diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/MergeICmps.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/MergeICmps.cpp | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/MergeICmps.cpp b/llvm/lib/Transforms/Scalar/MergeICmps.cpp index 4e54f1e47e7..5b82c320e7c 100644 --- a/llvm/lib/Transforms/Scalar/MergeICmps.cpp +++ b/llvm/lib/Transforms/Scalar/MergeICmps.cpp @@ -177,6 +177,15 @@ bool BCECmpBlock::doesOtherWork() const { // BCE atoms, returns the comparison. BCECmpBlock visitICmp(const ICmpInst *const CmpI, const ICmpInst::Predicate ExpectedPredicate) { + // The comparison can only be used once: + // - For intermediate blocks, as a branch condition. + // - For the final block, as an incoming value for the Phi. + // If there are any other uses of the comparison, we cannot merge it with + // other comparisons as we would create an orphan use of the value. + if (!CmpI->hasOneUse()) { + DEBUG(dbgs() << "cmp has several uses\n"); + return {}; + } if (CmpI->getPredicate() == ExpectedPredicate) { DEBUG(dbgs() << "cmp " << (ExpectedPredicate == ICmpInst::ICMP_EQ ? "eq" : "ne") |
