[PATCH] D42267: [ThinLTO] Allow 0 to be a valid value for pruning interval for C LTO API.

[Teresa Johnson via llvm-commits]

On Wed, Feb 7, 2018 at 6:20 PM, <katya.romanova at sony.com> wrote:

> Thank you! I will wait for a formal LGTM from the code owners and commit.
>

I'm not sure who the owner of the legacy LTO is, but LGTM. pcc is owner of
the new LTO API, but possibly that covers this as well?


> Apple could change ld64 not set up cache pruning interval to 0 when
> pruning_interval option was not set, then I suspect the default settings
> will be applied.
>
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> Steven, just a heads up. I’m planning to do a follow-up patch allowing 0
>  to be a meaningful value for the rest 4 cache pruning options. How would
> it affect you? The rational is the same: to make C LTO API more compatible
> with C++ LTO API. What do you think?
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>
> *From:* stevenwu at apple.com [mailto:stevenwu at apple.com]
> *Sent:* Wednesday, February 7, 2018 2:37 PM
> *To:* Teresa Johnson <tejohnson at google.com>
> *Cc:* reviews+D42267+public+4d77dea060c5b663 at reviews.llvm.org; Romanova,
> Katya <katya.romanova at sony.com>; Mehdi AMINI <joker.eph at gmail.com>;
> bd1976llvm at gmail.com; deadalnix+llvmreview at gmail.com; Duncan Exon Smith <
> dexonsmith at apple.com>; Bob Haarman <llvm at inglorion.net>; Easwaran Raman <
> eraman at google.com>; llvm-commits <llvm-commits at lists.llvm.org>
> *Subject:* Re: [PATCH] D42267: [ThinLTO] Allow 0 to be a valid value for
> pruning interval for C LTO API.
>
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> On Feb 7, 2018, at 2:17 PM, Teresa Johnson <tejohnson at google.com> wrote:
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> On Tue, Feb 6, 2018 at 4:58 PM, Katya Romanova via Phabricator <
> reviews at reviews.llvm.org> wrote:
>
> kromanova added a comment.
>
> Great! Teresa, please let me know if it's OK to commit or if you want me
> to change something in this patch.
> I got an OK from Steven Wu, Apple's ThinLTO/ld64 developer.
>
>
>
> It's ok with me. Just to confirm, my understanding after reading through
> the thread is that currently ld64 will pass the value 0 to this by default,
> so with this change and the current ld64, pruning will be forced
> immediately. But Apple will change ld64 so in the future it would not do
> this. Is that correct?
>
> As long as Apple is happy, I'm fine with that.
>
>
>
> I had a discussion with Duncan and we are ok with this. Just remember the
> next time when you use your custom libLTO on macOS during development, you
> might get cache pruning every time by default. However, the ld64 that
> supports thinLTO already has -prune_interval_lto which you can overwrite to
> get the behavior you want.
>
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>
> Steven
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> Repository:
>   rL LLVM
>
> https://reviews.llvm.org/D42267
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> --
>
> Teresa Johnson |
>
>  Software Engineer |
>
>  tejohnson at google.com |
>
>  408-460-2413 <(408)%20460-2413>
>
>
>



-- 
Teresa Johnson |  Software Engineer |  tejohnson at google.com |  408-460-2413
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