# prof-use, Qprof-use

Enables the use of profiling information during optimization.

## Syntax

Linux: | -prof-use[=keyword] -no-prof-use

macOS: | -prof-use[=keyword] -no-prof-use

Windows: | /Qprof-use[:keyword] /Qprof-use-

## Arguments

keyword | Specifies additional instructions. Possible values are:
weighted | Tells the profmerge utility to apply a weighting to the .dyn file values when creating the .dpi file to normalize the data counts when the training runs have differentexecution durations. This argument only has an effect when the compiler invokes the profmerge utility to create the .dpi file. This argument does not have an effect if the .dpi file was previously created without weighting.
[no]merge | Enables or disables automatic invocation of the profmerge utility. The default is merge. Note that you cannot specify both weighted and nomerge. If you try to specify both values, a warning will be displayed and nomerge takes precedence.
default | Enables the use of profiling information during optimization. The profmerge utility is invoked by default. This value is the same as specifying [Q]prof-use with no argument.

## Default

-no-prof-use or /Qprof-use- | Profiling information is not used during optimization.

## Description

This option enables the use of profiling information (including function splitting and function grouping) during optimization. It enables option /Qfnsplit (Windows*) and -fnsplit (Linux* and macOS) .

This option instructs the compiler to produce a profile-optimized executable and it merges available profiling output files into a pgopti.dpi file.

Note that there is no way to turn off function grouping if you enable it using this option.

To set the hotness threshold for function grouping and function ordering, use option [Q]prof-hotness-threshold.

## IDE Equivalent

Visual Studio: General > Profile Guided Optimization

Eclipse: Optimization > Profile Guided Optimization

Xcode: None

## Alternate Options

None

Parent topic: Profile Guided Optimization Options

## See Also

prof-hotness-threshold, Qprof-hotness-threshold compiler option
prof-gen, Qprof-gen compiler option
Profile an Application with Instrumentation