[all-commits] [llvm/llvm-project] f67fa3: [AArch64] Remove special-case inserted shuffle cost.

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f67fa3be4db68afc08c7f3d9523f1533fa5687b7
      https://github.com/llvm/llvm-project/commit/f67fa3be4db68afc08c7f3d9523f1533fa5687b7
  Author: David Green <david.green at arm.com>
  Date:   2024-07-25 (Thu, 25 Jul 2024)

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

  Log Message:
  -----------
  [AArch64] Remove special-case inserted shuffle cost.

This special case tried to measure if the shuffle vector will be multiple
inserts into an existing vector, with one of the lanes already in-place. If so
it reduces the cost by 1 to to represent it will can insert n-1 vector lanes.
This isn't always true though as the original vector may need to be moved to a
new value to start inserting new values into it, if other values from the
original are still needed.

This didn't effect performance much when I tried it, but should hopefully start
to address a regression we see from differences in SLP vectorization lane
orders.



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