Hi there!
I am developing software which tries to deliberately exploit the
compiler's autovectorization facilities by feeding data in
autovectorization-friendly loops. I'm currently using both g++ and
clang++ to see how well this approach works. Using simple arithmetic, I
often get good resul
Hi Kay,
On 09/01/19 08:29, Kay F. Jahnke wrote:
Hi there!
I am developing software which tries to deliberately exploit the
compiler's autovectorization facilities by feeding data in
autovectorization-friendly loops. I'm currently using both g++ and
clang++ to see how well this approach works. U
On 1/9/19 9:45 AM, Kyrill Tkachov wrote:
> Hi Kay,
>
> On 09/01/19 08:29, Kay F. Jahnke wrote:
>> Hi there!
>>
>> I am developing software which tries to deliberately exploit the
>> compiler's autovectorization facilities by feeding data in
>> autovectorization-friendly loops. I'm currently using
On Wed, 9 Jan 2019 at 09:50, Andrew Haley wrote:
> I don't agree. Sometimes vectorization is critical. It would be nice
> to have a warning which would fire if vectorization failed. That would
> surely help the OP.
Dave Malcolm has been working on something like that:
https://gcc.gnu.org/ml/gcc-pa
On Wed, Jan 9, 2019 at 9:50 AM Andrew Haley wrote:
>
> On 1/9/19 9:45 AM, Kyrill Tkachov wrote:
> > Hi Kay,
> >
> > On 09/01/19 08:29, Kay F. Jahnke wrote:
> >> Hi there!
> >>
> >> I am developing software which tries to deliberately exploit the
> >> compiler's autovectorization facilities by feed
On 09.01.19 10:45, Kyrill Tkachov wrote:
There's plenty of work being done on auto-vectorisation in GCC.
Auto-vectorisation is a performance optimisation and as such is not really
a user-visible feature that absolutely requires user documentation.
Since I'm trying to deliberately exploit it, a
On Wed, Jan 09, 2019 at 11:56:03AM +0100, Kay F. Jahnke wrote:
> The above is a typical example. So, to give a complete source 'vec_sqrt.cc':
>
> #include
>
> extern float data [ 32768 ] ;
>
> extern void vf1()
> {
> #pragma vectorize enable
> for ( int i = 0 ; i < 32768 ; i++ )
> data
On Wed, Jan 09, 2019 at 12:03:45PM +0100, Jakub Jelinek wrote:
> > The above is a typical example. So, to give a complete source 'vec_sqrt.cc':
> >
> > #include
> >
> > extern float data [ 32768 ] ;
> >
> > extern void vf1()
> > {
> > #pragma vectorize enable
> > for ( int i = 0 ; i < 32768
On Wed, 2019-01-09 at 09:56 +, Jonathan Wakely wrote:
> On Wed, 9 Jan 2019 at 09:50, Andrew Haley wrote:
> > I don't agree. Sometimes vectorization is critical. It would be
> > nice
> > to have a warning which would fire if vectorization failed. That
> > would
> > surely help the OP.
>
> Dave
On Wed, Jan 09, 2019 at 11:10:25AM -0500, David Malcolm wrote:
> extern void vf1()
> {
>#pragma vectorize enable
>for ( int i = 0 ; i < 32768 ; i++ )
> data [ i ] = std::sqrt ( data [ i ] ) ;
> }
>
> Compiling on this x86_64 box with -fopt-info-vec-missed shows the
> _7 = .SQRT (_1
On Wed, 2019-01-09 at 11:10 -0500, David Malcolm wrote:
> On Wed, 2019-01-09 at 09:56 +, Jonathan Wakely wrote:
> > On Wed, 9 Jan 2019 at 09:50, Andrew Haley wrote:
> > > I don't agree. Sometimes vectorization is critical. It would be
> > > nice
> > > to have a warning which would fire if vecto
On Wed, 9 Jan 2019, Jakub Jelinek wrote:
> On Wed, Jan 09, 2019 at 11:10:25AM -0500, David Malcolm wrote:
> > extern void vf1()
> > {
> >#pragma vectorize enable
> >for ( int i = 0 ; i < 32768 ; i++ )
> > data [ i ] = std::sqrt ( data [ i ] ) ;
> > }
> >
> > Compiling on this x86_64
d wasting resources.
Now I may be missing things here because I haven't dug deeply enough to
find documentation about autovectorization in gcc. This was why I have
asked to be pointed to 'where the action is'. I was hoping to maybe get
some helpful hints. My main objective is, after all,
On 10/01/2019 08:19, Richard Biener wrote:
> On Wed, 9 Jan 2019, Jakub Jelinek wrote:
>
>> On Wed, Jan 09, 2019 at 11:10:25AM -0500, David Malcolm wrote:
>>> extern void vf1()
>>> {
>>>#pragma vectorize enable
>>>for ( int i = 0 ; i < 32768 ; i++ )
>>> data [ i ] = std::sqrt ( data [
On Thu, 10 Jan 2019 at 09:25, Kay F. Jahnke wrote:
> Documentation is absolutely essential. If there is lots of development
> in autovectorization, not documenting this work in a way users can
> simply find is - in my eyes - a grave omission. The text
> 'Auto-vectorization in GCC' looks like it has
On Thu, 10 Jan 2019, Jonathan Wakely wrote:
>> [ https://gcc.gnu.org/projects/tree-ssa/vectorization.html ]
> I'm not disputing that there could be better documentation, but that
> page is not the place to find it. That page should probably get a
> notice added saying that the project is complete a
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