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MemCpyOpt: When merging memsets also merge the trivial case of two memsets with the same destination.

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The testcase is from PR19092, but I think the bug described there is actually a clang issue.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203489 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2014-03-10 21:05:13 +00:00
parent d89b0f200c
commit 8da0b7358d
2 changed files with 19 additions and 0 deletions
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7
lib/Transforms/Scalar/MemCpyOptimizer.cpp
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@ -75,6 +75,13 @@ static bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset,
const DataLayout &TD) {
Ptr1 = Ptr1->stripPointerCasts();
Ptr2 = Ptr2->stripPointerCasts();
// Handle the trivial case first.
if (Ptr1 == Ptr2) {
Offset = 0;
return true;
}
GEPOperator *GEP1 = dyn_cast<GEPOperator>(Ptr1);
GEPOperator *GEP2 = dyn_cast<GEPOperator>(Ptr2);

12
test/Transforms/MemCpyOpt/form-memset.ll
View File

@ -272,3 +272,15 @@ define void @test9() nounwind {
; CHECK-LABEL: @test9(
; CHECK: call void @llvm.memset.p0i8.i64(i8* bitcast ([16 x i64]* @test9buf to i8*), i8 -1, i64 16, i32 16, i1 false)
}
; PR19092
define void @test10(i8* nocapture %P) nounwind {
tail call void @llvm.memset.p0i8.i64(i8* %P, i8 0, i64 42, i32 1, i1 false)
tail call void @llvm.memset.p0i8.i64(i8* %P, i8 0, i64 23, i32 1, i1 false)
ret void
; CHECK-LABEL: @test10(
; CHECK-NOT: memset
; CHECK: call void @llvm.memset.p0i8.i64(i8* %P, i8 0, i64 42, i32 1, i1 false)
; CHECK-NOT: memset
; CHECK: ret void
}