Keil Logo

Technical Support

On-Line Manuals

Compiler User Guide

Preface Overview of the Compiler Getting Started with the Compiler Compiler Features Compiler intrinsics Performance benefits of compiler intrinsics ARM assembler instruction intrinsics Generic intrinsics Compiler intrinsics for controlling IRQ and FIQ in Compiler intrinsics for inserting optimization bar Compiler intrinsics for inserting native instructi Compiler intrinsics for Digital Signal Processing Compiler support for European Telecommunications S Overflow and carry status flags for C and C++ code Texas Instruments (TI) C55x intrinsics for optimiz Compiler support for accessing registers using nam Pragmas recognized by the compiler Compiler and processor support for bit-banding Compiler type attribute, __attribute__((bitband)) --bitband compiler command-line option How the compiler handles bit-band objects placed o Compiler support for thread-local storage Compiler support for literal pools Compiler eight-byte alignment features Precompiled Header (PCH) files Automatic Precompiled Header (PCH) file processing Precompiled Header (PCH) file processing and the h Precompiled Header (PCH) file creation requirement Compilation with multiple Precompiled Header (PCH) Obsolete Precompiled Header (PCH) files Manually specifying the filename and location of a Selectively applying Precompiled Header (PCH) file Suppressing Precompiled Header (PCH) file processi Message output during Precompiled Header (PCH) pro Performance issues with Precompiled Header (PCH) f Default compiler options that are affected by opti Compiler Coding Practices Compiler Diagnostic Messages Using the Inline and Embedded Assemblers of the AR Compiler Command-line Options Language Extensions Compiler-specific Features C and C++ Implementation Details What is Semihosting? Via File Syntax Summary Table of GNU Language Extensions Standard C Implementation Definition Standard C++ Implementation Definition C and C++ Compiler Implementation Limits

Precompiled Header (PCH) files

3.21 Precompiled Header (PCH) files

Precompiled Header files can help reduce compilation time when the same header file is used by multiple source files.

Note

Support for Precompiled Header (PCH) files is deprecated from ARM Compiler 5.05 onwards on all platforms. Note that ARM Compiler on Windows 8 never supported PCH files.
When you compile source files, the included header files are also compiled. If a header file is included in more than one source file, it is recompiled when each source file is compiled. Also, you might include header files that introduce many lines of code, but the primary source files that include them are relatively small. Therefore, it is often desirable to avoid recompiling a set of header files by precompiling them. These are referred to as PCH files.
The compiler can precompile and use PCH files automatically with the --pch option, or you can use the --create_pch and --use_pch options to manually control the use of PCH files.
By default, when the compiler creates a PCH file, it:
  • Takes the name of the primary source file and replaces the suffix with .pch.
  • Creates the file in the same directory as the primary source file.

Note

Support for PCH processing is not available when you specify multiple source files in a single compilation. In such a case, the compiler issues an error message and aborts the compilation.

Note

Do not assume that if a PCH file is available, it is used by the compiler. In some cases, system configuration issues mean that the compiler might not always be able to use the PCH file.
Non-ConfidentialPDF file icon PDF versionARM DUI0375H
Copyright © 2007, 2008, 2011, 2012, 2014-2016 ARM. All rights reserved. 
  Arm logo
Important information

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies.

Change Settings

Privacy Policy Update

Arm’s Privacy Policy has been updated. By continuing to use our site, you consent to Arm’s Privacy Policy. Please review our Privacy Policy to learn more about our collection, use and transfers
of your data.