[PATCH] D153351: [RISCV] Fold vmv.v.v into vops

[Philip Reames via Phabricator via llvm-commits]

reames requested changes to this revision.
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The example code from the description is wrong.  The "ta" needs to be "tu" to be correct.

  vsetivli zero, 2, e32, m1, ta, ma
  vadd.vv v8, v10, v11

Glancing at a few of the test, this appears wrong in the implementation as well.



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Comment at: llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp:3517
+
+    // Make sure there's a corresponding MaskedPseudo otherwise it's not safe to
+    // change VL.
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Please rebase this over D154620, and then use the exact same code structure as the vmerge transform.  Having them different makes it very hard to follow.  

Hm, this is just a thought.  But could we take the existing vmerge transform, and split it into two steps?  If a vmv.v.v is like a vmerge with a all ones mask, could the vmerge transform become "first form vmv.v.v" and "then fold vmv.v.v into true"?  We in fact already have both of these pieces, can we simply reorder and restructure?


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https://reviews.llvm.org/D153351