UnreachableBlockElim could incorrectly return false when it had not modified the CFG, but HAD modified some PHI nodes. Fixes PR8174.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115083 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/UnreachableBlockElim.cpp b/lib/CodeGen/UnreachableBlockElim.cpp
index 6dd3333..ebf1129 100644
--- a/lib/CodeGen/UnreachableBlockElim.cpp
+++ b/lib/CodeGen/UnreachableBlockElim.cpp
@@ -118,6 +118,7 @@
bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
SmallPtrSet<MachineBasicBlock*, 8> Reachable;
+ bool ModifiedPHI = false;
MMI = getAnalysisIfAvailable<MachineModuleInfo>();
MachineDominatorTree *MDT = getAnalysisIfAvailable<MachineDominatorTree>();
@@ -179,6 +180,7 @@
if (!preds.count(phi->getOperand(i).getMBB())) {
phi->RemoveOperand(i);
phi->RemoveOperand(i-1);
+ ModifiedPHI = true;
}
if (phi->getNumOperands() == 3) {
@@ -188,6 +190,7 @@
MachineInstr* temp = phi;
++phi;
temp->eraseFromParent();
+ ModifiedPHI = true;
if (Input != Output)
F.getRegInfo().replaceRegWith(Output, Input);
@@ -201,5 +204,5 @@
F.RenumberBlocks();
- return DeadBlocks.size();
+ return (DeadBlocks.size() || ModifiedPHI);
}