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When BasicAA can determine that two pointers have the same base but
differ by a dynamic offset, return PartialAlias instead of MayAlias. See the comment in the code for details. This fixes PR9971. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131781 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
parent
dc5948d472
commit
424b777171
@ -940,7 +940,17 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
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return NoAlias;
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}
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return MayAlias;
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// Statically, we can see that the base objects are the same, but the
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// pointers have dynamic offsets which we can't resolve. And none of our
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// little tricks above worked.
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//
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// TODO: Returning PartialAlias instead of MayAlias is a mild hack; the
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// practical effect of this is protecting TBAA in the case of dynamic
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// indices into arrays of unions. An alternative way to solve this would
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// be to have clang emit extra metadata for unions and/or union accesses.
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// A union-specific solution wouldn't handle the problem for malloc'd
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// memory however.
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return PartialAlias;
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}
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/// aliasSelect - Provide a bunch of ad-hoc rules to disambiguate a Select
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@ -1,4 +1,4 @@
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; RUN: opt < %s -basicaa -aa-eval -print-all-alias-modref-info -disable-output |& grep {1 may alias}
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; RUN: opt < %s -basicaa -aa-eval -print-all-alias-modref-info -disable-output |& grep {1 partial alias}
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; PR7959
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target datalayout = "e-p:32:32:32"
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131
test/Analysis/TypeBasedAliasAnalysis/dynamic-indices.ll
Normal file
131
test/Analysis/TypeBasedAliasAnalysis/dynamic-indices.ll
Normal file
@ -0,0 +1,131 @@
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; RUN: opt -tbaa -basicaa -gvn -S < %s | FileCheck %s
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; PR9971
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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"
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%struct.X = type { i32, float }
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%union.vector_t = type { [2 x i64] }
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; Don't delete the load after the loop, because it loads values stored
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; inside the loop.
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; CHECK: define void @vrlh(
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; CHECK: for.end:
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; CHECK: %arrayidx31 = getelementptr inbounds %union.vector_t* %t, i64 0, i32 0, i64 1
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; CHECK: %tmp32 = load i64* %arrayidx31, align 8, !tbaa !3
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define void @vrlh(%union.vector_t* %va, %union.vector_t* %vb, %union.vector_t* %vd) nounwind {
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entry:
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%t = alloca %union.vector_t, align 8
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br label %for.body
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for.body: ; preds = %entry, %for.body
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%i.01 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%sub = sub nsw i32 7, %i.01
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%idxprom = sext i32 %sub to i64
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%half = bitcast %union.vector_t* %vb to [8 x i16]*
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%arrayidx = getelementptr inbounds [8 x i16]* %half, i64 0, i64 %idxprom
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%tmp4 = load i16* %arrayidx, align 2, !tbaa !0
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%conv = zext i16 %tmp4 to i32
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%and = and i32 %conv, 15
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%sub6 = sub nsw i32 7, %i.01
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%idxprom7 = sext i32 %sub6 to i64
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%half9 = bitcast %union.vector_t* %va to [8 x i16]*
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%arrayidx10 = getelementptr inbounds [8 x i16]* %half9, i64 0, i64 %idxprom7
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%tmp11 = load i16* %arrayidx10, align 2, !tbaa !0
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%conv12 = zext i16 %tmp11 to i32
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%shl = shl i32 %conv12, %and
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%sub15 = sub nsw i32 7, %i.01
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%idxprom16 = sext i32 %sub15 to i64
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%half18 = bitcast %union.vector_t* %va to [8 x i16]*
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%arrayidx19 = getelementptr inbounds [8 x i16]* %half18, i64 0, i64 %idxprom16
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%tmp20 = load i16* %arrayidx19, align 2, !tbaa !0
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%conv21 = zext i16 %tmp20 to i32
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%sub23 = sub nsw i32 16, %and
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%shr = lshr i32 %conv21, %sub23
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%or = or i32 %shl, %shr
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%conv24 = trunc i32 %or to i16
