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fix PR8267 - Instcombine shouldn't optimizer away volatile memcpy's.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115296 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-10-01 05:51:02 +00:00
parent e94aa76d2a
commit 6eff75104e
2 changed files with 18 additions and 4 deletions
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7
lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -280,7 +280,8 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
// memmove/cpy/set of zero bytes is a noop.
if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
if (NumBytes->isNullValue())
return EraseInstFromFunction(CI);
if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
if (CI->getZExtValue() == 1) {
@ -289,6 +290,10 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
// alignment is sufficient.
}
}
// No other transformations apply to volatile transfers.
if (MI->isVolatile())
return 0;
// If we have a memmove and the source operation is a constant global,
// then the source and dest pointers can't alias, so we can change this

15
test/Transforms/InstCombine/memcpy.ll
View File

@ -2,9 +2,18 @@
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
define void @test4(i8* %a) {
define void @test1(i8* %a) {
tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a, i8* %a, i32 100, i32 1, i1 false)
ret void
}
; CHECK: define void @test4
; CHECK: define void @test1
; CHECK-NEXT: ret void
}
; PR8267
define void @test2(i8* %a) {
tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a, i8* %a, i32 100, i32 1, i1 true)
ret void
; CHECK: define void @test2
; CHECK-NEXT: call void @llvm.memcpy
}