I would like to have complete Win32 development toolchain without Microsoft SDKs. mingw64 works, but its linker is very slow. As an alternative, I am trying to use clang for windows. I can get clang 7.0.1 (but not 8.0.0) work with mingw headers/libraries, however only using mingw's ld.exe. If I force ldd.exe to be used (-fuse-ld=lld), everything compiles and links fine, but the application immediately crashes when started. Is there anything I can do here, like change something in the commandline?
This is how commandline and --verbose for the link step looks like:
Linking...
clang++ -static -o "C:\upp\out\MyApps\CLANG.Debug.Debug_Full\main.exe"
-ggdb -L"C:\upp\bin/mingw64/64/x86_64-w64-mingw32/lib"
-L"C:\uppbin/mingw64/64/opt/lib" -L"C:\upp\bin/SDL2/lib/x64"
-L"C:\upp\bin/pgsql/x64/bin"
-L"C:\upp\bin/mysql/lib64"
-Wl,--stack,20000000 --verbose -target x86_64-pc-windows-gnu
-fuse-ld=lld
"C:/upp/out/MyApps/main/CLANG.Debug.Debug_Full.Main\main.o"
-Wl,--start-group -Wl,--end-group
clang version 7.0.1 (tags/RELEASE_701/final)
Target: x86_64-pc-windows-gnu
Thread model: posix
InstalledDir: C:\xxx\LLVM2\bin
"C:\\xxx\\LLVM2\\bin\\ld.lld" -m i386pep -Bstatic
-o "C:\\upp\\out\\MyApps\\CLANG.Debug.Debug_Full\\main.exe"
"C:\\upp\\bin\\mingw64\\64\\x86_64-w64-mingw32\\lib\\crt2.o"
"C:\\upp\\bin\\mingw64\\64\\lib\\gcc\\x86_64-w64-mingw32\\8.1.0\\crtbegin.o"
"-LC:\\upp\\bin/mingw64/64/x86_64-w64-mingw32/lib"
"-LC:\\upp\\bin/mingw64/64/opt/lib"
"-LC:\\upp\\bin/SDL2/lib/x64" "-LC:\\upp\\bin/pgsql/x64/bin"
"-LC:\\upp\\bin/mysql/lib64"
"-LC:\\upp\\bin\\mingw64\\64\\lib\\gcc\\x86_64-w64-mingw32\\8.1.0"
"-LC:\\upp\\bin\\mingw64\\64\\x86_64-w64-mingw32\\lib"
"-LC:\\upp\\bin\\mingw64\\64\\lib"
"-LC:\\upp\\bin\\mingw64\\64\\x86_64-w64-mingw32/sys-root/mingw/lib"
--stack 20000000
"C:/upp/out/MyApps/main/CLANG.Debug.Debug_Full.Main\\main.o"
--start-group --end-group -lstdc++ --start-group -lmingw32
-lgcc -lgcc_eh -lmoldname -lmingwex -lmsvcrt -ladvapi32 -lshell32
-luser32 -lkernel32 --end-group
"C:\\upp\\bin\\mingw64\\64\\lib\\gcc\\x86_64-w64-mingw32\\8.1.0\\crtend.o"
The llvm-mingw toolchain is very easy to use and provides latest clang / libc++ / lld without any dependency on the Microsoft headers: https://github.com/mstorsjo/llvm-mingw
It links against the Microsoft ucrt and as such is compatible with MSVC-built DLLs (for the C API / ABI, not the C++ since it uses a different standard library implementation)
Related
I'm trying to tailor compiler flags of clang-11 to the apple-m1 CPU, which clang-11 doesn't know about yet.
The output of /usr/bin/clang -E - -mcpu=apple-m1 -### on macOS outputs a command with flags like these in it: "-target-feature" "+zcz"
From that you can infer the following features of the CPU:
armv8.5a+fp-armv8+neon+crc+crypto+dotprod+fp16fml+ras+lse+rdm+rcpc+zcm+zcz+fullfp16+sm4+sha3+sha2+aes
However, out of these, +fp-armv8+neon+zcm+zcz+fullfp16 are not recognised to be valid by any clang compiler:
$ cc -march=armv8.5a+zcz test.c
clang-11: error: the clang compiler does not support '-march=armv8.5a+zcz'
How can I tell clang to optimise for those target flags?
I have installed LLVM 5.0 on Windows 10 x64. When I call clang++ --version from cmd the message below is displayed.
clang version 5.0.0 (tags/RELEASE_500/final)
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\LLVM\bin
But when I call qbs setup-toolchains --detect in the resulting list neither clang nor clang++ is in. If I call qbs config --list profiles both clang and clang++ are not in the list. Am I missing something?
On Windows, the --detect option only looks for MSVC and mingw installations. Use the explicit mode instead:
qbs setup-toolchains C:\LLVM\bin\clang.exe clang
I have been using clang-3.5 to happily build bitcode versions of musl libc and
use the result to produce nice stand alone executables.
