[arch-dev-public] Changing compilation flags

Bartłomiej Piotrowski bpiotrowski at archlinux.org
Wed Jul 5 10:11:44 UTC 2017

On 2017-07-05 11:36, Evangelos Foutras wrote:
> On 2 July 2017 at 19:19, Daniel Micay via arch-dev-public
> <arch-dev-public at archlinux.org> wrote:
>> Using -fno-plt would be a nice tiny little performance boost at runtime
>> but then it's important to make sure everything is compiled with -Wl,-
>> z,now and there might be programs ignoring LDFLAGS but respecting
>> CFLAGS. Ideally -z now would be the default in the linker first. If we
>> aren't going to patch the default, then I think a configure flag for
>> that needs to land upstream.
> It's also worth noting that clang does not support the -fno-plt option
> and I couldn't find any discussions about adding support for it.
> If it's only a tiny performance improvement, I strongly believe we
> should skip it for now.

Repeating what I said on IRC.

First, it's easy to workaround - there is no magic about using bash
substitution and re-exporting CFLAGS in the environment.

Second, enabling PIE and SSP by default is already a breaking change
that we make an exception for clang. Apparently you can patch clang to
reflect this, but you can't make it ignore -fno-plt too?

This is not a huge change that will cause everything to fall apart, and
less than 40 packages need clang. I can live with having to change them.


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