ARM Compiler toolchain v4.1 for µVision Using the Compiler

Compiler Features
4.24 PreCompiled Header (PCH) file creation requirements
A PCH file is produced only if the header stop point and the code preceding it, mainly the header
files, meet the following requirements:
• The header stop point must appear at file scope. It must not be within an unclosed scope
established by a header file. For example, a PCH file is not created in this case:
// xxx.h
class A
{
// xxx.c
#include "xxx.h"
int i;
};
• The header stop point must not be inside a declaration that is started within a header file.
Also, in C++, it must not be part of a declaration list of a linkage specification. For
example, in the following case the header stop point is int, but because it is not the start
of a new declaration, no PCH file is created:
// yyy.h
static
// yyy.c
#include "yyy.h"
int i;
• The header stop point must not be inside a #if block or a #define that is started within a
header file.
• The processing that precedes the header stop point must not have produced any errors.
Note
Warnings and other diagnostics are not reproduced when the PCH file is reused.
• No references to predefined macros __DATE__ or __TIME__ must appear.
• No instances of the #line preprocessing directive must appear.
• #pragma no_pch must not appear.
• The code preceding the header stop point must have introduced a sufficient number of
declarations to justify the overhead associated with precompiled headers.
4.24.1 See also
Tasks
• Selectively applying PreCompiled Header (PCH) file processing on page 4-37
• Suppressing PreCompiled Header (PCH) file processing on page 4-38.
Concepts
• PreCompiled Header (PCH) files on page 4-29
• Automatic PreCompiled Header (PCH) file processing on page 4-30
• PreCompiled Header (PCH) file processing and the header stop point on page 4-31
• PreCompiled Header (PCH) file creation requirements
• Performance issues with PreCompiled Header (PCH) files on page 4-40.
ARM DUI 0375C Copyright © 2007-2008, 2011 ARM. All rights reserved. 4-32
ID061811
Non-Confidential