Add OpenMP SIMD pragmas to some loops

.github/workflows/openmp.yaml

@@ -0,0 +1,41 @@
+name: OpenMP SIMD
+
+on: [push, pull_request]
+
+env:
+ # The CMake build type
+ BUILD_TYPE: Release
+
+jobs:
+ build:
+ strategy:
+ fail-fast: false
+ matrix:
+ float: [ON, OFF]
+
+ name: OpenMP SIMD Build - ${{ matrix.float == 'ON' && 'single' || 'double' }}
+ runs-on: ubuntu-latest
+
+ steps:
+ - name: Check out repository
+ uses: actions/checkout@v2
+ with:
+ submodules: 'recursive'
+
+ - name: Setup Environment
+ run: cmake -E make_directory ${{ runner.workspace }}/build
+
+ - name: Configure
+ shell: bash
+ working-directory: ${{ runner.workspace }}/build
+ run: cmake --warn-uninitialized -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DQDLDL_UNITTESTS=ON -DQDLDL_FLOAT=${{ matrix.float }} -DCOVERAGE=OFF -DQDLDL_ENABLE_OPENMP_SIMD=ON $GITHUB_WORKSPACE
+
+ - name: Build
+ shell: bash
+ working-directory: ${{ runner.workspace }}/build
+ run: cmake --build . --config $BUILD_TYPE
+
+ - name: Run tests
+ shell: bash
+ working-directory: ${{ runner.workspace }}/build
+ run: ctest -C $BUILD_TYPE

CMakeLists.txt

@@ -10,6 +10,7 @@ set(QDLDL_VERSION "${QDLDL_VERSION_MAJOR}.${QDLDL_VERSION_MINOR}.${QDLDL_VERSION
 project(qdldl VERSION ${QDLDL_VERSION})
 
 include( CMakeDependentOption )
+include(CheckCCompilerFlag)
 
 option( QDLDL_BUILD_STATIC_LIB "Build the static library" ON )
 option( QDLDL_BUILD_SHARED_LIB "Build the shared library" ON )
@@ -53,6 +54,11 @@ if( NOT (CMAKE_SIZEOF_VOID_P EQUAL 8) )
 endif()
 message(STATUS "Long integers (64bit) are ${QDLDL_LONG}")
 
+option( QDLDL_ENABLE_OPENMP_SIMD "Enable OpenMP SIMD annotations" OFF )
+if( ${QDLDL_ENABLE_OPENMP_SIMD} )
+ message( STATUS "Enabling OpenMP SIMD annotations" )
+endif()
+
 
 # Set Compiler flags
 # ----------------------------------------------
@@ -74,6 +80,30 @@ if (NOT MSVC)
  set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -O0 -g")
 endif (NOT MSVC)
 
+# Add flags for OpenMP SIMD optimizations
+if( ${QDLDL_ENABLE_OPENMP_SIMD} )
+ # Flags for Clang/GCC, if supported
+ check_c_compiler_flag( "-fopenmp-simd" HAVE_FOPENMP_SIMD )
+ if( ${HAVE_FOPENMP_SIMD} )
+ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fopenmp-simd")
+ set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -fopenmp-simd")
+ endif()
+
+ # Flags for Intel linux compiler, if supported
+ check_c_compiler_flag( "-qopenmp-simd" HAVE_DASH_QOPENMP_SIMD )
+ if( ${HAVE_DASH_QOPENMP_SIMD} )
+ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -qopenmp-simd")
+ set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -qopenmp-simd")
+ endif()
+
+ # Flags for Intel Windows compiler, if supported
+ check_c_compiler_flag( "/Qopenmp-simd" HAVE_SLASH_QOPENMP_SIMD )
+ if( ${HAVE_SLASH_QOPENMP_SIMD} )
+ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /Qopenmp-simd")
+ set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} /Qopenmp-simd")
+ endif()
+endif()
+
 # Generate header file with the global options
 # ---------------------------------------------
 

src/qdldl.c

@@ -242,6 +242,8 @@ void QDLDL_Lsolve(const QDLDL_int n,
  QDLDL_int i,j;
  for(i = 0; i < n; i++){
  QDLDL_float val = x[i];
+
+ #pragma omp simd
  for(j = Lp[i]; j < Lp[i+1]; j++){
  x[Li[j]] -= Lx[j]*val;
  }
@@ -258,6 +260,8 @@ void QDLDL_Ltsolve(const QDLDL_int n,
  QDLDL_int i,j;
  for(i = n-1; i>=0; i--){
  QDLDL_float val = x[i];
+
+ #pragma omp simd reduction(-:val)
  for(j = Lp[i]; j < Lp[i+1]; j++){
  val -= Lx[j]*x[Li[j]];
  }
@@ -276,6 +280,10 @@ void QDLDL_solve(const QDLDL_int n,
  QDLDL_int i;
 
  QDLDL_Lsolve(n,Lp,Li,Lx,x);
- for(i = 0; i < n; i++) x[i] *= Dinv[i];
+
+ #pragma omp simd
+ for(i = 0; i < n; i++)
+ x[i] *= Dinv[i];
+
  QDLDL_Ltsolve(n,Lp,Li,Lx,x);
 }