I am running on an RHEL 6.x box, which of course has GCC 4.4 installed. I wish to have LLVM running on this machine. In order to do so, I must compile it from source. In order to do that, I need a more modern version of GCC.
So, following the instructions, I have built GCC 4.8.2:
[snip]
% $PWD/../gcc-4.8.2/configure --prefix=$HOME/toolchains --enable-languages=c,c++
% make -j$(nproc)
% make install
I'm logged in as root, so $HOME/toolchains resolves to /root/toolchains.
After satisfying prerequisites for LLVM, I'm ready to configure and build LLVM.
root#dev06 /root/llvm-build # ~/llvm/configure --enable-optimized --prefix=$HOME/toolchains/ --with-gcc-toolchain=/root/toolchains/
checking for clang... no
[snip]
checking target architecture... x86_64
checking whether GCC is new enough... no
configure: error:
The selected GCC C++ compiler is not new enough to build LLVM. Please upgrade
to GCC 4.7. You may pass --disable-compiler-version-checks to configure to
bypass these sanity checks.
root#dev06 /root/llvm-build #
configure thinks I'm using GCC 4.4 still, even though I passed --with-gcc-toolchain=/root/toolchains/ to configure1. Let's make sure that I installed 4.8.2 properly.
root#dev06 /root/llvm-build # $HOME/toolchains/bin/g++ --version
g++ (GCC) 4.8.2
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
How do I convince configure to use the GCC I have at /root/toolchains?
1: I have tried a number of variations of the path I specify in --with-gcc-toolchain, inclding /root/toolchain/bin, /root/toolchain/bin/g++, etc.
As you have discovered, the proper way to resolve this is by adding your custom toolchain to PATH. This is not a systemwide change, and is limited to your shell session. Alternatively, you can configure with:
../llvm/configure CXX=$HOME/toolchains/bin/g++
and similar options documented in configure's --help output.
The option --with-gcc-toolchain only tells the built Clang where to look for a C++ standard library and headers, it has nothing to do with the LLVM/Clang build process. I strongly suggest to also build and install libc++ and libc++abi and use those with your new Clang instead.
The LLVM project no longer supports building with configure & make.
I specified c, c++ and fortran compiler in the variables CC, CXX and FC.
export CC=/path/to/gcc
export CXX=/path/to/g++
export FC=/path/to/gfortran
cmake -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX=/opt/clang ../llvm-4.0.0
make
make install
Related
When using clang v8.0.0 on Windows (from llvm prebuilt binaries) with -g or -gline-tables-only source map tables are not being picked up by gdb or lldb debuggers.
Upon including -g flag file grows in size (which is to be expected) yet neither gdb nor lldb pickes the source up
When compiled with gcc though (with -g flag) source files are detected by debugger.
I have tried running the same command (clang -g <codefile>) on macOS High Sierra (clang -v says it is Apple LLVM version 10.0.0 (clang-1000/10.44.4)) where there source files are being picked up by lldb. So I guessed it is localized to my windows instance or llvm for windows build.
P.S. output of clang -v on windows:
clang version 8.0.0 (tags/RELEASE_800/final)
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\Program Files\LLVM\bin
On Windows, Clang is not self-sufficient (at least not the official binaries). You need to have either GCC or MSVC installed for it to function.
As Target: x86_64-pc-windows-msvc indicates, by default your Clang is operating in some kind of MSVC-compatible mode. From what I gathered, it means using the standard library and other libraries provided by your MSVC installation, and presumably generating debug info in some MSVC-specific format.
Add --target=x86_64-w64-windows-gnu to build in GCC-compatible mode. (If you're building for 32 bits rather than 64, replace x86_64 with i686). This will make Clang use headers & libraries provided by your GCC installation, and debug info should be generated in a GCC-compatible way. I'm able to debug resulting binaries with MSYS2's GDB (and that's also where my GCC installation comes from).
If you only have GCC installed and not MSVC, you still must use this flag.
How do I know this is the right --target? This is what MSYS2's Clang uses, and I assume they know what they're doing. If you don't want to type this flag every time, you can replace the official Clang with MSYS2's one, but I'm not sure if it's the best idea.
