[PATCH] D82663: [CodeGen] Have CodeGen for fixed-point unsigned with padding emit signed operations.

[Bevin Hansson via Phabricator via cfe-commits]

ebevhan added a comment.

In D82663#2117451 <https://reviews.llvm.org/D82663#2117451>, @rjmccall wrote:

> Why not legalize to the signed operation?


My feeling was that it wasn't right do so in LLVM, because LLVM has no notion of the padding bit and therefore doesn't really care about Clang's rationale for doing the legalization that way.
If an illegal udiv.fix.sat needs to be legalized via promotion, it makes more sense to legalize it to another unsigned operation rather than arbitrarily doing it as a signed one.

I guess it could be done in cases where the resulting signed operation was legal and the unsigned one was not, but that isn't testable upstream since none of the operations are legal on upstream targets.


Repository:
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