[OpenMP] Remove LLVM_ENABLE_PROJECTS=openmp build mode#176950
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Meinersbur merged 2 commits intollvm:mainfrom Jan 30, 2026
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[OpenMP] Remove LLVM_ENABLE_PROJECTS=openmp build mode#176950Meinersbur merged 2 commits intollvm:mainfrom
Meinersbur merged 2 commits intollvm:mainfrom
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Hoist handling of Doxygen into the top-level cmake/ directory so it can be shared between LLVM and RUNTIMES and a default/standalone runtimes build can support building Doxygen documentation as well. The openmp subproject currently supports doxygen documentation using an `LLVM_ENABLE_PROJECTS=openmp` build, but not with `LLVM_ENABLE_RUNTIMES=openmp` because of this missing boilerplate code in the runtimes build. This is a step towards removing the `LLVM_ENABLE_PROJECTS=openmp` build mode which was deprecated (#124014) and already scheduled to be removed in LLVM 21 (#136314). Eventual removal is planned with #176950. Hoisting CMake code for shared use with runtimes has been done before in e.g. #84641, 7017e6c, 44e3365, 7017e6c --------- Co-authored-by: Petr Hosek <phosek@google.com>
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Jan 23, 2026
Hoist handling of Doxygen into the top-level cmake/ directory so it can be shared between LLVM and RUNTIMES and a default/standalone runtimes build can support building Doxygen documentation as well. The openmp subproject currently supports doxygen documentation using an `LLVM_ENABLE_PROJECTS=openmp` build, but not with `LLVM_ENABLE_RUNTIMES=openmp` because of this missing boilerplate code in the runtimes build. This is a step towards removing the `LLVM_ENABLE_PROJECTS=openmp` build mode which was deprecated (llvm#124014) and already scheduled to be removed in LLVM 21 (llvm#136314). Eventual removal is planned with llvm#176950. Hoisting CMake code for shared use with runtimes has been done before in e.g. llvm#84641, 7017e6c, 44e3365, 7017e6c --------- Co-authored-by: Petr Hosek <phosek@google.com>
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Jan 24, 2026
Hoist handling of Doxygen into the top-level cmake/ directory so it can be shared between LLVM and RUNTIMES and a default/standalone runtimes build can support building Doxygen documentation as well. The openmp subproject currently supports doxygen documentation using an `LLVM_ENABLE_PROJECTS=openmp` build, but not with `LLVM_ENABLE_RUNTIMES=openmp` because of this missing boilerplate code in the runtimes build. This is a step towards removing the `LLVM_ENABLE_PROJECTS=openmp` build mode which was deprecated (llvm#124014) and already scheduled to be removed in LLVM 21 (llvm#136314). Eventual removal is planned with llvm#176950. Hoisting CMake code for shared use with runtimes has been done before in e.g. llvm#84641, 7017e6c, 44e3365, 7017e6c --------- Co-authored-by: Petr Hosek <phosek@google.com>
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The buildbot publish-doxygen-docs failure has been addressed (llvm/llvm-zorg@ed6884d) |
