src/cc: cmake file cleanup and split usdt into subdir

Move two usdt related files to a new subdirectory and link them into the
final product. Introduce a cmake option to disable that feature (turning
it off currently fails to compile).

Move some of the cmake flag computation into a helper cmake file and
include that rather than inlining it.
Signed-off-by: Brenden Blanco <bblanco@gmail.com>

cmake/clang_libs.cmake

+set(llvm_raw_libs bitwriter bpfcodegen irreader linker
+  mcjit objcarcopts option passes nativecodegen lto)
+list(FIND LLVM_AVAILABLE_LIBS "LLVMCoverage" _llvm_coverage)
+if (${_llvm_coverage} GREATER -1)
+  list(APPEND llvm_raw_libs coverage)
+endif()
+list(FIND LLVM_AVAILABLE_LIBS "LLVMCoroutines" _llvm_coroutines)
+if (${_llvm_coroutines} GREATER -1)
+  list(APPEND llvm_raw_libs coroutines)
+endif()
+llvm_map_components_to_libnames(_llvm_libs ${llvm_raw_libs})
+llvm_expand_dependencies(llvm_libs ${_llvm_libs})
+
+# order is important
+set(clang_libs
+  ${libclangFrontend}
+  ${libclangSerialization}
+  ${libclangDriver}
+  ${libclangParse}
+  ${libclangSema}
+  ${libclangCodeGen}
+  ${libclangAnalysis}
+  ${libclangRewrite}
+  ${libclangEdit}
+  ${libclangAST}
+  ${libclangLex}
+  ${libclangBasic})
+
+# prune unused llvm static library stuff when linking into the new .so
+set(_exclude_flags)
+foreach(_lib ${clang_libs})
+  get_filename_component(_lib ${_lib} NAME)
+  set(_exclude_flags "${_exclude_flags} -Wl,--exclude-libs=${_lib}")
+endforeach(_lib)
+set(clang_lib_exclude_flags "${_exclude_flags}")
+
+set(_exclude_flags)
+foreach(_lib ${llvm_libs})
+  get_filename_component(_lib ${_lib} NAME)
+  set(_exclude_flags "${_exclude_flags} -Wl,--exclude-libs=lib${_lib}.a")
+endforeach(_lib)
+set(llvm_lib_exclude_flags "${_exclude_flags}")

cmake/static_libstdc++.cmake

+# only turn on static-libstdc++ if also linking statically against clang
+string(REGEX MATCH ".*[.]a$" LIBCLANG_ISSTATIC "${libclangBasic}")
+# if gcc 4.9 or higher is used, static libstdc++ is a good option
+if (CMAKE_COMPILER_IS_GNUCC AND LIBCLANG_ISSTATIC)
+  execute_process(COMMAND ${CMAKE_C_COMPILER} -dumpversion OUTPUT_VARIABLE GCC_VERSION)
+  if (GCC_VERSION VERSION_GREATER 4.9 OR GCC_VERSION VERSION_EQUAL 4.9)
+    execute_process(COMMAND ${CMAKE_C_COMPILER} -print-libgcc-file-name OUTPUT_VARIABLE GCC_LIB)
+    get_filename_component(GCC_DIR "${GCC_LIB}" DIRECTORY)
+    find_library(GCC_LIBSTDCPP libstdc++.a PATHS "${GCC_DIR}" NO_DEFAULT_PATH)
+    if (GCC_LIBSTDCPP)
+      message(STATUS "Using static-libstdc++")
+      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -static-libstdc++")
+    endif()
+  endif()
+endif()

src/cc/CMakeLists.txt

@@ -17,21 +17,7 @@ configure_file(libbcc.pc.in ${CMAKE_CURRENT_BINARY_DIR}/libbcc.pc @ONLY)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC")
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC")
 
-# only turn on static-libstdc++ if also linking statically against clang
-string(REGEX MATCH ".*[.]a$" LIBCLANG_ISSTATIC "${libclangBasic}")
-# if gcc 4.9 or higher is used, static libstdc++ is a good option
-if (CMAKE_COMPILER_IS_GNUCC AND LIBCLANG_ISSTATIC)
-  execute_process(COMMAND ${CMAKE_C_COMPILER} -dumpversion OUTPUT_VARIABLE GCC_VERSION)
-  if (GCC_VERSION VERSION_GREATER 4.9 OR GCC_VERSION VERSION_EQUAL 4.9)
-    execute_process(COMMAND ${CMAKE_C_COMPILER} -print-libgcc-file-name OUTPUT_VARIABLE GCC_LIB)
-    get_filename_component(GCC_DIR "${GCC_LIB}" DIRECTORY)
-    find_library(GCC_LIBSTDCPP libstdc++.a PATHS "${GCC_DIR}" NO_DEFAULT_PATH)
-    if (GCC_LIBSTDCPP)
-      message(STATUS "Using static-libstdc++")
-      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -static-libstdc++")
-    endif()
-  endif()
-endif()
+include(static_libstdc++)
 
