/ORDER (Put Functions in Order)
Specify the link order for separately packaged (COMDAT) functions.
A text file that specifies the link order for COMDAT functions.
The /ORDER compiler option allows you to optimize your program's paging behavior by grouping a function together with the functions it calls. You can also group frequently called functions together. These techniques, known as swap tuning or paging optimization, increase the probability that a called function is in memory when it is needed and does not have to be paged from disk.
When you compile your source code into an object file, you can tell the compiler to put each function into its own section, called a COMDAT, by using the /Gy (Enable function-level linking) compiler option. The /ORDER linker option tells the linker to place COMDATs into the executable image in the order you specify.
To specify the COMDAT order, create a response file, a text file that lists each COMDAT by name, one per line, in the order you want them to be placed by the linker. Pass the name of this file as the filename parameter of the /ORDER option. For C++ functions, the name of a COMDAT is the decorated form of the function name. Use the undecorated name for C functions,
main, and for C++ functions declared as
extern "C". Function names and decorated names are case sensitive. For more information on decorated names, see Decorated Names.
To find the decorated names of your COMDATs, use the DUMPBIN tool's /SYMBOLS option on the object file. The linker automatically prepends an underscore (_) to function names in the response file unless the name starts with a question mark (?) or at sign (@). For example, if a source file, example.cpp, contains functions
extern "C" int c_func(int) and
int main(void), the command
DUMPBIN /SYMBOLS example.obj lists these decorated names:
... 088 00000000 SECT1A notype () External | ?cpp_func@@YAHH@Z (int __cdecl cpp_func(int)) 089 00000000 SECT22 notype () External | _c_func 08A 00000000 SECT24 notype () External | _main ...
In this case, specify the names as
main in your response file.
If more than one /ORDER option appears in the linker options, the last one specified takes effect.
The /ORDER option disables incremental linking. You may see linker warning LNK4075 when you specify this option if incremental linking is enabled, or if you have specified the /ZI (Incremental PDB) compiler option. To silence this warning, you can use the /INCREMENTAL:NO linker option to turn off incremental linking, and use the /Zi (Generate PDB) compiler option to generate a PDB without incremental linking.
LINK cannot order static functions because static function names are not public symbol names. When /ORDER is specified, linker warning LNK4037 is generated for each symbol in the order response file that is either static or not found.
To set this linker option in the Visual Studio development environment
Open the project's Property Pages dialog box. For details, see Set C++ compiler and build properties in Visual Studio.
Select the Configuration Properties > Linker > Optimization property page.
Modify the Function Order property to contain the name of your response file.
To set this linker option programmatically
- See FunctionOrder.
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