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Re: [PATCH][GCC][front-end][build-machinery][opt-framework] Allow setting of stack-clash via configure options. [Patch (4/6)]

On 07/19/2018 06:55 AM, Tamar Christina wrote:
>>> What's the purpose of including auto-host in params-list and
>>> params-options?  It seems like you're putting a property of the target
>>> (guard size) into the wrong place (auto-host.h).
>> The reason for this is because there's a test gcc.dg/params/blocksort-part.c
>> that uses these params-options to generate test cases to perform parameter
>> validation. However because now the params.def file can contain a CPP
>> macro these would then fail.
>> CPP is already called to create params-options and params-list so the easiest
>> way to fix this test was just to include auto-host which would get it the values
>> from configure.
>> This test is probably not needed anymore after my second patch series as
>> parameters are validated by the front-end now, so they can never go out of
>> range.
Right, but I don't immediately see a way to avoid the test.  ie, it just
walks down everything in params.options and except for a couple
exceptional values the test gets run.

I wonder if all this is an indication that having CPP constants in the
options isn't going to work well as we're mixing the distinction between

>>> It's also a bit unclear to me why this is necessary at all.  Are we
>>> planning to support both the 4k and 64k guards?  My goal (once the
>>> guard was configurable) was never for supporting multiple sizes on a
>>> target but instead to allow experimentation to find the right default.
> Having talked to people I believe we do need to support both 4k and 64k guards.
> For the Linux/Glibc world it wouldn't matter much, either 4 or 64k would do, though Glibc has settled on 64k pages.
> However other systems like (open/free)BSD or musl based systems do not want
> 64k pages but want 4k ones.  So we're ending up having to support both as a compromise.
Understood.  Thanks for verifying.  I wonder if we could just bury this
entirely in the aarch64 config files and not expose the default into


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