[all-commits] [llvm/llvm-project] 2c5a68: Fix non-splat vector SREM expansion when one of th...

[Owen Anderson via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2c5a68858b046c8a2ca3ba07ecd82771a5a9b884
      https://github.com/llvm/llvm-project/commit/2c5a68858b046c8a2ca3ba07ecd82771a5a9b884
  Author: Owen Anderson <resistor at mac.com>
  Date:   2024-02-25 (Sun, 25 Feb 2024)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    M llvm/test/CodeGen/X86/srem-seteq-vec-nonsplat.ll

  Log Message:
  -----------
  Fix non-splat vector SREM expansion when one of the divisors is a power of two. (#82706)

The expansion previously used, derived from Hacker's Delight,
does not work correctly when the dividend is INT_MIN and the
divisor is a power of two. We now use an alternate derivation
of the A and Q constants specifically for the power-of-two divisor
case to avoid this problem. Credit to Fabian Giesen for the
new derivation.

Fixes https://github.com/llvm/llvm-project/issues/77169



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