[PATCH] D63163: [GlobalISel][AArch64] Fold G_SUB into G_ICMP when it's safe to do so

[Amara Emerson via Phabricator via llvm-commits]

aemerson added inline comments.


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Comment at: llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp:2967
+                                             MachineRegisterInfo &MRI) const {
+  assert(I.getOpcode() == TargetOpcode::G_ICMP && "Expected G_ICMP");
+  // We want to find this sort of thing:
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This function generates semantically incorrect GMIR and then relies on the caller to fix and select it. I would rather we also modify the opcode in this function to `ANDS[WX]rr` and then have the caller check the return value to see if it needs to modify the opc. That way, on entry and exit we have semantically correct, if only partially selected, MIR.


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  https://reviews.llvm.org/D63163/new/

https://reviews.llvm.org/D63163