#5 Found the K6 related Bug -conditional move

closed
nobody
5
2006-03-18
2004-03-28
Falcosoft
No

hi !
I have found the reason why k6 processors with 3dnow
support (not only k6-2+, but k6-2, k6-III...) crash in the
3dnow code .

movd ecx, mm4
cmp ecx, esi
cmove ecx, ebx
mov dword ptr [edi],ecx ;SET PIXEL !
punpckhdq mm4, mm4 // lo = hi
movd ecx, mm4
cmp ecx, esi
cmove ecx, ebx
mov dword ptr [edi+4],ecx ;SET PIXEL !

In this code fragment You use conditional moves that
ARE NOT supported on the K6.

by the way the CPUID correctly shows that cmovs
(feature bit 15) is not supoorted, moreover indicates that
K6 is a 5th generation processor like pentiums and not
6th like pentium pros.

best regards:
falco

Discussion

  • Daniele Paccaloni

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    user_id=180260

    Thanks falco,
    This will be fixed in the next release.

     
  • Nobody/Anonymous

    Logged In: NO

    *sigh* ...was sadly not fixed in the last release.... :/

     
  • Daniele Paccaloni

    • status: open --> closed
     

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