When using mingw, the compiler adds a lot of version strings in the .rdata section. For instance in linux:
GCC: (Gentoo Hardened 4.8.1-r1 p1.2, pie-0.5.7) 4.8.1
GCC: (Gentoo Hardened 4.8.1-r1 p1.2, pie-0.5.7) 4.8.1
GCC: (Gentoo Hardened 4.8.1-r1 p1.2, pie-0.5.7) 4.8.1
...
Or in windows:
GCC: (GNU) 4.8.1
GCC: (GNU) 4.8.1
GCC: (GNU) 4.8.1
...
Is there a way to remove them, or at least to put them into a separate section (such as .comment)?
Thanks!
propper solution: recompile your toolchain without --with-pkgversion flag.
hacky solution: open g++ in hex editor, find said string, replace with 0x00s
Related
When I'm trying to compile my C/C++ software using gcc/g++ with -m32 option on RedHat 6.10 which is a 64bit OS, we have a Dell isilon file system exporting 64 bit file ID's we get a run-time error using code coverage compile options. I wrote a simple main() test app test.cpp and compile with the following compile options.
g++ --coverage -m32 test.cpp -o test
When I run the 32bit executable we get a run-time error relating to our file system exporting 64bit file ID's vs 32 bit. We don't want to change to a 32bit file ID export.
./test
profiling:test.gcda: Cannot open
If we compile the app without the -m32 option the problem goes away. However, I need to compile with -m32 for other reasons outside the scope of this discussion.
gcc version 4.4.7 20120313 (Red Hat 4.4.7-23) (GCC)
RedHat 6.10 64bit OS
Thank you for any help.
It appears that a later version of gcc has fixed this problem. I now know that gcc version 8.2.0 compiles properly and doesn't have the error about not being able to find the .gcda file. This makes sense since the Dell isilon system is newer and the gcc compiler version we've been using with RedHat 6.10 is quite old.
On my system default gcc version is 4.4.7 , But i want to build glib library with gcc 6.3 version.
For that i tried running ./configure from glib source as shown below:
../configure CC="/version/global/pkgs/gcc/v6.3.0/bin/gcc" CFLAGS='-fPIC' CXXFLAGS='-fPIC' --enable-static=yes --prefix=/home/kallel/glib_63/glib-2.56.1/new_glib63 --enable-libmount=no --with-pcre=/home/kallel/pcre_lib/pcre-8.20/pcre_library
Once after building glib library. To see on which gcc compiler version it got built with following command:-
strings -a libglib-2.0.so.0.5600.1 | grep "GCC: ("
o/p:-
GCC: (GNU) 4.4.7 20120313 (Red Hat 4.4.7-9)
GCC: (Synopsis) 6.3.0
GCC: (GNU) 4.4.7 20120313 (Red Hat 4.4.7-4)
I could not understand why it is still showing output with 4.4.7, Please help me in understanding the output. Is there anything wrong in my ./configure command? How do we make sure that library was built with gcc 6.3
I could not understand why it is still showing output with 4.4.7
Your library contains object code that you built, as well as parts of GLIBC that are required to support shared libraries (crti.o, crtn.o, etc.).
These parts will continue to show whatever GCC they were built with, regardless of what you build glib code with.
How can I force the gcc linker to link against a given version (soname) of a shared library on the system?
I need this to enforce that the version of openssl that is #include'ed matches the version that is linked, on any system, even if multiple versions of openssl are installed. To find the ABI version, my configure script first compiles and runs a program that extracts the SONAME from the headers:
#include <openssl/opensslv.h>
#include <stdio.h>
int main () {
printf(SHLIB_VERSION_NUMBER);
return 0;
}
The SHLIB_VERSION_NUMBER contains the so version string, e.g. 0.9.8 or 1.0.2k or 1.1.0. But how do I tell gcc to link against this version of libssl or libcrypto rather than just any -lssl?
I tried "in situ" linking, so that instead of linking with gcc main.c -lcrypto we use:
gcc main.c libcrypto.so.1.1.0
However it seems the linker libcrypto.so.1.1.0 cannot be found:
gcc: error: libcrypto.so.1.1.0: No such file or directory
I guess the system only searches in the standard locations when using the -l flag. Is there a better way to make my software link against libcrypto.so.1.1.0?
To select the correct version of the openssl shared libraries use:
gcc main.c -l:libssl.so.1.0.0 -l:libcrypto.so.1.0.0
The key to answering this question is "how do I control ld so that is links the correct version of a shared library?".
The correct way to pass a linker flag (a command line parameter to ld) using the gnu compilers (gcc, g++, gdc, etc...) is to use the normal ld parameter prefixed with "-l". For example -lssl or -L/usr/local/lib.
Edit: As per How to specify the library version to use at link time? you can read the manual for ld with:man ld.
I am currently trying to compile libxml2 on Solaris. When I run the ./configure script provided with the sources, the gcc and g++ compilers are automatically used. However, I would like to use cc and CC compilers. So I run :
./configure CC=cc CXX=CC
It works but then, when I run "make", I get some errors which prevent the libraries to be generated.
When gcc and g++ are used, everything goes well with no errors, so I was wondering: can I use the librairies generated with gcc/g++ the same way I would have used them if I had successively generated them with cc/CC?