Recent attempts with clang-3.8 have not been so happy. It seems that
the bitcode clang-3.8 generates uses functions defined in
compiler-rt/lib/builtins
Typical examples of functions I find polluting the bitcode are mulxc3, mulsc3, and muldc3. I can solve this by linking against libgcc, or even the llvm alternative if I had any clear idea of what that was. Though I would rather prevent the problem from happening in the first place.
I have seen mention of flags like rtlib=compiler-rt etc, but have found precious little documentation on the subject.
So here are some simple questions.
Is it possible to prevent clang from using the compiler-rt/lib/builtins
in the emitted bitcode? Or if not
Does llvm produce a version of libgcc that I could use. Actually I would
probably build a bitcode version of it, but that is besides the point.
Love to hear some guidance on this.
Added 12/8/2016: So I will illustrate my issues with a particular workflow that
people can reproduce if they wish, or, more likely, just point out where I am being stupid.
So start by checking out:
musllv
and follow the instructions in the README.to compile (here I am using clang-3.8 on ubuntu 14.04)
WLLVM_CONFIGURE_ONLY=1 CC=wllvm ./configure --target=LLVM --build=LLVM
make
cd lib
extract-bc -b libc.a
you will also need the bitcode of a simple executable. I will use nweb.c here.
wllvm nweb.c -o nweb
extract-bc nweb
Now we can do things like:
clang -static -nostdlib nweb.bc libc.a.bc crt1.o libc.a -o nweb
This workflow goes smoothly for clang-3.5 but for clang-3.8 we get:
clang -static -nostdlib nweb.bc libc.a.bc crt1.o libc.a -o nweb
/tmp/libc-f734a3.o: In function `cpowl':
libc.a.bc:(.text+0xbb9a): undefined reference to `__mulxc3'
/tmp/libc-f734a3.o: In function `cpowf':
libc.a.bc:(.text+0x38f7d): undefined reference to `__mulsc3'
/tmp/libc-f734a3.o: In function `csqrt':
libc.a.bc:(.text+0x78fc3): undefined reference to `__muldc3'
/tmp/libc-f734a3.o: In function `cpow':
libc.a.bc:(.text+0xafafc): undefined reference to `__muldc3'
clang-3.8: error: linker command failed with exit code 1 (use -v to seeinvocation)
So as #paul-brannan points out we could try
clang -static -nostdlib --rtlib=compiler-rt nweb.bc libc.a.bc crt1.o libc.a -o nweb
But this is where I am probably being stupid, because I get:
clang-3.8: warning: argument unused during compilation: '--rtlib=compiler-rt'
irregardless of whether I use it as a linking or compiling flag.
OK so I finally managed to make headway on this. I built llvm-3.8.1 together with the compiler-rt project using wllvm and wllvm++.
One of the build products was libclang_rt.builtins-x86_64.a,
and from this archive I was able to extract the bitcode module
libclang_rt.builtins-x86_64.bc
using the command:
extract-bc -b libclang_rt.builtins-x86_64.a
This bitcode module has definitions for those pesky instrinsics like
__mulxc3, __mulsc3, and __muldc3.
Hallelujah!
I am at a loss to solve a particular issue I have: I cannot pinpoint the culprit.
System: Jetson TX1, arm64 kernel, 32b userspace, opencv4tegra
Situation: Have been building projects using:
find_package( OpenCV )
And this has worked fine and compiled.
Fault: I built from source and installed CMake 3.5.2. Now I can no-longer build any projects that depend on OpenCV. I get linker errors that point cannot find:
opencv_dep_cudart
I am assuming the issues are caused in OpenCVCConfig.cmake, around this point:
# Import target "opencv_core" for configuration "Release"
set_property(TARGET opencv_core APPEND PROPERTY IMPORTED_CONFIGURATIONS RELEASE)
set_target_properties(opencv_core PROPERTIES
IMPORTED_LINK_INTERFACE_LIBRARIES_RELEASE "opencv_dep_cudart;opencv_dep_nppc;opencv_dep_nppi;opencv_dep_npps;dl;m;pthread;rt;tbb"
IMPORTED_LOCATION_RELEASE "${_IMPORT_PREFIX}/lib/libopencv_core.so.2.4.12"
IMPORTED_SONAME_RELEASE "libopencv_core.so.2.4"
)
Out of the file: /usr/share/OpenCV/OpenCVModules-release.cmake
However, this file doesn't change between CMake versions as it is an OpenCV file. So this must be how it is processed.
