|MAKEDEPEND(1)||General Commands Manual||MAKEDEPEND(1)|
makedepend - create dependencies in makefiles
makedepend [ -Dname=def ] [ -Dname ] [ -Iincludedir ] [ -Yincludedir ] [ -a ] [ -fmakefile ] [ -include file ] [ -oobjsuffix ] [ -pobjprefix ] [ -sstring ] [ -wwidth ] [ -v ] [ -m ] [ -- otheroptions -- ] sourcefile ...
The makedepend program reads each sourcefile in sequence and parses it like a C-preprocessor, processing all #include, #define, #undef, #ifdef, #ifndef, #endif, #if, #elif and #else directives so that it can correctly tell which #include, directives would be used in a compilation. Any #include, directives can reference files having other #include directives, and parsing will occur in these files as well.
Every file that a sourcefile includes, directly or indirectly, is what makedepend calls a dependency. These dependencies are then written to a makefile in such a way that make(1) will know which object files must be recompiled when a dependency has changed.
By default, makedepend places its output in the file named makefile if it exists, otherwise Makefile. An alternate makefile may be specified with the -f option. It first searches the makefile for the line
# DO NOT DELETE THIS LINE -- make depend depends on it.
or one provided with the -s option, as a delimiter for the dependency output. If it finds it, it will delete everything following this to the end of the makefile and put the output after this line. If it doesn't find it, the program will append the string to the end of the makefile and place the output following that. For each sourcefile appearing on the command line, makedepend puts lines in the makefile of the form
sourcefile.o: dfile ...
Where sourcefile.o is the name from the command line with its suffix replaced with ``.o'', and dfile is a dependency discovered in a #include directive while parsing sourcefile or one of the files it included.
Normally, makedepend will be used in a makefile target so that typing ``make depend'' will bring the dependencies up to date for the makefile. For example,
SRCS = file1.c file2.c ...
CFLAGS = -O -DHACK -I../foobar -xyz
makedepend -- $(CFLAGS) -- $(SRCS)
The program will ignore any option that it does not understand so that you may use the same arguments that you would for cc(1).
The approach used in this program enables it to run an order of magnitude faster than any other ``dependency generator'' I have ever seen. Central to this performance are two assumptions: that all files compiled by a single makefile will be compiled with roughly the same -I and -D options; and that most files in a single directory will include largely the same files.
Given these assumptions, makedepend expects to be called once for each makefile, with all source files that are maintained by the makefile appearing on the command line. It parses each source and include file exactly once, maintaining an internal symbol table for each. Thus, the first file on the command line will take an amount of time proportional to the amount of time that a normal C preprocessor takes. But on subsequent files, if it encounters an include file that it has already parsed, it does not parse it again.
For example, imagine you are compiling two files, file1.c and file2.c, they each include the header file header.h, and the file header.h in turn includes the files def1.h and def2.h. When you run the command
makedepend file1.c file2.c
makedepend will parse file1.c and consequently, header.h and then def1.h and def2.h. It then decides that the dependencies for this file are
file1.o: header.h def1.h def2.h
But when the program parses file2.c and discovers that it, too, includes header.h, it does not parse the file, but simply adds header.h, def1.h and def2.h to the list of dependencies for file2.o.
makedepend parses, but does not currently evaluate, the SVR4 #predicate(token-list) preprocessor expression; such expressions are simply assumed to be true. This may cause the wrong #include directives to be evaluated.
Imagine you are parsing two files, say file1.c and file2.c, each includes the file def.h. The list of files that def.h includes might truly be different when def.h is included by file1.c than when it is included by file2.c. But once makedepend arrives at a list of dependencies for a file, it is cast in concrete.
Todd Brunhoff, Tektronix, Inc. and MIT Project Athena
|makedepend 1.0.6||4th Berkeley Distribution|