LLVM Compiler

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Installation

Installing Pre-build Binaries

on Ubuntu

sudo apt-get install clang llvm

Installing from github master

Hardware/Operating system

Azure VM | Standard NC6_Promo (6 vcpus, 56 GiB memory)
Tesla K80, which has compute capability 3.7. You can find out what card you got via lshw -C display; you can find out the compute capability of your card https://developer.nvidia.com/cuda-gpus .
Linux (ubuntu 18.04)

Prerequisites

sudo apt update
sudo apt install build-essential
sudo apt install cmake
sudo apt install -y libelf-dev libffi-dev
sudo apt install -y pkg-config

Install CUDA 10.2 , using instructions https://developer.nvidia.com/cuda-downloads?target_os=Linux&target_arch=x86_64&target_distro=Ubuntu&target_version=1804&target_type=debnetwork

wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/cuda-ubuntu1804.pin
sudo mv cuda-ubuntu1804.pin /etc/apt/preferences.d/cuda-repository-pin-600
sudo apt-key adv --fetch-keys https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/7fa2af80.pub
sudo add-apt-repository "deb http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/ /"
sudo apt-get update
sudo apt-get -y install cuda

After installation, export two environment variables, vim ~/.bashrc to add two lines

export PATH=$PATH:/usr/local/cuda-10.2/bin/
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/cuda-10.2/lib/

Get source packages

Assuming you are in your home directory

cd

git clone https://github.com/llvm/llvm-project.git

Build using GCC

mkdir build

cd build/

cmake  -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;libcxx;libcxxabi;lld;openmp"   \ 
    -DCMAKE_BUILD_TYPE=Release   \
    -DLLVM_TARGETS_TO_BUILD="X86;NVPTX"     \
    -DCMAKE_INSTALL_PREFIX=$(pwd)/../llvm   \
    -DCLANG_OPENMP_NVPTX_DEFAULT_ARCH=sm_37    \
    -DLIBOMPTARGET_NVPTX_COMPUTE_CAPABILITIES=35,37,50,52,60,61,70,75  \
    -DCMAKE_C_COMPILER=gcc    \
    -DCMAKE_CXX_COMPILER=g++   \
    -G "Unix Makefiles" ../llvm-project/llvm

time make -j
time make -j install

Explanation for configuration options

-DCMAKE_C_COMPILER=gcc // the C compiler used to compile clang/llvm, GCC
-DCMAKE_CXX_COMPILER=g++ // the C++ compiler used to compile clang/llvm: G++
-DLLVM_TARGETS_TO_BUILD=X86;PowerPC;NVPTX;AMDGPU // explicitly specify target devices to support, Intel ,Nvidia, IBM, and AMD CPUs or GPUs
-DCLANG_OPENMP_NVPTX_DEFAULT_ARCH=sm_70 // default GPU computing capability version to support, https://developer.nvidia.com/cuda-gpus lists such information.
-DLIBOMPTARGET_NVPTX_COMPUTE_CAPABILITIES=37,60,70 // all GPU computing capability versions to build in libomptarget

Other optional options

-DGCC_INSTALL_PREFIX=${GCC_PATH}
-DCMAKE_C_COMPILER=${GCC_PATH}/bin/gcc
-DCMAKE_CXX_COMPILER=${GCC_PATH}/bin/g++
-DCMAKE_Fortran_COMPILER=${GCC_PATH}/bin/gfortran
-DCUDA_PATH= // this option should be automatically set if cuda is in your search path
-DCUDA_TOOLKIT_ROOT_DIR= // this option should be automatically set if cuda is in your search path
-DOPENMP_ENABLE_LIBOMPTARGET=ON // this should be on by default
-DLIBOMP_FORTRAN_MODULES=ON
-DBUILD_SHARED_LIBS=OFF // turn off shared libs

More examples

cmake -G Ninja -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;libcxx;libcxxabi;lld;openmp" -DCMAKE_INSTALL_PREFIX=/Users/abc/llvm-research/inst-10.0.1 -DCMAKE_BUILD_TYPE=Debug ../llvm/
ninja -j8
ninja install

