https://github.com/zeroomega created https://github.com/llvm/llvm-project/pull/210496
…468) This reverts commit 42eb7db188f23625872b6f1d722979a3100d170e. This reland 3fbb037d03e7ff1ef1cd9156363e895af7caaf98 (#209922). Under CMake 4+, calling add_library(... SHARED IMPORTED) on a target platform that lacks dynamic linking support triggers a fatal error. This becomes an issue when building LLVM and runtimes for baremetal targets like armv6m-none-eabi. This patch adds the option "LLVM_OMIT_EXPORTS_FROM_CONFIG" in LLVM. When used in sub builds like LLVM runtimes, it makes CMake to skip including the LLVM and Clang exports. This mitigates the CMake 4 errors on baremetal runtimes. #[209922](https://github.com/llvm/llvm-project/pull/209922) originally apply this flag on all runtimes build and causing issues on runtimes like intel-sycl-gpu, amdgpu-offload-ubuntu-22-cmake-build-only. This PR only set this flag when the target platform lacks shared library support >From 6f10fe287ea9650066d262f38495ae1079e1f91c Mon Sep 17 00:00:00 2001 From: Haowei Wu <[email protected]> Date: Fri, 17 Jul 2026 17:26:19 -0700 Subject: [PATCH] Reapply "Skipping host target exports during cross-compilation" (#210468) This reverts commit 42eb7db188f23625872b6f1d722979a3100d170e. This reland 3fbb037d03e7ff1ef1cd9156363e895af7caaf98 (#209922). Under CMake 4+, calling add_library(... SHARED IMPORTED) on a target platform that lacks dynamic linking support triggers a fatal error. This becomes an issue when building LLVM and runtimes for baremetal targets like armv6m-none-eabi. This patch adds the option "LLVM_OMIT_EXPORTS_FROM_CONFIG" in LLVM. When used in sub builds like LLVM runtimes, it makes CMake to skip including the LLVM and Clang exports. This mitigates the CMake 4 errors on baremetal runtimes. --- clang/cmake/modules/ClangConfig.cmake.in | 9 +++++++-- compiler-rt/cmake/Modules/CompilerRTUtils.cmake | 10 ++++++++++ llvm/cmake/modules/LLVMConfig.cmake.in | 2 +- runtimes/CMakeLists.txt | 10 ++++++++++ 4 files changed, 28 insertions(+), 3 deletions(-) diff --git a/clang/cmake/modules/ClangConfig.cmake.in b/clang/cmake/modules/ClangConfig.cmake.in index 68f723d050117..3550c393d492d 100644 --- a/clang/cmake/modules/ClangConfig.cmake.in +++ b/clang/cmake/modules/ClangConfig.cmake.in @@ -12,8 +12,13 @@ set(CLANG_INCLUDE_DIRS "@CLANG_CONFIG_INCLUDE_DIRS@") set(CLANG_LINK_CLANG_DYLIB "@CLANG_LINK_CLANG_DYLIB@") set(CLANG_DEFAULT_LINKER "@CLANG_DEFAULT_LINKER@") -# Provide all our library targets to users. -@CLANG_CONFIG_INCLUDE_EXPORTS@ +# Provide all our library targets to users. Skip when +# LLVM_OMIT_EXPORTS_FROM_CONFIG flag is set. Runtimes build do not need these. +# These exports may contain shared libraries and they are causing cmake errors +# when the target platform is baremetal, which lack shared library support. +if(NOT LLVM_OMIT_EXPORTS_FROM_CONFIG) + @CLANG_CONFIG_INCLUDE_EXPORTS@ +endif() # By creating clang-tablegen-targets here, subprojects that depend on Clang's # tablegen-generated headers can always depend on this target whether building diff --git a/compiler-rt/cmake/Modules/CompilerRTUtils.cmake b/compiler-rt/cmake/Modules/CompilerRTUtils.cmake index c2bf2e54b9fd4..63e52327e3ccc 100644 --- a/compiler-rt/cmake/Modules/CompilerRTUtils.cmake +++ b/compiler-rt/cmake/Modules/CompilerRTUtils.cmake @@ -313,6 +313,16 @@ macro(load_llvm_config) "You are not using the monorepo layout. This configuration is DEPRECATED.") endif() + # Exports from LLVM and Clang may contain shared libraries. When targeting + # baremetal platforms that lacks shared library support, importing such + # exports unrestrictedly will trigger cmake errors. Set + # LLVM_OMIT_EXPORTS_FROM_CONFIG flag to skip importing these exports + # when the target platform does not support shared library. + get_property(HAS_SHARED_SUPPORT GLOBAL PROPERTY TARGET_SUPPORTS_SHARED_LIBS) + message(NOTICE "HAS_SHARED_SUPPORT is ${HAS_SHARED_SUPPORT}") + if (NOT HAS_SHARED_SUPPORT) + set(LLVM_OMIT_EXPORTS_FROM_CONFIG ON) + endif() find_package(LLVM HINTS "${LLVM_CMAKE_DIR}") if (NOT LLVM_FOUND) message(WARNING "UNSUPPORTED COMPILER-RT CONFIGURATION DETECTED: " diff --git a/llvm/cmake/modules/LLVMConfig.cmake.in b/llvm/cmake/modules/LLVMConfig.cmake.in index 300c25e7c6101..6f5fcc6a926f9 100644 --- a/llvm/cmake/modules/LLVMConfig.cmake.in +++ b/llvm/cmake/modules/LLVMConfig.cmake.in @@ -152,7 +152,7 @@ set(LLVM_ENABLE_SHARED_LIBS @BUILD_SHARED_LIBS@) set(LLVM_DEFAULT_EXTERNAL_LIT "@LLVM_CONFIG_DEFAULT_EXTERNAL_LIT@") set(LLVM_LIT_ARGS "@LLVM_LIT_ARGS@") -if(NOT TARGET LLVMSupport) +if(NOT TARGET LLVMSupport AND NOT LLVM_OMIT_EXPORTS_FROM_CONFIG) @LLVM_CONFIG_INCLUDE_EXPORTS@ @llvm_config_include_buildtree_only_exports@ endif() diff --git a/runtimes/CMakeLists.txt b/runtimes/CMakeLists.txt index 67ed49a7dcabb..4d90a30d1f2f3 100644 --- a/runtimes/CMakeLists.txt +++ b/runtimes/CMakeLists.txt @@ -76,6 +76,16 @@ if(LLVM_BINARY_DIR) list(APPEND llvm_search_paths "${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm") list(APPEND clang_search_paths "${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/cmake/clang") endif() + +# Exports from LLVM and Clang may contain shared libraries. When targeting +# baremetal platforms that lacks shared library support, importing such +# exports unrestrictedly will trigger cmake errors. Set +# LLVM_OMIT_EXPORTS_FROM_CONFIG flag to skip importing these exports. +get_property(HAS_SHARED_SUPPORT GLOBAL PROPERTY TARGET_SUPPORTS_SHARED_LIBS) +message(NOTICE "HAS_SHARED_SUPPORT is ${HAS_SHARED_SUPPORT}") +if (NOT HAS_SHARED_SUPPORT) + set(LLVM_OMIT_EXPORTS_FROM_CONFIG ON) +endif() find_package(LLVM PATHS ${llvm_search_paths} NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH) find_package(Clang PATHS ${clang_search_paths} NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH) _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
