[PATCH] D126175: [SelectionDAG] Add a freeze to ISD::ABS expansion.

[Eli Friedman via Phabricator via llvm-commits]

efriedma accepted this revision.
efriedma added a comment.
This revision is now accepted and ready to land.

LGTM

> Looking at the test deltas I wonder if it be valid to combine (sext_inreg (freeze (aextload X))) -> (freeze (sextload X)).

That doesn't directly work: if the loaded value is poison, it isn't sign-extended.  You'd have to represent it some other way.

For example, you could introduce a "frozen sextload".  Or you could combine abs(sextload(x)) -> y = (freeze (sextload X)); umin(y,sub(0,y)).  Or you could introduce a form of "freeze" that freezes undef, but not poison.


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https://reviews.llvm.org/D126175