[PATCH] D39536: [PowerPC] Eliminate redundant register copys after register allocation

[Zaara Syeda via Phabricator via llvm-commits]

syzaara added inline comments.


================
Comment at: lib/Target/PowerPC/PPCRegCopyElim.cpp:80
+  MF = &MFParm;
+  TII = MF->getSubtarget<PPCSubtarget>().getInstrInfo();
+  DEBUG(dbgs() <<
----------------
I don't see any uses of TII, but there are uses of TRI. Maybe replace this with TRI?


================
Comment at: lib/Target/PowerPC/PPCRegCopyElim.cpp:430
+        MachineOperand *SrcMO = nullptr, *DstMO = nullptr;
+        if (isRegCopy(CopyMI, SrcMO, DstMO)) {
+          // We avoid processing same MI twice when we re-iterate this BB.
----------------
Can we change this to

```
if (!isRegCopy(CopyMI, SrcMO, DstMO))
   continue;
```
so that we don't have to nest the rest of the code.


================
Comment at: lib/Target/PowerPC/PPCRegCopyElim.cpp:454
+          DefMI = findDefBackward(++MBBRI, MBB, DstReg, SrcReg,
+                                  IsClobbered, IsDstUsed, OperandsToRewrite1,
+                                  TRI);
----------------
It seems a little messy to me for this function to have a parameter for OperandsToRewrite1. I wonder if it would be better to have another function like getOperandsToRewrite which we can call on line 482 after we know that we have erased an instruction.


https://reviews.llvm.org/D39536