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) {
     (void)MIB;
     LLVM_DEBUG(dbgs() << "\tFrom: "; MIIt->dump());
     LLVM_DEBUG(dbgs() << "\tTo: "; MIB->dump());
 
     // Add this PHI to the rewrite table.
     RegRewriteTable[DestReg] = std::make_pair(Op1Reg, Op2Reg);
   }
 
+  // Reset the NoPHIs property if a PHI was inserted to prevent a conflict with
+  // the MachineVerifier during testing.
+  if (MIItBegin != MIItEnd)
+    F->getProperties().reset(MachineFunctionProperties::Property::NoPHIs);
+
   // Now remove the CMOV(s).
   MBB->erase(MIItBegin, MIItEnd);
 
   // Add new basic blocks to MachineLoopInfo.
   if (MachineLoop *L = MLI->getLoopFor(MBB)) {
     L->addBasicBlockToLoop(FalseMBB, MLI->getBase());
     L->addBasicBlockToLoop(SinkMBB, MLI->getBase());
   }