While I have yet to hear of any problems with us using thunks. The EGCS
mailing list notes some have problems with it and not using them are a
safer default. People wanting to use them, can set the appropiate
compiler flag.
* Turn on DEFAULT_VTABLE_THUNKS. (it is the default anyway, I'm just being
explicit about it, in case it causes us trouble it might be easier for
someone to notice it this way)
with a numeric value that describes the feature level of the
compiler. This can be used to check for the presence/absence of
FreeBSD-specific compiler features. The value is a decimal number
whose digits have the form VRRRRFF, where:
V = Compiler vendor. 0 (elided) means gcc.
RRRR = Vendor's version number, e.g., 2721 for the current
gcc version (2.7.2.1).
FF = FreeBSD-specific revision level. 00 means the stock
compiler from the vendor.
The value of "__FreeBSD_cc_version" is hard-coded in
"src/contrib/gcc/config/i386/freebsd.h" and must be incremented
when new FreeBSD-specific compiler features are added. I considered
simply picking up the value of FreeBSD_version from <osreldate.h>.
But that would break cross compiles of gcc.
PR: Part of the fix for gnu/8452
Suggested by: bde
the executable file, so it will work for both a.out and ELF format
files. I have split the object format specific code into separate
source files. It's cleaner than it was before, but it's still
pretty crufty.
Don't cheat on your make world for this update. A lot of things
have to be rebuilt for it to work, including the compiler and all
of the profiled libraries.
aout and elf support. freebsd-elf.h died as a result, so the BINFORMAT
test for elf in src/gnu/usr.bin/cc/cc_tool/Makefile will need to
use freebsd.h, not freebsd-elf.h. That means that alpha will have to
go the same way. The new alpha/freebsd.h has the alpha/freebsd-elf.h
definitions merged in.
i386-elf because that is what will be used for FreeBSD/Alpha.
Change the STARTFILE_SPEC to match the non-aout version of i386 so
that the csu files can be built in exactly the same way as i386-elf.
This means that FreeBSD/Alpha departs from NetBSD/Alpha which uses
crt0 and crtbegin/crtend. Since i386-aout uses crt0, I guess it was
decided that i386-elf should use crt1. i386-elf also references
crti and with this change, so does FreeBAS/Alpha.
I think it is important for FreeBSD to have a consistent implementation
across architectures and since ELF is quite compatible (ignoring
differences in 32 and 64 bits), gcc might as well be configured the
same.
Another change is that the entry symbol is _start, not __start as
in NetBSD.
a.out gas and the binutils gas (elf or a.out) with a single compiler.
This uses other infrastructure not yet committed, in order to support
both a.out and elf it needs to be able to get to both a.out and elf
gas, ld, libs, crt* etc. So for now, the support is pretty much dormant.
The new freebsd.h file is based on the old freebsd-elf.h file (which has a
long lineage, right back through linux and svr4 files). The change is
pretty dramatic from a gcc internals standpoint as it overrides a lot of
definitions in order to generate different output based on target mode.
There is potential for screw-ups, so please be on the lookout - gcc's
configuration mechanism wasn't really meant for this kind of thing.
It's believed to compile world etc just fine under both a.out and elf, can
handle global constructors and destructors, handles the differences in
a.out and elf stabs, and what sections things like exceptions go in.
The initial idea came from i386/osfrose.h which is a dual rose/elf format
target. These two are not as diverse as a.out and elf it would seem.
The cc front-end uses external configuration to determine default object
format (still being thrashed out, so read the source if you want to see
it so far), and has a '-aout' and '-elf' override command line switch.
There are some other internal switches that can be accessed, namely -maout,
-mno-aout, -munderscores and -mnounderscores. The underscore and local
symbol prefixing rules are controllable seperately to the output format.
(ie: it's possible to generate a.out without the _ prefixes on symbols and
also to generate elf with the _ prefixes. This isn't quite optimal, but
does seem to work pretty well, except the linkers don't always recognise
the local symbols without their normal names)
The default format is a.out (still), nobody should see any major changes.
With both elf and a.out tools and libraries installed:
[1:26pm]/tmp-223> cc -elf -o hello hello.c
peter@beast[1:27pm]/tmp-224> file hello
hello: ELF 32-bit LSB executable, Intel 80386, version 1 (FreeBSD), dynamically linked, not stripped
[1:27pm]/tmp-225> ./hello
hello world!
[1:27pm]/tmp-226> cc -aout -o hello hello.c
[1:27pm]/tmp-227> file hello
hello: FreeBSD/i386 compact demand paged dynamically linked executable not stripped
1:27pm]/tmp-228> ./hello
hello world!
Since my co-conspirators put a lot of effort into this too, I'll add them
so they can share the blame^H^H^H^H^Hglory. :-)
Reviewed by: sos, jdp
See freebsd.h and freebsd-elf.h for the silly comment that cgd@netbsd.org
wanted me to add about his claim that uncommented source files that
have been publicly available for ftp for nearly a year; that are
configuration patches to a GPL'ed program; are owned by his previous
employer who refuses to release them. Well... I did as he said. As if
that makes a difference!
At this point we've got cpp, gcc, g++ ported to FreeBSD/Alpha so all
the code that uses __FreeBSD__ is correctly pre-processed. Yay.
I'll commit the bootstrap makefile next to let others play, then on
to libc.
it can be built via BINFORMAT=elf in the environment. Most likely
some of the directory defines such as STANDARD_EXEC_PREFIX will
change again soon, as we settle on the proper locations for the
various components.
Note, the build still fails when it tries to compile libgcc2.c
using the ELF compiler, unless arrangements have been made for the
compiler to find the ELF assembler instead of the a.out assembler.
"-pg" and gprof(1) instead. FreeBSD does not support plain "-p" or
prof(1).
Plain "-p" is still allowed when just compiling. In the compile
phase, "-p" is identical "-pg". It is used by <bsd.lib.mk> for
building profiled object files.
Without this, compiled programs die with FP errors.
This is originally credited to: jlemon@netcom.com (Jonathan Lemon), and
has been forwarded to me by quite a few of people.
The symptom was an assembler warning
"GOT relocation burb: `___EXCEPTION_TABLE__' should be global"
followed (sometimes) by a core dump. The fix makes the compiler
generate the correct GOTOFF addressing for that symbol, rather than the
GOT addressing it was emitting before.
Warning: There is still at least one serious bug in the i386 exception
code for PIC. The exception code that is generated clobbers the GOT
register (%ebx) and then tries to use it later. That leads to core
dumps at program execution time. I know where the problem is, but I do
not have a fix for it at this time. Until it is fixed, exceptions will
not work in PIC code. This is a general problem for all i386 platforms;
it is not specific to FreeBSD.
