[PATCH] D105525: [GISel] Add fpext/fptrunc combines
Jay Foad via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 8 03:35:39 PDT 2021
foad added inline comments.
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Comment at: llvm/include/llvm/Target/GlobalISel/Combine.td:346
// Fold fp_op(cst) to the constant result of the floating point operation.
def constant_fp_op_matchinfo: GIDefMatchData<"Optional<APFloat>">;
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I didn't know we had these as combines. Do we really want this, instead of constant-folding them in CSEMIRBuilder? See D99036 and D104528 for some steps in that direction.
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Comment at: llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp:2490
+ // floating point types, but will have altered precision when folded to
+ // float. We will only allow this fold for Unsafe and 8bit cases.
+ Register SrcInputReg = SrcMI->getOperand(1).getReg();
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Is there a precedent for using "UnsafeFPMath" to enable this particular unsafe combine?
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https://reviews.llvm.org/D105525/new/
https://reviews.llvm.org/D105525
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