On Thu, Sep 12, 2019 at 02:54:50PM -0700, Nick Desaulniers wrote:
> I have seen instances where instruction selection fails to select the
> appropriate way to branch when inline asm size is misjudged, resulting
> in un-encodeable jumps (as in the branch target is too far to be
> encoded in the
On 12/09/2019 23.54, Nick Desaulniers wrote:
> On Sat, Sep 7, 2019 at 6:11 AM Segher Boessenkool
> wrote:
>>
>> On Fri, Sep 06, 2019 at 06:04:54PM -0700, Nick Desaulniers wrote:
>>
>>> How would you even write a version check for that?
>>
>> I wouldn't. Please stop using that straw man. I'm not
On Sat, Sep 7, 2019 at 6:11 AM Segher Boessenkool
wrote:
>
> On Fri, Sep 06, 2019 at 06:04:54PM -0700, Nick Desaulniers wrote:
> > On Fri, Sep 6, 2019 at 5:14 PM Segher Boessenkool
> > wrote:
> > > On Fri, Sep 06, 2019 at 04:42:58PM -0700, Nick Desaulniers via
> > > gcc-patches wrote:
> > > >
On Sat, Sep 7, 2019 at 3:11 PM Segher Boessenkool
wrote:
>
> I wouldn't. Please stop using that straw man. I'm not saying version
> checks are good, or useful for most things. I am saying they are not.
>
> Predefined compiler symbols to do version checking (of a feature) is
> just a lesser
On Fri, Sep 06, 2019 at 06:04:54PM -0700, Nick Desaulniers wrote:
> On Fri, Sep 6, 2019 at 5:14 PM Segher Boessenkool
> wrote:
> > On Fri, Sep 06, 2019 at 04:42:58PM -0700, Nick Desaulniers via gcc-patches
> > wrote:
> > > Just to prove my point about version checks being brittle, it looks
> > >
On Fri, Sep 6, 2019 at 5:14 PM Segher Boessenkool
wrote:
>
> On Fri, Sep 06, 2019 at 04:42:58PM -0700, Nick Desaulniers via gcc-patches
> wrote:
> > Just to prove my point about version checks being brittle, it looks
> > like Rasmus' version check isn't even right. GCC supported `asm
> >
On Fri, Sep 06, 2019 at 04:42:58PM -0700, Nick Desaulniers via gcc-patches
wrote:
> On Fri, Sep 6, 2019 at 3:56 PM Segher Boessenkool
> wrote:
> Oh, I misunderstood. I see your point. Define the symbol as a number
> for what level of output flags you support (ie. the __cplusplus
> macro).
On Fri, Sep 6, 2019 at 3:56 PM Segher Boessenkool
wrote:
>
> On Fri, Sep 06, 2019 at 03:35:02PM -0700, Nick Desaulniers wrote:
> > On Fri, Sep 6, 2019 at 3:03 PM Segher Boessenkool
> > wrote:
> > > And if instead you tested whether the actual feature you need works as
> > > you need it to, it
On Fri, Sep 06, 2019 at 03:35:02PM -0700, Nick Desaulniers wrote:
> On Fri, Sep 6, 2019 at 3:03 PM Segher Boessenkool
> wrote:
> > And if instead you tested whether the actual feature you need works as
> > you need it to, it would even work fine if there was a bug we fixed that
> > breaks things
On Fri, Sep 6, 2019 at 3:03 PM Segher Boessenkool
wrote:
>
> On Fri, Sep 06, 2019 at 11:14:08AM -0700, Nick Desaulniers wrote:
> > Here's the case that I think is perfect:
> > https://developers.redhat.com/blog/2016/02/25/new-asm-flags-feature-for-x86-in-gcc-6/
> >
> > Specifically the feature
On Fri, Sep 06, 2019 at 11:14:08AM -0700, Nick Desaulniers wrote:
> Here's the case that I think is perfect:
> https://developers.redhat.com/blog/2016/02/25/new-asm-flags-feature-for-x86-in-gcc-6/
>
> Specifically the feature test preprocessor define __GCC_ASM_FLAG_OUTPUTS__.
