[PATCH] Improved __builtin_constant_p

[Richard Smith]

On Tue, Jul 15, 2014 at 4:10 AM, Janusz Sobczak <janusz.sobczak at mobica.com>
wrote:

> >>! In D4492#5, @rsmith wrote:
> > This makes Clang's constant expression evaluator and its IR generation
> disagree about the value of `__builtin_constant_p`.
> How would you address this issue? My concern is that there are cases,
> where we need to fold to a constant early (i.e. global variable
> initialisation) and other cases where we can emit IR code and make the
> decision about 'constantness' at a later stage.
>
> >
> > What's the motivation behind this change?
> Matching GCC behaviour as closely as we can.


That seems like a means to an end, rather than a goal in itself. Also, we
currently match GCC's -O0 behavior pretty closely.
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