Rebuild using Clang

add the path to the installed clang, vim ~/.bashrc

export PATH=~/llvm/bin:$PATH
export LD_LIBRARY_PATH=~/llvm/lib:$LD_LIBRARY_PATH

cd 
build-openmp
cd build-openmp/

cmake -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;libcxx;libcxxabi;lld;openmp"  \
 -DCMAKE_BUILD_TYPE=Release \
 -DLLVM_TARGETS_TO_BUILD="X86;NVPTX"  \
 -DCMAKE_INSTALL_PREFIX=$(pwd)/../llvm  \
 -DCLANG_OPENMP_NVPTX_DEFAULT_ARCH=sm_37   \
 -DLIBOMPTARGET_NVPTX_COMPUTE_CAPABILITIES=35,37,50,52,60,61,70,75    \
 -DCMAKE_C_COMPILER=clang  \
 -DCMAKE_CXX_COMPILER=clang++   \
 -G "Unix Makefiles" ../llvm-project/llvm

 make -j
 make -j install

Optional options, explictly turn on bitcode lib, and the compiler/linker to build it

-DLIBOMPTARGET_NVPTX_ENABLE_BCLIB=true
-DLIBOMPTARGET_NVPTX_CUDA_COMPILER=${PREFIX}/bin/clang
-DLIBOMPTARGET_NVPTX_BC_LINKER=${PREFIX}/bin/llvm-link

Installing from releases

Hardware/Operating system

Azure VM | Standard NC6_Promo (6 vcpus, 56 GiB memory)
Tesla K80, which has compute capability 3.7. You can find out what card you got via lshw -C display; you can find out the compute capability of your card here.
Linux (ubuntu 18.04)

Prerequisites

sudo apt update
sudo apt install build-essential
sudo apt install cmake
sudo apt install -y libelf-dev libffi-dev
sudo apt install -y pkg-config

Install CUDA 10.2 , using instructions https://developer.nvidia.com/cuda-downloads?target_os=Linux&target_arch=x86_64&target_distro=Ubuntu&target_version=1804&target_type=debnetwork

Assuming you current path is

/home/ubuntu/omp5-gpu-llvm

wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/cuda-ubuntu1804.pin
sudo mv cuda-ubuntu1804.pin /etc/apt/preferences.d/cuda-repository-pin-600
sudo apt-key adv --fetch-keys https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/7fa2af80.pub
sudo add-apt-repository "deb http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/ /"
sudo apt-get update
sudo apt-get -y install cuda

After installation, export two environment variables, vim ~/.bashrc to add two lines

export PATH=$PATH:/usr/local/cuda-10.2/bin/
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/cuda-10.2/lib/

Get source packages

Three steps to download, untar, and put them into the right locations.

wget https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/llvm-10.0.0.src.tar.xz
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/clang-10.0.0.src.tar.xz
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/openmp-10.0.0.src.tar.xz
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/compiler-rt-10.0.0.src.tar.xz


tar xf llvm-10.0.0.src.tar.xz
tar xf clang-10.0.0.src.tar.xz
tar xf openmp-10.0.0.src.tar.xz
tar xf compiler-rt-10.0.0.src.tar.xz

mv clang-10.0.0.src llvm-10.0.0.src/tools/clang
mv openmp-10.0.0.src llvm-10.0.0.src/projects/openmp
mv compiler-rt-10.0.0.src llvm-10.0.0.src/projects/compiler-rt

In the end, the directory layout should look like

llvm-10.0.0.src
- tools/clang
- projects/openmp
- projects/compiler-rt

Build the Compiler with OpenMP offloading support

You need to know the Compute Capability version of your GPU. https://developer.nvidia.com/cuda-gpus lists such information. For example, some typical GPUs and their CC versions are:

Tesla K80 3.7, sm_37
Tesla P100 6.0, sm_37
Tesla V100 7.0, sm_37

mkdir build
cd build

# this step is to generate a make file using cmake. picking gcc/g++ as the compiler
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$(pwd)/../install \
	-DCLANG_OPENMP_NVPTX_DEFAULT_ARCH=sm_37 \
        -DCMAKE_C_COMPILER=gcc    \
        -DCMAKE_CXX_COMPILER=g++   \
	-DLIBOMPTARGET_NVPTX_COMPUTE_CAPABILITIES=37,60,70 ../llvm-10.0.0.src

# the screen output of the step above should show the following info: 
# -- Found LIBOMPTARGET_DEP_CUDA_DRIVER: /usr/lib/x86_64-linux-gnu/libcuda.so
# -- LIBOMPTARGET: Building offloading runtime library libomptarget.
# -- LIBOMPTARGET: Building CUDA offloading plugin.
# -- LIBOMPTARGET: Building x86_64 offloading plugin.

