Intel® Fortran Compiler Classic and Intel® Fortran Compiler Developer Guide and Reference

ID 767251
Date 7/13/2023
Public

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Document Table of Contents

fast

Maximizes speed across the entire program.

Syntax

Linux:

-fast

macOS:

-fast

Windows:

/fast

Arguments

None

Default

OFF

The optimizations that maximize speed are not enabled.

Description

This option maximizes speed across the entire program.

Linux

It sets the following options:

-ipo, -O3, -no-prec-div,-static, -fp-model fast=2, and -xHost

macOS

It sets the following options:

-ipo, -mdynamic-no-pic,-O3, -no-prec-div,-fp-model fast=2, and -xHost

Windows

It sets the following options:

/O3, /Qipo, /Qprec-div-, /fp:fast=2, and /QxHost

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:

Linux

If you specify option -fast -xSSE3, option -xSSE3 takes effect. However, if you specify -xSSE3 -fast, option -xHost takes effect.

Windows

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.

NOTE:

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.

NOTE:

This option only applies to host compilation. When offloading is enabled, it does not impact device-specific compilation. Offloading can only be enabled when using ifx.

Product and Performance Information

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

Notice revision #20201201

IDE Equivalent

None

Alternate Options

None

See Also