[FFmpeg-cvslog] r12165 - trunk/libavcodec/dsputil.c

[Rich Felker]

On Thu, Feb 21, 2008 at 08:56:40AM -0700, Loren Merritt wrote:
> >> Modified: trunk/libavcodec/dsputil.c
> >> ==============================================================================
> >> --- trunk/libavcodec/dsputil.c	(original)
> >> +++ trunk/libavcodec/dsputil.c	Thu Feb 21 08:54:46 2008
> >> @@ -50,6 +50,9 @@ void ff_add_png_paeth_prediction(uint8_t
> >>  uint8_t ff_cropTbl[256 + 2 * MAX_NEG_CROP] = {0, };
> >>  uint32_t ff_squareTbl[512] = {0, };
> >>
> >> +static const unsigned long pb_7f = 0x7f7f7f7f7f7f7f7fUL;
> >> +static const unsigned long pb_80 = 0x8080808080808080UL;
> >
> > Wouldn't it be faster to put these constants inline in the code
> > instead of as 'static const'?
> 
> gcc does that. Any value derivable at compile time is equivalent to an 
> inline constant.

This is surely not traditional compiler behavior; if your intent is to
have them inlined then preprocessor constants or literals are
preferred. Even if gcc does optimize them in the function, it probably
also leaves the variables in the .data section, wasting space. In any
case I don't like writing overly verbose code and relying on the
compiler to thin it down when one could just write it simpler to begin
with.

Rich