[Openmp-commits] [openmp] dd145eb - [openmp][flang] To add a cmake option to build OPENMP Fortran modules only without building the libomp lib (#195576)

[via Openmp-commits]

Author: Daniel Chen
Date: 2026-05-06T11:58:00-04:00
New Revision: dd145eb8997878143f648a7601741f6409330963

URL: https://github.com/llvm/llvm-project/commit/dd145eb8997878143f648a7601741f6409330963
DIFF: https://github.com/llvm/llvm-project/commit/dd145eb8997878143f648a7601741f6409330963.diff

LOG: [openmp][flang] To add a cmake option to build OPENMP Fortran modules only without building the libomp lib (#195576)

PR #192687 Introduces a dependency to the Fortran intrinsic module when
building `openmp` Fortran modules, which requires a Flang enabled llvm
build in order to build `openmp` Fortran modules.

This PR is to add a cmake option `LIBOMP_FORTRAN_MODULES_ONLY` to allow
users to build 'openmp` Fortran modules only for Flang without building
the libomp runtime library.
This will allow libomp.a/so build still be independent from the Flang
build as before.

E.g. To build `openmp` Fortran modules only for Flang, one would need to
use the following options.
```
cmake \
...
  -DLIBOMP_FORTRAN_MODULES_ONLY=ON \
  -DLLVM_ENABLE_PROJECTS="flang" \
  -DLLVM_ENABLE_RUNTIMES="openmp" \
  ...

Added: 
    

Modified: 
    openmp/CMakeLists.txt

Removed: 
    


################################################################################
diff  --git a/openmp/CMakeLists.txt b/openmp/CMakeLists.txt
index a629c9065f85a..9a0f809a1fc02 100644
--- a/openmp/CMakeLists.txt
+++ b/openmp/CMakeLists.txt
@@ -109,6 +109,12 @@ set(LIBOMP_BUILD_DATE "No_Timestamp")
 set(LIBOMP_FORTRAN_MODULES FALSE CACHE BOOL
   "Create Fortran module files? (requires fortran compiler)")
 
+option(LIBOMP_FORTRAN_MODULES_ONLY
+  "Build only Fortran modules without libomp runtime library" OFF)
+if(LIBOMP_FORTRAN_MODULES_ONLY)
+  set(LIBOMP_FORTRAN_MODULES TRUE)
+endif()
+
 # Set up testing infrastructure.
 include(OpenMPTesting)
 
@@ -154,7 +160,9 @@ else()
 
   # Build host runtime library, after LIBOMPTARGET variables are set since they
   # are needed to enable time profiling support in the OpenMP runtime.
-  add_subdirectory(runtime)
+  if(NOT LIBOMP_FORTRAN_MODULES_ONLY)
+    add_subdirectory(runtime)
+  endif()	
 
   set(ENABLE_OMPT_TOOLS ON)
   # Currently tools are not tested well on Windows or MacOS X.