[Bug rtl-optimization/33790] New: postreload can handle the case where the memory locations use different modes

[Bug rtl-optimization/33790] New: postreload can handle the case where the memory locations use different modes

[pinskia at gcc dot gnu dot org]

Take the following testcase (either on spu-elf or powerpc-linux-gnu with
-maltivec):
#define vector __attribute__((__vector_size__(16) ))

typedef vector float vec_float4;
typedef struct {
        vec_float4 data;
} VecFloat4;

typedef struct {
        vec_float4 a;
        vec_float4 b;
} VecFloat4x2;


VecFloat4 test1(VecFloat4 a, VecFloat4 b)
{
        a.data = a.data+b.data;
        return a;
}


VecFloat4x2 test2(VecFloat4x2 data)
{
        data.a = data.a+data.a;
        data.b = data.b+data.b;
        return data;
}

----- cut -----
Right now we do (for spu-elf, it is a similar issue for PPC):
_Z5test211VecFloat4x2:
        hbr     .L5,$lr
        stqd    $sp,-128($sp)
        ai      $sp,$sp,-128
        stqd    $3,64($sp)
        stqd    $4,80($sp)
        lqd     $5,80($sp)
        lqd     $4,64($sp)
        fa      $2,$5,$5
        fa      $3,$4,$4
        stqd    $2,48($sp)
        stqd    $3,32($sp)
        lqd     $4,48($sp)
        lqd     $3,32($sp)
        ai      $sp,$sp,128
.L5:
        bi      $lr

---- cut ----
With the patch which I will attach, we get:
_Z5test211VecFloat4x2:
        fa      $2,$3,$3
        hbr     .L5,$lr
        stqd    $sp,-128($sp)
        ai      $sp,$sp,-128
        nop     127
        stqd    $3,64($sp)
        fa      $3,$4,$4
        stqd    $4,80($sp)
        nop     127
        stqd    $2,32($sp)
        ori     $4,$3,0
        stqd    $3,48($sp)
        ori     $3,$2,0
        ai      $sp,$sp,128
.L5:
        bi      $lr


----------- cut ------
Notice how the loads are gone.
Note dse could do the same.


-- 
           Summary: postreload can handle the case where the memory
                    locations use different modes
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33790

[Bug rtl-optimization/33790] postreload can handle the case where the memory locations use different modes

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2007-10-16 01:37 -------
Mine.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |pinskia at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-10-16 01:37:37
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33790

[Bug rtl-optimization/33790] postreload can handle the case where the memory locations use different modes

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2007-10-16 01:39 -------
Created an attachment (id=14357)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=14357&action=view)
Patch 

This patch has been tested on powerpc64-linux-gnu with no regressions and also
test for spu-elf with no regressions.  I have not looked into the code size
differences though but it should just decrease them instead of increase them as
we change a load to a move which then maybe register rename can rename
registers around to get one less register usage.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33790

[Bug rtl-optimization/33790] postreload can handle the case where the memory locations use different modes

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2008-03-29 08:55 -------
Hmm, I wonder how important this is now after the DSE patch for PR 33927 which
basically does the same thing and it also runs after reload.  I really don't
want to make cselib any slower than it is already and post reload cse is really
to me a hack for reload (or really RA) not doing its job so I don't want to
slow down post reload cse.

I am going to close this as won't fix as the reasons mentioned about.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |WONTFIX


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33790

Re: [Bug rtl-optimization/33790] postreload can handle the case where the memory locations use different modes

[Andrew Pinski]

I forgot to mention that the dse patch fixes the problem earlier on so  
we now do the optimization pre-reload. We still have an extra store  
but that is recorded as another bug I filed.

Sent from my iPhone

On Mar 29, 2008, at 1:55, "pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org 
 > wrote:

>
>
> ------- Comment #3 from pinskia at gcc dot gnu dot org  2008-03-29  
> 08:55 -------
> Hmm, I wonder how important this is now after the DSE patch for PR  
> 33927 which
> basically does the same thing and it also runs after reload.  I  
> really don't
> want to make cselib any slower than it is already and post reload  
> cse is really
> to me a hack for reload (or really RA) not doing its job so I don't  
> want to
> slow down post reload cse.
>
> I am going to close this as won't fix as the reasons mentioned about.
>
>
> -- 
>
> pinskia at gcc dot gnu dot org changed:
>
>           What    |Removed                     |Added
> --- 
> --- 
> ----------------------------------------------------------------------
>             Status|ASSIGNED                    |RESOLVED
>         Resolution|                            |WONTFIX
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33790
>

[Bug rtl-optimization/33790] postreload can handle the case where the memory locations use different modes

[pinskia at gmail dot com]

------- Comment #4 from pinskia at gmail dot com  2008-03-29 09:02 -------
Subject: Re:  postreload can handle the case where the memory locations use
different modes

I forgot to mention that the dse patch fixes the problem earlier on so  
we now do the optimization pre-reload. We still have an extra store  
but that is recorded as another bug I filed.

Sent from my iPhone

On Mar 29, 2008, at 1:55, "pinskia at gcc dot gnu dot org"
<gcc-bugzilla@gcc.gnu.org 
 > wrote:

>
>
> ------- Comment #3 from pinskia at gcc dot gnu dot org  2008-03-29  
> 08:55 -------
> Hmm, I wonder how important this is now after the DSE patch for PR  
> 33927 which
> basically does the same thing and it also runs after reload.  I  
> really don't
> want to make cselib any slower than it is already and post reload  
> cse is really
> to me a hack for reload (or really RA) not doing its job so I don't  
> want to
> slow down post reload cse.
>
> I am going to close this as won't fix as the reasons mentioned about.
>
>
> -- 
>
> pinskia at gcc dot gnu dot org changed:
>
>           What    |Removed                     |Added
> --- 
> --- 
> ----------------------------------------------------------------------
>             Status|ASSIGNED                    |RESOLVED
>         Resolution|                            |WONTFIX
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33790
>


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33790