diff options
Diffstat (limited to 'llvm/lib/Analysis/BasicAliasAnalysis.cpp')
| -rw-r--r-- | llvm/lib/Analysis/BasicAliasAnalysis.cpp | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp index 03785fd0ebe..c292999262b 100644 --- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp +++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp @@ -949,6 +949,19 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size, 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 @@ -975,9 +988,7 @@ BasicAliasAnalysis::aliasSelect(const SelectInst *SI, uint64_t SISize, 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 @@ -994,9 +1005,7 @@ BasicAliasAnalysis::aliasSelect(const SelectInst *SI, uint64_t SISize, 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 @@ -1026,8 +1035,9 @@ BasicAliasAnalysis::aliasPHI(const PHINode *PN, uint64_t PNSize, 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; } @@ -1065,8 +1075,9 @@ BasicAliasAnalysis::aliasPHI(const PHINode *PN, uint64_t PNSize, 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; |
