[all-commits] [llvm/llvm-project] cb961d: [ValueTracking][KnownFPClass] Cover known no-infin...

[Max Graey via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: cb961d331f40368d1856ad2dc00fde7ef3deb9e2
      https://github.com/llvm/llvm-project/commit/cb961d331f40368d1856ad2dc00fde7ef3deb9e2
  Author: Max Graey <maxgraey at gmail.com>
  Date:   2026-04-15 (Wed, 15 Apr 2026)

  Changed paths:
    M llvm/lib/Analysis/ValueTracking.cpp
    M llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp
    M llvm/lib/Support/KnownFPClass.cpp
    M llvm/test/Transforms/Attributor/nofpclass-powi.ll
    M llvm/unittests/Analysis/ValueTrackingTest.cpp
    M llvm/unittests/CodeGen/GlobalISel/KnownFPClassTest.cpp

  Log Message:
  -----------
  [ValueTracking][KnownFPClass] Cover known no-infinity cases for powi (#191736)

Teach `computeKnownFPClass` to infer non-infinity cass for `powi`.

Rules out `inf` for `powi(x, exp)` when:
- `x ?= inf` && `exp > 0`
- `x ?= +/-0` && `exp < 0`
- `x ?= finite` && `|exp| > 1`
- `x ?= subnormal` && `exp ?= -1` (special asym case after |exp| > 1)

where `?=` is maybe equal.

It's a bit conservative, and we could refine it further, but I'd take an
iterative improvement.



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