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%sub26 = sub nsw i32 7, %i.01
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%idxprom27 = sext i32 %sub26 to i64
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%half28 = bitcast %union.vector_t* %t to [8 x i16]*
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%arrayidx29 = getelementptr inbounds [8 x i16]* %half28, i64 0, i64 %idxprom27
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store i16 %conv24, i16* %arrayidx29, align 2, !tbaa !0
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%inc = add nsw i32 %i.01, 1
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%cmp = icmp slt i32 %inc, 8
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br i1 %cmp, label %for.body, label %for.end
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for.end: ; preds = %for.body
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%arrayidx31 = getelementptr inbounds %union.vector_t* %t, i64 0, i32 0, i64 1
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%tmp32 = load i64* %arrayidx31, align 8, !tbaa !3
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%arrayidx35 = getelementptr inbounds %union.vector_t* %vd, i64 0, i32 0, i64 1
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store i64 %tmp32, i64* %arrayidx35, align 8, !tbaa !3
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%arrayidx37 = getelementptr inbounds %union.vector_t* %t, i64 0, i32 0, i64 0
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%tmp38 = load i64* %arrayidx37, align 8, !tbaa !3
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%arrayidx41 = getelementptr inbounds %union.vector_t* %vd, i64 0, i32 0, i64 0
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store i64 %tmp38, i64* %arrayidx41, align 8, !tbaa !3
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ret void
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}
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; Do delete the load after the loop.
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; CHECK: define i32 @test0(
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; CHECK: ret i32 0
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define i32 @test0(%struct.X* %a) nounwind {
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entry:
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%i = getelementptr inbounds %struct.X* %a, i64 0, i32 0
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store i32 0, i32* %i, align 4, !tbaa !4
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br label %for.body
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for.body: ; preds = %entry, %for.body
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%i2.01 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
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%f = getelementptr inbounds %struct.X* %a, i64 %i2.01, i32 1
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%tmp6 = load float* %f, align 4, !tbaa !5
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%mul = fmul float %tmp6, 0x40019999A0000000
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store float %mul, float* %f, align 4, !tbaa !5
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%inc = add nsw i64 %i2.01, 1
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%cmp = icmp slt i64 %inc, 10000
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br i1 %cmp, label %for.body, label %for.end
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for.end: ; preds = %for.body
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%i9 = getelementptr inbounds %struct.X* %a, i64 0, i32 0
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%tmp10 = load i32* %i9, align 4, !tbaa !4
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ret i32 %tmp10
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}
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; Do delete the load after the loop.
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; CHECK: define float @test1(
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; CHECK: ret float 0x3FD3333340000000
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define float @test1(%struct.X* %a) nounwind {
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entry:
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%f = getelementptr inbounds %struct.X* %a, i64 0, i32 1
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store float 0x3FD3333340000000, float* %f, align 4, !tbaa !5
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br label %for.body
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for.body: ; preds = %entry, %for.body
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%i.01 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
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%i5 = getelementptr inbounds %struct.X* %a, i64 %i.01, i32 0
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%tmp6 = load i32* %i5, align 4, !tbaa !4
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%mul = mul nsw i32 %tmp6, 3
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store i32 %mul, i32* %i5, align 4, !tbaa !4
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%inc = add nsw i64 %i.01, 1
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%cmp = icmp slt i64 %inc, 10000
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br i1 %cmp, label %for.body, label %for.end
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for.end: ; preds = %for.body
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%f9 = getelementptr inbounds %struct.X* %a, i64 0, i32 1
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%tmp10 = load float* %f9, align 4, !tbaa !5
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ret float %tmp10
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}
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!0 = metadata !{metadata !"short", metadata !1}
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!1 = metadata !{metadata !"omnipotent char", metadata !2}
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!2 = metadata !{metadata !"Simple C/C++ TBAA", null}
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!3 = metadata !{metadata !"long long", metadata !1}
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!4 = metadata !{metadata !"int", metadata !1}
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!5 = metadata !{metadata !"float", metadata !1}
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