diff --git a/lib/Analysis/AliasAnalysis.cpp b/lib/Analysis/AliasAnalysis.cpp index 054930c0e19..5be5613b124 100644 --- a/lib/Analysis/AliasAnalysis.cpp +++ b/lib/Analysis/AliasAnalysis.cpp @@ -361,9 +361,11 @@ AliasAnalysis::getModRefInfo(const AtomicRMWInst *RMW, const Location &Loc) { } namespace { - // Conservatively return true. Return false, if there is a single path - // starting from "From" and the path does not reach "To". - static bool hasPath(const BasicBlock *From, const BasicBlock *To) { + /// Determine whether there is a path from From to To within a single + /// function. Returns false only if we can prove that once 'From' has been + /// executed then 'To' can not be executed. Conservatively returns true. + static bool isPotentiallyReachable(const BasicBlock *From, + const BasicBlock *To) { const unsigned MaxCheck = 5; const BasicBlock *Current = From; for (unsigned I = 0; I < MaxCheck; I++) { @@ -400,7 +402,7 @@ namespace { // there is no need to explore the use if BeforeHere dominates use. // Check whether there is a path from I to BeforeHere. if (BeforeHere != I && DT->dominates(BeforeHere, I) && - !hasPath(BB, BeforeHere->getParent())) + !isPotentiallyReachable(BB, BeforeHere->getParent())) return false; return true; } @@ -412,7 +414,7 @@ namespace { if (BeforeHere != I && !DT->isReachableFromEntry(BB)) return false; if (BeforeHere != I && DT->dominates(BeforeHere, I) && - !hasPath(BB, BeforeHere->getParent())) + !isPotentiallyReachable(BB, BeforeHere->getParent())) return false; Captured = true; return true;