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In the process of fixing the noalias parameter -> metadata conversion process that will take place during inlining (which will be committed soon, but not turned on by default), I have come to realize that the semantics provided by yesterday's commit are not really what we want. Here's why: void foo(noalias a, noalias b, noalias c, bool x) { *q = x ? a : b; *c = *q; } Generically, we know that *c does not alias with *a and with *b (so there is an 'and' in what we know we're not), and we know that *q might be derived from *a or from *b (so there is an 'or' in what we know that we are). So we do not want the semantics currently, where any noalias scope matching any alias.scope causes a NoAlias return. What we want to know is that the noalias scopes form a superset of the alias.scope list (meaning that all the things we know we're not is a superset of all of things the other instruction might be). Making that change, however, introduces a composibility problem. If we inline once, adding the noalias metadata, and then inline again adding more, and we append new scopes onto the noalias and alias.scope lists each time. But, this means that we could change what was a NoAlias result previously into a MayAlias result because we appended an additional scope onto one of the alias.scope lists. So, instead of giving scopes the ability to have parents (which I had borrowed from the TBAA implementation, but seems increasingly unlikely to be useful in practice), I've given them domains. The subset/superset condition now applies within each domain independently, and we only need it to hold in one domain. Each time we inline, we add the new scopes in a new scope domain, and everything now composes nicely. In addition, this simplifies the implementation. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213948 91177308-0d34-0410-b5e6-96231b3b80d8
42 lines
2.5 KiB
LLVM
42 lines
2.5 KiB
LLVM
; RUN: opt < %s -basicaa -scoped-noalias -aa-eval -evaluate-aa-metadata -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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define void @foo2(float* nocapture %a, float* nocapture %b, float* nocapture readonly %c) #0 {
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entry:
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; CHECK-LABEL: Function: foo2
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%0 = load float* %c, align 4, !alias.scope !0
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%arrayidx.i = getelementptr inbounds float* %a, i64 5
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store float %0, float* %arrayidx.i, align 4, !alias.scope !5, !noalias !4
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%arrayidx1.i = getelementptr inbounds float* %b, i64 8
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store float %0, float* %arrayidx1.i, align 4, !alias.scope !0, !noalias !5
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%1 = load float* %c, align 4
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%arrayidx = getelementptr inbounds float* %a, i64 7
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store float %1, float* %arrayidx, align 4
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ret void
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; CHECK: MayAlias: %0 = load float* %c, align 4, !alias.scope !0 <-> store float %0, float* %arrayidx.i, align 4, !alias.scope !4, !noalia
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; CHECK: s !5
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; CHECK: MayAlias: %0 = load float* %c, align 4, !alias.scope !0 <-> store float %0, float* %arrayidx1.i, align 4, !alias.scope !0, !noali
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; CHECK: as !4
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; CHECK: MayAlias: %0 = load float* %c, align 4, !alias.scope !0 <-> store float %1, float* %arrayidx, align 4
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; CHECK: MayAlias: %1 = load float* %c, align 4 <-> store float %0, float* %arrayidx.i, align 4, !alias.scope !4, !noalias !5
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; CHECK: MayAlias: %1 = load float* %c, align 4 <-> store float %0, float* %arrayidx1.i, align 4, !alias.scope !0, !noalias !4
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; CHECK: MayAlias: %1 = load float* %c, align 4 <-> store float %1, float* %arrayidx, align 4
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; CHECK: NoAlias: store float %0, float* %arrayidx1.i, align 4, !alias.scope !0, !noalias !4 <-> store float %0, float* %arrayidx.i, align
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; CHECK: 4, !alias.scope !4, !noalias !5
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; CHECK: NoAlias: store float %1, float* %arrayidx, align 4 <-> store float %0, float* %arrayidx.i, align 4, !alias.scope !4, !noalias !5
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; CHECK: MayAlias: store float %1, float* %arrayidx, align 4 <-> store float %0, float* %arrayidx1.i, align 4, !alias.scope !0, !noalias !
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; CHECK: 4
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}
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attributes #0 = { nounwind uwtable }
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!0 = metadata !{metadata !1, metadata !3}
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!1 = metadata !{metadata !1, metadata !2, metadata !"some scope"}
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!2 = metadata !{metadata !2, metadata !"some domain"}
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!3 = metadata !{metadata !3, metadata !2, metadata !"some other scope"}
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!4 = metadata !{metadata !1}
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!5 = metadata !{metadata !3}
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