flac dev - Dec 2015 - FLAC__BYTES_PER_WORD==8 test results

I wrote a patch that enables FLAC__BYTES_PER_WORD==8 in
libFLAC/bitreader.c and libFLAC\bitwriter.c.
The tests were done on an Intel Nehalem CPU, and flac was compiled
with CGG 4.9.x.


Average speed increase for FLAC__BYTES_PER_WORD change from 4 to 8:

Decoding speed:
     ia32 architecture
         16-bit .flac: -15%
         24-bit .flac: -11%
     x86-64 architecture
         16-bit .flac: +3%
         24-bit .flac: -0.6%

Encoding speed (only fastest presets (-0...-5) were tested):
     ia32 architecture
         16-bit .wav: +0.6%
         24-bit .wav: +3%
     x86-64 architecture
         16-bit .wav: +6%
         24-bit .wav: +7%

On 29 December 2015 at 17:10, lvqcl <lvqcl.mail at gmail.com>
wrote:
> I wrote a patch that enables FLAC__BYTES_PER_WORD==8 in
> libFLAC/bitreader.c and libFLAC\bitwriter.c.
> The tests were done on an Intel Nehalem CPU, and flac was compiled
> with CGG 4.9.x.
If you want to share the patch, I am happy to repeat some testing on
Sandy Bridge and Core2 with clang.
> Average speed increase for FLAC__BYTES_PER_WORD change from 4 to 8:
> [...]
The slower decoding speed for 24 bit content on x86_64 seems
surprising, but minor.
However losing 15% decoding speed on i386 would be very bad.

Riggs

Thomas Zander wrote:
> If you want to share the patch, I am happy to repeat some testing on
> Sandy Bridge and Core2 with clang.
The patch changes many files, libFLAC/bitwriter.c and
test_libFLAC/bitwriter.c among them. So now I wait for the decision
for patches #3 and #4 that I posted yesterday.

> The slower decoding speed for 24 bit content on x86_64 seems
> surprising, but minor.
> However losing 15% decoding speed on i386 would be very bad.
So, does it make sense to #define FLAC__BYTES_PER_WORD (in bitreader.c)
as 4 for 32-bit and as 8 for 64-bit targets?