(I think they used to provide some patches to increase compatibility with MinGW, but now the official binaries work equally well, except for the need to specify the target. Also, last time I checked their binary distribution was several GB larger, due to their inability to get dynamic linking to work. Also some of the versions they provided were prone to crashing. All those problems come from them building their Clang with MinGW, which Clang doesn't seem to support very well out of the box. In their defence, they're actively maintaining their distribution, and I think they even ship libc++ for Windows, which the official distribution doesn't do.)
I tried using this tutorial to download the newest version of g++, and I changed the version number from 4.7 to the newest (which is believe is) 8.1. But I get the following errors
Error: No available formula with the name "gcc81"
==> Searching for a previously deleted formula (in the last month)...
Warning: homebrew/core is shallow clone. To get complete history run:
git -C "$(brew --repo homebrew/core)" fetch --unshallow
Error: No previously deleted formula found.
==> Searching for similarly named formulae...
==> Searching local taps...
Error: No similarly named formulae found.
==> Searching taps...
==> Searching taps on GitHub...
Error: No formulae found in taps.
Does anyone know how to update my g++ version? This is what I get when I try to find out my current version.
g++ --version
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 9.1.0 (clang-902.0.39.1)
Target: x86_64-apple-darwin17.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
Sorry Im such a noob, I really trying to learn here.
I know this post is a little old but I can shine some light regarding how to accomplish this.
Firstly, to install gcc/g++ using Homebrew, you should use the following command as mentioned in the comments above: brew install gcc
After doing this, Homebrew should place the installed binaries/symlinks in the correct folders.
To correctly setup the gcc/g++ command on mac to use the version you just downloaded, I do this by not changing the symlinks gcc/g++ but instead creating aliases for both gcc and g++ within my shell environment.
alias gcc='gcc-10'
alias g++='g++-10'
gcc-10 and g++-10 were downloaded using Homebrew. When doing this, Homebrew places gcc-10 and g++-10 in /usr/local/bin (which is on the path) and it allows you to create an alias for the regular gcc/g++ commands which point to the versions installed by Homebrew.
After doing this, running the command g++ --version should give you the following:
g++-10 (Homebrew GCC 10.2.0) 10.2.0
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
You may need to restart your terminal or run source ~/.bashrc depending on the type of shell you're using.
The other week I installed GCC 5.2 from source on my ubuntu machine. I wanted to be able to use fully supported cilk features. Now I would like to revert back to GCC 4.9. How can I uninstall GCC 5.2? I tried using make uninstall but as I understand this is not supported.
I believe you don't need to revert to the system compiler; it is a matter of path. Or set up your $PATH appropriately. Use /usr/bin/g++ for the system compiler, and probably /usr/local/bin/g++ for the compiler you have built from source code from GCC
BTW, you probably could use your GCC 5.2 for almost all your future builds
It depends how you have configured it. You should have configured it with ../gcc-5.2/configure --program-suffix=-my-5.2 then you would use g++-my-5.2 instead of g++
Try to type g++ -v (i.e. probably /usr/local/bin/g++ -v) to understand how it was configured.
You probably could remove the gcc and g++ binaries under /usr/local/bin/ and several other files and directories under /usr/local/ (but be careful).
Indeed, GCC does not support make uninstall
This has been plaguing me for awhile now. I am trying to compile a huge C++ file (I know it works as I it works fine on my Arch Linux computer at work). When I checked my GCC version on my mac It returns the following
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-600.0.57) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.1.0
Thread model: posix
I have also installed the most recent GCC version using Homebrew with
brew install gcc49
My question now is how do I apply that newly installed GCC version to be the default version that the terminal uses?
I am also aware that when you use homebrew to isntall gcc it names it gcc-49 so that there is no confusion between packages.
I have no idea how to replace the 4.2.1 version that comes with XCode with the 4.9 version I have installed.
Thanks
Edit:
Switched to my mac to get the full return statement of gcc --version
Edit 2:
My end game here is to be able to navigate to the directory and be able to type
make
sudo make install
to install the daemon that has been made. Right now that returns tons of errors with random packages and the Standard Library
By default, homebrew places the executables (binaries) for the packages it installs into /usr/local/bin - which is a pretty sensible place for binaries installed by local users when you think about it - compared to /bin which houses standardisded binaries belonging to the core OS. So, your brew command should have installed gcc-4.9 into /usr/local/bin. The question is now how to use it... you have several options.
