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985dac6579
The "invariant.load" metadata indicates the memory unit being accessed is immutable. A load annotated with this metadata can be moved across any store. As I am not sure if it is legal to move such loads across barrier/fence, this change dose not allow such transformation. rdar://11311484 Thank Arnold for code review. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176562 91177308-0d34-0410-b5e6-96231b3b80d8
30 lines
854 B
LLVM
30 lines
854 B
LLVM
; RUN: opt < %s -basicaa -gvn -S | FileCheck %s
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; The input *.ll is obtained by manually annotating "invariant.load" to the
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; two loads. With "invariant.load" metadata, the second load is redundant.
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;
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; int foo(int *p, char *q) {
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; *q = (char)*p;
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; return *p + 1;
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; }
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define i32 @foo(i32* nocapture %p, i8* nocapture %q) {
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entry:
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%0 = load i32* %p, align 4, !tbaa !0, !invariant.load !3
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%conv = trunc i32 %0 to i8
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store i8 %conv, i8* %q, align 1, !tbaa !1
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%1 = load i32* %p, align 4, !tbaa !0, !invariant.load !3
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%add = add nsw i32 %1, 1
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ret i32 %add
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; CHECK: foo
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; CHECK: %0 = load i32* %p
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; CHECK: store i8 %conv, i8* %q,
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; CHECK: %add = add nsw i32 %0, 1
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}
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!0 = metadata !{metadata !"int", metadata !1}
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!1 = metadata !{metadata !"omnipotent char", metadata !2}
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!2 = metadata !{metadata !"Simple C/C++ TBAA"}
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!3 = metadata !{}
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