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544533301e
'nocapture' attribute. The nocapture attribute only specifies that no copies are made that outlive the function. This isn't the same as there being no copies at all. This fixes PR14045. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167381 91177308-0d34-0410-b5e6-96231b3b80d8
37 lines
1.0 KiB
LLVM
37 lines
1.0 KiB
LLVM
; RUN: opt < %s -basicaa -gvn -instcombine -S | FileCheck %s
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declare i32* @test(i32* nocapture)
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define i32 @test2() {
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; CHECK: ret i32 0
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%P = alloca i32
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%Q = call i32* @test(i32* %P)
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%a = load i32* %P
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store i32 4, i32* %Q ;; cannot clobber P since it is nocapture.
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%b = load i32* %P
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%c = sub i32 %a, %b
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ret i32 %c
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}
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declare void @test3(i32** %p, i32* %q) nounwind
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define i32 @test4(i32* noalias nocapture %p) nounwind {
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; CHECK: call void @test3
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; CHECK: store i32 0, i32* %p
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; CHECK: store i32 1, i32* %x
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; CHECK: %y = load i32* %p
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; CHECK: ret i32 %y
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entry:
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%q = alloca i32*
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; Here test3 might store %p to %q. This doesn't violate %p's nocapture
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; attribute since the copy doesn't outlive the function.
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call void @test3(i32** %q, i32* %p) nounwind
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store i32 0, i32* %p
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%x = load i32** %q
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; This store might write to %p and so we can't eliminate the subsequent
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; load
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store i32 1, i32* %x
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%y = load i32* %p
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ret i32 %y
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}
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