make -j6

make install -j6

After the installation, you should expand your PATH and LD_LIBRARY_PATH again

export PATH=$PATH:/home/ubuntu/omp5-gpu-llvm/install/bin
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/ubuntu/omp5-gpu-llvm/install/lib

Rebuild the OpenMP runtime libraries

You should use the freshly installed clang to rebuild the OpenMP runtime library

cd /home/ubuntu/omp5-gpu-llvm
mkdir build-openmp
cd build-openmp

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$(pwd)/../install \
	-DCMAKE_C_COMPILER=$(pwd)/../install/bin/clang \
	-DCMAKE_CXX_COMPILER=$(pwd)/../install/bin/clang++ \
	-DLIBOMPTARGET_NVPTX_COMPUTE_CAPABILITIES=37,60,70 \
	../llvm-10.0.0.src/projects/openmp

make -j6
make install -j6

Test the installation

save the following code into a file named ongpu.c

#include <stdio.h>
#include <omp.h>

int main()
{
  int runningOnGPU = 0;
  /* Test if GPU is available using OpenMP4.5 */
#pragma omp target map(from:runningOnGPU)
  {
    if (omp_is_initial_device() == 0)
      runningOnGPU = 1;
  }
  /* If still running on CPU, GPU must not be available */
  if (runningOnGPU)
    printf("### Able to use the GPU! ### \n");
  else
    printf("### Unable to use the GPU, using CPU! ###\n");

  return 0;
}

Compile and run it

clang -fopenmp -fopenmp-targets=nvptx64-nvidia-cuda ongpu.c

 ./a.out

### Able to use the GPU! ###

Troubleshooting

error while loading libomp.so

./a.out: error while loading shared libraries: libomp.so: cannot open shared object file: No such file or directory solution

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/pathTo/installed-llvm/lib

External Links

OpenMP 5 GPU offloading instructions [Fabio]: https://github.com/devitocodes/devito/wiki/OpenMP-5-GPU-offloading-instructions--%5BFabio%5D
- Clang_with_OpenMP_Offloading_to_NVIDIA_GPUs: https://hpc-wiki.info/hpc/Building_LLVM/Clang_with_OpenMP_Offloading_to_NVIDIA_GPUs
OpenMP 5 GPU offloading instructions with Clang 11 [Italo] https://github.com/devitocodes/devito/wiki/OpenMP-5-GPU-offloading-instructions-with-Clang-11-%5BItalo%5D
a docker file showing LLVM installation: https://github.com/freeCompilerCamp/play-with-compiler/blob/master/dockerfiles/dind/Dockerfile.llvm10

Clang Plugins

How to Debug a Plugin

There are two ways to run a Clang plugin:

call the clang frontend directly: clang -cc1 ...
call the compiler driver, clang -v, to find out real command lines

OpenMP Support

With the release of Clang 3.8.0, OpenMP 3.1 support is enabled in Clang by default, and the OpenMP runtime is therefore built as a normal part of the Clang build, and distributed with the binary distributions. You do not, therefore, need explicitly to check out this code, or build it out of tree; a normal Clang check out and build will automatically include building these runtime libraries.

https://openmp.llvm.org/

installation

cmake -G Ninja -DCMAKE_BUILD_TYPE=RELEASE -DCMAKE_INSTALL_PREFIX=$LLVM_PATH -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;compiler-rt;openmp" -DCLANG_BUILD_EXAMPLES=1 $LLVM_SRC/llvm

ninja install -j8 -l8

OpenMP lowering or Code Geneneration

Hello example

cat omp_hello.c 
#include <omp.h>
#include <stdio.h>

int main (int argc, char *argv[]) 
{
  int nthreads, tid;

#pragma omp parallel private(nthreads, tid)
  {

    tid = omp_get_thread_num();
    printf("Hello World from thread = %d\n", tid);
  } 

