[PATCH] D100486: [COST]Improve cost model for shuffles in SLP.

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


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Comment at: llvm/test/Analysis/CostModel/X86/reduction.ll:64
 ; SSE-LABEL: 'reduction_cost_int'
-; SSE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %rdx.shuf = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 undef, i32 undef, i32 undef, i32 undef>
+; SSE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %rdx.shuf = shufflevector <8 x i32> %rdx, <8 x i32> undef, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 undef, i32 undef, i32 undef, i32 undef>
 ; SSE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %bin.rdx = add <8 x i32> %rdx, %rdx.shuf
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Something might be still going wrong here - SSE max legal type is v4i32 so this cost should be 0 as its referencing a single existing vector


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  https://reviews.llvm.org/D100486/new/

https://reviews.llvm.org/D100486