Developer Guide and Reference

Contents

Using the -fp-model (/fp) Option

The
-fp-model
(Linux*) or
/fp
(Windows*) option allows you to control the optimizations on floating-point data. You can use this option to tune the performance, level of accuracy, or result consistency for floating-point applications across platforms and optimization levels.
The -fpmodel (/fp) option is only available for C++; it is not available for DPC++.
You can use keywords to specify the semantics to be used. The keywords specified for this option may influence the choice of math routines that are invoked. Many routines in the
libirc
,
libm
, and
libsvml
libraries are more highly optimized for Intel microprocessors than for non-Intel microprocessors. Possible values of the keywords are as follows:
Keyword
Description
precise
Enables value-safe optimizations on floating-point data.
fast
Enables more aggressive optimizations on floating-point data.
double
Rounds intermediate results to 53-bit (double) precision and enables value-safe optimizations.
Using the default option keyword
-fp-model fast
or
/fp:fast
, you may get significant differences in your result depending on whether the compiler uses x87 or SSE/AVX instructions to implement floating-point operations. Results are more consistent when the other option keywords are used.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.