[Qemu-devel] [Patch] Swapping functions for Mac OS X

[Qemu-devel] [Patch] Swapping functions for Mac OS X

[Pierre d'Herbemont]

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Hi Fabrice,

I think it should be quite useful to use the swapping functions on Mac 
OS X. However I don't see a huge performance gain with this patch.

Thanks,

Pierre.

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Index: bswap.h
===================================================================
RCS file: /cvsroot/qemu/qemu/bswap.h,v
retrieving revision 1.3
diff -u -r1.3 bswap.h
--- bswap.h	21 Mar 2004 17:06:25 -0000	1.3
+++ bswap.h	17 Jul 2004 13:47:35 -0000
@@ -7,6 +7,11 @@
 
 #ifdef HAVE_BYTESWAP_H
 #include <byteswap.h>
+#elif defined(__APPLE__)
+#include <machine/byte_order.h>
+#define bswap_16(x) NXSwapShort(x)
+#define bswap_32(x) NXSwapInt(x)
+#define bswap_64(x) NXSwapLongLong(x)
 #else
 
 #define bswap_16(x) \

Re: [Qemu-devel] [Patch] Swapping functions for Mac OS X

[Benjamin Herrenschmidt]

On Sat, 2004-07-17 at 09:50, Pierre d'Herbemont wrote:
> Hi Fabrice,
> 
> I think it should be quite useful to use the swapping functions on Mac 
> OS X. However I don't see a huge performance gain with this patch.

Ugh ? How cna it be useful to call into library functions why you can
use inline assembly ? Actually, if the swap is done on data loaded/stored
from/to memory, then you can use the ppc endian swapped load/store
instructions

Ben.

Re: [Qemu-devel] [Patch] Swapping functions for Mac OS X

[stegefin]

Benjamin,

I think that the NXSwap functions are defined as inlined asm in the header.

Pierre

Quoting Benjamin Herrenschmidt <benh@kernel.crashing.org>:

>
> On Sat, 2004-07-17 at 09:50, Pierre d'Herbemont wrote:
> > Hi Fabrice,
> >
> > I think it should be quite useful to use the swapping functions on Mac
> > OS X. However I don't see a huge performance gain with this patch.
>
> Ugh ? How cna it be useful to call into library functions why you can
> use inline assembly ? Actually, if the swap is done on data loaded/stored
> from/to memory, then you can use the ppc endian swapped load/store
> instructions
>
> Ben.
>
>
>
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>

Re: [Qemu-devel] [Patch] Swapping functions for Mac OS X

[Laurent Amon]

Since I just looked, I can confirm it.

cpp includes this when including bswap.h :

static __inline
uint16_t
OSReadSwapInt16(
     __volatile void               * base,
     uintptr_t                          offset
)
{
     uint16_t result;
     __asm__ __volatile("lhbrx %0, %1, %2"
                      : "=r" (result)
                      : "b%"  (base), "r" (offset)
                      : "memory");
     return result;
}

And all wrappers are static inline so everything *should* get ASM 
inline.

However, I ran a few benchmarks and it makes no difference. So either 
gcc 3.3 is intelligent enough to do it anyway, or the code does not 
rely much on them, or they do not perform on my PPC7410. This bears 
more investigation.

Lga.

On 26 juil. 04, at 19:48, stegefin@free.fr wrote:

> Benjamin,
>
> I think that the NXSwap functions are defined as inlined asm in the 
> header.
>
> Pierre
>
> Quoting Benjamin Herrenschmidt <benh@kernel.crashing.org>:
>
>>
>> On Sat, 2004-07-17 at 09:50, Pierre d'Herbemont wrote:
>>> Hi Fabrice,
>>>
>>> I think it should be quite useful to use the swapping functions on 
>>> Mac
>>> OS X. However I don't see a huge performance gain with this patch.
>>
>> Ugh ? How cna it be useful to call into library functions why you can
>> use inline assembly ? Actually, if the swap is done on data 
>> loaded/stored
>> from/to memory, then you can use the ppc endian swapped load/store
>> instructions
>>
>> Ben.
>>
>>
>>
>> _______________________________________________
>> Qemu-devel mailing list
>> Qemu-devel@nongnu.org
>> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>>
>
>
>
>
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>
>

Re: [Qemu-devel] [Patch] Swapping functions for Mac OS X

[Benjamin Herrenschmidt]

On Mon, 2004-07-26 at 13:48, stegefin@free.fr wrote:
> Benjamin,
> 
> I think that the NXSwap functions are defined as inlined asm in the header.

Ah ok. Sorry for the noise then.

Ben.