[all-commits] [llvm/llvm-project] 7ca3e2: [SDAG] narrow truncated sign_extend_inreg

[Sanjay Patel via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7ca3e23f250dc679bdd6660fd6877e1e5c275871
      https://github.com/llvm/llvm-project/commit/7ca3e23f250dc679bdd6660fd6877e1e5c275871
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2022-07-16 (Sat, 16 Jul 2022)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/test/CodeGen/AMDGPU/mul_int24.ll
    M llvm/test/CodeGen/X86/pmulh.ll
    M llvm/test/CodeGen/X86/sar_fold64.ll

  Log Message:
  -----------
  [SDAG] narrow truncated sign_extend_inreg

trunc (sign_ext_inreg X, iM) to iN --> sign_ext_inreg (trunc X to iN), iM

There are improvements on existing tests from this, and there are a pair
of large regressions in D127115 for Thumb2 caused by not folding this
pattern.

Differential Revision: https://reviews.llvm.org/D129890