[GISel][NFC]: Add missing call to record CSE hits in the CSEMIRBuilder

[aditya_nandakumar]

Summary

Missing call to record CSE hits. Can be used to figure out what opcodes are CSEd frequently and how many times.
NFC.

[arsenm]

Can this be tested?

[aditya_nandakumar]

Updated to add test case for CSE debug output and standardize the debug printing format inside CSE.

[arsenm]

test/CodeGen/AArch64/GlobalISel/legalize-ext-csedebug-output.mir

2 ↗

(On Diff #186006)

Needs a REQUIRES: asserts?

[aditya_nandakumar]

Added missing REQUIRES: asserts to the test.

[arsenm]

LGTM

[aditya_nandakumar]

Thanks. r353553

lib/CodeGen/GlobalISel/CSEMIRBuilder.cpp

 CSEMIRBuilder::getDominatingInstrForID(FoldingSetNodeID &ID,
                                        void *&NodeInsertPos) {
   GISelCSEInfo *CSEInfo = getCSEInfo();
   assert(CSEInfo && "Can't get here without setting CSEInfo");
   MachineBasicBlock *CurMBB = &getMBB();
   MachineInstr *MI =
       CSEInfo->getMachineInstrIfExists(ID, CurMBB, NodeInsertPos);
   if (MI) {
+    CSEInfo->countOpcodeHit(MI->getOpcode());
     auto CurrPos = getInsertPt();
     if (!dominates(MI, CurrPos))
       CurMBB->splice(CurrPos, CurMBB, MI);
     return MachineInstrBuilder(getMF(), MI);
   }
   return MachineInstrBuilder();
 }