[PATCH] D132374: [TTI] Add SK_Splice shuffle mask detection and X86 costs

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


================
Comment at: llvm/lib/IR/Instructions.cpp:2309
+    // Splice is sequential starting from StartIndex.
+    if (MaskEltVal != (StartIndex + I))
+      return false;
----------------
fhahn wrote:
> Do we also need to check if we are extracting exactly half the original elements here? I see `isSplice` checks the length isn't changed, but other calls of `isSpliceMask` don't seem to do it (in BasicTTI)
None of the static shuffle kind matches know the width of the input types - they assume they match Mask.size()


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  https://reviews.llvm.org/D132374/new/

https://reviews.llvm.org/D132374