More dead code removal (using -Wunreachable-code)

[oota-llvm.git] / lib / CodeGen / OptimizePHIs.cpp

diff --git a/lib/CodeGen/OptimizePHIs.cpp b/lib/CodeGen/OptimizePHIs.cpp
index cfdf46d05956e09fffabfb888ddaf0e591a87831..85fa04180088f1a74339576174240a617c497cfa 100644 (file)
--- a/lib/CodeGen/OptimizePHIs.cpp
+++ b/lib/CodeGen/OptimizePHIs.cpp
@@ -33,7 +33,9 @@ namespace {
 
   public:
     static char ID; // Pass identification
-    OptimizePHIs() : MachineFunctionPass(ID) {}
+    OptimizePHIs() : MachineFunctionPass(ID) {
+      initializeOptimizePHIsPass(*PassRegistry::getPassRegistry());
+    }
 
     virtual bool runOnMachineFunction(MachineFunction &MF);
 
@@ -163,7 +165,11 @@ bool OptimizePHIs::OptimizeBB(MachineBasicBlock &MBB) {
     InstrSet PHIsInCycle;
     if (IsSingleValuePHICycle(MI, SingleValReg, PHIsInCycle) &&
         SingleValReg != 0) {
-      MRI->replaceRegWith(MI->getOperand(0).getReg(), SingleValReg);
+      unsigned OldReg = MI->getOperand(0).getReg();
+      if (!MRI->constrainRegClass(SingleValReg, MRI->getRegClass(OldReg)))
+        continue;
+
+      MRI->replaceRegWith(OldReg, SingleValReg);
       MI->eraseFromParent();
       ++NumPHICycles;
       Changed = true;