From a3d1cd259a625032dfc01b55b3c1c4177171a842 Mon Sep 17 00:00:00 2001
From: scivision <scivision@users.noreply.github.com>
Date: Wed, 1 May 2024 21:18:43 -0400
Subject: [PATCH] ScalaPACK optional

---
 CMakeLists.txt      | 9 ++++++---
 Readme_options.md   | 9 +++++++++
 cmake/mumps.cmake   | 6 +++++-
 cmake/summary.cmake | 1 +
 options.cmake       | 5 +++++
 5 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index dd9c67c..690a8cb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -43,13 +43,16 @@ find_package(Threads)
 
 if(parallel)
   find_package(MPI COMPONENTS C Fortran REQUIRED)
-  if(NOT DEFINED ENV{MKLROOT})
+  if(NOT DEFINED ENV{MKLROOT} OR NOT scalapack)
     # oneMKL MKLConfig.cmake must be invoked only once
     include(cmake/lapack.cmake)
   endif()
-  include(cmake/scalapack.cmake)
+  set(NUMERIC_LIBS LAPACK::LAPACK)
 
-  set(NUMERIC_LIBS SCALAPACK::SCALAPACK LAPACK::LAPACK)
+  if(scalapack)
+    include(cmake/scalapack.cmake)
+    list(PREPEND NUMERIC_LIBS SCALAPACK::SCALAPACK)
+  endif()
 
   # avoid MPICH -fallow flag leakage
   set(NUMERIC_INC ${MPI_Fortran_INCLUDE_DIRS})
diff --git a/Readme_options.md b/Readme_options.md
index 9b61014..526daea 100644
--- a/Readme_options.md
+++ b/Readme_options.md
@@ -29,6 +29,15 @@ HOWEVER, this requires all libraries INCLUDING MPI to be compiled with 64-bit in
 Otherwise, the program will crash at runtime with MPI errors.
 For example, oneAPI / oneMPI work, but default system installs of OpenMPI / MPICH will generally fail--the user will need to specially compile an MPI library with 64-bit integers.
 
+## ScalaPACK
+
+ScalaPACK is only used for `parallel=on`.
+ScalaPACK can be omitted with MUMPS &ge; 5.7.0 by option:
+
+```sh
+cmake -Dscalapack=off
+```
+
 ## MPI
 
 For systems where MPI, BLACS and SCALAPACK are not available, or where non-parallel execution is suitable, the default parallel can be disabled at CMake configure time by option:
diff --git a/cmake/mumps.cmake b/cmake/mumps.cmake
index 3b38577..f1ac19c 100644
--- a/cmake/mumps.cmake
+++ b/cmake/mumps.cmake
@@ -122,7 +122,10 @@ target_include_directories(mumps_common PUBLIC
 $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
 )
 
-target_compile_definitions(mumps_common PRIVATE ${ORDERING_DEFS})
+target_compile_definitions(mumps_common PRIVATE
+${ORDERING_DEFS}
+$<$<AND:$<COMPILE_LANGUAGE:Fortran>,$<NOT:$<BOOL:${scalapack}>>>:NOSCALAPACK>
+)
 set(BLAS_HAVE_GEMMT FALSE)
 if(BLAS_HAVE_sGEMMT OR BLAS_HAVE_dGEMMT OR BLAS_HAVE_cGEMMT OR BLAS_HAVE_zGEMMT)
   target_compile_definitions(mumps_common PRIVATE $<$<COMPILE_LANGUAGE:Fortran>:GEMMT_AVAILABLE>)
@@ -216,6 +219,7 @@ target_compile_definitions(${a}mumps PRIVATE
 MUMPS_ARITH=MUMPS_ARITH_${a}
 ${ORDERING_DEFS}
 $<$<AND:$<BOOL:${BLAS_HAVE_${a}GEMMT}>,$<COMPILE_LANGUAGE:Fortran>>:GEMMT_AVAILABLE>
+$<$<AND:$<COMPILE_LANGUAGE:Fortran>,$<NOT:$<BOOL:${scalapack}>>>:NOSCALAPACK>
 )
 target_include_directories(${a}mumps PUBLIC
 "$<BUILD_INTERFACE:${mumps_SOURCE_DIR}/include;${NUMERIC_INC};${CMAKE_CURRENT_BINARY_DIR}/include>"
diff --git a/cmake/summary.cmake b/cmake/summary.cmake
index f6772ea..36e7407 100644
--- a/cmake/summary.cmake
+++ b/cmake/summary.cmake
@@ -3,6 +3,7 @@ add_feature_info(Parallel parallel "parallel MUMPS (using MPI and Scalapack)")
 add_feature_info(64-bit-integer intsize64 "use 64-bit integers in C and Fortran")
 add_feature_info(GEMMT BLAS_HAVE_GEMMT "use GEMMT for symmetric matrix-matrix multiplication")
 
+add_feature_info(ScalaPACK scalapack "Scalapack linear algebra library https://www.netlib.org/scalapack/")
 add_feature_info(METIS metis "METIS graph partitioning https://github.com/KarypisLab/METIS")
 add_feature_info(parMETIS parmetis "parMETIS parallel graph partitioning")
 
diff --git a/options.cmake b/options.cmake
index 87237ba..8e1dc2e 100644
--- a/options.cmake
+++ b/options.cmake
@@ -10,6 +10,11 @@ option(parallel "parallel (use MPI)" ON)
 
 option(intsize64 "use 64-bit integers in C and Fortran")
 
+option(scalapack "Use ScalaPACK to speed up the solution of linear systems" ON)
+if(MUMPS_UPSTREAM_VERSION VERSION_LESS 5.7 AND NOT scalapack)
+  message(FATAL_ERROR "MUMPS version < 5.7 requires scalapack=on")
+endif()
+
 option(scotch "use Scotch orderings ")
 
 option(parmetis "use parallel METIS ordering")