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 edb4eea71b8a72032f1d1a3ec5ddb06ce36de287..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);
 
@@ -55,7 +57,7 @@ namespace {
 
 char OptimizePHIs::ID = 0;
 INITIALIZE_PASS(OptimizePHIs, "opt-phis",
-                "Optimize machine instruction PHIs", false, false);
+                "Optimize machine instruction PHIs", false, false)
 
 FunctionPass *llvm::createOptimizePHIsPass() { return new OptimizePHIs(); }
 
@@ -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;