[all-commits] [llvm/llvm-project] fa784f: [AArch64] Insert subvector costs

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: fa784f63827d046c1dad5cbdf2bb5eabaf456c75
      https://github.com/llvm/llvm-project/commit/fa784f63827d046c1dad5cbdf2bb5eabaf456c75
  Author: David Green <david.green at arm.com>
  Date:   2022-04-07 (Thu, 07 Apr 2022)

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

  Log Message:
  -----------
  [AArch64] Insert subvector costs

An insert subvector under aarch64 can often be done as a single lane mov
operation. For example a v4i8 inserted into a v16i8 is a s-reg mov, so
long as the index is a multiple of 4. This teaches the cost model that,
using code copied over from the X86 backend.

Some of the costs (v16i16_4_0) are still high because they get matched
as a SK_Select, not an SK_InsertSubvector. D120879 has some codegen
tests for inserting subvectors, which I were added as
llvm/test/CodeGen/AArch64/insert-subvector.ll.

Differential Revision: https://reviews.llvm.org/D120880