 add_library(bpf-static STATIC libbpf.c perf_reader.c)
 set_target_properties(bpf-static PROPERTIES OUTPUT_NAME bpf)
@@ -40,8 +26,8 @@ set_target_properties(bpf-shared PROPERTIES OUTPUT_NAME bpf)
 
 add_library(bcc-shared SHARED bpf_common.cc bpf_module.cc table_storage.cc
   shared_table.cc bpffs_table.cc json_map_decl_visitor.cc exported_files.cc
-  bcc_elf.c bcc_perf_map.c bcc_proc.c bcc_syms.cc ns_guard.cc usdt_args.cc
-  usdt.cc common.cc BPF.cc BPFTable.cc)
+  bcc_elf.c bcc_perf_map.c bcc_proc.c bcc_syms.cc ns_guard.cc common.cc BPF.cc
+  BPFTable.cc)
 set_target_properties(bcc-shared PROPERTIES VERSION ${REVISION_LAST} SOVERSION 0)
 set_target_properties(bcc-shared PROPERTIES OUTPUT_NAME bcc)
 
@@ -49,42 +35,25 @@ add_library(bcc-loader-static STATIC bcc_elf.c bcc_perf_map.c bcc_proc.c
   bcc_syms.cc ns_guard.cc)
 add_library(bcc-static STATIC bpf_common.cc bpf_module.cc shared_table.cc
   bpffs_table.cc json_map_decl_visitor.cc table_storage.cc exported_files.cc
-  usdt_args.cc usdt.cc common.cc BPF.cc BPFTable.cc)
+  common.cc BPF.cc BPFTable.cc)
 set_target_properties(bcc-static PROPERTIES OUTPUT_NAME bcc)
 
-set(llvm_raw_libs bitwriter bpfcodegen irreader linker
-  mcjit objcarcopts option passes nativecodegen lto)
-list(FIND LLVM_AVAILABLE_LIBS "LLVMCoverage" _llvm_coverage)
-if (${_llvm_coverage} GREATER -1)
-  list(APPEND llvm_raw_libs coverage)
-endif()
-list(FIND LLVM_AVAILABLE_LIBS "LLVMCoroutines" _llvm_coroutines)
-if (${_llvm_coroutines} GREATER -1)
-  list(APPEND llvm_raw_libs coroutines)
-endif()
-llvm_map_components_to_libnames(llvm_libs ${llvm_raw_libs})
-llvm_expand_dependencies(expanded_libs ${llvm_libs})
+include(clang_libs)
+set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${clang_lib_exclude_flags}")
+set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${llvm_lib_exclude_flags}")
 
-# order is important
-set(clang_libs ${libclangFrontend} ${libclangSerialization} ${libclangDriver} ${libclangParse}
-  ${libclangSema} ${libclangCodeGen} ${libclangAnalysis} ${libclangRewrite} ${libclangEdit}
-  ${libclangAST} ${libclangLex} ${libclangBasic})
+set(bcc_common_libs b_frontend clang_frontend bpf-static
+  ${clang_libs} ${llvm_libs} ${LIBELF_LIBRARIES})
 
-# prune unused llvm static library stuff when linking into the new .so
-foreach(lib ${clang_libs})
-  get_filename_component(lib ${lib} NAME)
-  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--exclude-libs=${lib}")
-endforeach(lib)
-foreach(lib ${expanded_libs})
-  get_filename_component(lib ${lib} NAME)
-  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--exclude-libs=lib${lib}.a")
-endforeach(lib)
+option(ENABLE_USDT "Enable User-level Statically Defined Tracing" ON)
+if(ENABLE_USDT)
+  add_subdirectory(usdt)
+  list(APPEND bcc_common_libs usdt-static)
+endif()
 
 # Link against LLVM libraries
-target_link_libraries(bcc-shared b_frontend clang_frontend bpf-static
-  ${clang_libs} ${expanded_libs} ${LIBELF_LIBRARIES})
-target_link_libraries(bcc-static b_frontend clang_frontend bcc-loader-static
-  bpf-static ${clang_libs} ${expanded_libs} ${LIBELF_LIBRARIES})
+target_link_libraries(bcc-shared ${bcc_common_libs})
+target_link_libraries(bcc-static ${bcc_common_libs} bcc-loader-static)
 
 install(TARGETS bcc-shared LIBRARY COMPONENT libbcc
   DESTINATION ${CMAKE_INSTALL_LIBDIR})

src/cc/usdt/CMakeLists.txt

+add_library(usdt-static STATIC usdt_args.cc usdt.cc)