What are the differences between a lib generated with cc and the same lib generated with gcc on Solaris?
You can use either the gcc or cc C compilers pretty much interchangeably.
You can mix the g++ and CC C++ compilers in certain ways, but only on x86 Solaris and if your CC compiler is new enough to have the -compat=g option available.
The GNU g++ and the Solaris Studio CC C++ compilers default to completely different ABIs and C++ run-time libraries. On x86 Solaris platforms, newer versions (since version 12.?, if I remember correctly) provide a -compat=g option to use the g++ ABI and run-time libraries. The Studio 12.4 CC compiler adds a -std=v option to select different versions of the g++ or Sun C++ ABI and run-time libraries:
c++03 (zero-3, not oh-3)
Equivalent to the -compat=g option. It selects C++ 03 dialect and g++ ABI; it is binary compatible with g++ on Solaris and Linux It
sets the __SUNPRO_CC_COMPAT preprocessor macro to 'G'.
c++11
Selects C++ 11 dialect and g++ binary compatibility. It sets the __SUNPRO_CC_COMPAT preprocessor macro to 'G'.
c++0x (zero-x, not oh-x)
Equivalent to c++11.
and
The -std=c++03 provides compatibility with the gcc/g++ compiler on
all Oracle Solaris and Linux platforms.
With -std=c++03, binary compatibility extends only to shared
(dynamic or .so) libraries, not to individual .o files or archive (.a)
libraries. The gcc headers and libraries used are those provided with
the compiler, rather than the version of gcc installed on the system.
Note that the Studio 12.4 CC compiler uses the g++ headers and libraries supplied bundled with the CC compiler itself. 12.3 and earlier use the g++ headers and libraries installed on the system under /usr/sfw.
On SPARC Solaris, you have to use either g++ or CC for the entire application.
I am trying to build GraphChi on OS X Yosemite but get the following error:
fatal error: 'omp.h' file not found
From this question - How to include omp.h in OS X? - I learned that Yosemite uses Clang instead of gcc, which does not include omp.h.
$ which gcc
/usr/bin/gcc
$ gcc -v
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.1.0
Thread model: posix
Next, I installed gcc via Homebrew
$ brew info gcc
gcc: stable 4.9.2 (bottled)
http://gcc.gnu.org
/usr/local/Cellar/gcc/4.9.2_1 (1092 files, 177M)
Built from source with: --without-multilib
and updated $PATH to include the path to the new gcc version
$ echo $PATH
/usr/local/Cellar/gcc/4.9.2_1:usr/local/bin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin
however, gcc -v and which gcc still point to the old version, and building GraphChi still doesn't work due to the missing omp.h file
Does anyone know what else I need to do?
Update
locate omp.h returned:
/usr/local/Cellar/apple-gcc42/4.2.1-5666.3/lib/gcc/i686-apple-darwin11/4.2.1/include/omp.h
/usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.1.0/4.9.2/include/omp.h
/usr/local/Cellar/gfortran/4.8.2/gfortran/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/include/omp.h
my ~/.profile:
export PATH=/usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.1.0/4.9.2/include:/usr/local/Cellar/gcc/4.9.2_1/bin:usr/local/bin:/opt/local/bin:/opt/local/sbin:$PATH
I solved this with installing gcc with homebrew:
brew install gcc --without-multilib
and then building the source code with
CC=gcc-5 CXX=g++-5 cmake ..
CC=gcc-5 CXX=g++-5 make -j7
Once you have installed gcc-4.9 with homebrew, it will automatically be in your path. To use OpenMP, you just need to make sure you are using the newly installed gcc-4.9, and it will be able to find omp.h.
In the case of GraphChi, you will have to go change line 3 of the Makefile to be gcc-4.9. From there, running make should just work. They describe this in their README, but at least the version they describe is out of date https://github.com/GraphChi/graphchi-cpp#problems-compiling-on-mac.
clang does not support OpenMP yet. Also gcc by default links to Apple's LLVM clang compiler (not the GCC installed from brew).
Instead gcc-4.9 would link to GCC. I think if -fopenmp is specified omp.h is included automatically.
It is possible to manually build a version of clang with OpenMP support, see http://clang-omp.github.io
You shouldn't add the include path to PATH; instead, specify it as CFLAGS, including the -I option. You can export the CFLAGS variable, or set it on the fly.
Depending on how you compile things, you could do
CFLAGS=-I/usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.1.0/4.9.2/include/omp.h gcc <whatever>
Of course, in this case you can specify it directly on the gcc command (as -I/usr/local/....), but the CFLAGS variable also works with configure (as configure often won't have an option to specify where it should look for specific include files); probably with make, or even for those installing a Python package: CFLAGS=-I... pip install <some-package>.
Other flags to consider are
CXXFLAGS: C++ specific pre-processor flags
LDFLAGS: linker specific flags (e.g. LDFLAGS=-L/some/path/... for linking with dynamic libraries).
CC: specify the C compiler to use. This is an easy way to avoid the built-in gcc alias for clang on OS X. Just use CC=/usr/local/bin/gcc-4 make or similar.
CXX: specify the C++ compiler to use.