operator new returns nonzero

[Gabriel Dos Reis]

On Sat, Sep 7, 2013 at 6:44 AM, Basile Starynkevitch
<basile@starynkevitch.net> wrote:
> On Sat, 2013-09-07 at 12:33 +0200, Marc Glisse wrote:
>> Hello,
>>
>> this patch teaches the compiler that operator new, when it can throw,
>> isn't allowed to return a null pointer. Note that it doesn't work for
>> placement new (that one may have to be handled in the front-end or the
>> inliner), and it will not work on user-defined operator new if they are
>> inlined. I guess it would be possible to teach the inliner to insert an
>> assert_expr or something when inlining such a function, but that's not for
>> now. The code I removed from vrp_visit_stmt was duplicated in
>> stmt_interesting_for_vrp and thus useless.
>
>
> Interesting patch. However, I feel that we should give advanced users
> the ability to say that their new operator is never returning null...
> In particular, if I define my own new operator which never returns nil,
> I find strange that it would be less optimized than the system's
> operator new.
>
> Perhaps we need an attribute `nonnullresult'  which whould means that.
> (we already the nonnull attribute for function arguments)

'operator new' is a replaceable function, so when you define it, you have
to abide by the standard semantics.

-- Gaby