[PATCH] D89767: [CostModel][X86] teach TTI calculate cost of chain of vector inserts/extracts more precisely and correctly:In each 128-lane, if there is at least one index is demanded and not all indices are demanded...

[Pengfei Wang via Phabricator via llvm-commits]

pengfei added inline comments.


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Comment at: llvm/lib/Target/X86/X86TargetTransformInfo.cpp:3088
+        // inserti128.
+        // Case#3: inserting into 4,5,6,7 index needs 4*vpinsrd + inserti128.
+        unsigned Num128Lanes = LT.second.getSizeInBits() / 128 * LT.first;
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Why inserting 5th in case 2 needs extracti128 but case 3 doesn't?


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Comment at: llvm/lib/Target/X86/X86TargetTransformInfo.cpp:3089
+        // Case#3: inserting into 4,5,6,7 index needs 4*vpinsrd + inserti128.
+        unsigned Num128Lanes = LT.second.getSizeInBits() / 128 * LT.first;
+        unsigned NumElts = LT.second.getVectorNumElements() * LT.first;
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Do we need to skip if LT.second.getSizeInBits() == 128?


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  https://reviews.llvm.org/D89767/new/

https://reviews.llvm.org/D89767