add OpenMP to SPEX (required for thread safety)

ChangeLog

@@ -1,4 +1,4 @@
-Feb XX, 2024: version 7.7.0
+Mar XX, 2024: version 7.7.0
 
     * SPEX 3.1.0: major revision to API, new methods.  Added SPEX_Cholesky,
         SPEX_Backslash, and python interface.  MATLAB interface revised.

Makefile

@@ -20,6 +20,9 @@ export SUITESPARSE = $(CURDIR)
 
 # Compile the default rules for each package.
 
+# Note that CSparse is compiled but not installed by "make install";
+# CXSparse is installed instead.
+
 # default: "make install" will install all libraries in /usr/local/lib
 # and include files in /usr/local/include.  Not installed in SuiteSparse/lib.
 default: library
@@ -59,7 +62,6 @@ local:
 	( cd CCOLAMD && $(MAKE) local )
 	( cd CHOLMOD && $(MAKE) local )
 	( cd CSparse && $(MAKE) )  
-# CSparse is compiled but not installed
 	( cd CXSparse && $(MAKE) local )
 	( cd LDL && $(MAKE) local )
 	( cd KLU && $(MAKE) local )
@@ -83,7 +85,6 @@ global:
 	( cd CCOLAMD && $(MAKE) global )
 	( cd CHOLMOD && $(MAKE) global )
 	( cd CSparse && $(MAKE) )  
-# CSparse is compiled but not installed
 	( cd CXSparse && $(MAKE) global )
 	( cd LDL && $(MAKE) global )
 	( cd KLU && $(MAKE) global )
@@ -106,7 +107,6 @@ install:
 	( cd CCOLAMD && $(MAKE) install )
 	( cd CHOLMOD && $(MAKE) install )
 	( cd CXSparse && $(MAKE) install ) 
-# CXSparse is installed instead
 	( cd LDL && $(MAKE) install )
 	( cd KLU && $(MAKE) install )
 	( cd UMFPACK && $(MAKE) install )

README.md

@@ -1023,6 +1023,11 @@ build type).  The static libraries will not be built (since
   If `ON`, OpenMP is used in ParU if it is available.
   Default: `SUITESPARSE_USE_OPENMP`.
 
+* `SPEX_USE_OPENMP`:
+
+  If `ON`, OpenMP is used in SPEX if it is available.
+  Default: `SUITESPARSE_USE_OPENMP`.
+
 * `SUITESPARSE_DEMOS`:
 
   If `ON`, build the demo programs for each package.  Default: `OFF`.

SPEX/CMakeLists.txt

@@ -40,6 +40,34 @@ set ( CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH}
 
 include ( SuiteSparsePolicy )
 
+#-------------------------------------------------------------------------------
+# find OpenMP
+#-------------------------------------------------------------------------------
+
+option ( SPEX_USE_OPENMP "ON: Use OpenMP in SPEX if available.  OFF: Do not use OpenMP.  (Default: SUITESPARSE_USE_OPENMP)" ${SUITESPARSE_USE_OPENMP} )
+if ( SPEX_USE_OPENMP )
+    if ( CMAKE_VERSION VERSION_LESS 3.24 )
+        find_package ( OpenMP COMPONENTS C )
+    else ( )
+        find_package ( OpenMP COMPONENTS C GLOBAL )
+    endif ( )
+else ( )
+    # OpenMP has been disabled
+    set ( OpenMP_C_FOUND OFF )
+endif ( )
+
+if ( SPEX_USE_OPENMP AND OpenMP_C_FOUND )
+    set ( SPEX_HAS_OPENMP ON )
+else ( )
+    set ( SPEX_HAS_OPENMP OFF )
+endif ( )
+message ( STATUS "SPEX has OpenMP: ${SPEX_HAS_OPENMP}" )
+
+# check for strict usage
+if ( SUITESPARSE_USE_STRICT AND SPEX_USE_OPENMP AND NOT SPEX_HAS_OPENMP )
+    message ( FATAL_ERROR "OpenMP required for SPEX but not found" )
+endif ( )
+
 #-------------------------------------------------------------------------------
 # find library dependencies
 #-------------------------------------------------------------------------------
@@ -208,6 +236,25 @@ if ( BUILD_STATIC_LIBS )
     target_include_directories ( SPEX_static SYSTEM AFTER PUBLIC ${GMP_INCLUDE_DIR} )
 endif ( )
 