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@llvm/pr-subscribers-github-workflow @llvm/pr-subscribers-clang-static-analyzer-1 Author: Michael Kruse (Meinersbur) ChangesReapply #152189 and #174963 which were reverted because it broke publish-sphinx-docs and publish-doxygen-docs. The build mode has been deprecated in #136314 and was supposed to be removed in the LLVM 21 release (#136314). OpenMP currently supports 4 build modes:
Each build mode increased the maintanance overhead since all build modes must continue working and user confusion when there do not (see #151117, #174126, #154117, ...). Let's finally remove it. The LLVM_ENABLE_RUNTIMES system currently does not support building doxygen. Landing this PR will wait to add support in llvm-project (#176948) and llvm-zorg. Full diff: https://github.com/llvm/llvm-project/pull/176950.diff 7 Files Affected:
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 1b1f027be1a7e..11a453b84418e 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -186,10 +186,10 @@ jobs:
steps.docs-changed-subprojects.outputs.openmp_any_changed == 'true' ||
steps.docs-changed-subprojects.outputs.workflow_any_changed == 'true'
run: |
- cmake -B openmp-build -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;openmp" -DLLVM_ENABLE_SPHINX=ON ./llvm
+ cmake -B openmp-build -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_RUNTIMES="openmp" -DLLVM_ENABLE_SPHINX=ON -DLLVM_INCLUDE_TESTS=OFF ./runtimes
TZ=UTC ninja -C openmp-build docs-openmp-html
mkdir built-docs/openmp
- cp -r openmp-build/docs/* built-docs/openmp/
+ cp -r openmp-build/openmp/docs/* built-docs/openmp/
- name: Build Polly docs
if: |
steps.docs-changed-subprojects.outputs.polly_any_changed == 'true' ||
diff --git a/clang/utils/analyzer/entrypoint.py b/clang/utils/analyzer/entrypoint.py
index c8dfc1a9f2ed8..20390d62374b8 100644
--- a/clang/utils/analyzer/entrypoint.py
+++ b/clang/utils/analyzer/entrypoint.py
@@ -53,8 +53,8 @@ def is_cmake_needed():
CMAKE_COMMAND = (
"cmake -G Ninja -DCMAKE_BUILD_TYPE=Release "
"-DCMAKE_INSTALL_PREFIX=/analyzer -DLLVM_TARGETS_TO_BUILD=X86 "
- '-DLLVM_ENABLE_PROJECTS="clang;openmp" -DLLVM_BUILD_RUNTIME=OFF '
- "-DCLANG_ENABLE_STATIC_ANALYZER=ON"
+ '-DLLVM_ENABLE_PROJECTS="clang" -DLLVM_ENABLE_RUNTIMES="openmp" '
+ "-DLLVM_BUILD_RUNTIME=OFF -DCLANG_ENABLE_STATIC_ANALYZER=ON"
)
diff --git a/flang-rt/README.md b/flang-rt/README.md
index 4fe66a85a269c..eecb7b8cbfdfd 100644
--- a/flang-rt/README.md
+++ b/flang-rt/README.md
@@ -58,8 +58,8 @@ not provide all C-ABI functionality (such as Windows).
cmake -S <path-to-llvm-project-source>/llvm \
-GNinja \
-DCMAKE_BUILD_TYPE=Release \
- -DLLVM_ENABLE_PROJECTS="clang;flang;openmp" \
- -DLLVM_ENABLE_RUNTIMES="compiler-rt;flang-rt" \
+ -DLLVM_ENABLE_PROJECTS="clang;flang" \
+ -DLLVM_ENABLE_RUNTIMES="compiler-rt;flang-rt;openmp" \
...
```
diff --git a/flang/tools/f18/CMakeLists.txt b/flang/tools/f18/CMakeLists.txt
index 58ea782ce213e..ffd92f033840b 100644
--- a/flang/tools/f18/CMakeLists.txt
+++ b/flang/tools/f18/CMakeLists.txt
@@ -135,18 +135,7 @@ if (NOT CMAKE_CROSSCOMPILING)
