[all-commits] [llvm/llvm-project] 48636d: [GlobalISel] Add G_UAVGFLOOR/G_UAVGCEIL/G_SAVGFLOO...

[Joel Walker via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 48636d19ab5e3bf82cbff593a82573e8094abed1
      https://github.com/llvm/llvm-project/commit/48636d19ab5e3bf82cbff593a82573e8094abed1
  Author: Joel Walker <theagingboy05 at gmail.com>
  Date:   2026-07-14 (Tue, 14 Jul 2026)

  Changed paths:
    M llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp
    A llvm/test/CodeGen/AArch64/GlobalISel/knownbits-avg.mir
    M llvm/test/CodeGen/AArch64/aarch64-known-bits-hadd.ll

  Log Message:
  -----------
  [GlobalISel] Add G_UAVGFLOOR/G_UAVGCEIL/G_SAVGFLOOR/G_SAVGCEIL to computeKnownBits (#209171)

Add known-bits handling for the averaging (halving add) opcodes G_UAVGFLOOR,
G_UAVGCEIL, G_SAVGFLOOR and G_SAVGCEIL in GISelValueTracking, using the
existing `KnownBits::avg{Floor,Ceil}{S,U}` helpers. This matches
SelectionDAG's handling of the corresponding ISD::AVGFLOOR*/AVGCEIL*
nodes.

This lets GlobalISel drop the redundant masking around hadd/rhadd of
zero-extended operands on AArch64 (see aarch64-known-bits-hadd.ll, where the
GlobalISel output now matches SelectionDAG). The sign-extended cases are
unaffected, since the masking is not redundant there.

Part of #150515.

---
Assisted by Claude (Anthropic).



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications