return MayAlias;
}
+static AliasAnalysis::AliasResult
+MergeAliasResults(AliasAnalysis::AliasResult A, AliasAnalysis::AliasResult B) {
+ // If the results agree, take it.
+ if (A == B)
+ return A;
+ // A mix of PartialAlias and MustAlias is PartialAlias.
+ if ((A == AliasAnalysis::PartialAlias && B == AliasAnalysis::MustAlias) ||
+ (B == AliasAnalysis::PartialAlias && A == AliasAnalysis::MustAlias))
+ return AliasAnalysis::PartialAlias;
+ // Otherwise, we don't know anything.
+ return AliasAnalysis::MayAlias;
+}
+
/// aliasSelect - Provide a bunch of ad-hoc rules to disambiguate a Select
/// instruction against another.
AliasAnalysis::AliasResult
AliasResult ThisAlias =
aliasCheck(SI->getFalseValue(), SISize, SITBAAInfo,
SI2->getFalseValue(), V2Size, V2TBAAInfo);
- if (ThisAlias != Alias)
- return MayAlias;
- return Alias;
+ return MergeAliasResults(ThisAlias, Alias);
}
// If both arms of the Select node NoAlias or MustAlias V2, then returns
AliasResult ThisAlias =
aliasCheck(V2, V2Size, V2TBAAInfo, SI->getFalseValue(), SISize, SITBAAInfo);
- if (ThisAlias != Alias)
- return MayAlias;
- return Alias;
+ return MergeAliasResults(ThisAlias, Alias);
}
// aliasPHI - Provide a bunch of ad-hoc rules to disambiguate a PHI instruction
aliasCheck(PN->getIncomingValue(i), PNSize, PNTBAAInfo,
PN2->getIncomingValueForBlock(PN->getIncomingBlock(i)),
V2Size, V2TBAAInfo);
- if (ThisAlias != Alias)
- return MayAlias;
+ Alias = MergeAliasResults(ThisAlias, Alias);
+ if (Alias == MayAlias)
+ break;
}
return Alias;
}
AliasResult ThisAlias = aliasCheck(V2, V2Size, V2TBAAInfo,
V, PNSize, PNTBAAInfo);
- if (ThisAlias != Alias || ThisAlias == MayAlias)
- return MayAlias;
+ Alias = MergeAliasResults(ThisAlias, Alias);
+ if (Alias == MayAlias)
+ break;
}
return Alias;
--- /dev/null
+; RUN: opt < %s -basicaa -aa-eval -print-all-alias-modref-info |& FileCheck %s
+
+; When merging MustAlias and PartialAlias, merge to PartialAlias
+; instead of MayAlias.
+
+
+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"
+
+; CHECK: PartialAlias: i16* %bigbase0, i8* %phi
+define i8 @test0(i8* %base, i1 %x) {
+entry:
+ %baseplusone = getelementptr i8* %base, i64 1
+ br i1 %x, label %red, label %green
+red:
+ br label %green
+green:
+ %phi = phi i8* [ %baseplusone, %red ], [ %base, %entry ]
+ store i8 0, i8* %phi
+
+ %bigbase0 = bitcast i8* %base to i16*
+ store i16 -1, i16* %bigbase0
+
+ %loaded = load i8* %phi
+ ret i8 %loaded
+}
+
+; CHECK: PartialAlias: i16* %bigbase1, i8* %sel
+define i8 @test1(i8* %base, i1 %x) {
+entry:
+ %baseplusone = getelementptr i8* %base, i64 1
+ %sel = select i1 %x, i8* %baseplusone, i8* %base
+ store i8 0, i8* %sel
+
+ %bigbase1 = bitcast i8* %base to i16*
+ store i16 -1, i16* %bigbase1
+
+ %loaded = load i8* %sel
+ ret i8 %loaded
+}