diff options
Diffstat (limited to 'llvm/lib/Transforms/Utils/SimplifyCFG.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index f08ab18..805bc32 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -4241,11 +4241,6 @@ bool SimplifyCFGOpt::SimplifyBranchOnICmpChain(BranchInst *BI, BasicBlock *BB = BI->getParent(); - // MSAN does not like undefs as branch condition which can be introduced - // with "explicit branch". - if (ExtraCase && BB->getParent()->hasFnAttribute(Attribute::SanitizeMemory)) - return false; - LLVM_DEBUG(dbgs() << "Converting 'icmp' chain with " << Values.size() << " cases into SWITCH. BB is:\n" << *BB); @@ -4263,6 +4258,16 @@ bool SimplifyCFGOpt::SimplifyBranchOnICmpChain(BranchInst *BI, Instruction *OldTI = BB->getTerminator(); Builder.SetInsertPoint(OldTI); + // There can be an unintended UB if extra values are Poison. Before the + // transformation, extra values may not be evaluated according to the + // condition, and it will not raise UB. But after transformation, we are + // evaluating extra values before checking the condition, and it will raise + // UB. It can be solved by adding freeze instruction to extra values. + AssumptionCache *AC = Options.AC; + + if (!isGuaranteedNotToBeUndefOrPoison(ExtraCase, AC, BI, nullptr)) + ExtraCase = Builder.CreateFreeze(ExtraCase); + if (TrueWhenEqual) Builder.CreateCondBr(ExtraCase, EdgeBB, NewBB); else |