[all-commits] [llvm/llvm-project] f3261a: [AArch64] Add invalid 1 x vscale costs for reducti...

[David Green via All-commits]

  Branch: refs/heads/release/19.x
  Home:   https://github.com/llvm/llvm-project
  Commit: f3261a5a64d8ff2c76eb9c1ae2aa7d348c75e97c
      https://github.com/llvm/llvm-project/commit/f3261a5a64d8ff2c76eb9c1ae2aa7d348c75e97c
  Author: David Green <david.green at arm.com>
  Date:   2024-08-10 (Sat, 10 Aug 2024)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
    M llvm/test/Analysis/CostModel/AArch64/arith-fp-sve.ll
    M llvm/test/Analysis/CostModel/AArch64/cttz_elts.ll
    M llvm/test/Analysis/CostModel/AArch64/sve-arith.ll
    M llvm/test/Analysis/CostModel/AArch64/sve-intrinsics.ll
    M llvm/test/Analysis/CostModel/AArch64/sve-min-max.ll

  Log Message:
  -----------
  [AArch64] Add invalid 1 x vscale costs for reductions and reduction-operations. (#102105)

The code-generator is currently not able to handle scalable vectors of
<vscale x 1 x eltty>. The usual "fix" for this until it is supported is
to mark the costs of loads/stores with an invalid cost, preventing the
vectorizer from vectorizing at those factors. But on rare occasions
loops do not contain load/stores, only reductions.

So whilst this is still unsupported return an invalid cost to avoid
selecting vscale x 1 VFs. The cost of a reduction is not currently used
by the vectorizer so this adds the cost to the add/mul/and/or/xor or
min/max that should feed the reduction. It includes reduction costs
too, for completeness. This change will be removed when code-generation
for these types is sufficiently reliable.

Fixes #99760

(cherry picked from commit 0b745a10843fc85e579bbf459f78b3f43e7ab309)



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