[RFC] test builtin ratio for loop distribution

[Alexandre Oliva]

On Feb 16, 2021, Alexandre Oliva <oliva@adacore.com> wrote:

>> So I wonder whether we should instead re-run CCP after loop opts which
>> computes nonzero bits as well instead of the above "hack".

That works.  It takes care of both the dest alignment and the len ctz.

Explicitly masking out the len tz from nonzero bits also works, but I
suppose the ccp pass does a better job, and it takes care of memcpy and
memmove as well.


I noticed that ccp releases CDI_DOMINATORS information.  It looks like
the last copy_prop pass, now replaced with ccp in my tree, was late
enough that it doesn't seem to matter, but at first I thought you meant
an earlier copy_prop, that runs before graphite, and dropping dominator
info at that point was a problem for e.g. cunroll.

-- 
Alexandre Oliva, happy hacker  https://FSFLA.org/blogs/lxo/
   Free Software Activist         GNU Toolchain Engineer
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