diff options
Diffstat (limited to 'lib/Transforms/Utils/SimplifyCFG.cpp')
| -rw-r--r-- | lib/Transforms/Utils/SimplifyCFG.cpp | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index 089d0ac86e..09153ed3bb 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -331,8 +331,15 @@ static void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred, // isValueEqualityComparison - Return true if the specified terminator checks to // see if a value is equal to constant integer value. static Value *isValueEqualityComparison(TerminatorInst *TI) { - if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) + if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { + // Do not permit merging of large switch instructions into their + // predecessors unless there is only one predecessor. + if (SI->getNumSuccessors() * std::distance(pred_begin(SI->getParent()), + pred_end(SI->getParent())) > 128) + return 0; + return SI->getCondition(); + } if (BranchInst *BI = dyn_cast<BranchInst>(TI)) if (BI->isConditional() && BI->getCondition()->hasOneUse()) if (SetCondInst *SCI = dyn_cast<SetCondInst>(BI->getCondition())) |