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'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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