Teach two-address pass to update the "source" map so it doesn't perform a

non-profitable commute using outdated info. The test case would still fail
because of poor pre-RA schedule. That will be fixed by MI scheduler.

rdar://11472010


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157038 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 1 deletions

diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index e299671b68..8164690e40 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1521,6 +1521,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
 #endif
 
           // Emit a copy or rematerialize the definition.
+          bool isCopy = false;
           const TargetRegisterClass *rc = MRI->getRegClass(regB);
           MachineInstr *DefMI = MRI->getVRegDef(regB);
           // If it's safe and profitable, remat the definition instead of
@@ -1537,10 +1538,11 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
           } else {
             BuildMI(*mbbi, mi, mi->getDebugLoc(), TII->get(TargetOpcode::COPY),
                     regA).addReg(regB);
+            isCopy = true;
           }
 
-          MachineBasicBlock::iterator prevMI = prior(mi);
           // Update DistanceMap.
+          MachineBasicBlock::iterator prevMI = prior(mi);
           DistanceMap.insert(std::make_pair(prevMI, Dist));
           DistanceMap[mi] = ++Dist;
 
@@ -1554,6 +1556,10 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
             RemovedKillFlag = true;
           }
           MO.setReg(regA);
+
+          if (isCopy)
+            // Propagate SrcRegMap.
+            SrcRegMap[regA] = regB;
         }
 
         if (AllUsesCopied) {