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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /gcc/doc/collect2.texi | |
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Diffstat (limited to 'gcc/doc/collect2.texi')
-rw-r--r-- | gcc/doc/collect2.texi | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/gcc/doc/collect2.texi b/gcc/doc/collect2.texi new file mode 100644 index 000000000..7cd5c9355 --- /dev/null +++ b/gcc/doc/collect2.texi @@ -0,0 +1,89 @@ +@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc. +@c This is part of the GCC manual. +@c For copying conditions, see the file gcc.texi. + +@node Collect2 +@chapter @code{collect2} + +GCC uses a utility called @code{collect2} on nearly all systems to arrange +to call various initialization functions at start time. + +The program @code{collect2} works by linking the program once and +looking through the linker output file for symbols with particular names +indicating they are constructor functions. If it finds any, it +creates a new temporary @samp{.c} file containing a table of them, +compiles it, and links the program a second time including that file. + +@findex __main +@cindex constructors, automatic calls +The actual calls to the constructors are carried out by a subroutine +called @code{__main}, which is called (automatically) at the beginning +of the body of @code{main} (provided @code{main} was compiled with GNU +CC)@. Calling @code{__main} is necessary, even when compiling C code, to +allow linking C and C++ object code together. (If you use +@option{-nostdlib}, you get an unresolved reference to @code{__main}, +since it's defined in the standard GCC library. Include @option{-lgcc} at +the end of your compiler command line to resolve this reference.) + +The program @code{collect2} is installed as @code{ld} in the directory +where the passes of the compiler are installed. When @code{collect2} +needs to find the @emph{real} @code{ld}, it tries the following file +names: + +@itemize @bullet +@item +a hard coded linker file name, if GCC was configured with the +@option{--with-ld} option. + +@item +@file{real-ld} in the directories listed in the compiler's search +directories. + +@item +@file{real-ld} in the directories listed in the environment variable +@code{PATH}. + +@item +The file specified in the @code{REAL_LD_FILE_NAME} configuration macro, +if specified. + +@item +@file{ld} in the compiler's search directories, except that +@code{collect2} will not execute itself recursively. + +@item +@file{ld} in @code{PATH}. +@end itemize + +``The compiler's search directories'' means all the directories where +@command{gcc} searches for passes of the compiler. This includes +directories that you specify with @option{-B}. + +Cross-compilers search a little differently: + +@itemize @bullet +@item +@file{real-ld} in the compiler's search directories. + +@item +@file{@var{target}-real-ld} in @code{PATH}. + +@item +The file specified in the @code{REAL_LD_FILE_NAME} configuration macro, +if specified. + +@item +@file{ld} in the compiler's search directories. + +@item +@file{@var{target}-ld} in @code{PATH}. +@end itemize + +@code{collect2} explicitly avoids running @code{ld} using the file name +under which @code{collect2} itself was invoked. In fact, it remembers +up a list of such names---in case one copy of @code{collect2} finds +another copy (or version) of @code{collect2} installed as @code{ld} in a +second place in the search path. + +@code{collect2} searches for the utilities @code{nm} and @code{strip} +using the same algorithm as above for @code{ld}. |