[all-commits] [llvm/llvm-project] 673da8: [LLVM][CodeGen][AArch64] Remove bogus lowering of ...

[Paul Walker via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 673da8c83413c4d1e7e76e1b52a2924e837e7221
      https://github.com/llvm/llvm-project/commit/673da8c83413c4d1e7e76e1b52a2924e837e7221
  Author: Paul Walker <paul.walker at arm.com>
  Date:   2024-04-15 (Mon, 15 Apr 2024)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
    M llvm/test/CodeGen/AArch64/sve2-intrinsics-while.ll

  Log Message:
  -----------
  [LLVM][CodeGen][AArch64] Remove bogus lowering of sve_while{gt/ge/hi/hs} intrinsics. (#88126)

When fed constant operands we try to lower WHILE intrinsics to PTRUE
using a fixed length pattern. This is not valid for the decrementing
variants of WHILE because they construct their result predicate vector
by traversing from high->low lanes whereas the incrementing variants and
PTRUE traverse from low->high lanes.

Whilst we can still utilise PTRUE by reversing its result I figure
replacing a single WHILE with multiple SVE instructions is likely
counterproductive.



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