[all-commits] [llvm/llvm-project] a3d5f1: [x86] Fix infinite loop inside DAG combiner with l...

[goussepi via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a3d5f1cf5d88dfbbed931951e07f328d5ceba510
      https://github.com/llvm/llvm-project/commit/a3d5f1cf5d88dfbbed931951e07f328d5ceba510
  Author: Pierre Gousseau <pierre.gousseau at sony.com>
  Date:   2022-04-05 (Tue, 05 Apr 2022)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/lzcnt-zext-cmp.ll

  Log Message:
  -----------
  [x86] Fix infinite loop inside DAG combiner with lzcnt feature.

The issue affects targets supporting fast-lzcnt such as btver2.
This removes extraneous zext/trunc node insertions to fix the infinite
loop.
This fixes Issue https://github.com/llvm/llvm-project/issues/54694

Differential Revision: https://reviews.llvm.org/D122900

Reviewed By: RKSimon, spatel, lebedev.ri