[PATCH] D96287: [TTI] Change getOperandsScalarizationOverhead to take Type args

[Dave Green via Phabricator via llvm-commits]

dmgreen added inline comments.


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Comment at: llvm/include/llvm/CodeGen/BasicTTIImpl.h:647
+    if (!Args.empty()) {
+      SmallVector<Type *> Tys(Args.size(), Ty);
+      Cost += getOperandsScalarizationOverhead(Args, Tys);
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sdesmalen wrote:
> Is this not doing something different than it did before, i.e. it now always uses `InTy` for each of the arguments to get the cost, where it previously used the types from each of the arguments?
> I expected something similar to what you did in LoopVectorize with `MaybeVectorizeType`.
Yeah. This version of getScalarizationOverhead is only called from getArithmeticInstrCost (or ARMTTIImpl::getArithmeticInstrCost etc). So the arguments/return value are all likely to all be the same value, and this is making that assumption.  It is probably at least good enough as a heuristic, when compared to the else below. I've added a comment too.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D96287/new/

https://reviews.llvm.org/D96287