diff options
| -rw-r--r-- | llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 27 |
1 files changed, 21 insertions, 6 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index dc36a6e1f0b..d8f8851c72d 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -174,7 +174,9 @@ public: /// Return true if it is safe to merge these two /// terminator instructions together. -static bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) { +static bool +SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2, + SmallPtrSetImpl<BasicBlock *> *FailBlocks = nullptr) { if (SI1 == SI2) return false; // Can't merge with self! @@ -183,18 +185,22 @@ static bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) { // conflicting incoming values from the two switch blocks. BasicBlock *SI1BB = SI1->getParent(); BasicBlock *SI2BB = SI2->getParent(); - SmallPtrSet<BasicBlock *, 16> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB)); + SmallPtrSet<BasicBlock *, 16> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB)); + bool Fail = false; for (BasicBlock *Succ : successors(SI2BB)) if (SI1Succs.count(Succ)) for (BasicBlock::iterator BBI = Succ->begin(); isa<PHINode>(BBI); ++BBI) { PHINode *PN = cast<PHINode>(BBI); if (PN->getIncomingValueForBlock(SI1BB) != - PN->getIncomingValueForBlock(SI2BB)) - return false; + PN->getIncomingValueForBlock(SI2BB)) { + if (FailBlocks) + FailBlocks->insert(Succ); + Fail = true; + } } - return true; + return !Fail; } /// Return true if it is safe and profitable to merge these two terminator @@ -954,7 +960,16 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, TerminatorInst *PTI = Pred->getTerminator(); Value *PCV = isValueEqualityComparison(PTI); // PredCondVal - if (PCV == CV && SafeToMergeTerminators(TI, PTI)) { + if (PCV == CV && TI != PTI) { + SmallPtrSet<BasicBlock*, 4> FailBlocks; + if (!SafeToMergeTerminators(TI, PTI, &FailBlocks)) { + for (auto *Succ : FailBlocks) { + std::vector<BasicBlock*> Blocks = { TI->getParent() }; + if (!SplitBlockPredecessors(Succ, Blocks, ".fold.split")) + return false; + } + } + // Figure out which 'cases' to copy from SI to PSI. std::vector<ValueEqualityComparisonCase> BBCases; BasicBlock *BBDefault = GetValueEqualityComparisonCases(TI, BBCases); |
