[PATCH] D102393: [DAGCombiner] Relax an assertion to an early return

Thu May 13 04:53:47 PDT 2021

frasercrmck added a comment.

In D102393#2756528 <https://reviews.llvm.org/D102393#2756528>, @lebedev.ri wrote:

> We got here because in `foldSelectOfConstants()`
>
>   auto *C1 = dyn_cast<ConstantSDNode>(N1);
>   auto *C2 = dyn_cast<ConstantSDNode>(N2);
>   if (!C1 || !C2)
>     return SDValue();
>
> didn't return.
> So what are those constants?

They're constants but they have implicit truncation. After legalization, RV64 -- which doesn't have legal i32 -- sees:

  t9: v4i32 = BUILD_VECTOR Constant:i64<878082066>, Constant:i64<878082066>, Constant:i64<878082066>, Constant:i64<878082066>
  t11: v4i32 = BUILD_VECTOR Constant:i64<1164411171>, Constant:i64<1164411171>, Constant:i64<1164411171>, Constant:i64<1164411171>

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D102393/new/

https://reviews.llvm.org/D102393