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Compilation with multiple Precompiled Header (PCH) files

More than one PCH file might apply to a given compilation. If so, the compiler uses the largest PCH file.


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.

That is, the compiler uses the PCH file representing the most preprocessing directives from the primary source file.

For example, a primary source file might begin with:

#include "xxx.h"
#include "yyy.h"
#include "zzz.h"

If there is one PCH file for xxx.h and a second for xxx.h and yyy.h, the latter PCH file is selected, assuming that both apply to the current compilation. Additionally, after the PCH file for the first two headers is read in and the third is compiled, a new PCH file for all three headers is created if the requirements for PCH file creation are met.