[MergeICmp] Fix a bug in entry block shuffled to middle of the chain
Summary: Fix a bug in entry block shuffled to middle of the chain.
Reviewers: davide, courbet
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D44642
llvm-svn: 327971
diff --git a/llvm/lib/Transforms/Scalar/MergeICmps.cpp b/llvm/lib/Transforms/Scalar/MergeICmps.cpp
index 5b82c32..9ccba2d 100644
--- a/llvm/lib/Transforms/Scalar/MergeICmps.cpp
+++ b/llvm/lib/Transforms/Scalar/MergeICmps.cpp
@@ -403,6 +403,17 @@
Phi_.removeIncomingValue(Comparison.BB, false);
}
+ // If entry block is part of the chain, we need to make the first block
+ // of the chain the new entry block of the function.
+ BasicBlock *Entry = &Comparisons_[0].BB->getParent()->getEntryBlock();
+ for (size_t I = 1; I < Comparisons_.size(); ++I) {
+ if (Entry == Comparisons_[I].BB) {
+ BasicBlock *NEntryBB = BasicBlock::Create(Entry->getContext(), "",
+ Entry->getParent(), Entry);
+ BranchInst::Create(Entry, NEntryBB);
+ }
+ }
+
// Point the predecessors of the chain to the first comparison block (which is
// the new entry point).
if (EntryBlock_ != Comparisons_[0].BB)