[PATCH] D122875: [DAGCombiner] Scalarize extend/truncate for splat vector.

[Jianjian Guan via Phabricator via llvm-commits]

jacquesguan added inline comments.


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Comment at: llvm/test/CodeGen/RISCV/rvv/vnsra-sdnode.ll:33
+; RV64-NEXT:    vncvt.x.x.w v8, v8
+; RV64-NEXT:    ret
   %head = insertelement <vscale x 1 x i32> poison, i32 %b, i32 0
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frasercrmck wrote:
> jacquesguan wrote:
> > RKSimon wrote:
> > > Still a regression - can RISCV64 really not be coaxed into generating something better?
> > In order to generate widening instruction, I disable scalarizing of sign_ext and zero_ext, because the scalar type integer extention is easy to combine with other node, make it won't match the pattern.
> Do you think there's any way to fix it?
I think if we change the widen pattern to DAG combiner, maybe could generte some, but common DAG folder may fold extend to  for others example: ext_inreg firstly. So more condition we need to consider


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  https://reviews.llvm.org/D122875/new/

https://reviews.llvm.org/D122875