[Openmp-dev] Down with LD_LIBRARY_PATH, up with D101960

[Jon Chesterfield via Openmp-dev]

Today, to run an openmp application, one compiles it:
> clang -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa hello.c -o a.out
execute,
> ./a.out
error while loading shared libraries: libomp.so: cannot open shared object
file: No such file or directory

D101960, and this email, starts a discussion to remove that property of our
toolchain. Today, the next steps go something like:

> find $HOME -type f -iname libomp.so
and gets, on the machine I'm currently using,
$HOME/llvm-install/lib/libomp.so
$HOME/llvm-install-dbg/lib/libomp.so
$HOME/llvm-build-dbg/llvm/runtimes/runtimes-bins/openmp/runtime/src/libomp.so
$HOME/llvm-build/llvm/runtimes/runtimes-bins/openmp/runtime/src/libomp.so
$HOME/.emacs.d/lib/libomp.so
$HOME/.emacs.d/llvm/openmp/runtime/exports/lin_32e.ompt.optional/lib/libomp.so
$HOME/aomp/build/openmp/runtime/src/libomp.so
$HOME/aomp/build/openmp_debug/runtime/src/libomp.so
$HOME/rocm/aomp_13.0-3/lib/libomp.so
$HOME/rocm/aomp_13.0-3/lib-debug/libomp.so
$HOME/ROCm-llvm-build/llvm/lib/libomp.so

Brief confusion while I convince myself that I wanted the first one in that
list,
> export LD_LIBRARY_PATH=$HOME/llvm-install/lib/
> ./a.out
> success

Similarly, if one takes a failing openmp test, it has a RUN line that can
be copied into a shell, e.g.

$HOME/llvm-build/llvm/./bin/clang++ -fopenmp  -fno-experimental-isel   -I
$HOME/llvm-project/openmp/libomptarget/test -I
$HOME/llvm-build/llvm/runtimes/runtimes-bins/openmp/runtime/src -L
$HOME/llvm-build/llvm/runtimes/runtimes-bins/openmp/libomptarget -L
$HOME/llvm-build/llvm/runtimes/runtimes-bins/openmp/runtime/src
 -fopenmp-targets=amdgcn-amd-amdhsa
$HOME/llvm-project/openmp/libomptarget/test/offloading/parallel_offloading_map.cpp
-o
$HOME/llvm-build/llvm/runtimes/runtimes-bins/openmp/libomptarget/test/amdgcn-amd-amdhsa/offloading/Output/parallel_offloading_map.cpp.tmp
&&
$HOME/llvm-build/llvm/runtimes/runtimes-bins/openmp/libomptarget/test/amdgcn-amd-amdhsa/offloading/Output/parallel_offloading_map.cpp.tmp
| $HOME/llvm-build/llvm/./bin/FileCheck
$HOME/llvm-project/openmp/libomptarget/test/offloading/parallel_offloading_map.cpp

That will also fail, but for different reasons. Lit sets up LD_LIBRARY_PATH
to find libomp + libomptarget, and LIBRARY_PATH to find the devicertl. The
build tree puts the first two in different places, so the invocation to
successfully hit the same failure from the test suite is something like
> export
LD_LIBRARY_PATH="$HOME/llvm-build/llvm/runtimes/runtimes-bins/openmp/libomptarget:$HOME/llvm-build/llvm/runtimes/runtimes-bins/openmp/runtime/src"
> export
LIBRARY_PATH="$HOME/llvm-build/llvm/runtimes/runtimes-bins/openmp/libomptarget/"
then the above.

Instead of this, let's do something roughly equivalent to
https://reviews.llvm.org/D101960.

That does a bunch of small, semi-orthogonal things with the end result that
clang -fopenmp makes an executable that runs, without an environment
variable, and the failures from the test suite can be copied into a new
shell for debugging.

Thanks all,

Jon
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