Reduce the entries in a phi before testing it for deadness, because removing the entries might make it dead.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54535 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/UnreachableBlockElim.cpp b/lib/CodeGen/UnreachableBlockElim.cpp
index 57811ca..152f2f8 100644
--- a/lib/CodeGen/UnreachableBlockElim.cpp
+++ b/lib/CodeGen/UnreachableBlockElim.cpp
@@ -152,6 +152,12 @@
MachineBasicBlock::iterator phi = BB->begin();
while (phi != BB->end() &&
phi->getOpcode() == TargetInstrInfo::PHI) {
+ for (unsigned i = phi->getNumOperands() - 1; i >= 2; i-=2)
+ if (!preds.count(phi->getOperand(i).getMBB())) {
+ phi->RemoveOperand(i);
+ phi->RemoveOperand(i-1);
+ }
+
if (phi->getNumOperands() == 3) {
unsigned Input = phi->getOperand(1).getReg();
unsigned Output = phi->getOperand(0).getReg();
@@ -162,15 +168,9 @@
if (Input != Output)
F.getRegInfo().replaceRegWith(Output, Input);
-
+
continue;
}
-
- for (unsigned i = phi->getNumOperands() - 1; i >= 2; i-=2)
- if (!preds.count(phi->getOperand(i).getMBB())) {
- phi->RemoveOperand(i);
- phi->RemoveOperand(i-1);
- }
++phi;
}