ATTRIBUTES OPTIMIZATION

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

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ID 767251

Date 9/08/2022

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ATTRIBUTES OPTIMIZATION_PARAMETER

The ATTRIBUTES directive option OPTIMIZATION_PARAMETER passes certain information about a procedure or main program to the optimizer.

Syntax

!DIR$ ATTRIBUTES OPTIMIZATION_PARAMETER: string::{ procedure-name | named-main-program}

string

Is a character constant that is passed to the optimizer. The constant must be delimited by apostrophes or quotation marks, and it may have one of the following values:

TARGET_ARCH= cpu

Tells the compiler to generate code specialized for a particular processor. For the list of cpus you can specify, see option [Q]x.
G2S = {ON | OFF}

Disables or enables the use of gather/scatter instructions in the specified program unit.

ON tells the optimizer to disable the generation of gather/scatter and to transform gather/scatter into unit-strided loads/stores plus a set of shuffles wherever possible.

OFF tells the optimizer to enable the generation of gather/scatter instructions and not to transform gather/scatter into unit-strided loads/stores.
INLINE_MAX_PER_ROUTINE= n

Specifies the maximum number of times the inliner may inline into the procedure. The n is one of the following:
- A non-negative scalar integer constant (>=0) that specifies the maximum number of times the the inliner may inline into the procedure. If you specify zero, no inlining is done into the routine.
- The keyword UNLIMITED, which means that there is no limit to the number of times the inliner may inline into the procedure.
For more information, see option [Q]inline-max-per-routine.
INLINE_MAX_TOTAL_SIZE= n

Specifies how much larger a routine can normally grow when inline expansion is performed. The n is one of the following:
- A non-negative scalar integer constant (>=0) that specifies the permitted increase in the routine's size when inline expansion is performed. If you specify zero, no inlining is done into the routine.
- The keyword UNLIMITED, which means that there is no limit to the size a routine may grow when inline expansion is performed.
For more information, see option [Q]inline-max-total-size.

procedure-name

Is the name of a procedure.

named-main-program

Is the name of a main program

Description

The characters in string can appear in any combination of uppercase and lowercase. The following rules also apply to string:

If string does not contain an equal sign (=), then the entire value of string is converted to lowercase before being passed to the optimizer.
If string contains an equal sign, then all characters to the left of the equal sign are converted to lowercase before all of string is passed to the optimizer.

Characters to the right of the equal sign are not converted to lowercase since their value may be case sensitive to the optimizer, for example “target_arch=AVX”.

You can specify multiple ATTRIBUTES OPTIMIZATION_PARAMETER directives for one procedure or one main program.

For the named procedure or main program, the values specified for ATTRIBUTES OPTIMIZATION_PARAMETER override any settings specified for the following compiler options:

[Q]x, -m, and /arch
[Q]inline-max-per-routine
[Q]inline-max-total-size

Example

Consider the two attributes optimization_parameter directives in the following code:

function f (x)
!dir$ attributes optimization_parameter: “inline_max_per_routine=10” :: f
!dir$ attributes optimization_parameter: “inline_max_total_size=2000” :: f
real :: f, x
…

The two directives have the same effect as if the function F had been complied with "/Qinline-max-per-routine:10 /Qinline-max-total-size:2000" on Windows* or with "-inline-max-per-routine=10 -inline-max-total-size=2000" on Linux* or macOS, that is, inlining will not increase the size of F by more than 2000 and the inliner will not inline routines into F more than 10 times.

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ATTRIBUTES OPTIMIZATION_PARAMETER

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