[PATCH] D79202: [SVE] Fix invalid usages of getNumElements() in ValueTracking

[Sander de Smalen via Phabricator via llvm-commits]

sdesmalen added a comment.

Is there a way we can test/guard this?



================
Comment at: llvm/lib/Analysis/ValueTracking.cpp:378
   APInt DemandedElts =
-      Ty->isVectorTy()
-          ? APInt::getAllOnesValue(cast<VectorType>(Ty)->getNumElements())
-          : APInt(1, 1);
+      FVTy ? APInt::getAllOnesValue(FVTy->getNumElements()) : APInt(1, 1);
   return ComputeNumSignBits(V, DemandedElts, Depth, Q);
----------------
By checking the result of `dyn_cast<FixedVectorType>`, this switch will select APInt(1, 1) when Ty is a `ScalableVectorType`.
I guess this should just bail out when the type is a scalable vector.


================
Comment at: llvm/lib/Analysis/ValueTracking.cpp:2698
+               DemandedElts.getBitWidth()) ||
+          (!isa<FixedVectorType>(Ty) && DemandedElts == APInt(1, 1))) &&
          "Unexpected vector size");
----------------
This should be `!isa<VectorType>`, because APInt(1, 1) doesn't work for scalable vectors.

Should this function also bail out early when the type is a scalablevector?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D79202/new/

https://reviews.llvm.org/D79202