[MIRVRegNamerUtils] Add additional hashing on MachineInstr flags.

[plotfi]

Summary

How does this idea sound? I'd also add the inline asm stuff, but I know that is not useful atm.

TODO: Will post test before any landing.

[aditya_nandakumar]

llvm/lib/CodeGen/MIRVRegNamerUtils.cpp

123

I'd probably just do

if (unsigned Flag = MI.getFlags())
  MIOperands.push_back(Flag);

That should be equivalent to what you're doing above.
In fact, I'd just simplify it to

MIOperands.push_back(MI.getFlags());

with 0 (no flags) being also valid enough to contribute to the hash.

[plotfi]

Adding test case.

[plotfi]

llvm/lib/CodeGen/MIRVRegNamerUtils.cpp

123

ditto

llvm/lib/CodeGen/MIRVRegNamerUtils.cpp

auto HashOperand = [this](const MachineOperand &MO) -> unsigned {
     // (Opcodes,other registers etc) that this will likely not be a problem.
     return 0;
   };
   SmallVector<unsigned, 16> MIOperands;
   MIOperands.push_back(MI.getOpcode());
   for (auto &Op : MI.uses()) {
     MIOperands.push_back(HashOperand(Op));
   }
+
+  if (MI.getFlag(MachineInstr::FrameSetup))
+    MIOperands.push_back(MachineInstr::FrameSetup);
+  if (MI.getFlag(MachineInstr::FrameDestroy))
+    MIOperands.push_back(MachineInstr::FrameDestroy);
+  if (MI.getFlag(MachineInstr::FmNoNans))
+    MIOperands.push_back(MachineInstr::FmNoNans);
+  if (MI.getFlag(MachineInstr::FmNoInfs))
+    MIOperands.push_back(MachineInstr::FmNoInfs);
+  if (MI.getFlag(MachineInstr::FmNsz))
+    MIOperands.push_back(MachineInstr::FmNsz);
+  if (MI.getFlag(MachineInstr::FmArcp))
+    MIOperands.push_back(MachineInstr::FmArcp);
+  if (MI.getFlag(MachineInstr::FmContract))
+    MIOperands.push_back(MachineInstr::FmContract);
+  if (MI.getFlag(MachineInstr::FmAfn))
+    MIOperands.push_back(MachineInstr::FmAfn);
+  if (MI.getFlag(MachineInstr::FmReassoc))
+    MIOperands.push_back(MachineInstr::FmReassoc);
+  if (MI.getFlag(MachineInstr::NoUWrap))
+    MIOperands.push_back(MachineInstr::NoUWrap);
+  if (MI.getFlag(MachineInstr::NoSWrap))
+    MIOperands.push_back(MachineInstr::NoSWrap);
+  if (MI.getFlag(MachineInstr::IsExact))
+    MIOperands.push_back(MachineInstr::IsExact);
+  if (MI.getFlag(MachineInstr::FPExcept))
+    MIOperands.push_back(MachineInstr::FPExcept);
+
   auto HashMI = hash_combine_range(MIOperands.begin(), MIOperands.end());
   return std::to_string(HashMI).substr(0, 5);
 }
 
 unsigned VRegRenamer::createVirtualRegister(unsigned VReg) {
   return createVirtualRegisterWithName(
       VReg, getInstructionOpcodeHash(*MRI.getVRegDef(VReg)));
 }