[llvm-commits] [llvm] r115083 - /llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp

[Owen Anderson]

Author: resistor
Date: Wed Sep 29 15:57:19 2010
New Revision: 115083

URL: http://llvm.org/viewvc/llvm-project?rev=115083&view=rev
Log:
UnreachableBlockElim could incorrectly return false when it had not modified the CFG, but HAD modified some PHI nodes.  Fixes PR8174.

Modified:
    llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp

Modified: llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp?rev=115083&r1=115082&r2=115083&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp (original)
+++ llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp Wed Sep 29 15:57:19 2010
@@ -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);
 }