[llvm] r281180 - [TwoAddressInstruction] When commuting an instruction don't assume that the destination register is operand 0. Pass it from the caller.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Sun Sep 11 17:10:42 2016
New Revision: 281180

URL: http://llvm.org/viewvc/llvm-project?rev=281180&view=rev
Log:
[TwoAddressInstruction] When commuting an instruction don't assume that the destination register is operand 0. Pass it from the caller.

In practice it probably is 0 so this may not be a functional change.

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

Modified: llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp?rev=281180&r1=281179&r2=281180&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp (original)
+++ llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp Sun Sep 11 17:10:42 2016
@@ -109,7 +109,7 @@ class TwoAddressInstructionPass : public
   bool isProfitableToCommute(unsigned regA, unsigned regB, unsigned regC,
                              MachineInstr *MI, unsigned Dist);
 
-  bool commuteInstruction(MachineInstr *MI,
+  bool commuteInstruction(MachineInstr *MI, unsigned DstIdx,
                           unsigned RegBIdx, unsigned RegCIdx, unsigned Dist);
 
   bool isProfitableToConv3Addr(unsigned RegA, unsigned RegB);
@@ -651,6 +651,7 @@ isProfitableToCommute(unsigned regA, uns
 /// Commute a two-address instruction and update the basic block, distance map,
 /// and live variables if needed. Return true if it is successful.
 bool TwoAddressInstructionPass::commuteInstruction(MachineInstr *MI,
+                                                   unsigned DstIdx,
                                                    unsigned RegBIdx,
                                                    unsigned RegCIdx,
                                                    unsigned Dist) {
@@ -671,7 +672,7 @@ bool TwoAddressInstructionPass::commuteI
   // Update source register map.
   unsigned FromRegC = getMappedReg(RegC, SrcRegMap);
   if (FromRegC) {
-    unsigned RegA = MI->getOperand(0).getReg();
+    unsigned RegA = MI->getOperand(DstIdx).getReg();
     SrcRegMap[RegA] = FromRegC;
   }
 
@@ -1202,7 +1203,8 @@ bool TwoAddressInstructionPass::tryInstr
     }
 
     // If it's profitable to commute, try to do so.
-    if (DoCommute && commuteInstruction(MI, BaseOpIdx, OtherOpIdx, Dist)) {
+    if (DoCommute && commuteInstruction(MI, DstOpIdx, BaseOpIdx, OtherOpIdx,
+                                        Dist)) {
       ++NumCommuted;
       if (AggressiveCommute)
         ++NumAggrCommuted;