[all-commits] [llvm/llvm-project] f90b78: [WebAssembly] Do not form minnum/maxnum (#184796)

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f90b783c3f2b29378bc2913db9995422c70579ea
      https://github.com/llvm/llvm-project/commit/f90b783c3f2b29378bc2913db9995422c70579ea
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2026-03-06 (Fri, 06 Mar 2026)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
    M llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
    M llvm/test/CodeGen/WebAssembly/simd-relaxed-fmax.ll
    M llvm/test/CodeGen/WebAssembly/simd-relaxed-fmin.ll

  Log Message:
  -----------
  [WebAssembly] Do not form minnum/maxnum (#184796)

For wasm, forming minnum/maxnum style ISD nodes is non-profitable,
because (in cases where any float min/max support exists at all), it has
pmin/pmax instructions that correspond to the fcmp+select semantics, or
relaxed_fmin/relaxed_fmax (for the nnan+nsz case) with even loser
semantics.

As such, return false from isProfitableToCombineMinNumMaxNum(), and also
respect that hook in the SDAGBuilder.



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