[all-commits] [llvm/llvm-project] 858afe: Revert "[RISCV] Add isel optimization for (and (sr...

[Hans via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 858afe90aad9ca45165d64baec9249dd680c85d5
      https://github.com/llvm/llvm-project/commit/858afe90aad9ca45165d64baec9249dd680c85d5
  Author: Hans Wennborg <hans at chromium.org>
  Date:   2024-08-23 (Fri, 23 Aug 2024)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
    M llvm/test/CodeGen/RISCV/rv64zba.ll

  Log Message:
  -----------
  Revert "[RISCV] Add isel optimization for (and (sra y, c2), c1) to recover regression from #101751. (#104114)"

This caused an assert to fire:

  llvm/include/llvm/Support/Casting.h:566:
  decltype(auto) llvm::cast(const From &) [To = llvm::ConstantSDNode, From = llvm::SDValue]:
  Assertion `isa<To>(Val) && "cast<Ty>() argument of incompatible type!"' failed.

see comment on the PR.

> If c1 is a shifted mask with c3 leading zeros and c4 trailing zeros. If
> c2 is greater than c3, we can use (srli (srai y, c2 - c3), c3 + c4)
> followed by a SHXADD with c4 as the X amount.
>
> Without Zba we can use (slli (srli (srai y, c2 - c3), c3 + c4), c4).
> Alive2: https://alive2.llvm.org/ce/z/AwhheR

This reverts commit 514481736cf943464125ef34570a7df0a19290de.



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