[flac-dev] GCC generates slow code for IA32

[lvqcl]

Martijn van Beurden <mvanb1 at gmail.com> писал(а) в своём письме Sun, 22 Sep 2013 14:45:31 +0400:

> On 22-09-13 10:31, lvqcl wrote:
>> I measured encoding speed of 24-bit WAV files. It turns out that 32-bit
>> encoder made by GCC is ~1.7x times slower than 32-bit encoder made by MSVS.
>
> Strange, I'm not able to reproduce your findings. I did found something
> rather odd though. I thought MSVC, ICL and GCC would produce the same
> files, but for some reason a GCC compile creates slightly smaller files.
> Looks like there is some GCC-specific code that influences compression
> ratio? I haven't noticed that in any of the tests I did before. GCC is a
> bit slower, but nowhere near 1.7x


Sorry I forgot to mention that I tested only -8 preset as the most CPU
intensive. Input file is 44.1/24/stereo, test CPU is Core2 Q9300.

Tested FLAC encoders:
* 32-bit from Rarewares
* 64-bit from Rarewares
* 32-bit from http://www.saunalahti.fi/~cse/temp/flac-1.3.0-win32.zip
* 32-bit from http://www.icer.nl/misc_stuff/flac-1.3.0-final-minGW.zip
I also downloaded MSYS-MinGW 4.8.1 from http://xhmikosr.1f0.de/tools/ and
compiled 32-bit and 64-bit versions of FLAC 1.3.0 myself.

Encoding time, in seconds,

for 64-bit builds:
rarewares:   84.9 s  (ICL)
my compile:  90.9 s  (MinGW 4.8.1)

for 32-bit builds:
rarewares:  137.5 s  (ICL)
saunalahti: 120.9 s  (MSVS 2012)
icer.nl:    204.8 s  (MinGW)
my compile: 234.4 s  (MinGW 4.8.1)

234.4/120.9 = 1.94 and 204.8/137.5 = 1.49, and 1.7 is somwhere between these ratios.