r232439 - GCOV: Expose the -coverage-exit-block-before-body flag in clang -cc1

[David Blaikie]

On Mon, Mar 16, 2015 at 6:18 PM, Nick Lewycky <nlewycky at google.com> wrote:

> On 16 March 2015 at 18:06, Justin Bogner <mail at justinbogner.com> wrote:
>
>> David Blaikie <dblaikie at gmail.com> writes:
>> > On Mar 16, 2015 4:57 PM, "Justin Bogner" <mail at justinbogner.com> wrote:
>> >>
>> >> Author: bogner
>> >> Date: Mon Mar 16 18:52:21 2015
>> >> New Revision: 232439
>> >>
>> >> URL: http://llvm.org/viewvc/llvm-project?rev=232439&view=rev
>> >> Log:
>> >> GCOV: Expose the -coverage-exit-block-before-body flag in clang -cc1
>> >>
>> >> This exposes the optional exit block placement logic from r232438 as a
>> >> clang -cc1 option. There is a test on the llvm side, but there isn't
>> >> really a way to inspect the gcov options from clang to test it here as
>> >> well.
>> >
>> > I'm missing something probably - what's the benefit of that over just
>> using
>> > -mllvm to pass this flag to llvm directly? (If I'm remembering how this
>> stuff
>> > works)
>>
>> I'm not sure - I was matching the -coverage-cfg-checksum and
>> -coverage-no-function-names-in-data CC1 options here. Maybe Nick has
>> thoughts?
>>
>
> LLVM flags are global state which will carry from one TU to the next.
> Suppose you want to use clang as a library, and you want to pass flags for
> one TU, then parse another TU with different flags. It is an error to set
> the same LLVM flag twice, so that will terminate your program. In general
> the -mllvm flags are bad news and we should get rid of all of them and
> certainly not add new ones.
>

I figured this flag was just as a utility for experiments - if it was for
more than experiments I would imagine it'd need to come up to a frontend
option, not just a -cc1 option, no?

- David


>
> Nick
>
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