Reverting my CMake back to 2.8.12.2 manually allowed me to build again. Here is an example of a make command that uses OpenCV. Note the correct cuda libs:
Linking CXX executable DuoInterfaceTest
/usr/local/bin/cmake -E cmake_link_script CMakeFiles/DuoInterfaceTest.dir/link.txt --verbose=1
/usr/bin/c++ -O2 -g -DNDEBUG -std=gnu++11 CMakeFiles/DuoInterfaceTest.dir/src/mainTest.cpp.o -o DuoInterfaceTest -L/home/ubuntu/catkin_ws/duointerface/lib/linux/arm -rdynamic libDuoInterface.a /usr/lib/libopencv_vstab.so.2.4.12 /usr/lib/libopencv_tegra.so.2.4.12 /usr/lib/libopencv_imuvstab.so.2.4.12 /usr/lib/libopencv_facedetect.so.2.4.12 /usr/lib/libopencv_esm_panorama.so.2.4.12 /usr/lib/libopencv_detection_based_tracker.so.2.4.12 /usr/lib/libopencv_videostab.so.2.4.12 /usr/lib/libopencv_video.so.2.4.12 /usr/lib/libopencv_ts.a /usr/lib/libopencv_superres.so.2.4.12 /usr/lib/libopencv_stitching.so.2.4.12 /usr/lib/libopencv_photo.so.2.4.12 /usr/lib/libopencv_objdetect.so.2.4.12 /usr/lib/libopencv_ml.so.2.4.12 /usr/lib/libopencv_legacy.so.2.4.12 /usr/lib/libopencv_imgproc.so.2.4.12 /usr/lib/libopencv_highgui.so.2.4.12 /usr/lib/libopencv_gpu.so.2.4.12 /usr/lib/libopencv_flann.so.2.4.12 /usr/lib/libopencv_features2d.so.2.4.12 /usr/lib/libopencv_core.so.2.4.12 /usr/lib/libopencv_contrib.so.2.4.12 /usr/lib/libopencv_calib3d.so.2.4.12 /usr/lib/libopencv_tegra.so.2.4.12 /usr/lib/libopencv_stitching.so.2.4.12 /usr/lib/libopencv_gpu.so.2.4.12 /usr/lib/libopencv_photo.so.2.4.12 /usr/lib/libopencv_legacy.so.2.4.12 /usr/local/cuda-7.0/lib/libcufft.so /usr/lib/libopencv_video.so.2.4.12 /usr/lib/libopencv_objdetect.so.2.4.12 /usr/lib/libopencv_ml.so.2.4.12 /usr/lib/libopencv_calib3d.so.2.4.12 /usr/lib/libopencv_features2d.so.2.4.12 /usr/lib/libopencv_highgui.so.2.4.12 /usr/lib/libopencv_imgproc.so.2.4.12 /usr/lib/libopencv_flann.so.2.4.12 /usr/lib/libopencv_core.so.2.4.12 /usr/local/cuda-7.0/lib/libcudart.so /usr/local/cuda-7.0/lib/libnppc.so /usr/local/cuda-7.0/lib/libnppi.so /usr/local/cuda-7.0/lib/libnpps.so -ldl -lm -lpthread -lrt -ltbb -lDUO -Wl,-rpath,/home/ubuntu/catkin_ws/duointerface/lib/linux/arm:/usr/local/cuda-7.0/lib
Thoughts? I would like to be able to keep the newer CMake on my system but don't understand enough to fix the problem. If you think this is too system-unique I will withdraw the question.
As noted by Michael Mairegger, you have to cmake in the build directory by doing
sudo cmake .. -DCUDA_USE_STATIC_CUDA_RUNTIME=false
But one extra thing I noticed is that if I try to make afterwards it won't work unless I do the cmake command twice.
I'm seeing a factor of four slowdown in Clang compilation versus GCC. Any idea what causes this?
ebg#tsuki(250)$ time /usr/bin/cc -DHC4 -DSAFETY -DNOREDUCE -DNFAIR=3 -O2 -o files2 pan.c
real 2m3.073s
user 1m59.484s
sys 0m3.585s
ebg#tsuki(251)$ time /usr/local/gcc/bin/gcc -DHC4 -DSAFETY -DNOREDUCE -DNFAIR=3 -O2 -o files1 pan.c
real 0m28.310s
user 0m27.590s
sys 0m0.706s
ebg#tsuki(252)$ /usr/bin/cc -v
Apple clang version 4.0 (tags/Apple/clang-421.0.60) (based on LLVM 3.1svn)
Target: x86_64-apple-darwin12.2.0
Thread model: posix
ebg#tsuki(253)$ /usr/local/gcc/bin/gcc -v
Using built-in specs.
COLLECT_GCC=/usr/local/gcc/bin/gcc
COLLECT_LTO_WRAPPER=/usr/local/gcc/libexec/gcc/x86_64-apple-darwin10.7.0/4.6.0/lto-wrapper
Target: x86_64-apple-darwin10.7.0
Configured with: ./configure --prefix=/usr/local/gcc --enable-languages='c c++' --enable-lto --with-gmp=/usr/local/gcc --with-mpfr=/usr/local/gcc --with-mpc=/usr/local/gcc
Thread model: posix
gcc version 4.6.0 (GCC)
When I had the same problem it was due to clang was build for debug mode and not for release mode.