[compiler-rt] Explicitly enable C extensions for profile (llvm#110555)

The profiling code requires GNU extensions as it uses functions such as getpagesize(), fdopen(), etc.

The problem manifests when the compiler is built to not default to the extensions mode, e.g. custom config with -std=c2x. CMake didn't support this scenario very well, but it's been fixed by CMP0128. Set the policy to NEW as we now conform to it.

compiler-rt/CMakeLists.txt

@@ -12,6 +12,11 @@ endif()
 include(${LLVM_COMMON_CMAKE_UTILS}/Modules/CMakePolicy.cmake
   NO_POLICY_SCOPE)
 
+# TODO(CMake 3.22): remove
+if(POLICY CMP0128)
+  cmake_policy(SET CMP0128 NEW)
+endif()
+
 # Check if compiler-rt is built as a standalone project.
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR COMPILER_RT_STANDALONE_BUILD)
   project(CompilerRT C CXX ASM)

compiler-rt/cmake/Modules/AddCompilerRT.cmake

@@ -161,7 +161,8 @@ endmacro()
 #                         LINK_LIBS <linked libraries> (only for shared library)
 #                         OBJECT_LIBS <object libraries to use as sources>
 #                         PARENT_TARGET <convenience parent target>
-#                         ADDITIONAL_HEADERS <header files>)
+#                         ADDITIONAL_HEADERS <header files>
+#                         EXTENSIONS <boolean>)
 function(add_compiler_rt_runtime name type)
   if(NOT type MATCHES "^(OBJECT|STATIC|SHARED|MODULE)$")
     message(FATAL_ERROR
@@ -171,7 +172,7 @@ function(add_compiler_rt_runtime name type)
   cmake_parse_arguments(LIB
     ""
     "PARENT_TARGET"
-    "OS;ARCHS;SOURCES;CFLAGS;LINK_FLAGS;DEFS;DEPS;LINK_LIBS;OBJECT_LIBS;ADDITIONAL_HEADERS"
+    "OS;ARCHS;SOURCES;CFLAGS;LINK_FLAGS;DEFS;DEPS;LINK_LIBS;OBJECT_LIBS;ADDITIONAL_HEADERS;EXTENSIONS"
     ${ARGN})
   set(libnames)
   # Until we support this some other way, build compiler-rt runtime without LTO
@@ -435,6 +436,10 @@ function(add_compiler_rt_runtime name type)
     if(type STREQUAL "SHARED")
       rt_externalize_debuginfo(${libname})
     endif()
+
+    if(DEFINED LIB_EXTENSIONS)
+      set_target_properties(${libname} PROPERTIES C_EXTENSIONS ${LIB_EXTENSIONS})
+    endif()
   endforeach()
   if(LIB_PARENT_TARGET)
     add_dependencies(${LIB_PARENT_TARGET} ${libnames})

compiler-rt/lib/profile/CMakeLists.txt

@@ -138,13 +138,15 @@ if(APPLE)
     CFLAGS ${EXTRA_FLAGS}
     SOURCES ${PROFILE_SOURCES}
     ADDITIONAL_HEADERS ${PROFILE_HEADERS}
-    PARENT_TARGET profile)
+    PARENT_TARGET profile
+    EXTENSIONS ON)
 else()
   add_compiler_rt_runtime(clang_rt.profile
     STATIC
     ARCHS ${PROFILE_SUPPORTED_ARCH}
     CFLAGS ${EXTRA_FLAGS}
     SOURCES ${PROFILE_SOURCES}
     ADDITIONAL_HEADERS ${PROFILE_HEADERS}
-    PARENT_TARGET profile)
+    PARENT_TARGET profile
+    EXTENSIONS ON)
 endif()