Intel® C++ Compiler Classic Developer Guide and Reference

ID 767249
Date 3/31/2023
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.

It sets the following options:

  • On macOS 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

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.

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.

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