I'm currently compiling sources using --coverage, with GCC. The generated .gcno files (and the instrumented libraries) are to be packed in a RPM and the code coverage evaluated on another, target platform.
Now, I'm having a problem getting the coverage data, because when I run the programs calling the instrumented code, I get messages telling me that I have a version mismatch. They look like:
".gcda:Version mismatch - expected A85R got B12R"
Now, I've seen this question: GCOV Version mismatch - expected 700e got 408R which says I must use the same toolchain when compiling and when executing the code.
I'm compiling using gcc 11.2.1, and gcov --version says the same thing, on the source platform.
On the target platform, gcc --version and gcov --version both give that very same version number.
The compiling and the testing is done on the same "physical" machine, but on different Docker containers. On both of them, the GCC version and gcov version are the same
I've done further testing: even on the Docker container where we compile, we cannot run the coverage, and get the same error. Or, to be more precise, when compiled using gcc 11, it will say "version mismatch". However, when compiled using gcc 8.5, it works.
The setup is that we have the GCC 11 toolset, which requires gcc 8.5 to install. By default, gcc 8.5 is enabled, and you have to use a script (provided by the gcc 11 toolset) to enable the later. That script updates different variables, like the PATH, LIBRARY_PATH, etc., to look at GCC 11 first.
However, I'm pretty sure it doesn't upgrade the libc.so library, and that it's the cause of the problem: I compiled two of our simplest libs (each of them having no dependencies whatsoever, except libc) with gcc 11, in coverage mode. Then I compiled a simple test program, without coverage, calling some functions from the two instrumented libs. I checked (with elfread -d), the program only links to these two libs (and libc).
Calling this test program while on the compilation container results in the Version mismatch error, which would lead me to conclude that our libc.so isn't compatible with gcc 11.
I wonder if there is a way to get a "native" gcc 11, instead of a "toolkit" package which has to be installed over a gcc 8.5 (my colleague in charge of creating the Docker containers tells me that for gcc 9 and above, there are only "toolkit" packages, requiring gcc 8.5 to install).
Our target architecture runs on Rocky Linux, and I think our development architecture is a Redhat, if it has any importance here.
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 am trying to compile a Matlab mex program that uses openmp on a mac. I would like to distribute this to other Matlab users so that they can use it, without them needing to install other software.
From what I can tell, xcode doesn't allow this, so I've installed gcc. I am able to compile the program fine, and run it locally, but it links to dependencies that are not available by default on a mac (I think). In particular, otool points to libgomp.1.dylib and libgcc_s.1.dylib, which from what I can tell, are not a part of the standard os installation.
I am able to link against libgomp.a statically, which from some testing (renaming the .dylib file) seems to have properly removed that dependency (i.e. the code still works when I rename the dylib file, and otool does not list it as well). However, I am unsure how to remove the libgcc_s.1.dylib dependency. In windows, copying the dll locally would fix the issue, but this doesn't work on a mac. I could not find a static library for that dependency. Instead, I am trying to get some version of rpath working (with a locally copied file), but otool consistently points to /usr/local/opt/gcc/lib/gcc/6/libgcc_s.1.dylib
The relevant parts of the Matlab command were:
'LDFLAGS="$LDFLAGS -fopenmp -Wl,-rpath,$ORIGIN/"' and
'-lgcc_s.1'
I found one solution here: Openmp with mex in Matlab on mac
However, for another project, I am using gcc specific commands so I'd really like to get this working with gcc.
So, I had some luck bypassing the mex compiling infrastructure and just passing the commands directly to gcc. To start, I ran what I currently had using the '-v' option to see the commands that Matlab was sending to the compiler. The 4 edits I then made were, 1) removed the crazy object output paths that Matlab creates (uses some temporary folder) 2) removed the reference to xcode 3) added a -L directive to the mex folder (although I will probably change this to the proper gcc directory - I'm just used to copying files locally to compile due to Matlab problems) and 4) added '-static-libgcc' (which I swear I had tried before ...) oh, and 5) I also updated the min osx version
This is the final line, the first two just had the -o options removed
/usr/local/Cellar/gcc/6.3.0_1/bin/gcc-6 -Wl,-twolevel_namespace -static-libgcc -L"/Users/jim/Documents/repos/matlab_git/matlab_sl_modules/plotBig_Matlab/+big_plot/private" -undefined error -arch x86_64 -mmacosx-version-min=10.12 -bundle -Wl,-exported_symbols_list,"/Applications/MATLAB_R2017a.app/extern/lib/maci64/mexFunction.map" -fopenmp reduce_to_width_mex.o c_mexapi_version.o -O -Wl,-exported_symbols_list,"/Applications/MATLAB_R2017a.app/extern/lib/maci64/c_exportsmexfileversion.map" libgomp.a -L"/Applications/MATLAB_R2017a.app/bin/maci64" -lmx -lmex -lmat -lc++ -o reduce_to_width_mex.mexmaci64
Oh and finally I should mention I just ran these commands in the terminal, rather than in the Matlab command window ...
