[libc] [NFC] Split the CMake rules into multiple files.

Summary:
The single file was getting too long to be convenient to navigate. This
patch splits it up two into 4 files one each for header rules,
object rules, library rules, and test rules.

Reviewers: abrachet, alexshap

Subscribers: mgorny, tschuett, libc-commits

Tags: #libc-project

Differential Revision: https://reviews.llvm.org/D78536

1 files changed, 126 insertions, 0 deletions

diff --git a/libc/cmake/modules/LLVMLibCLibraryRules.cmake b/libc/cmake/modules/LLVMLibCLibraryRules.cmake
new file mode 100644
index 0000000..9b30b85
--- /dev/null
+++ b/libc/cmake/modules/LLVMLibCLibraryRules.cmake
@@ -0,0 +1,126 @@
+# A rule to build a library from a collection of entrypoint objects.
+# Usage:
+#     add_entrypoint_library(
+#       DEPENDS <list of add_entrypoint_object targets>
+#     )
+function(add_entrypoint_library target_name)
+  cmake_parse_arguments(
+    "ENTRYPOINT_LIBRARY"
+    "" # No optional arguments
+    "" # No single value arguments
+    "DEPENDS" # Multi-value arguments
+    ${ARGN}
+  )
+  if(NOT ENTRYPOINT_LIBRARY_DEPENDS)
+    message(FATAL_ERROR "'add_entrypoint_library' target requires a DEPENDS list "
+                        "of 'add_entrypoint_object' targets.")
+  endif()
+
+  set(obj_list "")
+  foreach(dep IN LISTS ENTRYPOINT_LIBRARY_DEPENDS)
+    get_target_property(dep_type ${dep} "TARGET_TYPE")
+    if(NOT (${dep_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE}))
+      message(FATAL_ERROR "Dependency '${dep}' of 'add_entrypoint_collection' is "
+                          "not an 'add_entrypoint_object' target.")
+    endif()
+    get_target_property(target_obj_files ${dep} "OBJECT_FILES")
+    list(APPEND obj_list "${target_obj_files}")
+  endforeach(dep)
+  list(REMOVE_DUPLICATES obj_list)
+
+  set(library_file "${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}${target_name}${CMAKE_STATIC_LIBRARY_SUFFIX}")
+  add_custom_command(
+    OUTPUT ${library_file}
+    COMMAND ${CMAKE_AR} -r ${library_file} ${obj_list}
+    DEPENDS ${obj_list}
+  )
+  add_custom_target(
+    ${target_name}
+    ALL
+    DEPENDS ${library_file}
+  )
+endfunction(add_entrypoint_library)
+
+# Rule to build a shared library of redirector objects.
+function(add_redirector_library target_name)
+  cmake_parse_arguments(
+    "REDIRECTOR_LIBRARY"
+    ""
+    ""
+    "DEPENDS"
+    ${ARGN}
+  )
+
+  set(obj_files "")
+  foreach(dep IN LISTS REDIRECTOR_LIBRARY_DEPENDS)
+    # TODO: Ensure that each dep is actually a add_redirector_object target.
+    list(APPEND obj_files $<TARGET_OBJECTS:${dep}>)
+  endforeach(dep)
+
+  # TODO: Call the linker explicitly instead of calling the compiler driver to
+  # prevent DT_NEEDED on C++ runtime.
+  add_library(
+    ${target_name}
+    SHARED
+    ${obj_files}
+  )
+  set_target_properties(${target_name} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+
+  target_link_libraries(
+    ${target_name}
+    -nostdlib -lc -lm
+  )
+
+  set_target_properties(
+    ${target_name}
+    PROPERTIES
+      LINKER_LANGUAGE "C"
+  )
+endfunction(add_redirector_library)
+
+# Rule to add header only libraries.
+# Usage
+#    add_header_library(
+#      <target name>
+#      HDRS  <list of .h files part of the library>
+#      DEPENDS <list of dependencies>
+#    )
+function(add_header_library target_name)
+  cmake_parse_arguments(
+    "ADD_HEADER"
+    "" # No optional arguments
+    "" # No Single value arguments
+    "HDRS;DEPENDS" # Multi-value arguments
+    ${ARGN}
+  )
+
+  if(NOT ADD_HEADER_HDRS)
+    message(FATAL_ERROR "'add_header_library' target requires a HDRS list of .h files.")
+  endif()
+
+  get_fq_target_name(${target_name} fq_target_name)
+
+  set(FULL_HDR_PATHS "")
+  # TODO: Remove this foreach block when we can switch to the new
+  # version of the CMake policy CMP0076.
+  foreach(hdr IN LISTS ADD_HEADER_HDRS)
+    list(APPEND FULL_HDR_PATHS ${CMAKE_CURRENT_SOURCE_DIR}/${hdr})
+  endforeach()
+
+  set(interface_target_name "${fq_target_name}_header_library__")
+
+  add_library(${interface_target_name} INTERFACE)
+  target_sources(${interface_target_name} INTERFACE ${FULL_HDR_PATHS})
+  if(ADD_HEADER_DEPENDS)
+    get_fq_deps_list(fq_deps_list ${ADD_HEADER_DEPENDS})
+    add_dependencies(${interface_target_name} ${fq_deps_list})
+  endif()
+
+  add_custom_target(${fq_target_name})
+  add_dependencies(${fq_target_name} ${interface_target_name})
+  set_target_properties(
+    ${fq_target_name}
+    PROPERTIES
+      "TARGET_TYPE" "HDR_LIBRARY"
+  )
+endfunction(add_header_library)