[Qemu-devel] [PATCH] Fix qemu_ld64 on arm

[Qemu-devel] [PATCH] Fix qemu_ld64 on arm

[Pablo Virolainen]

Emulating fldl on arm doesn't seem to work too well. It's the way 
qemu_ld64 is translated to arm instructions.

         tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
         tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);


Consider case where data_reg==0, data_reg2==1, and addr_reg==0. First 
load overwrited addr_reg. So let's put an if (data_ref==addr_reg).

Index: tcg-target.c
===================================================================
--- tcg-target.c        (revision 6642)
+++ tcg-target.c        (working copy)
@@ -1011,8 +1011,14 @@
      case 3:
          /* TODO: use block load -
           * check that data_reg2 > data_reg or the other way */
-        tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
-        tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
+
+        if (data_reg==addr_reg) {
+            tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
+            tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
+        } else {
+            tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
+            tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
+        }
          break;
      }
  #endif

Re: [Qemu-devel] [PATCH] Fix qemu_ld64 on arm

[Laurent Desnogues]

On Tue, Feb 24, 2009 at 9:03 AM, Pablo Virolainen
<Pablo.Virolainen@nomovok.com> wrote:
>
> Emulating fldl on arm doesn't seem to work too well. It's the way qemu_ld64
> is translated to arm instructions.
>
>        tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
>        tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);

It seems you are using an old version of qemu.  Taking a quick
look at current svn, I think your patch is not needed anymore.


Laurent

>
>
> Consider case where data_reg==0, data_reg2==1, and addr_reg==0. First load
> overwrited addr_reg. So let's put an if (data_ref==addr_reg).
>
> Index: tcg-target.c
> ===================================================================
> --- tcg-target.c        (revision 6642)
> +++ tcg-target.c        (working copy)
> @@ -1011,8 +1011,14 @@
>     case 3:
>         /* TODO: use block load -
>          * check that data_reg2 > data_reg or the other way */
> -        tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
> -        tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
> +
> +        if (data_reg==addr_reg) {
> +            tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
> +            tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
> +        } else {
> +            tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
> +            tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
> +        }
>         break;
>     }
>  #endif
>
>
>

Re: [Qemu-devel] [PATCH] Fix qemu_ld64 on arm

[Pablo Virolainen]

Laurent Desnogues kirjoitti:
> On Tue, Feb 24, 2009 at 9:03 AM, Pablo Virolainen
> <Pablo.Virolainen@nomovok.com> wrote:
>> Emulating fldl on arm doesn't seem to work too well. It's the way qemu_ld64
>> is translated to arm instructions.
>>
>>        tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
>>        tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
> 
> It seems you are using an old version of qemu.  Taking a quick
> look at current svn, I think your patch is not needed anymore.

So I should get the source from other source than
svn co svn://svn.savannah.nongnu.org/qemu/trunk ?

Pablo

Re: [Qemu-devel] [PATCH] Fix qemu_ld64 on arm

[Laurent Desnogues]

On Tue, Feb 24, 2009 at 9:44 AM, Pablo Virolainen
<Pablo.Virolainen@nomovok.com> wrote:
> Laurent Desnogues kirjoitti:
>>
>> On Tue, Feb 24, 2009 at 9:03 AM, Pablo Virolainen
>> <Pablo.Virolainen@nomovok.com> wrote:
>>>
>>> Emulating fldl on arm doesn't seem to work too well. It's the way
>>> qemu_ld64
>>> is translated to arm instructions.
>>>
>>>       tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
>>>       tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
>>
>> It seems you are using an old version of qemu.  Taking a quick
>> look at current svn, I think your patch is not needed anymore.
>
> So I should get the source from other source than
> svn co svn://svn.savannah.nongnu.org/qemu/trunk ?

OK, I am gonna get some more coffee...  I mistakenly thought
you were talking about ARM front-end.  Sorry for the
confusion.

Your patch looks correct (but bear in mind, that I did not take
more coffee and that I never played with ARM back-end).


Laurent

Re: [Qemu-devel] [PATCH] Fix qemu_ld64 on arm

[Aurelien Jarno]

On Tue, Feb 24, 2009 at 10:03:54AM +0200, Pablo Virolainen wrote:
>
> Emulating fldl on arm doesn't seem to work too well. It's the way  
> qemu_ld64 is translated to arm instructions.
>
>         tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
>         tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
>
>
> Consider case where data_reg==0, data_reg2==1, and addr_reg==0. First  
> load overwrited addr_reg. So let's put an if (data_ref==addr_reg).

Thanks, applied.

> Index: tcg-target.c
> ===================================================================
> --- tcg-target.c        (revision 6642)
> +++ tcg-target.c        (working copy)
> @@ -1011,8 +1011,14 @@
>      case 3:
>          /* TODO: use block load -
>           * check that data_reg2 > data_reg or the other way */
> -        tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
> -        tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
> +
> +        if (data_reg==addr_reg) {
> +            tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
> +            tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
> +        } else {
> +            tcg_out_ld32_12(s, COND_AL, data_reg, addr_reg, 0);
> +            tcg_out_ld32_12(s, COND_AL, data_reg2, addr_reg, 4);
> +        }
>          break;
>      }
>  #endif
>
>
>

-- 
Aurelien Jarno	                        GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net