diff options
Diffstat (limited to 'llvm/lib/Analysis')
| -rw-r--r-- | llvm/lib/Analysis/ValueTracking.cpp | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index 6fdf4afebc2..b292af6cee7 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -1821,13 +1821,16 @@ unsigned ComputeNumSignBits(Value *V, const DataLayout *TD, case Instruction::PHI: { PHINode *PN = cast<PHINode>(U); + unsigned NumIncomingValues = PN->getNumIncomingValues(); // Don't analyze large in-degree PHIs. - if (PN->getNumIncomingValues() > 4) break; + if (NumIncomingValues > 4) break; + // Unreachable blocks may have zero-operand PHI nodes. + if (NumIncomingValues == 0) break; // Take the minimum of all incoming values. This can't infinitely loop // because of our depth threshold. Tmp = ComputeNumSignBits(PN->getIncomingValue(0), TD, Depth+1, Q); - for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) { + for (unsigned i = 1, e = NumIncomingValues; i != e; ++i) { if (Tmp == 1) return Tmp; Tmp = std::min(Tmp, ComputeNumSignBits(PN->getIncomingValue(i), TD, |
