. Impressum . PrivacyHello Matthias
I had a look at your ./mic/intrinsics.h file.
This looks a bit blurry to me:
Machine instruction for those kind of intrinsic have a field of 3 bits in the mnemonic to specify the conversion argument (so called MVEX.SSS field) – same for the memory hint: the hint is represented by one bit ( MVEX.EH).
Hence the compiler can’t generate the final machine instruction unless the conversion and hit are a fixed compile time constant. In case it would want to do so, it would have to enable some kind of ‘text segment editing’ at run time: You would need to change the instruction just before it is being executed.
This would be difficult to do but even worse: It would be a disaster for performance since changing the text segment is something requiring a total stall of the pipeline, a wait on all ongoing operations to complete ( like writes to memory) etc Not to mention, that you would have to make the text segment ‘writeable’ before etc
I just tried to compile the below code. None of the below instantiation could work, but maybe this is not really representative of your current implementation ?
Feel free to ping me ..
#include <immintrin.h>
template<typename DownConv>
void scatter(void *m, __m512i i, __m512i v, DownConv downconv, int scale)
{
_mm512_i32extscatter_epi32(m, i, v, downconv, scale, _MM_HINT_NONE);
}
void foo()
{
void *m;
__m512i i, v;
int scale, downconv;
// Should instanciate scatter<_MM_DOWNCONV_EPI32_ENUM>
void (*ptr) (void *, __m512i , __m512i , _MM_DOWNCONV_EPI32_ENUM, int) = scatter;
scatter<int>(m,i,v,downconv,scale);
scatter<_MM_DOWNCONV_EPI32_ENUM>(m,i,v,_MM_DOWNCONV_EPI32_NONE,scale);
}
Regards;
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-----Original Message-----
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Sent: Tuesday, September 8, 2015 9:03 PM
To: Duhem, Laurent; Oertel, Klaus-Dieter
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Subject: Re: Vc issue
I had a chance today to try ICC 16 and it looks like a mess.
Most puzzling issue at this point:
extern void __cdecl _mm512_i32extscatter_epi32(void* mv, __m512i index, __m512i v1, _MM_DOWNCONV_EPI32_ENUM conv, int scale, int hint); (cf. https://software.intel.com/en-us/node/582418)
The intrinsic is still declared with the enum for the conv parameter in zmmintrin.h, but the compiler actually thinks conv is of type unsigned int.
I.e. if I pass an int it compiles without error or even a warning. If I pass a type that is implicitly convertible to either _MM_DOWNCONV_EPI32_ENUM or _MM_UPCONV_EPI32_ENUM, the compiler stops, saying both are equally good candidates for conversion to unsigned int. Did you really just release a source incompatible change to the MIC intrinsics? Without even adjusting the documentation?
Seems like I have to rewrite a significant part of my code once more. The MIC implementation has been the most frustrating experience in that regard. :(
Cheers,
Matthias
On Monday 07 September 2015 12:24:44 Matthias Kretz wrote:
> I applied your FindMIC.cmake patch. Is there anything else missing?
>
> I just installed ICC 16 on a test system and I hope I can find some
> time to look at it myself soon. But please keep the patches coming in
> - though feel free to post it as a pull request on Github, which makes
> it easier to comment on the changes if necessary.
>
> Cheers,
> Matthias
>
> On Friday 04 September 2015 11:15:47 Duhem, Laurent wrote:
> > Thx Matthias.
> >
> >
> >
> > I guess detection of newest Intel compiler 16 is also broken, as we
> > heavily changed installation layout.
> >
> > Can you also look at fixing related Findxxx.cmake script pls ?
> >
> >
> >
> > Regards
>
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