I have been using gcc version 5.3.0. It says that it comes with openmp support. But every time when I compile a program using either gcc [by terminal] or via xCode 7, I get same error, "file omp.h not found". I have searched too much on this issue and tried almost everything I found.
First I tried to locate omp.h on my mac. I found some files; then in header file, I used that specific location of omp.h but no help [it gave me linker error].
I installed gcc version 6.0 (pre-release) but no help. I tried changing C_INCLUDE_PATH [which is now, and previously set to none] but that didn't helped me as well.
I reinstalled clang-omp but no help.
I am using llvm compiler version 7.0. Although i have installed clang-omp, there is no omp.h in my /usr/include/*
I changed the compiler and now I am able to run it. [It was issue of clang, which I couldn't solve].
I am a student and Intel is giving Intel Parallel Studio 1 year licence for free to students.
So I downloaded, and installed it.
In xCode, under build settings, I set my compiler to 'Intel C/C++ compiler' and in parallalization, I turned it to 'yes'. That was it. Then it compiled successfully. But, note that you won't be using header file 'omp.h' anymore.
By the way, I am still looking for answers, just to know what I was doing wrong.
You can install 'clang-omp' or 'gcc' (corresponds to GCC 5.3 right now) packages via Homebrew, both of which support OpenMP.
The built in GCC is based upon GCC 4.2.1 abs uses LLVM back end via Dragonegg, which is why it doesn't support OpenMP.
As noted already, Intel compilers support OpenMP on Mac.
I don't use Xcode editor so I don't know how to use any of these from there, but all will work from terminal just as they do on Linux.
the compiler on the mac is clang (based on llvm 3.5) which does not support openmp.
you can try install llvm/clang/openmp from source or using prebuild binaries, but I must admit it does not work as advertised for me…
edit unless you use the -fopenmp=libomp flag.
I have downloaded gcc binaries (gcc-4.8.2-16.el7.x86_64.rpm). i extracted (it created a directory usr) and checked the version of
gcc using
usr/bin/x86_64-redhat-linux-gcc -dumpversion
It says it as 4.4.6. But it should have been 4.8.2. right. I tried downloading 4.8.2 rpm from different mirrors but "dumpversion" is not showing right version.
Can you please let me know the reason and also tell me how to download the 4.8.2 gcc.?
The "dumped" version number is correct, that you can be sure of.
The path that you query is very odd. Normally it should be gcc, x86_64-linux-gnu-gcc or something similar.¹
And GCC always has a variant with the explicit version number, so try gcc-4.8 or x86_64-linux-gnu-gcc-4.8.
1) But Redhat is known to invent their own rules ...
I have two binary files generated via 'objcopy -O binary' from respective ELF files. The ELF files are built with arm-none-linux-gnueabi toolchains; one is from linaro gcc 4.6.2 and other is from codesourcery gcc 4.6.3.
I load the binary files into memory via Uboot. While the one built with Linaro executes as expected the one built with codesourcery crashes (most probably as) there is no error on Uboot prompt but the program seems to hang.
Using 'arm-none-linux-gnueabi-readelf -S' from binutils of respective toolchains does not show much difference between files except for address offsets. Are there any tools/techniques that can help in this kind of situation before I attempt runtime debugging on target.
Thanks!
The difference turned out to be compiler option -munaligned-access. Code Sourcery toolchain enables this by default for ARMv6 and later architectures.
http://gcc.gnu.org/gcc-4.7/changes.html
Although this appeared in upstream gcc in 4.7 version, Code Sourcery had added this support earlier in their tool chain.
To figure this out I tracked the data abort exception and then compiled the culprit file with -save-temps options. Comparing intermediate .s file provided the hint.
What I can advice you is to compare default flags both compilers were built with:
/path/to/cross-compiler/bin/arm-*-*-gcc -Q -v
And preprocessor definitions:
/path/to/cross-compiler/bin/arm-*-*-gcc -dM -E - < /dev/null
The reason why your code compiled using Linaro GCC works is fact, that
it may have some options enabled by default, when CodeSourcery one
may have not.