37 lines
1 KiB
LLVM
37 lines
1 KiB
LLVM
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; RUN: opt < %s -aa-pipeline=basic-aa -passes=gvn,instcombine -S | FileCheck %s
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declare ptr @test(ptr 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 ptr @test(ptr %P)
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%a = load i32, ptr %P
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store i32 4, ptr %Q ;; cannot clobber P since it is nocapture.
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%b = load i32, ptr %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(ptr %p, ptr %q) nounwind
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define i32 @test4(ptr noalias nocapture %p) nounwind {
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; CHECK: call void @test3
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; CHECK: store i32 0, ptr %p
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; CHECK: store i32 1, ptr %x
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; CHECK: %y = load i32, ptr %p
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; CHECK: ret i32 %y
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entry:
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%q = alloca ptr
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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(ptr %q, ptr %p) nounwind
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store i32 0, ptr %p
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%x = load ptr, ptr %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, ptr %x
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%y = load i32, ptr %p
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ret i32 %y
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}
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