}

clang -fopenmp -S -O3 -emit-llvm omp_hello.c

cat omp_hello.ll

 1 ; ModuleID = 'omp_hello.c'
  2 source_filename = "omp_hello.c"
  3 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
  4 target triple = "x86_64-unknown-linux-gnu"
  5 
  6 %struct.ident_t = type { i32, i32, i32, i32, i8* }
  7 
  8 @.str = private unnamed_addr constant [30 x i8] c"Hello World from thread = %d\0A\00", align 1
  9 @.str.1 = private unnamed_addr constant [23 x i8] c";unknown;unknown;0;0;;\00", align 1
 10 @0 = private unnamed_addr global %struct.ident_t { i32 0, i32 2, i32 0, i32 0, i8* getelementptr inbounds ([23 x i8], [23 x i8]* @.str.1, i32 0, i32 0) }, align 8
 11 
 12 ; Function Attrs: nounwind uwtable
 13 define dso_local i32 @main(i32 %argc, i8** nocapture readnone %argv) local_unnamed_addr #0 {
 14 entry:
 15   tail call void (%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(%struct.ident_t* nonnull @0, i32 0, void (i32*, i32*, ...)* bitcast (void (i32*,     i32*)* @.omp_outlined. to void (i32*, i32*, ...)*)) #4
 16   ret i32 0
 17 }
 18 
 19 ; Function Attrs: norecurse nounwind uwtable
 20 define internal void @.omp_outlined.(i32* noalias nocapture readnone %.global_tid., i32* noalias nocapture readnone %.bound_tid.) #1 {
 21 entry:
 22   %call = tail call i32 @omp_get_thread_num() #4
 23   %call1 = tail call i32 (i8*, ...) @printf(i8* nonnull dereferenceable(1) getelementptr inbounds ([30 x i8], [30 x i8]* @.str, i64 0, i64 0), i32 %call)
 24   ret void
 25 }
 26 
 27 declare dso_local i32 @omp_get_thread_num() local_unnamed_addr #2
 28 
 29 ; Function Attrs: nofree nounwind
 30 declare dso_local i32 @printf(i8* nocapture readonly, ...) local_unnamed_addr #3
 31 
 32 declare !callback !2 dso_local void @__kmpc_fork_call(%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...) local_unnamed_addr

offloading example

#include <stdio.h>
#include <omp.h>

int main(void) {
  int isHost = 0;

#pragma omp target map(from: isHost)
  { isHost = omp_is_initial_device(); }

  if (isHost < 0) {
    printf("Runtime error, isHost=%d\n", isHost);
  }

  // CHECK: Target region executed on the device
  printf("Target region executed on the %s\n", isHost ? "host" : "device");

  return isHost;
}

clang -fopenmp -S -O3 -emit-llvm -fopenmp-targets=nvptx64-nvidia-cuda offloading_success.cpp

relevant source files

List

tests: clang/test/OpenMP
Clang CodeGen for OpenMP IR:
- clang/lib/CodeGen/CGOpenMPRuntime.cpp
- clang/lib/CodeGen/CGStmtOpenMP.cpp //This contains code to emit OpenMP nodes as LLVM code.
LLVM OMP IR Builder: llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
Runtime support: openmp/runtime/src/kmp_csupport.cpp

How to Debug

First, use -v to show the actual command line used by the clang driver:

clang -v -fopenmp omp_hello.c

clang version 10.0.1 (https://github.com/llvm/llvm-project d24d5c8e308e689dcd83cbafd2e8bd32aa845a15)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/ubuntu/install/llvm_install/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Candidate multilib: .;@m64
Selected multilib: .;@m64

/home/ubuntu/install/llvm_install/bin/clang-10 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -mrelax-all -disable-free -main-file-name omp_hello.c -mrelocation-model static -mthread-model posix -mframe-pointer=all -fmath-errno -fno-rounding-math -masm-verbose -mconstructor-aliases -munwind-tables -target-cpu x86-64 -dwarf-column-info -fno-split-dwarf-inlining -debugger-tuning=gdb -v -resource-dir /home/ubuntu/install/llvm_install/lib/clang/10.0.1 -internal-isystem /usr/local/include -internal-isystem /home/ubuntu/install/llvm_install/lib/clang/10.0.1/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdebug-compilation-dir /home/ubuntu -ferror-limit 19 -fmessage-length 0 -fopenmp -fgnuc-version=4.2.1 -fobjc-runtime=gcc -fdiagnostics-show-option -fcolor-diagnostics -faddrsig -o /tmp/omp_hello-c73985.o -x c omp_hello.c


clang -cc1 version 10.0.1 based upon LLVM 10.0.1 default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /home/ubuntu/install/llvm_install/lib/clang/10.0.1/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
 "/usr/bin/ld" -z relro --hash-style=gnu --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o a.out /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../x86_64-linux-gnu/crt1.o /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/7.5.0/crtbegin.o -L/usr/lib/gcc/x86_64-linux-gnu/7.5.0 -L/usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../x86_64-linux-gnu -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../.. -L/home/ubuntu/install/llvm_install/bin/../lib -L/lib -L/usr/lib /tmp/omp_hello-c73985.o -lomp -lgcc --as-needed -lgcc_s --no-as-needed -lpthread -lc -lgcc --as-needed -lgcc_s --no-as-needed /usr/lib/gcc/x86_64-linux-gnu/7.5.0/crtend.o /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../x86_64-linux-gnu/crtn.o