>
> See exactly how
On Fri, Sep 6, 2019 at 9:39 AM Jakub Jelinek wrote:
>
> On Fri, Sep 06, 2019 at 11:30:28AM -0500, Segher Boessenkool wrote:
> > On Fri, Sep 06, 2019 at 05:13:54PM +0200, Miguel Ojeda wrote:
> > > On Fri, Sep 6, 2019 at 2:23 PM Segher Boessenkool
> > > wrote:
> > > > I can't find anything with
On Fri, Sep 6, 2019 at 6:30 PM Segher Boessenkool
wrote:
>
> (Which isn't the C++ standard yet, okay).
At this stage, it pretty much is. It is basically bug fixing at this point.
> No, that is not what it does. A user defines such a macro, and that
> makes the library change behaviour.
That
On Fri, Sep 06, 2019 at 11:30:28AM -0500, Segher Boessenkool wrote:
> On Fri, Sep 06, 2019 at 05:13:54PM +0200, Miguel Ojeda wrote:
> > On Fri, Sep 6, 2019 at 2:23 PM Segher Boessenkool
> > wrote:
> > > I can't find anything with "feature" and "macros" in the C++ standard,
> > > it's "predefined
On Fri, Sep 06, 2019 at 05:13:54PM +0200, Miguel Ojeda wrote:
> On Fri, Sep 6, 2019 at 2:23 PM Segher Boessenkool
> wrote:
> > I can't find anything with "feature" and "macros" in the C++ standard,
> > it's "predefined macros" there I guess? In C, it is also "predefined
> > macros" in general,
On Fri, Sep 6, 2019 at 2:23 PM Segher Boessenkool
wrote:
>
> I can't find anything with "feature" and "macros" in the C++ standard,
> it's "predefined macros" there I guess? In C, it is also "predefined
> macros" in general, and there is "conditional feature macros".
They are introduced in
On Thu, Sep 05, 2019 at 05:52:44PM +0200, Miguel Ojeda wrote:
> On Thu, Sep 5, 2019 at 3:45 PM Segher Boessenkool
> wrote:
> >
> > [ That's not what a feature test macro is; a feature test macro allows the
> > user to select some optional behaviour. Things like _GNU_SOURCE. ]
>
> Yes and no.
On Thu, Sep 5, 2019 at 5:52 PM Miguel Ojeda
wrote:
>
> Yes and no. GNU libc defines feature test macros like you say, but
> C++'s feature macros are like Rasmus/Nick are saying. I think libc's
> definition is weird, I would call those "feature selection macros"
> instead, because the user is
On Thu, Sep 5, 2019 at 3:45 PM Segher Boessenkool
wrote:
>
> [ That's not what a feature test macro is; a feature test macro allows the
> user to select some optional behaviour. Things like _GNU_SOURCE. ]
Yes and no. GNU libc defines feature test macros like you say, but
C++'s feature macros
On Thu, Sep 05, 2019 at 04:23:11PM +0200, Rasmus Villemoes wrote:
> On 05/09/2019 15.45, Segher Boessenkool wrote:
> > On Thu, Sep 05, 2019 at 01:07:11PM +0200, Rasmus Villemoes wrote:
> >> Perhaps something like below, though that
> >> won't affect the already released gcc 9.1 and 9.2, of course.
On 05/09/2019 15.45, Segher Boessenkool wrote:
> Hi Rasmus,
>
> On Thu, Sep 05, 2019 at 01:07:11PM +0200, Rasmus Villemoes wrote:
>> On 05/09/2019 02.18, Nick Desaulniers wrote:
>>> Is it too late to ask for a feature test macro? Maybe one already
>>> exists?
>>
>> No, not as far as I know.
>
>
Hi Rasmus,
On Thu, Sep 05, 2019 at 01:07:11PM +0200, Rasmus Villemoes wrote:
> On 05/09/2019 02.18, Nick Desaulniers wrote:
> > Is it too late to ask for a feature test macro? Maybe one already
> > exists?
>
> No, not as far as I know.
[ That's not what a feature test macro is; a feature test
On 05/09/2019 02.18, Nick Desaulniers wrote:
> On Fri, Aug 30, 2019 at 4:15 PM Rasmus Villemoes
> wrote:
>>
>> This adds an asm_inline macro which expands to "asm inline" [1] when gcc
>> is new enough (>= 9.1), and just asm for older gccs and other
>> compilers.
>>
>> Signed-off-by: Rasmus
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