[PATCH] D75689: [VectorCombine] fold extract-extract-op with different extraction indexes

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon accepted this revision.
RKSimon added a comment.

LGTM - You might want to add some test cases with 256/512-bit vectors (with indices coming from the same/different 128-bit subvectors) as well to get a broader range of extraction costs.

I'm not certain a SK_Splat will make much difference - the shuffle masks with a single non-undef index would be in most cases a lot cheaper even than that, especially on early SSE targets, so maybe we need to either consider another shuffle enum type or just provide the ability to compute costs from raw shuffle masks?


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