[PATCH] D116886: [M68k] Instruction selection to choose neg x when mul x -1 (Fix issue 48588)

[Douglas Chen via Phabricator via llvm-commits]

dougpuob marked an inline comment as done.
dougpuob added inline comments.


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Comment at: llvm/lib/Target/M68k/M68kISelDAGToDAG.cpp:326
+    case ISD::SUB: {
+      SDNode *Dividend = U->getOperand(0).getNode();
+      if (ConstantSDNode *CSDN = dyn_cast<ConstantSDNode>(Dividend))
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RKSimon wrote:
> Any reason why you can't just use llvm::isNullConstant(U->getOperand(0)) ?
Thank you for the reminder. It makes the code cleaner.


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Comment at: llvm/test/CodeGen/M68k/Arith/imul-neg.ll:4
 
 define i32 @mul4294967295_32(i32 %A) {
 ; CHECK-LABEL: mul4294967295_32:
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RKSimon wrote:
> Should we have i16/i8 test coverage as well?
Sure. Increase test coverage is good.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D116886/new/

https://reviews.llvm.org/D116886