# ipo, Qipo

Enables interprocedural optimization between files.

## Syntax

Linux: | -ipo[n] -no-ipo

macOS: | -ipo[n] -no-ipo

Windows: | /Qipo[n] /Qipo-

## Arguments

n | Is an optional integer that specifies the number of object files the compiler should create. The integer must be greater than or equal to 0.

## Default

-no-ipo or /Qipo- | Multifile interprocedural optimization is not enabled.

## Description

This option enables interprocedural optimization between files. This is also called multifile interprocedural optimization (multifile IPO) or Whole Program Optimization (WPO).

When you specify this option, the compiler performs inline function expansion for calls to functions defined in separate files.

You cannot specify the names for the files that are created.

If n is 0, the compiler decides whether to create one or more object files based on an estimate of the size of the application. It generates one object file for small applications, and two or more object files for large applications.

If n is greater than 0, the compiler generates n object files, unless n exceeds the number of source files (m), in which case the compiler generates only m object files.

If you do not specify n, the default is 0.

### Note

When you specify option [Q]ipo with option [q or Q]opt-report, IPO information is generated in the compiler optimization report at link time. After linking, you will see a report named ipo_out.optrpt in the folder where you linked all of the object files.

## IDE Equivalent

Visual Studio: Optimization > Interprocedural Optimization

Eclipse: Optimization > Enable Whole Program Optimization

Xcode: None

## Alternate Options

None

Parent topic: Interprocedural Optimization Options