Re: [PATCH, 5.x/6.x/7.x] Be more conservative in early inliner if FDO is enabled

[Richard Biener <richard dot guenther at gmail dot com>]

On Tue, Sep 20, 2016 at 1:57 PM, Yuan, Pengfei <ypf@pku.edu.cn> wrote:
>> > Btw, It occurs to me that then win in code-size might be purely due to the
>> > smaller base value for the TU size we use to compute the maximum unit
>> > growth with ... any idea how to improve it on this side?  Say, computing
>> > the TU size before early optimization (uh, probably not ...)
>> >
>> > That said, the inliner always completely fills its budged, that is, increase
>> > the unit by max-unit-growth?
>>
>> What I'm trying to say is that rather than limiting early inlining we should
>> maybe decrease inline-unit-growth when FDO is in effect?  Because we
>> can better control where the inlining goes.  If there is over 8% reduction
>> in size benchmarking (unpatched) compiler on Firefox with FDO and
>> --param inline-unit-growth=12 might show if the results are the same.
>>
>> Richard.
>>
>> > Richard.
>
> AFAIK, param inline-unit-growth only affects pass_ipa_inline. However, the code
> size reduction achieved with my patch is from pass_early_inline.

Any inlining you don't do at early inlining time will a) decrease the
size inline-unit-growth
is computed on b) just delays inlining to IPA inlining (with the now
more constrained size budget).

Richard.

> Yuan, Pengfei