[PATCH] D89392: [GlobalISel] Fold unary opcodes in CSEMIRBuilder

Wed Oct 14 07:41:13 PDT 2020

foad added a comment.

In D89392#2330084 <https://reviews.llvm.org/D89392#2330084>, @arsenm wrote:

> Automatically folding legalization artifacts makes me a bit nervous. What happens if you want to legalize a constant by widening, and the legalizer wants to insert the trunc from a widened constant?

I don't know. I did wonder about that. It didn't seem to cause any problems in the test suite.

Are you suggesting that the existing BinOp folding is OK but only because it doesn't introduce constants of any new types, only of the same type as other constants that already exist?

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  https://reviews.llvm.org/D89392/new/

https://reviews.llvm.org/D89392