Erik de Castro Lopo wrote:
> Googling suggests that use of restrict is a little controvertial.
Maybe, but Opus encoder uses this keyword in its en-/decoding routines.
So I think it's not dangerous.
> Also, do you have any idea why this causes such a slow down in VS10 and
> VS12?
Without __restrict, VS12 generates the following pattern:
...
mov eax, DWORD PTR [edi+32]
adc esi, edx
imul DWORD PTR [ebx+8]
add ecx, eax
...etc...
With __restrict:
...
mov eax, DWORD PTR [ecx+16]
cdq
mov DWORD PTR tv7279[esp+116], eax
mov DWORD PTR tv7278[esp+116], edx
...etc...
followed by
...
push DWORD PTR tv7278[esp+116]
mov eax, DWORD PTR [ebx+24]
push DWORD PTR tv7279[esp+120]
adc edi, edx
cdq
push edx
push eax
call __allmul
add esi, eax
...etc...
I have no idea why it does this. Maybe it tries to "optimize"
32bit * 32bit -> 64bit multiplication?
_______________________________________________
flac-dev mailing list
flac-dev@xiph.org
http://lists.xiph.org/mailman/listinfo/flac-dev
