[PATCH] D73832: Ignore/Drop droppable uses for code-sinking in InstCombine

Sun Feb 2 11:20:04 PST 2020

jdoerfert added a comment.

In D73832#1853708 <https://reviews.llvm.org/D73832#1853708>, @Tyker wrote:

> In D73832#1853677 <https://reviews.llvm.org/D73832#1853677>, @jdoerfert wrote:
>
> > Please add a commit message on this one and maybe remove the `WIP` tag as it is supposed to be reviewed and actually working, right?
>
>
> the title kind says it all. yes it is working as expected and should be ready for review.

Arguably, "droppable uses" is a new concept you need to explain in the commit message.

> code-sinking in InstCombine is far from as aggressive as it could be. is it also done somewhere else ?
>  i think that instead of a single use in the successor block we could just code-sink to the successor block dominate all undroppable uses of the instruction if it exists.
>  or maybe find the highest common dominator of all undroppable uses and if it is not the current basic block code-sink the instruction to it.

There is for sure potential, I think we have another sinking pass but I'd need to check.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D73832/new/

https://reviews.llvm.org/D73832