Next, use gdb to debug the actual executable with the full command line options

gdb -args /home/ubuntu/install/llvm_install/bin/clang-10 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -mrelax-all -disable-free -main-file-name omp_hello.c -mrelocation-model static -mthread-model posix -mframe-pointer=all -fmath-errno -fno-rounding-math -masm-verbose -mconstructor-aliases -munwind-tables -target-cpu x86-64 -dwarf-column-info -fno-split-dwarf-inlining -debugger-tuning=gdb -v -resource-dir /home/ubuntu/install/llvm_install/lib/clang/10.0.1 -internal-isystem /usr/local/include -internal-isystem /home/ubuntu/install/llvm_install/lib/clang/10.0.1/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdebug-compilation-dir /home/ubuntu -ferror-limit 19 -fmessage-length 0 -fopenmp -fgnuc-version=4.2.1 -fobjc-runtime=gcc -fdiagnostics-show-option -fcolor-diagnostics -faddrsig -o /tmp/omp_hello-c73985.o -x c omp_hello.c

Warmup run of the compiler within gdb

(gdb) r

Set a breakpoint at 1829 llvm::FunctionCallee CGOpenMPRuntime::createRuntimeFunction(unsigned Function)

b CGOpenMPRuntime.cpp:1829
r # run it

Now can check the backtrace/call stack

Breakpoint 1, clang::CodeGen::CGOpenMPRuntime::createRuntimeFunction (this=0x555565d75fd0, Function=0)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGOpenMPRuntime.cpp:1829
1829	llvm::FunctionCallee CGOpenMPRuntime::createRuntimeFunction(unsigned Function) {
(gdb) bt
#0  clang::CodeGen::CGOpenMPRuntime::createRuntimeFunction (this=0x555565d75fd0, Function=0) at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGOpenMPRuntime.cpp:1829
#1  0x000055555af54a62 in clang::CodeGen::CGOpenMPRuntime::<lambda(clang::CodeGen::CodeGenFunction&, clang::CodeGen::PrePostActionTy&)>::operator()(clang::CodeGen::CodeGenFunction &, clang::CodeGen::PrePostActionTy &) const (__closure=0x7fffffff80a0, CGF=...) at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGOpenMPRuntime.cpp:3109
#2  0x000055555af89801 in clang::CodeGen::RegionCodeGenTy::CallbackFn<clang::CodeGen::CGOpenMPRuntime::emitParallelCall(clang::CodeGen::CodeGenFunction&, clang::SourceLocation, llvm::Function*, llvm::ArrayRef<llvm::Value*>, const clang::Expr*)::<lambda(clang::CodeGen::CodeGenFunction&, clang::CodeGen::PrePostActionTy&)> >(intptr_t, clang::CodeGen::CodeGenFunction &, clang::CodeGen::PrePostActionTy &) (CodeGen=140737488322720, CGF=..., Action=...) at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGOpenMPRuntime.h:76
#3  0x000055555af45212 in clang::CodeGen::RegionCodeGenTy::operator() (this=0x7fffffff8080, CGF=...)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGOpenMPRuntime.cpp:787
#4  0x000055555af55072 in clang::CodeGen::CGOpenMPRuntime::emitParallelCall (this=0x555565d75fd0, CGF=..., Loc=..., OutlinedFn=0x555565d0bf78, CapturedVars=..., IfCond=0x0)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGOpenMPRuntime.cpp:3145
#5  0x000055555aabd108 in emitCommonOMPParallelDirective (CGF=..., S=..., InnermostKind=llvm::omp::Directive::OMPD_parallel, CodeGen=..., CodeGenBoundParameters=...)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGStmtOpenMP.cpp:1329
#6  0x000055555aabdbbf in clang::CodeGen::CodeGenFunction::EmitOMPParallelDirective (this=0x7fffffff8880, S=...)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGStmtOpenMP.cpp:1439
#7  0x000055555aa94671 in clang::CodeGen::CodeGenFunction::EmitStmt (this=0x7fffffff8880, S=0x555565e22980, Attrs=...)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGStmt.cpp:193
#8  0x000055555aa95392 in clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope (this=0x7fffffff8880, S=..., GetLast=false, AggSlot=...)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CGStmt.cpp:444
