[PATCH] D141778: [DAGCombiner][X86] `mergeConsecutiveStores()`: support merging splat-stores of the same value

[Phoebe Wang via Phabricator via llvm-commits]

pengfei added a comment.

obious -> obvious



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Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:674-675
         return StoreSource::Load;
       default:
-        return StoreSource::Unknown;
+        return StoreSource::Splat;
       }
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Is this too strong to assume all the other cases are `Splat`? If this is the fact, why adding it in `StoreSource` rather than replacing `Unknown`?


================
Comment at: llvm/test/CodeGen/X86/legalize-shl-vec.ll:247-252
+; X64-NEXT:    movq %r8, %xmm0
+; X64-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[0,1,0,1]
+; X64-NEXT:    psrad $31, %xmm0
+; X64-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[1,1,3,3]
+; X64-NEXT:    movdqa %xmm0, 16(%rdi)
+; X64-NEXT:    movdqa %xmm0, (%rdi)
----------------
Looks like regression here.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D141778/new/

https://reviews.llvm.org/D141778