[llvm-commits] [llvm] r142287 - /llvm/trunk/lib/CodeGen/OptimizePHIs.cpp

[Cameron Zwarich]

Author: zwarich
Date: Mon Oct 17 16:54:46 2011
New Revision: 142287

URL: http://llvm.org/viewvc/llvm-project?rev=142287&view=rev
Log:
When deleting a phi cycle after looking through copies, constrain the register
to match its final use.

With this change, all of test-suite compiles for Thumb2 with -verify-coalescing
enabled.

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

Modified: llvm/trunk/lib/CodeGen/OptimizePHIs.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/OptimizePHIs.cpp?rev=142287&r1=142286&r2=142287&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/OptimizePHIs.cpp (original)
+++ llvm/trunk/lib/CodeGen/OptimizePHIs.cpp Mon Oct 17 16:54:46 2011
@@ -165,7 +165,11 @@
     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;