Arbalest-VEC - Dynamic Data Inconsistency Detector for OpenMP programs

This directory and its sub-directories contain the source code for a customized LLVM 15. We modified ThreadSanitizer (compiler-rt/lib/tsan) to implement a prototype of our data inconsistency detector. In addition, we also implemented all OpenMP Tool interface (OMPT) callbacks for OpenMP device offloading according to the 5.2 version specification.

Note: this prototype only supports the x86-64 architecture

How to install Arbalest-VEC

We have provided a bash script to help you install Arbalest-VEC.

install_arbalest.sh [BUILD_DIR] [INSTALL_DIR]

// [BUILD_DIR]: the directory where cmake & ninja compile the source code
// [INSTALL_DIR]: the directory where the customized LLVM will be installed

How to use Arbalest-VEC

We will use the following example (example.cpp) to show how to use Arbalest-VEC

     1	#include <cstdio>
     2	#define N 1000
     3
     4	int main() {
     5	    int a[N];
     6	    #pragma omp target teams distribute map(from: a[0:N]) // map-type should be "tofrom"
     7	    for (int i = 0; i < N; i++) {
     8	        a[i] += i;                                 // read uninitialized value from a[i]
     9	    }
    10
    11	    printf("a[%d] = %d\n", 3, a[3]);
    12	    return 0;
    13	}

Compile the OpenMP program with OpenMP and ThreadSanitizer enabled

   clang++ -fopenmp -fopenmp-targets=x86_64-pc-linux-gnu -farbalest -fsanitize=thread -g -o example.exe example.cpp

Execute the OpenMP program

   export TSAN_OPTIONS='ignore_noninstrumented_modules=1' // this option is needed to avoid false positives
   ./example.exe

Arbalest-VEC's Output

Note: The line numbers in the Arbalest-VEC report may experience slight discrepancies, either shifting up or down. The underlying issue lies in ThreadSanitizer's inability to accurately retrieve every line number when OpenMP is enabled. We are actively working on resolving this issue to ensure accurate line numbers in the report.

*****************************
Arbalest successfully starts
*****************************

==================
WARNING: ThreadSanitizer: data inconsistency (uninitialized access) (pid=5075) on the target
  Read of size 4 at 0x7b8000002000 by main thread:
    #0 .omp_outlined._debug__ /home/lyu/Test/example.cpp:8:14 (tmpfile_KlukIr+0xb8e)
    #1 .omp_outlined. /home/lyu/Test/example.cpp:6:5 (tmpfile_KlukIr+0xcd4)
    #2 __kmp_invoke_microtask <null> (libomp.so+0xb9202)

  Location is heap block of size 4000 at 0x7b8000002000 allocated by main thread:
    #0 malloc /home/lyu/Repository/arbalest-vec/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:667:5 (example.exe+0x4d221)
    #1 DeviceTy::getTargetPointer(void*, void*, long, void*, bool, bool, bool, bool, bool, bool, bool, AsyncInfoTy&, void*) <null> (libomptarget.so.15+0xdfca)
    #2 main /home/lyu/Test/example.cpp:6:5 (example.exe+0xd76c9)
    #3 __libc_start_main /build/glibc-CVJwZb/glibc-2.27/csu/../csu/libc-start.c:310 (libc.so.6+0x21c86) (BuildId: f7307432a8b162377e77a182b6cc2e53d771ec4b)

  Variable/array involved in data inconsistency: a[0] (4-byte element)

SUMMARY: ThreadSanitizer: data inconsistency (uninitialized access) /home/lyu/Test/example.cpp:8:14 in .omp_outlined._debug__
==================
a[3] = 3
ThreadSanitizer: reported 1 warnings