[PATCH] D138542: [InstSimplify] Use dominate condtion to simplify xor/sub

Wed Nov 23 05:36:26 PST 2022

bcl5980 added a comment.

In D138542#3946536 <https://reviews.llvm.org/D138542#3946536>, @spatel wrote:

> There's a question of where this kind of transform belongs - CVP, SCCP?

I guess if one of the compare value is constant, it should be IPSCCP. If both of them are not constant, it should be CVP.

> This seems fine to me, but it should probably be split off into a helper function. We could do the same for srem/urem? sdiv/udiv with a slight adjustment? any other opcodes?

Yeah, you are right. div/rem should work also.

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Comment at: llvm/test/Transforms/InstSimplify/domcondition.ll:36
+; CHECK:       cond.end:
+; CHECK-NEXT:    ret i32 0
+;
----------------
spatel wrote:
> Something went wrong - this should not simplify?
Yeah, this is a negative test. The condition is icmp ne.

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https://reviews.llvm.org/D138542