# Special case for omp_lib.mod, because its source comes from openmp/runtime/src/include.
# It also produces two module files: omp_lib.mod and omp_lib_kinds.mod. Compile these
# files only if OpenMP support has been configured.
- if (LLVM_TOOL_OPENMP_BUILD)
- message(STATUS "OpenMP runtime support enabled via LLVM_ENABLE_PROJECTS, building omp_lib.mod")
- set(base ${FLANG_INTRINSIC_MODULES_DIR}/omp_lib)
- add_custom_command(OUTPUT ${base}.mod ${base}_kinds.mod
- COMMAND ${CMAKE_COMMAND} -E make_directory ${FLANG_INTRINSIC_MODULES_DIR}
- COMMAND flang -cpp -fsyntax-only ${opts} -module-dir ${FLANG_INTRINSIC_MODULES_DIR}
- ${CMAKE_BINARY_DIR}/projects/openmp/runtime/src/omp_lib.F90
- DEPENDS flang ${FLANG_INTRINSIC_MODULES_DIR}/iso_c_binding.mod ${CMAKE_BINARY_DIR}/projects/openmp/runtime/src/omp_lib.F90 ${depends}
- )
- list(APPEND MODULE_FILES ${base}.mod ${base}_kinds.mod)
- install(FILES ${base}.mod ${base}_kinds.mod DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/flang" COMPONENT flang-module-interfaces)
- elseif ("openmp" IN_LIST LLVM_ENABLE_RUNTIMES)
+ if ("openmp" IN_LIST LLVM_ENABLE_RUNTIMES)
message(STATUS "OpenMP runtime support enabled via LLVM_ENABLE_RUNTIMES, assuming omp_lib.mod is built there")
else()
message(WARNING "Not building omp_lib.mod, no OpenMP runtime in either LLVM_ENABLE_PROJECTS or LLVM_ENABLE_RUNTIMES")
@@ -160,11 +149,7 @@ set_target_properties(module_files PROPERTIES FOLDER "Flang/Resources")
# TODO Move this to a more suitable location
# Copy the generated omp_lib.h header file, if OpenMP support has been configured.
-if (LLVM_TOOL_OPENMP_BUILD)
- message(STATUS "OpenMP runtime support enabled via LLVM_ENABLE_PROJECTS, building omp_lib.h")
- file(COPY ${CMAKE_BINARY_DIR}/projects/openmp/runtime/src/omp_lib.h DESTINATION "${CMAKE_BINARY_DIR}/include/flang/OpenMP/" FILE_PERMISSIONS OWNER_READ OWNER_WRITE)
- install(FILES ${CMAKE_BINARY_DIR}/include/flang/OpenMP/omp_lib.h DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/flang/OpenMP")
-elseif ("openmp" IN_LIST LLVM_ENABLE_RUNTIMES)
+if ("openmp" IN_LIST LLVM_ENABLE_RUNTIMES)
message(STATUS "OpenMP runtime support enabled via LLVM_ENABLE_RUNTIMES, assuming omp_lib.h is built there")
else()
message(STATUS "Not copying omp_lib.h, no OpenMP runtime in either LLVM_ENABLE_PROJECTS or LLVM_ENABLE_RUNTIMES")
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index bfc60bdae8c4f..be028c1dab1f5 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -104,12 +104,7 @@ endif()
# This allows an easy way of setting up a build directory for llvm and another
# one for llvm+clang+... using the same sources.
# These projects will be included when "all" is included in LLVM_ENABLE_PROJECTS.
-set(LLVM_ALL_PROJECTS "bolt;clang;clang-tools-extra;compiler-rt;cross-project-tests;libclc;lld;lldb;mlir;openmp;polly")
-if ("${CMAKE_SYSTEM_NAME}" MATCHES "AIX")
- # Disallow 'openmp' as a LLVM PROJECT on AIX as the supported way is to use
- # LLVM_ENABLE_RUNTIMES.
- list(REMOVE_ITEM LLVM_ALL_PROJECTS openmp)
-endif()
+set(LLVM_ALL_PROJECTS "bolt;clang;clang-tools-extra;compiler-rt;cross-project-tests;libclc;lld;lldb;mlir;polly")
# The "libc" project, which is not part of "all" projects, could be included in
# LLVM_ENABLE_PROJECTS. It is preferred to include "libc" in
@@ -126,6 +121,15 @@ if( LLVM_ENABLE_PROJECTS STREQUAL "all" )
set( LLVM_ENABLE_PROJECTS ${LLVM_ALL_PROJECTS})
endif()
+if ("openmp" IN_LIST LLVM_ENABLE_PROJECTS)
+ message(FATAL_ERROR "
+Support for the LLVM_ENABLE_PROJECTS=openmp build mode has been removed. Please switch to the bootstrapping build
+ cmake -S <llvm-project>/llvm -B build -DLLVM_ENABLE_PROJECTS=clang -DLLVM_ENABLE_RUNTIMES=openmp
+or to the runtimes default build
+ cmake -S <llvm-project>/runtimes -B build -DLLVM_ENABLE_RUNTIMES=openmp
+")
+endif()
+
foreach(proj ${LLVM_ENABLE_PROJECTS})
if (NOT proj STREQUAL "llvm" AND NOT "${proj}" IN_LIST LLVM_KNOWN_PROJECTS)
MESSAGE(FATAL_ERROR "${proj} isn't a known project: ${LLVM_KNOWN_PROJECTS}. Did you mean to enable it as a runtime in LLVM_ENABLE_RUNTIMES?")
