[all-commits] [llvm/llvm-project] de5d58: [AArch64] Tweak the costs of experimental_cttz_elt...

[David Sherwood via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: de5d5888043ae022756ecdda31b550343a4dfeff
      https://github.com/llvm/llvm-project/commit/de5d5888043ae022756ecdda31b550343a4dfeff
  Author: David Sherwood <david.sherwood at arm.com>
  Date:   2025-02-04 (Tue, 04 Feb 2025)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
    M llvm/test/Analysis/CostModel/AArch64/cttz_elts.ll

  Log Message:
  -----------
  [AArch64] Tweak the costs of experimental_cttz_elts intrinsic (#125093)

The experimental_cttz_elts intrinsic currently returns a cost
of 1 for all types, however we know that it currently requires
2 SVE instructions when lowering this - brkb and cntp. Both of
these instructions have a throughput that is half of a basic
vector instruction such as a vector add. This patch bumps the
cost of this intrinsic up to 4 to reflect two instructions of
lower throughput.



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