[all-commits] [llvm/llvm-project] 644de6: Revert "[NVPTX] designate fabs and fneg as free (#...

[Benjamin Kramer via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 644de6ad1c758d3bf754d7d50b98c555df5231b1
      https://github.com/llvm/llvm-project/commit/644de6ad1c758d3bf754d7d50b98c555df5231b1
  Author: Benjamin Kramer <benny.kra at googlemail.com>
  Date:   2025-01-09 (Thu, 09 Jan 2025)

  Changed paths:
    M llvm/lib/Target/NVPTX/NVPTXISelLowering.h
    M llvm/test/CodeGen/NVPTX/bf16x2-instructions.ll
    R llvm/test/CodeGen/NVPTX/fabs-fneg-free.ll

  Log Message:
  -----------
  Revert "[NVPTX] designate fabs and fneg as free (#121513)"

This reverts commit 45d46983bf7bda53bd7ee8e36a47571b3980fbd7.

NVPTX fabs & fneg are incompatible with LLVM's semantics as LLVM
guarantees the payload of NaNs to stay the same while PTX mangles NaNs.

The bad patterns are still in the NVPTX backend and should probably be
removed, since this change only exposed the bad behavior.



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