[Bug middle-end/29171] forgotten memcpy with -ffreestanding -fwhole-program --combine

["acahalan at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

------- Comment #6 from acahalan at gmail dot com  2007-06-26 03:37 -------
(In reply to comment #5)
> This is related to or really a dup of bug 4417.

It's only related, not a dup, though bug 4417 is sort of a subset.

There appears to be no possible set of gcc options that will allow compiling
non-trivial programs with -fwhole-program --combine. With or without the
-ffreestanding option, gcc will leave undefined references to various string.h
things. It does not matter if the program provides these functions in *.c
files.

With -ffreestanding, gcc ought to avoid using memcpy. Without, gcc ought to
call the one I'm providing. (both should work; neither one does)

Right now neither works, making -fwhole-program --combine 100% useless.

Alternately, the documentation is not correct, and the user can indeed link
with other things. (if I supply memcpy via some other binary file, then I am
NOT supplying the "whole program" to the compiler and am thus violating the
rules -- perhaps "whole program" needs a very detailed definition regarding *.S
files, system headers, libgcc.a, libgcc.so, libc.so, and so on) According to
the documentation, a command line with "--combine foo.c bar.c baz.S" would
invoke the C front end on foo.c and bar.c only; they thus become the
compilation unit. Adding -fwhole-program adds the requirement that the current
compilation unit (foo.c and bar.c) be the whole program, thereby excluding
baz.h from being part of the program.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29171