+# OpenMP:
+if ( SPEX_HAS_OPENMP )
+    message ( STATUS "OpenMP C libraries:      ${OpenMP_C_LIBRARIES}" )
+    message ( STATUS "OpenMP C include:        ${OpenMP_C_INCLUDE_DIRS}" )
+    message ( STATUS "OpenMP C flags:          ${OpenMP_C_FLAGS}" )
+    if ( BUILD_SHARED_LIBS )
+        target_link_libraries ( SPEX PRIVATE OpenMP::OpenMP_C )
+    endif ( )
+    if ( BUILD_STATIC_LIBS )
+        target_link_libraries ( SPEX_static PRIVATE OpenMP::OpenMP_C )
+        list ( APPEND SPEX_STATIC_LIBS ${OpenMP_C_LIBRARIES} )
+    endif ( )
+else ( )
+    # use threadprivate variables for SPEX instead of globals, so multiple user
+    # threads can call SPEX in parallel on different matrices.  Otherwise, SPEX
+    # is not thread-safe (see SPEX_Utilities/Source/SPEX_gmp.c).
+    include ( SuiteSparse__thread )
+endif ( )
+
 # libm:
 include ( CheckSymbolExists )
 check_symbol_exists ( fmax "math.h" NO_LIBM )
@@ -425,6 +472,15 @@ if ( SUITESPARSE_DEMOS )
         target_link_libraries ( spex_demo_threaded          PUBLIC SPEX_static SuiteSparse::AMD_static SuiteSparse::COLAMD_static )
     endif ( )
 
+    if ( SPEX_USE_OPENMP )
+        if ( BUILD_SHARED_LIBS )
+            target_link_libraries ( spex_demo_threaded PUBLIC OpenMP::OpenMP_C )
+        endif ( )
+        if ( BUILD_STATIC_LIBS )
+            target_link_libraries ( spex_demo_threaded PUBLIC OpenMP::OpenMP_C )
+        endif ( )
+    endif ( )
+
 else ( )
 
     message ( STATUS "Skipping the demos in SPEX/Demo" )

SPEX/Demo/spex_demo_threaded.c

@@ -53,6 +53,12 @@ int main( int argc, char *argv[] )
     // by calling the SPEX_initialize() function.
     //--------------------------------------------------------------------------
 
+    #ifdef _OPENMP
+    printf ("spex_demo_threaded: with OpenMP\n") ;
+    #else
+    printf ("spex_demo_threaded: without OpenMP\n") ;
+    #endif
+
     SPEX_TRY (SPEX_initialize ( )) ;
 
     //--------------------------------------------------------------------------

SPEX/Makefile

@@ -59,10 +59,10 @@ demos:
 	./build/spex_demo_lu_extended       f ExampleMats/10teams.mat.txt   ExampleMats/10teams.rhs.txt
 	./build/spex_demo_lu_doub           f ExampleMats/10teams.mat.txt   ExampleMats/10teams.rhs.txt
 	./build/spex_demo_backslash         f ExampleMats/10teams.mat.txt   ExampleMats/10teams.rhs.txt
-	./build/spex_demo_backslash         f ExampleMats/Trefethen_500.mat.txt ExampleMats/Trefethen_500.rhs.txt
-	./build/spex_demo_cholesky_simple   f ExampleMats/494_bus.mat.txt        ExampleMats/494_bus.rhs.txt
-	./build/spex_demo_cholesky_extended f ExampleMats/494_bus.mat.txt        ExampleMats/494_bus.rhs.txt
+	./build/spex_demo_cholesky_simple   f ExampleMats/494_bus.mat.txt   ExampleMats/494_bus.rhs.txt
+	./build/spex_demo_cholesky_extended f ExampleMats/494_bus.mat.txt   ExampleMats/494_bus.rhs.txt
 	./build/spex_demo_threaded          f ExampleMats/10teams.mat.txt   ExampleMats/10teams.rhs.txt
+	./build/spex_demo_backslash         f ExampleMats/Trefethen_500.mat.txt ExampleMats/Trefethen_500.rhs.txt
 
 cov:
 	( cd Tcov && $(MAKE) )

SPEX/SPEX_Utilities/Source/SPEX_gmp.c

@@ -120,6 +120,7 @@
 
     // SPEX will not be thread-safe.
     spex_gmp_t *spex_gmp = NULL ;
+    #warning "SPEX not compiled with OpenMP or thread keyword; SPEX will not be thread-safe!"
 
 #endif
 

SPEX/TODO.txt

@@ -1,6 +1,4 @@
 
-Tim: put in OpenMP
-
 Lorena: test python interface
 
 Tim: test MATLAB interface

SuiteSparse_config/Config/README.md.in

@@ -1023,6 +1023,11 @@ build type).  The static libraries will not be built (since
   If `ON`, OpenMP is used in ParU if it is available.
   Default: `SUITESPARSE_USE_OPENMP`.
 
+* `SPEX_USE_OPENMP`:
+
+  If `ON`, OpenMP is used in SPEX if it is available.
+  Default: `SUITESPARSE_USE_OPENMP`.
+
 * `SUITESPARSE_DEMOS`:
 
   If `ON`, build the demo programs for each package.  Default: `OFF`.