On 23/12/13 12:40, Michael Veksler wrote:
Hello All,
When I started using gcc-4.8.1 I was glad to observe a substantial
speed-up of about 10% in my code, as compared with gcc-4.7.3.
Usually, switching to newer compilers has a relatively minor effect
and definitely not a 10% speed-up. Was there anything significant
in gcc-4.8.1 which may explain this dramatic improvement?
My code is C++98 which is compiled with profile-driven optimizations,
with -O2. My target is generic 32 bit Intel architecture. The result
is run
on Intel Xeon. The application is CPU intensive.
After some more testing, I found out that there is about 12% improvement
even when comparing two executables compiled without profile-driven
optimization.
Unfortunately, the vast improvement is observed only for x86, not for
x86-64. The speed-up on x86-64 is "only" 2-3%.
Michael.
