[PATCH] D91386: [PowerPC] Add peephole to remove redundant accumulator prime/unprime instructions

[Victor Huang via Phabricator via llvm-commits]

NeHuang added inline comments.


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Comment at: llvm/lib/Target/PowerPC/PPCPreEmitPeephole.cpp:373
+        // If we are visiting a xxmtacc instruction, we add its operand register
+        // to the candidate set.
+        if (Opc == PPC::XXMTACC) {
----------------
Question: Besides adding the operand register to the candidate, are we also recording the machine instruction used the register candidate? If I understand it properly, can we also add it in the comment? This would help understand your comment below `we mark the two instructions for removal.`  - line 380


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Comment at: llvm/lib/Target/PowerPC/PPCPreEmitPeephole.cpp:376
+          Register Acc = BBI.getOperand(0).getReg();
+          assert(PPC::ACCRCRegClass.contains(Acc) && "Unexpected register");
+          Candidates[Acc - PPC::ACC0] = &BBI;
----------------
nit: do you think we need to add instruction OPC information in the message to differentiate them?


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Comment at: llvm/lib/Target/PowerPC/PPCPreEmitPeephole.cpp:379
+        }
+        // If we are visiting a xxmfacc instruction and its operand is in the
+        // candidate set, we mark the two instructions for removal.
----------------
nit: operand -> operand register


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https://reviews.llvm.org/D91386