[PATCH] D143180: DAG: Expand legalization of is.fpclass to fcmp for DAZ

Sun Jun 4 03:55:52 PDT 2023

arsenm added inline comments.

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Comment at: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp:8060
   if (Flags.hasNoFPExcept() &&
+      // TODO: Should check isCondCodeLegal
       isOperationLegalOrCustom(ISD::SETCC, OperandVT.getScalarType())) {
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sepavloff wrote:
> arsenm wrote:
> > sepavloff wrote:
> > > What prevents to put the check here?
> > Expanded logic which I have no way of testing. If I can't write a test I'm not writing the handling for it
> To test `isCondCodeLegal` here we need a target in which `SETOEQ` is not legal. It is hard to imagine that a target supports FP numbers natively but comparison of them for equality is absent. Probably this TODO is not useful and could be removed. Alternatively, you could put the call to `isCondCodeLegal` and leave it untested just because there is no way to test it. 
Checking isCondCodeLegal actually results in some x86 codegen diffs, so I'll do that separately 

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D143180/new/

https://reviews.llvm.org/D143180