Author: Fangrui Song Date: 2022-01-20T13:29:49-08:00 New Revision: 6349865a8f3751a651f9451eac0405e01ee03a11
URL: https://github.com/llvm/llvm-project/commit/6349865a8f3751a651f9451eac0405e01ee03a11 DIFF: https://github.com/llvm/llvm-project/commit/6349865a8f3751a651f9451eac0405e01ee03a11.diff LOG: [CMake] Don't use -fno-semantic-interposition with Clang<=13 Clang 13 has a -fsanitize-coverage -fno-semantic-interposition bug (D117190) which may lead to `relocation R_X86_64_PC32 cannot be used against symbol` linker error in -DLLVM_USE_SANITIZE_COVERAGE=ON build when a shared object is built (e.g. -DLLVM_BUILD_LLVM_DYLIB=on). For simplicity, just disallow Clang 13 entirely. Note: GCC -fPIC performance benefits from -fno-semantic-interposition dramatically. Clang benefits little. Using this option is more for a dogfood purpose to test correctness of this option, because in the wild some important packages like CPython uses this option. Differential Revision: https://reviews.llvm.org/D117183 (cherry picked from commit 1661c8cfcd6b286a1b5a599544afd87aa6b90243) Added: Modified: llvm/cmake/modules/HandleLLVMOptions.cmake Removed: ################################################################################ diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake index 0c3419390c275..cfcbb8f8aec37 100644 --- a/llvm/cmake/modules/HandleLLVMOptions.cmake +++ b/llvm/cmake/modules/HandleLLVMOptions.cmake @@ -316,12 +316,11 @@ if( LLVM_ENABLE_PIC ) # Note: GCC<10.3 has a bug on SystemZ. # # Note: Clang allows IPO for -fPIC so this optimization is less effective. - # Older Clang may support -fno-semantic-interposition but it used local - # aliases to optimize global variables, which is incompatible with copy - # relocations due to -fno-pic. + # Clang 13 has a bug related to -fsanitize-coverage + # -fno-semantic-interposition (https://reviews.llvm.org/D117183). if ((CMAKE_COMPILER_IS_GNUCXX AND NOT (LLVM_NATIVE_ARCH STREQUAL "SystemZ" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 10.3)) - OR (CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND CMAKE_CXX_COMPILER_VERSION GREATER_EQUAL 13)) + OR (CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND CMAKE_CXX_COMPILER_VERSION GREATER_EQUAL 14)) add_flag_if_supported("-fno-semantic-interposition" FNO_SEMANTIC_INTERPOSITION) endif() endif() _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
