testsuite run-time test for sse2 support

[Joel Sherrill]

Uros Bizjak wrote:
> On Thu, Mar 13, 2008 at 2:35 PM, Joel Sherrill
> <joel.sherrill@oarcorp.com> wrote:
>
>   
>>  I hacked on that test program to get the attached
>>  program.  I ran it multiple times on qemu.
>>
>>  ext=0x0 sig=0x756e6547
>>  0x781abfd YES on SSE2
>>
>>     
I am now printing the return value from __get_cpuid_max()


ext=0x0 sig=0x756e6547 returned=0x2
0x781abfd YES on SSE2

Isn't the "sig" supposed to be >= 0x80000000?
>>  I ran the same program natively and got this:
>>
>>  ext=0x0 sig=0x756e6547
>>  0xbfebfbff YES on SSE2
>>
>>  I wonder if qemu is just reporting things wrong. :(
>>  I searched the qemu manual and googled some but
>>  didn't see anything that jumped out.
>>
>>  Does this look like qemu reporting a bogus cpuid or
>>  gcc not parsing it correctly?
>>     
>
> This all depends on the return value of __get_cpuid_max(). It returns
> max value of base cpuid level (5 in my case), and shoould return 0 if
> cpuid is not supported. This follows the procedure outlined in
> http://download.intel.com/design/processor/applnots/24161832.pdf,
> section 2: "Detecting the CPUID Instruction".
>
>   
I added a print before the return on !__get_cpuid and it is returning
non-zero.
> It is true, that this is not the most maintained code on the planet,
> so some bitrot is possible. The return value of __get_cpuid_max() on
> your target will tell...
>
>   
The call to __get_cpuid is checking against level 1 and this is a level 2.

--joel
> Thanks,
> Uros.
>   


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Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill@OARcorp.com        On-Line Applications Research
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