I want to use openMP library in my project but it seems as if there is no option for openMP in xcode 5.1. if someone knows then please help me
There is clang with OpenMP 3.1/4.0 support (though not official). You can take it here http://clang-omp.github.io/
OpenMP is not a library but a language extension to C, C++ and Fortran. It requires support built into the compiler. Xcode uses compilers based on the LLVM infrastructure. It used to provide two different compiler front-ends - Clang and GCC. Of those two, the former does not have support for OpenMP (yet). The GCC front-end provided some support for old OpenMP features but is no longer part of Xcode. It used to be based on a very old GCC version (4.2.1) and not actively updated since Apple started throwing all their resources into improving Clang.
In other words - no OpenMP support in Xcode 5.1. You can build your own modern (but non-LLVM) GCC from source and use it on the command line, but it's hard to integrate it with Xcode.
Related
I was wondering which compiler is better to use on Windows OS (8.1) in temrs of compatibility to c++11's (and later 14) functions, liberies and features (like lambdas) and is also comfortable to use (less bugs).
I am a university student hence I'm not looking at the subject product-wise (even though I do like to code a bit more than just projects for my studies).
I am currently using eclipse luna IDE if it matters.
Notice that compiler != IDE.
VC++ is one of the most populars on Windows and depending on its version it has a good support for C++11 features. Check the list on the msdn blog to find out if there's everything you need.
Gcc is also ported to Windows and you can install MinGW to use it (4.8.1.4 at the moment of writing this). It is pretty complete on C++11.
Clang is also available for the Windows platform and it is also complete on C++11 support (plus it has good diagnostic messages), but notice that you will have to use another linker since clang doesn't ship with one (although there is an ongoing effort to write it: http://lld.llvm.org/)
All the compilers I cited above are pretty stable but, based on my experience, if you're looking for latest and greatest C++11/14/17 features, you might just want to go for gcc or clang (VC++ is slower in adding support for newest features and the compiler is undergoing a huge update to modernize). Just keep in mind that these are compilers and not just IDEs, an IDE is a front-end supporting program that uses a compiler undercover to compile files.
To set up a C++11 compiler, I suggest installing MSYS2, it has a package manager (pacman) that can install fresh versions of GCC, GDB, Clang and many libraries like SDL, Lua etc. Very easy to use too.
As far as GCC vs CLang goes - I really tried hard to make CLang work (which is presumably faster and more friendly than GCC - produces better warnings, etc.), but failed. Issues were that CLang (which comes with MSYS2) is hard-coded to use GCC linker which produces some strange linker errors when using libstdc++ (std implementation from GCC). libc++ (a new implementation designed to work with CLang) didn't worked for me on Windows either.
So you either try build CLang from sources and hope that some configuration will work with C++11 library, OR just stick with GCC which works just fine out of the box.
As IDE, I suggest to take a look at CLion. It is very comfortable (infinitely more user-friendly and intuitive than Visual Studio, IMO). Just install it and point it to the mingw64 (or mingw32) folder of MSYS2, it will auto-detect everything for you.
It only works with CMake projects though.
so, C++11 has been around for a while and, given there already are compilers supporting it on most platforms, it would be nice to use it in some real software -- e.g. one that can be packaged in as-portable-as-possible package, preferably providing ./configure and so.
Because both Clang and GCC currently need -std=c++11 flag to compile c++11 source, and both sometimes require specific flags to work correctly (see for example How to compile C++11 with clang 3.2 on OSX lion? or C++11 Thread not working ), I'm quite afraid that the package won't work on some platforms that already support c++11 because of wrong invocation of compiler.
Q: Is there some standard how to correctly and portably compile c++11? E.g. autotools/autoconf check or some list of compiler/platform directives that describe all possible needed options? Or does the situation come from the fact that c++11 standard implementations are currently marked as "experimental" and the standard will eventually stabilize and become the default choice, not needing any usage of extra compiler flags?
Thanks
-exa
Well, if you`re trying to write portable code, i would recommend using cmake
a very powerful cross-platform, open-source build system.
Using cmake you should be able to identify the compilers available in your current machine and then generate your makefiles using the flags that you want in each case.
I have been using cmake for almost a year by now and it has significantly reduced the time consumed when trying to get a project compiling in different platforms.
I`m using CMake to generate Makefiles of C++11 projects. The only change in CMakeLists.txt I need to do is add the following:
ADD_DEFINITIONS("-std=gnu++11")
ADD_DEFINITIONS("-D_GLIBCXX_USE_C99_STDINT_TR1")
ADD_DEFINITIONS("-D_GLIBCXX_HAS_GTHREADS")
However, as I use Qt, I re-compile QtSDK with a new gcc version 4.8 and get a complete mingw system that use gcc in version 4.8.
