[PATCH] Remove loop crossing restriction from the backward threader.

Jeff Law jeffreyalaw@gmail.com
Thu Nov 11 17:35:24 GMT 2021

On 11/11/2021 10:24 AM, Aldy Hernandez wrote:
> We have much more thorough restrictions, that are shared between both
> threader implementations, in the registry.  I've been meaning to
> remove the backward threader one, since it's only purpose was reducing
> the search space.  Previously there was a small time penalty for its
> removal, but with the various patches in the past month, it looks like
> the removal is a wash performance wise.
> This catches 8 more jump threads in the backward threader in my suite.
> Presumably, because we disallowed all loop crossing, whereas the
> registry restrictions allow some crossing (if we exit the loop, etc).
> OK pending tests on x86-64 Linux?
> gcc/ChangeLog:
> 	* tree-ssa-threadbackward.c
> 	(back_threader_profitability::profitable_path_p): Remove loop
> 	crossing restriction.

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