#9  0x000055555ab1ff79 in clang::CodeGen::CodeGenFunction::EmitFunctionBody (this=0x7fffffff8880, Body=0x555565e229b8)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CodeGenFunction.cpp:1146
#10 0x000055555ab20be3 in clang::CodeGen::CodeGenFunction::GenerateCode (this=0x7fffffff8880, GD=..., Fn=0x555565d0bd38, FnInfo=...)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CodeGenFunction.cpp:1311
#11 0x000055555ab498d0 in clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition (this=0x555565d73210, GD=..., GV=0x555565d0bd38)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CodeGenModule.cpp:4474
#12 0x000055555ab42709 in clang::CodeGen::CodeGenModule::EmitGlobalDefinition (this=0x555565d73210, GD=..., GV=0x0)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CodeGenModule.cpp:2864
#13 0x000055555ab4123f in clang::CodeGen::CodeGenModule::EmitGlobal (this=0x555565d73210, GD=...) at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CodeGenModule.cpp:2567
#14 0x000055555ab4d9a0 in clang::CodeGen::CodeGenModule::EmitTopLevelDecl (this=0x555565d73210, D=0x555565e20f20)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CodeGenModule.cpp:5279
#15 0x000055555baa4537 in (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl (this=0x555565d72870, DG=...)
    at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/ModuleBuilder.cpp:170
#16 0x000055555ba9de7a in clang::BackendConsumer::HandleTopLevelDecl (this=0x555565d72690, D=...) at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CodeGenAction.cpp:214
#17 0x000055555cf95464 in clang::ParseAST (S=..., PrintStats=false, SkipFunctionBodies=false) at /home/ubuntu/source/llvm_src/clang/lib/Parse/ParseAST.cpp:162
#18 0x000055555b1ba873 in clang::ASTFrontendAction::ExecuteAction (this=0x555565d52ac0) at /home/ubuntu/source/llvm_src/clang/lib/Frontend/FrontendAction.cpp:1043
#19 0x000055555ba9bd46 in clang::CodeGenAction::ExecuteAction (this=0x555565d52ac0) at /home/ubuntu/source/llvm_src/clang/lib/CodeGen/CodeGenAction.cpp:1179
#20 0x000055555b1ba1d4 in clang::FrontendAction::Execute (this=0x555565d52ac0) at /home/ubuntu/source/llvm_src/clang/lib/Frontend/FrontendAction.cpp:936
#21 0x000055555b14eb74 in clang::CompilerInstance::ExecuteAction (this=0x555565d4f490, Act=...) at /home/ubuntu/source/llvm_src/clang/lib/Frontend/CompilerInstance.cpp:965
#22 0x000055555b325e07 in clang::ExecuteCompilerInvocation (Clang=0x555565d4f490) at /home/ubuntu/source/llvm_src/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:290
#23 0x0000555557d60900 in cc1_main (Argv=..., Argv0=0x7fffffffe2fb "/home/ubuntu/install/llvm_install/bin/clang-10", 
    MainAddr=0x555557d541aa <GetExecutablePath[abi:cxx11](char const*, bool)>) at /home/ubuntu/source/llvm_src/clang/tools/driver/cc1_main.cpp:240
#24 0x0000555557d55a4c in ExecuteCC1Tool (ArgV=...) at /home/ubuntu/source/llvm_src/clang/tools/driver/driver.cpp:329
#25 0x0000555557d561ca in main (argc_=54, argv_=0x7fffffffdef8) at /home/ubuntu/source/llvm_src/clang/tools/driver/driver.cpp:403

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LLVM Compiler/Printable version

Contents

Installation

Installing Pre-build Binaries

Installing from github master

Prerequisites

Get source packages

Build using GCC

Rebuild using Clang

Installing from releases

Prerequisites

Get source packages

Build the Compiler with OpenMP offloading support

Rebuild the OpenMP runtime libraries

Test the installation

Troubleshooting

error while loading libomp.so

External Links

Clang Plugins

How to Debug a Plugin

OpenMP Support

installation

OpenMP lowering or Code Geneneration

Hello example

offloading example

relevant source files

How to Debug