[PATCH] D48172: [CostModel][AArch64] Add some initial costs for SK_Select and SK_PermuteSingleSrc

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


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Comment at: lib/Target/AArch64/AArch64TargetTransformInfo.cpp:966
+      { TTI::SK_PermuteSingleSrc, MVT::v2i32, 1 }, // mov.
+      { TTI::SK_PermuteSingleSrc, MVT::v4i32, 2 }, // rev+trn or similar.
+      { TTI::SK_PermuteSingleSrc, MVT::v2i64, 1 }, // mov.
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efriedma wrote:
> `egrep -c "[0-3],[0-3],[0-3],[0-3].*Cost [3-4]" lib/Target/AArch64/AArch64PerfectShuffle.h` says there are 182 permutes which cost more than 2.  But I guess this is a reasonable estimate not knowing anything else.
Out of interest, are those perfect shuffle costs based off throughput or number of instructions?


Repository:
  rL LLVM

https://reviews.llvm.org/D48172