libomp fails runtime/test/barrier/omp_barrier.c for X86

[llvmbot]

Bugzilla Link	26253
Resolution	FIXED
Resolved on	Jan 26, 2016 07:22
Version	unspecified
OS	Linux
Blocks	#26433
Attachments	Pre-processed source, Assembly
Reporter	LLVM Bugzilla Contributor
CC	@hfinkel

Extended Description

I don't know OpenMP or X86 very well so I'd appreciate some help debugging this.

I've attached the pre-processed source and I'll attach the assembly shortly (bugzilla only allows one attachment during submit).

Here's the llvm-lit output:
/home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/./bin/clang -fopenmp=libomp -I /home/das-local/llvm-release-3.8/release/rc1/llvm.src/projects/openmp/runtime/test -I /home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/projects/openmp/runtime/src -L /home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/lib /home/das-local/llvm-release-3.8/release/rc1/openmp.src/runtime/test/barrier/omp_barrier.c -o /home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/projects/openmp/runtime/test/barrier/Output/omp_barrier.c.tmp -lm && /home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/projects/openmp/runtime/test/barrier/Output/omp_barrier.c.tmp

Exit Code: 10

Command Output (stdout):

Command 0: "/home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/./bin/clang" "-fopenmp=libomp" "-I" "/home/das-local/llvm-release-3.8/release/rc1/llvm.src/projects/openmp/runtime/test" "-I" "/home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/projects/openmp/runtime/src" "-L" "/home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/lib" "/home/das-local/llvm-release-3.8/release/rc1/openmp.src/runtime/test/barrier/omp_barrier.c" "-o" "/home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/projects/openmp/runtime/test/barrier/Output/omp_barrier.c.tmp" "-lm"
Command 0 Result: 0
Command 0 Output:

Command 0 Stderr:

Command 1: "/home/das-local/llvm-release-3.8/release/rc1/Phase3/Release/llvmCore-3.8.0-rc1.obj/projects/openmp/runtime/test/barrier/Output/omp_barrier.c.tmp"
Command 1 Result: 10
Command 1 Output:

Command 1 Stderr:

[llvmbot]

From my understanding, inside a parallel region the return value of omp_get_thread_num() varies from 0 to omp_get_num_threads()-1 inclusive. However,
the rank variable, which holds the return value from that function, is tested for equality only with 1 and 2. If the total number of threads is 2, as it was in my case when testing on CI20 board with 2 cores, then this test will fail either way.

[llvmbot]

I think you're right, I'm running on a 2-core machine too and this test assumes there are at least three threads. I've tried it on a 4-core machine and the test passes there unless I limit it to two threads with OMP_NUM_THREADS.

I've read a small amount of the openmp spec and it seems that this test doesn't really need the third thread so I've posted http://reviews.llvm.org/D16532.

[llvmbot]

Fixed in r258695 and merged in r258719