds [4 x i32], [4 x i32]* [[PTR]], i64 0, i32 2
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds [4 x i32], [4 x i32]* [[PTR]], i64 0, i32 3
; CHECK-NEXT: [[TMP4:%.*]] = bitcast i32* [[TMP0]] to i8*
; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* align 1 [[TMP4]], i8 0, i64 16, i1 false)
; CHECK-NEXT: call void @clobber()
; CHECK-NEXT: ret void
;
entry:
%0 = getelementptr inbounds [4 x i32], [4 x i32]* %ptr, i64 0, i32 0
store i32 0, i32* %0, align 1
%1 = getelementptr inbounds [4 x i32], [4 x i32]* %ptr, i64 0, i32 1
store i32 0, i32* %1, align 1
%2 = getelementptr inbounds [4 x i32], [4 x i32]* %ptr, i64 0, i32 2
store i32 0, i32* %2, align 1
%3 = getelementptr inbounds [4 x i32], [4 x i32]* %ptr, i64 0, i32 3
store i32 0, i32* %3, align 1
call void @clobber()
ret void
}
declare void @clobber()
; Function Attrs: argmemonly nounwind willreturn
declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) #0