[FFmpeg-devel] Patch: Inline asm fixes for Intel compiler on Windows

Matt Oliver protogonoi at gmail.com
Sat Mar 29 14:38:14 CET 2014

> have you tested this ?
> i get no error when compiling asm cdq on opensolaris

cdq works fine for me with icl and gcc but I dont have access to suncc so
its beyond my testing capabilities. What I can confirm is that cltd is not
supported by icl.

2 instructions instead of 1 increase pressure on the code cache
> and codecs like h264 are complex enough so the code cache size
> should have signifiant effects

That depends on the hardware, modern processors have a 2 uop version of CDQ
so for processors that cache at the uop level its already 2 instructions.

did you benchmark this ?

Generated some random data and then ran a few thousand loops over
get_cabac_bypass_sign. It was a quick test but didnt show any real world
difference (outside of random testing variation). That said I only tested
it on my pc which is one of those with a 2 clock cycle cdq and a uop cache
so it may be different on others.

i tried both but i havnt checked what they generated

Of course if cdq is actually supported then I guess all the changes are
somewhat moot.

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