[PATCH] D130895: [RISCV] Make VL choosing for a splat-like VMV based on its users

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp:2569
+  const MCInstrDesc &MCID = TII.get(UI->getMachineOpcode());
+  if (!RISCVII::hasMergeOp(MCID.TSFlags) ||
+      getMergeOpIdx(*UI, MCID) != UI.getOperandNo())
----------------
reames wrote:
> It's not clear to me why merge ops have anything to do with the legality here.  
The policy applies to how the merge operand is merged. If it doesn't have a merge operand or the use isn't the merge operand then the splat is an input to the arithmetic portion of the instruction which usually obeys VL. Except for the special case instructions above.


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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D130895/new/

https://reviews.llvm.org/D130895