Intel® Fortran Compiler 17.0 Developer Guide and Reference
Maximizes speed across the entire program.
Linux and macOS: | -fast |
Windows: | /fast |
None
OFF |
The optimizations that maximize speed are not enabled. |
This option maximizes speed across the entire program.
It sets the following options:
On OS X* systems:
-ipo,
-mdynamic-no-pic,
-O3,
-no-prec-div,
-fp-model fast=2, and
-xHost
On Windows* systems:
/O3,
/Qipo,
/Qprec-div-,
/fp:fast=2, and
/QxHost
On Linux* systems:
-ipo,
-O3,
-no-prec-div,
-static,
-fp-model fast=2, and
-xHost
On Intel® 64 architecture-based
systems targeting the
Intel® Xeon Phi™ coprocessor x100 product
family (formerly code name Knights Corner):
[Q]ipo,
O3,
-no-prec-div (Linux*) or
/Qprec-div- (Windows*),
-fp-model fast=2 (Linux*) or
/fp:fast=2 (Windows*)
When option fast is specified, you can override the [Q]xHost option setting by specifying a different processor-specific [Q]x option on the command line. However, the last option specified on the command line takes precedence.
For example:
On Linux* systems, if you specify option -fast -xSSE3, option -xSSE3 takes effect. However, if you specify -xSSE3 -fast, option -xHost takes effect.
On Windows* systems, if you specify option /fast /QxSSE3, option/QxSSE3 takes effect. However, if you specify /QxSSE3 /fast, option /QxHost takes effect.
For implications on non-Intel processors, refer to the [Q]xHost documentation.
Option fast sets some aggressive optimizations that may not be appropriate for all applications. The resulting executable may not run on processor types different from the one on which you compile. You should make sure that you understand the individual optimization options that are enabled by option fast.
Optimization Notice |
|---|
Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice. Notice revision #20110804 |
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