Option 1
If you just want to compile one or two things today and tomorrow, and then probably not use the compiler again, you may as well just invoke the gcc installed by homebrew with the full path like this:
/usr/local/bin/gcc-4.9 --version
Option 2
If you are going to be using gcc quite a lot, it gets a bit tiresome explicitly typing the full path every time, so you could put the following into your ~/.bash_profile
export PATH=/usr/local/bin:$PATH
and then start a new Terminal and it will know it needs to look in /usr/local/bin, so you will be able to get away with simply typing
gcc-4.9 --version
Option 3
If you just want to use gcc to invoke the compiler, without worrying about the actual version, you can do Option 2 above and additionally create a symbolic link like this
cd /usr/local/bin
ln -s gcc-4.9 gcc
That will allow you to run the homebrew-installed gcc by simply typing gcc at the command line, like this
gcc --version
Note:
If you later want to install, say gcc-4.13 or somesuch, you would do your brew install as before, then change the symbolic link like this:
cd /usr/local/bin
rm gcc # remove old link from gcc to gcc-4.9
ln -s gcc-4.13 gcc # make new link from gcc to gcc-4.13
Note that if you are actually using C++ rather than C, you will need to adapt the above for g++ in place of gcc.
simply updating the order of $PATH in ~/.bash_profile to the brew installed version 'export PATH=/usr/local/Cellar/gcc/5.1.0/bin:$PATH' was not enough to make the switch for me
changing the alias in your ~./bash_profile (alias gcc='gcc-5') works, but can be confusing i.e. which gcc will return the Clang version
what worked for me was to make a symbolic link in the brew gcc directory as well as update the path (point 1 above)
cd /usr/local/Cellar/gcc/5.1.0/bin/gcc
ln -s gcc-5 gcc
now which gcc returns the correct version 5.1.0
OS X does not come with GCC installed (4.2.1 or otherwise). Clang is the default system compiler and has been for some time. It is using the C++ headers from 4.2.1 when invoked as GCC. Have you tried compiling your code with Clang natively, instead of calling "gcc" (which calls Clang)? It has more modern headers and C++ support than the GCC emulation mode.
Download the gcc binaries untar and copy the bin, lib include share and libexec files to your /usr directory then type gcc --version this is what i expect you to see
gcc --version
gcc (GCC) 4.9.2 20141029 (prerelease)
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
What is the difference between Apple gcc and GNU gcc? Is Apple gcc a superset of the standard one?
The g++ version information in my OSX shows:
$ g++ --version
i686-apple-darwin11-llvm-g++-4.2 (GCC) 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)
Some of the latest features of C++11 are in gcc 4.3/4.4 as per this. Is there any newer version of Apple gcc I can upgrade to. if so, how can i do it? I have Xcode 4.1
Well, for the first part, Apple in this case is using the LLVM backend for g++ as the default g++. Apple also installs the wonderfully named clang and clang++ front-ends for LLVM. However, there is absolutely nothing stopping you from installing newer branches of GCC; MacPorts has packages for everything up to 4.6. If you look for "APPLE ONLY" in the gcc man page, you can see what won't be available outside of Apple branches.
Beside the already mentioned llvm-gcc and clang, there is also an Apple-supplied gcc-4.2 (without LLVM backend) at /usr/bin/gcc-4.2 in Xcode 4.1. But do not overwrite the Apple-supplied versions in /usr/bin. All three support a superset of features include multi-arch support and multi-abi support not found in the vanilla GNU distributions and many third-party packages depend on these features in OS X. If you install something via MacPorts or from source, it will be installed to a different path, like /opt/local/bin or /usr/local/bin. Use PATHs or environment variables to manage which compiler you use.
You can use macport to install newer versions. You can download it here. Once you have installed gcc with macport, you can use it with xcode by adding an user-defined setting to your build :
- Go to the build setting of your project
- Click on the add build setting button
- Choose user-defined setting
- Name it CC
- In the value field, put the path of the gcc version installed by macport.
One thing that definitely is present in the Apple GCC branch but not in GNU GCC is blocks.