llvm-reduce: Inform MRI of used phys reg masks

[arsenm]

Summary

I'm not sure how to directly observe this invisible cache for a test.

[MatzeB]

I'm not sure how to directly observe this invisible cache for a test.

Only thing I can think of is to have the MachineVerifier check.

Comparing this with MIRParserImpl::setupRegisterInfo there also needs to be some handling for landing pads (getCustomEHPadPreservedMask(MF))...

Either way this change only makes things better. LGTM

[MatzeB]

In D123742#3450257, @MatzeB wrote:

I'm not sure how to directly observe this invisible cache for a test.

Only thing I can think of is to have the MachineVerifier check.

Which on the other hand doesn't really work either, since this information seems to only exist after register rewriting; and I don't think the verifier has a notion of running before/after a pass like the rewriter...

[arsenm]

e33b07f8599523e1e39b20b134dfc870635353bc

llvm/tools/llvm-reduce/ReducerWorkItem.cpp

static std::unique_ptr<MachineFunction> cloneMF(MachineFunction *SrcMF) {
   auto *SrcMRI = &SrcMF->getRegInfo();
   auto *DstMRI = &DstMF->getRegInfo();
 
   // Create vregs.
   for (auto &SrcMBB : *SrcMF) {
     for (auto &SrcMI : SrcMBB) {
       for (unsigned I = 0, E = SrcMI.getNumOperands(); I < E; ++I) {
         auto &DMO = SrcMI.getOperand(I);
+        if (DMO.isRegMask()) {
+          DstMRI->addPhysRegsUsedFromRegMask(DMO.getRegMask());
+          continue;
+        }
+
         if (!DMO.isReg())
           continue;
         Register SrcReg = DMO.getReg();
         if (Register::isPhysicalRegister(SrcReg))
           continue;
         Register DstReg = DstMRI->createIncompleteVirtualRegister(
             SrcMRI->getVRegName(SrcReg));
         DstMRI->setRegClassOrRegBank(DstReg,