PositDebug

A debugger to detect numerical errors in applications using posits.

How to build

Get llvm and clang version 9

  wget http://releases.llvm.org/9.0.0/llvm-9.0.0.src.tar.xz

  wget http://releases.llvm.org/9.0.0/cfe-9.0.0.src.tar.xz

Build llvm and clang

  tar -xvf llvm-9.0.0.src.tar.xz
  mv llvm-9.0.0.src/ llvm
  tar -xvf cfe-9.0.0.src.tar.xz
  mv cfe-9.0.0.src/* clang
  mkdir build
  cd build
  cmake -DLLVM_ENABLE_PROJECTS=clang -G "Unix Makefiles" ../llvm
  make -j8

Set env variable LLVM_HOME to the LLVM build directory

  export LLVM_HOME=<path to LLVM build>

Clone PositDebug git repo.

  git clone https://github.com/rutgers-apl/PositDebug.git

If your compiler does not support C++11 by default, add the following line to llvm-pass/PSan/CMakefile

  target_compile_feature(PSanitizer PRIVATE cxx_range_for cxx_auto_type)

otherwise, use the followng line

  target_compile_features(PSanitizer PRIVATE )

Build the PSan LLVM pass

  cd PositDebug/llvm-pass
  mkdir build
  cd build
  cmake ../
  make
  cd ../..

Download and build the SoftPosit library with PositDebug Extensions

   git clone https://gitlab.com/cerlane/SoftPosit.git
   cd SoftPosit/build/Linux-x86_64-GCC/
   make
   cd ../../..

Set the following environment variables to build the PositDebug runtime environment

  export PD_HOME=<path to the PositDebug github checkout>

  export SOFTPOSIT_HOME=$PD_HOME/SoftPosit/

Build the PositDebug runtime environment

  cd runtime
  make

Finally return back to the top-level PositDebug directory

Try out the tests in regression_tests directory. Set the following environment variables

  export LLVM_HOME=<LLVM build directory>

  export PD_HOME=<path to the PositDebug github checkout>

  export SOFTPOSIT_HOME=$PD_HOME/SoftPosit/

  export PATH=<LLVM build directory>/bin:$PATH

  export LD_LIBRARY_PATH=$PD_HOME/runtime/obj/

and then,

  make

  ./diff-root-simple.pd.o

It should report that there is one instance of more than 55 bits of error in error.log