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

qopt-dynamic-align, Qopt-dynamic-align

Enables or disables dynamic data alignment optimizations.

Syntax

Linux:

-qopt-dynamic-align

-qno-opt-dynamic-align

macOS:

-qopt-dynamic-align

-qno-opt-dynamic-align

Windows:

/Qopt-dynamic-align

/Qopt-dynamic-align-

Arguments

None

Default

ifort: -qopt-dynamic-align
or /Qopt-dynamic-align

The compiler may generate code dynamically dependent on alignment. It may do optimizations based on data location for the best performance. The result of execution on some algorithms may depend on data layout.

ifx: -qno-opt-dynamic-align
or /Qopt-dynamic-align-

The compiler does not generate code dynamically dependent on alignment.

Description

This option enables or disables dynamic data alignment optimizations.

If you specify -qno-opt-dynamic-align or /Qopt-dynamic-align-, the compiler generates no code dynamically dependent on alignment. It will not do any optimizations based on data location and results will depend on the data values themselves.

When you specify [q or Q]opt-dynamic-align, the compiler may implement conditional optimizations based on dynamic alignment of the input data. These dynamic alignment optimizations may result in different bitwise results for aligned and unaligned data with the same values.

Dynamic alignment optimizations can improve the performance of some vectorized code, especially for long trip count loops, but there is an associated cost of increased code size and compile time. Disabling such optimizations can improve the performance of some other vectorized code. It may also improve bitwise reproducibility of results, factoring out data location from possible sources of discrepancy.

IDE Equivalent

None

Alternate Options

None