Makings these changes, the project compile and run in Windows XP, Windows 7 and linux both 32 and 64 bits. I didn`t test it in OSX yet.
I'm working on someone else's application and so far he has built it in XCode 4. XCode 4 has eliminated support for PowerPC architectures, but we would still like to support PowerPCs for some of our users.
I have followed this tutorial on SO, informing me how to restore ppc compatibility to XCode 4, however, this is for the GCC (4.2) compiler which throws a lot of warnings and some errors when compiling the code. The code is optimized around Apple's LLVM 3.0.
My questions:
Is it possible to use Apple LLVM
compiler 3.0 for Power PC deployment?
How would one go about doing this?
What settings variables do I need to
set in order to get PPC compatibility
when compiling?
Thank you!
Pretty much no, it's not possible. Apple LLVM 3.0 hasn't been tested or verified to work at all with PowerPC.
I'm an iOS developer, I don't know how compilers work and I want to ask what is the difference between the LLVM GCC 4.2, the Xcode 4 default compiler and the GCC 4.2 compiler, the Xcode 3 default compiler.
Here is my understanding
GCC 4.2 is the (mostly) stock standard open source GNU C compiler that works with C, C++ and Objective-C. Its pretty much the standard compiler used in all open source, and its tried and true tested. But because its old technology, its just a compiler, it has no hooks for other uses. And its quite generic, being CPU and platform agnostic.
LLVM is the next generation of compilation software. It's syntax and semantically aware, compiling to a byte code and then to native, and it provides hooks so IDE's and other tools can use its knowledge. It's this awareness that allows Apple to improve auto-completion, implement fixit and do the build and analyze stuff in Xcode 4. LLVM is the future for Apple, and the future for GCC. LLVM also produces allegedly tighter code, as its optimizations are smarter (not sure about this). LLVM also allows for more dynamic language bindings at some point.
LLVM GCC is the half-way mark, the syntax and semantic preprocessing of LLVM with the old GCC back end compiler.
The way I use them
I use LLVM during development, as it keeps me warned of any and all issues. Really helped when I ran it the first time on legacy code and found some issues.
I use GCC to produce the final executable for iOS 3.1.3 apps, and LLVM for all the iOS 4.0 / Mac 10.6 apps.
We are compiling an application that uses OpenMP. We are using gcc 4.4, with -fopenmp. The app also uses IPP, which includes its own version of OpenMP (libiomp5). (Note: we are disabling IPP's internal threading by calling ippSetNumThread(1). According to Intel's documentation, this should avoid conflicts with other threading libraries. However, linking with IPP still links in libiomp5.so.)
Since libiomp5.so is already linked in, we have not been linking with libgomp.so (gcc's version of OpenMP). For a long time this has worked, but after a seemingly inconsequential change we started seeing very odd OpenMP-related crashes on one of four platforms we support (the other three platforms still work fine).
I can make the crashes go away if I link in libgomp.so as well as libiomp5.so.
I have a couple questions about this:
Is linking with both these libraries safe? It seems like they would both define the same symbols.
Is there a way to tell what version of OpenMP libiomp5.so supports? With gcc 4.4, libgomp.so should be at OpenMP v3.0. I can't find any information in Intel's documentation about the OpenMP version of libiomp5.so.
Since no one has answered for a few days, I'll just report what I've found out independently:
Is linking with both these libraries safe?
No. Here's the most useful page I found on this topic:
http://software.intel.com/sites/products/documentation/studio/composer/en-us/2011/compiler_c/optaps/common/optaps_par_openmp_multiple_compilers.htm
Intel recommends that if you are going to be mixing IPP's internal OpenMP threading with your own OpenMP threading, you link to libiomp5 instead of your compiler's OpenMP library. The current version of libiomp5 provides "source compatibility and object-level interoperability" with gcc's OpenMP, but only if you are using gcc "4.42" (sic; I assume they mean 4.4.2) or later.
Is there a way to tell what version of OpenMP libiomp5.so supports?
Yes. Set the environment variable KMP_VERSION=1, then run your application. You'll get some debugging output printed by libiomp5 to your console. If you are using IPP v7 or later, one line will be something like
Intel(R) OMP API version: 3.0 (200805)
If you are using IPP 6, it won't tell you the API version, but it will tell you when it was built and with which version of the Intel compiler. Then you can check and see what version of OpenMP that compiler supported. (11.0 was the first version of the Intel compiler to support OpenMP v3.0.)