@@ -195,13 +199,6 @@ if ("offload" IN_LIST LLVM_ENABLE_PROJECTS)
"https://openmp.llvm.org/ for building the runtimes.")
endif()
-if ("openmp" IN_LIST LLVM_ENABLE_PROJECTS)
- message(WARNING "Using LLVM_ENABLE_PROJECTS=openmp is deprecated now, and will "
- "become a fatal error in a future release. Please use "
- "-DLLVM_ENABLE_RUNTIMES=openmp or see the instructions at "
- "https://openmp.llvm.org/ for building the runtimes.")
-endif()
-
if ("flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
if (NOT "flang" IN_LIST LLVM_ENABLE_PROJECTS)
message(FATAL_ERROR "Flang is not enabled, but is required for the Flang-RT runtime")
diff --git a/llvm/runtimes/CMakeLists.txt b/llvm/runtimes/CMakeLists.txt
index ed1fc94168f03..f0ef353a2c66c 100644
--- a/llvm/runtimes/CMakeLists.txt
+++ b/llvm/runtimes/CMakeLists.txt
@@ -700,13 +700,6 @@ if(build_runtimes)
# We need to add the runtimes as a dependency because compiler-rt can be
# built as part of runtimes and we need the profile runtime for PGO
add_dependencies(clang-bootstrap-deps runtimes)
- # The bootstrap build will attempt to configure the offload runtime
- # before the openmp project which will error out due to failing to
- # find libomp.so. We must add omp as a dependency before runtimes
- # are configured.
- if("openmp" IN_LIST LLVM_ENABLE_PROJECTS AND "offload" IN_LIST LLVM_ENABLE_RUNTIMES)
- add_dependencies(clang-bootstrap-deps omp)
- endif()
endif()
if(LLVM_INCLUDE_TESTS)
diff --git a/openmp/docs/ReleaseNotes.rst b/openmp/docs/ReleaseNotes.rst
index 6c1a46caf1d81..b99947540acd7 100644
--- a/openmp/docs/ReleaseNotes.rst
+++ b/openmp/docs/ReleaseNotes.rst
@@ -27,3 +27,4 @@ Device Runtime
always build support for AMDGPU and NVPTX targets.
- Updated the offloading entry format but retained backwards compatibility with
the old format.
+- The LLVM_ENABLE_PROJECTS=openmp build mode has been removed.
\ No newline at end of file
Footnotes |
Meinersbur
requested review from
TerryLWilmarth,
boomanaiden154,
mgorny and
mjklemm
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/27/builds/22390 Here is the relevant piece of the build log for the reference |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/166/builds/6291 Here is the relevant piece of the build log for the reference |
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Reapply #152189 and #174963 which were reverted because it broke publish-sphinx-docs and publish-doxygen-docs.
The build mode has been deprecated in #136314 and was supposed to be removed in the LLVM 21 release (#136314).
OpenMP currently supports 4 build modes:
cmake <llvm-project>/llvm -DLLVM_ENABLE_PROJECTS=openmpcmake <llvm-project>/llvm -DLLVM_ENABLE_RUNTIMES=openmp(bootstrapping build)cmake <llvm-project>/openmp(standalone build)cmake <llvm-project>/runtimes -DLLVM_ENABLE_RUNTIMES=openmp(runtimes default1/standalone2 build)Each build mode increased the maintanance overhead since all build modes must continue working and user confusion when there do not (see #151117, #174126, #154117, ...). Let's finally remove it.
The LLVM_ENABLE_RUNTIMES system currently does not support building doxygen. Landing this PR will wait to add support in llvm-project (#176948) and llvm-zorg.
Footnotes
According to https://libcxx.llvm.org/VendorDocumentation.html#the-default-build ↩
According to https://github.com/llvm/llvm-project/blob/main/runtimes/CMakeLists.txt#L14 ↩