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Re: [PATCH 1/2] xtensa: add --tramp-limit option to gas
- From: "augustine dot sterling at gmail dot com" <augustine dot sterling at gmail dot com>
- To: Max Filippov <jcmvbkbc at gmail dot com>
- Cc: binutils at sourceware dot org, David Weatherford <weath at cadence dot com>, Marc Gauthier <marc at cadence dot com>, "linux-xtensa at linux-xtensa dot org" <linux-xtensa at linux-xtensa dot org>
- Date: Wed, 12 Aug 2015 09:32:23 -0700
- Subject: Re: [PATCH 1/2] xtensa: add --tramp-limit option to gas
- Authentication-results: sourceware.org; auth=none
- References: <1439340867-980-1-git-send-email-jcmvbkbc at gmail dot com> <1439340867-980-2-git-send-email-jcmvbkbc at gmail dot com>
On Tue, Aug 11, 2015 at 5:54 PM, Max Filippov <jcmvbkbc@gmail.com> wrote:
> Hardcoded frag count limit for trampoline frag emission may not work for
> all configurations. Make that limit configurable.
Frags, and especially frag-counts are a gas internal implementation
detail, and exposing them to the command line is not a good idea. The
count can change depending on the other obstacks involved, and many
other things.
You can tell the exact maximum size of all frags--it's decided when
they are closed, so you would be far better off determining the
maximum distance from one trampoline to the next and basing the
decision on that. If the issue is that they need to be created prior
to closing a frag, you can check if you need to close one by keeping a
running max size, perhaps at every instruction.
So, unfortunately, I think this change needs more work.