[PATCH] D47816: [InstCombine] Don't sink instructions across inlined function call.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> Generally , the sinking will increase the live range of variables

This isn't a good description.  It increases the live range of the operands, and reduces the live range of the result.  Which one matters more isn't obvious.  And in some cases, the cost of the operation itself might be more important than the cost of spilling.

Granted, instcombine might not be the best place to make that kind of decision; it's very hard to estimate register pressure before isel.


https://reviews.llvm.org/D47816