Are the Intel compilers worth it?

Prety straight forward, are the Intel compilers worth getting? I do mostly systems level and desktop work so I figure I might benefti. Can anyone with some more experience shed some light?开发者_开发技巧

If you are on Windows, they do provide a nice speed boost over other compilers on Intel processors. There is a known behavior where they pick a very slow code path with non-Intel processors (AMD, VIA), and antitrust probes surrounding the issue.

If you use the thread building blocks or other features, you also risk tying your code to the Intel compiler long term as the functionality doesn't exist elsewhere.

GCC 4.5 on Linux is nearly on-par with the Intel compiler. There is no clear winner on that platform.

In the small experience I've had with intel compilers (C only), I would say their are vastly superior. Specifically the OpenMP library was much much faster than the open source version. "Worth it" depends on your situation though, they are expensive, but they are better IMO.

From the benchmarks I've seen, it does look like using the Intel specific compilers provide some performance/multithreading benefit over their Open Source alternatives.

if floating number precision is important to you then use Visual studio compiler and not intel compiler. 32 bit vs 64 bit application Can give you different result on calculation with Intel compiler. (checked). Visual studio compiler result on 32 bit vs 64 bit will be same.

If you're comparing the numerical behavior of ICL vs. MSVC++ you must take into account the different behavior of the /fp: settings. ICL /fp:source (less aggressive than default) is equivalent to MSVC /fp:fast (more aggressive than default). Microsoft doesn't perform any of the optimizations which are enabled by ICL default. These include simd reductions (which usually improve accuracy, but by an unpredictable margin). ICL also violates the standard about parens by default. There still seems to be a controversy about whether to fix that by better performing means than /fp:source.