MAKEDEPEND(1) X Version 11(Release 5) MAKEDEPEND(1)
NAME
makedepend - create dependencies in makefiles
SYNOPSIS
makedepend [ -Dname=def ] [ -Dname ] [ -Iincludedir ] [ -a ] [ -fmakefile
] [ -oobjsuffix ] [ -pobjprefix ] [ -sstring ] [ -wwidth ] [ - -
otheroptions - - ] sourcefile ...
DESCRIPTION
Makedepend reads each sourcefile in sequence and parses it like a C-
preprocessor, processing all #include, #define, #undef, #ifdef, #ifndef,
#endif, #if 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.
EXAMPLE
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
depend:
makedepend -- $(CFLAGS) -- $(SRCS)
OPTIONS
Makedepend will ignore any option that it does not understand so that you
may use the same arguments that you would for cc(1).
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-Dname=def or -Dname
Define. This places a definition for name in makedepend's symbol
table. Without =def the symbol becomes defined as "1".
-Iincludedir
Include directory. This option tells makedepend to prepend
includedir to its list of directories to search when it encounters a
#include directive. By default, makedepend only searches
/usr/include.
-a Append the dependencies to the end of the file instead of replacing
them.
-fmakefile
Filename. This allows you to specify an alternate makefile in which
makedepend can place its output.
-oobjsuffix
Object file suffix. Some systems may have object files whose suffix
is something other than ".o". This option allows you to specify
another suffix, such as ".b" with -o.b or ":obj" with -o:obj and so
forth.
-pobjprefix
Object file prefix. The prefix is prepended to the name of the
object file. This is usually used to designate a different directory
for the object file. The default is the empty string.
-sstring
Starting string delimiter. This option permits you to specify a
different string for makedepend to look for in the makefile.
-wwidth
Line width. Normally, makedepend will ensure that every output line
that it writes will be no wider than 78 characters for the sake of
readability. This option enables you to change this width.
- - options - -
If makedepend encounters a double hyphen (- -) in the argument list,
then any unrecognized argument following it will be silently
ignored; a second double hyphen terminates this special treatment.
In this way, makedepend can be made to safely ignore esoteric
compiler arguments that might normally be found in a CFLAGS make
macro (see the EXAMPLE section above). All options that makedepend
recognizes and appear between the pair of double hyphens are
processed normally.
ALGORITHM
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;
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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 encounter's 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.
SEE ALSO
cc(1), make(1)
BUGS
If you do not have the source for cpp, the Berkeley C preprocessor, then
makedepend will be compiled in such a way that all #if directives will
evaluate to "false" regardless of their actual value. This may cause the
wrong #include directives to be evaluated. Makedepend should simply have
its own parser written for #if expressions.
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.
AUTHOR
Todd Brunhoff, Tektronix, Inc. and MIT Project Athena
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