Gentle ping
> On 20 Jan 2026, at 3:45 PM, Prachi Godbole <[email protected]> wrote:
>
> <0001-ipa-reorder-for-locality-Adjust-bootstrap-lto-locali.patch>
>
> I’ve updated the patch as per discussion and lowered the default value.
> Attaching the new version here.
>
> This patch turns off -fipa-reorder-for-locality for -fprofile-generate because
> it's not required and contributes to the bloated time taken by bootstrap. It
> also reduces the default partition size by half; the increased number of
> partitions speeds up LTRANS phase.
>
> Bootstrapped and tested on aarch64-none-linux-gnu. OK for mainline?
>
> Signed-off-by: Prachi Godbole <[email protected]>
>
> config/ChangeLog:
>
> * bootstrap-lto-locality.mk (STAGE2_CFLAGS): Add param
> lto-max-locality-partition.
> (STAGE3_CFLAGS): Ditto.
> (STAGEprofile_CFLAGS): Remove -fipa-reorder-for-locality.
> (STAGEtrain_CFLAGS): Ditto.
>
> gcc/Changelog:
>
> * params.opt: Change default param value.
>
>
>
>> On 16 Jan 2026, at 6:09 PM, Prachi Godbole <[email protected]> wrote:
>>
>>
>>
>>> On 16 Jan 2026, at 5:56 PM, Jan Hubicka <[email protected]> wrote:
>>>
>>> External email: Use caution opening links or attachments
>>>
>>>
>>>> Thank you Honza for the review
>>>>
>>>>
>>>> The default value was tuned according to the target applications - large
>>>> applications that benefit from the higher size. This results in majority
>>>> of the target applications not needing param adjustment. I see ~5-10%
>>>> improvement for the current default over a lower value.
>>>>
>>>> The adjustment I made here was for additional build time improvement
>>>> specifically for GCC bootstrap with the intention that the target
>>>> applications can use the pass without needing it.
>>>
>>> I see that 5-10% improvement is quite important for the specific
>>> use-case. It is kind of unfortunate that we need to tune the parameter
>>> so high. Is it something that can be fixed by better code placement
>>> across adjacent partitions (which can be acomplished by tp_first_run
>>> machinery and also your new numbered textsubsections) or is it really
>>> about late IPA optimizations (such as register alloation) being important
>>> and ltrans partition being in a way?
>>>
>>> I think we should go with reasonable defaults (which does not bow up
>>> build times) in GCC, so perhaps param should be lowered by default to
>>> what we need for bootstrap and have the target app to bump it up in its
>>> config.
>>>
>>> Hozna
>>
>> Unfortunately, it’s about IPA optimizations and specifically how many clones
>> are created - having too low a default will blow up the code size. Following
>> your suggestion, I’ll try with a lowered default - meeting halfway between
>> current default and the param here so that we don’t blow up build time and
>> also the apps don’t require too much adjustment. I’ll be back with that patch
>>
>> Thanks,
>> Prachi
>>
>
