[llvm-commits] [llvm] r122608 - /llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp

[Cameron Zwarich]

Author: zwarich
Date: Tue Dec 28 17:02:56 2010
New Revision: 122608

URL: http://llvm.org/viewvc/llvm-project?rev=122608&view=rev
Log:
Revert the optimization in r122596. It is correct for all current targets, but
it relies on assumptions that may not be true in the future.

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

Modified: llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp?rev=122608&r1=122607&r2=122608&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp (original)
+++ llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp Tue Dec 28 17:02:56 2010
@@ -472,9 +472,16 @@
   for (MachineBasicBlock::iterator BBI = MBB.begin(), BBE = MBB.end();
   BBI != BBE; ++BBI) {
     for (MachineInstr::const_mop_iterator I = BBI->operands_begin(),
-         E = BBI->operands_end(); I != E && I->isReg() && I->isDef(); ++I) {
+         E = BBI->operands_end(); I != E; ++I) {
       const MachineOperand& MO = *I;
 
+      // FIXME: This would be faster if it were possible to bail out of checking
+      // an instruction's operands after the explicit defs, but this is incorrect
+      // for variadic instructions, which may appear before register allocation
+      // in the future.
+      if (!MO.isReg() || !MO.isDef())
+        continue;
+
       unsigned DestReg = MO.getReg();
       if (!DestReg || !TargetRegisterInfo::isVirtualRegister(DestReg))
         continue;