Reset NoPHI MachineFunction property in X86CmovConversion

[Orlando]

Summary

In order to placate the machine-verifier, X86CmovConversion needs to reset the NoPHI property when it inserts a PHI.

Fixes buildbot failure: https://lab.llvm.org/buildbot/#/builders/16/builds/50453

[StephenTozer]

The pass inserts a PHI, so needs to reset the NoPHIs property - makes sense. The property reset could be taken out of the loop and put under a conditional if (MIItBegin != MIItEnd) - I'd leave that as optional though, because I imagine it makes very little difference in practice.

[Orlando]

In D153950#4455311, @StephenTozer wrote:

The pass inserts a PHI, so needs to reset the NoPHIs property - makes sense. The property reset could be taken out of the loop and put under a conditional if (MIItBegin != MIItEnd) - I'd leave that as optional though, because I imagine it makes very little difference in practice.

SGTM - done, thanks.

llvm/lib/Target/X86/X86CmovConversion.cpp

for (MachineBasicBlock::iterator MIIt = MIItBegin; MIIt != MIItEnd; ++MIIt) {
     auto Op1Itr = RegRewriteTable.find(Op1Reg);
     if (Op1Itr != RegRewriteTable.end())
       Op1Reg = Op1Itr->second.first;
 
     auto Op2Itr = RegRewriteTable.find(Op2Reg);
     if (Op2Itr != RegRewriteTable.end())
       Op2Reg = Op2Itr->second.second;
 
+    // Required to avoid conflict with the MachineVerifier during testing.
+    F->getProperties().reset(MachineFunctionProperties::Property::NoPHIs);
+
     //  SinkMBB:
     //   %Result = phi [ %FalseValue, FalseMBB ], [ %TrueValue, MBB ]
     //  ...
     MIB = BuildMI(*SinkMBB, SinkInsertionPoint, DL, TII->get(X86::PHI), DestReg)
               .addReg(Op1Reg)
               .addMBB(FalseMBB)
               .addReg(Op2Reg)
               .addMBB(MBB);