On Wed, 3 Apr 2019, Richard Biener wrote:
> > 1) Is there some reason to align vectors on the same boundary
> > as their size no matter how big it is? I can't find such
> > a requirement in the ABIs I looked at. Or would it be more
> > appropriate to align the big ones on the preferr
On 4/3/19 11:40 PM, Richard Biener wrote:
On April 3, 2019 7:59:47 PM GMT+02:00, Martin Sebor wrote:
On 4/3/19 5:13 AM, Richard Biener wrote:
On Tue, Apr 2, 2019 at 6:20 PM Martin Sebor wrote:
GCC tries to align a vector on its natural boundary, i.e., that
given by its size, up to MAX_OBJEC
ow do you suggest to deal with it? (Presumably for GCC 10.)
>Issuing an ABI warning and adding an option to override
>the new setting come to mind as possible mitigating solutions.
We could reject these vector types in aggregates in favor of arrays. Of course
that ship has sailed...
&
0.)
Issuing an ABI warning and adding an option to override
the new setting come to mind as possible mitigating solutions.
2) If not, is it then appropriate to underalign very large
vectors on a boundary less than their size?
Yes.
Ack.
3) Should the aligned attribute not override t
If not, is it then appropriate to underalign very large
> vectors on a boundary less than their size?
Yes.
> 3) Should the aligned attribute not override the default vector
> alignment?
Yes, but doesn't it already?
> I would like to think the answer to (1) is that vectors sho
oes it make more sense to
align a 64KB vector on a 64KB boundary than on, say,
a 64-byte boundary (or some other boundary less than 64K?)
2) If not, is it then appropriate to underalign very large
vectors on a boundary less than their size?
3) Should the aligned attribute not override t
On Thu, Oct 13, 2011 at 6:57 PM, Andi Kleen wrote:
>> Or I am missing someting?
>
> I often see the x86 vectorizer with -mtune=generic generate a lot of
> complicated code just to adjust for potential misalignment.
>
> My thought was just if the alias oracle knows what the original
> declaration i
On Thu, Oct 13, 2011 at 06:57:47PM +0200, Andi Kleen wrote:
> > Or I am missing someting?
>
> I often see the x86 vectorizer with -mtune=generic generate a lot of
> complicated code just to adjust for potential misalignment.
>
> My thought was just if the alias oracle knows what the original
> de
> Or I am missing someting?
I often see the x86 vectorizer with -mtune=generic generate a lot of
complicated code just to adjust for potential misalignment.
My thought was just if the alias oracle knows what the original
declaration is, and it's available for changes (e.g. LTO), it would be
like
On Thu, Oct 13, 2011 at 4:54 PM, Andi Kleen wrote:
> Artem Shinkarov writes:
>>
>> 1) Currently in C we cannot provide information that an array is
>> aligned to a certain number. The problem is hidden in the fact, that
>
> Have you considered doing it the other way round: when an optimization
>
Artem Shinkarov writes:
>
> 1) Currently in C we cannot provide information that an array is
> aligned to a certain number. The problem is hidden in the fact, that
Have you considered doing it the other way round: when an optimization
needs something to be aligned, make the declaration aligned?
Hi
I would like to share some plans about improving the situation with
vector alignment tracking. First of all, I would like to start with a
well-known bug: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50716.
There are several aspects of the problem:
1) We would like to avoid the quiet
> On Wed, Jun 08, 2005 at 12:50:32PM -0700, Steve Ellcey wrote:
> > I noticed that vectors are always aligned based on their size, i.e. an
> > 8 byte vector has an aligment of 8 bytes, 16 byte vectors an alignment
> > of 16, a 256 byte vector an alignment of 256, etc.
> >
> > Is this really inten
On Wed, Jun 08, 2005 at 12:50:32PM -0700, Steve Ellcey wrote:
> I noticed that vectors are always aligned based on their size, i.e. an
> 8 byte vector has an aligment of 8 bytes, 16 byte vectors an alignment
> of 16, a 256 byte vector an alignment of 256, etc.
>
> Is this really intended?
Yes.
I noticed that vectors are always aligned based on their size, i.e. an
8 byte vector has an aligment of 8 bytes, 16 byte vectors an alignment
of 16, a 256 byte vector an alignment of 256, etc.
Is this really intended?
I looked in stor-layout.c and found:
/* Always naturally align vectors
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