[llvm-build] Allow to specify a prefix to library

[serge-sans-paille]

Summary

This fixes an old FIXME in llvm-build

[serge-sans-paille]

Update doc.

llvm/docs/LLVMBuild.rst

-  ``type = Library``
 
    Components with this type use the following properties:
 
    -  ``library_name`` **[optional]**
 
       If given, the name to use for the actual library file on disk. If
       not given, the name is derived from the component name itself.
 
+   -  ``prefix`` **[optional]**
+
+      If given, the prefix used when deriving the library filename from
+      ``library_name``. If not given, use the ``LLVM`` prefix.
+
    -  ``required_libraries`` **[optional]**
 
       If given, a list of the names of ``Library`` or ``LibraryGroup``
       components which must also be linked in whenever this library is
       used. That is, the link time dependencies for this component. When
       tools are built, the build system will include the transitive closure
       of all ``required_libraries`` for the components the tool needs.
 

llvm/utils/llvm-build/llvmbuild/componentinfo.py

 
 class LibraryComponentInfo(ComponentInfo):
     type_name = 'Library'
 
     @staticmethod
     def parse_items(items):
         kwargs = ComponentInfo.parse_items(items)
         kwargs['library_name'] = items.get_optional_string('library_name')
+        kwargs['prefix'] = items.get('prefix')
         kwargs['required_libraries'] = items.get_list('required_libraries')
         kwargs['add_to_library_groups'] = items.get_list(
             'add_to_library_groups')
         kwargs['installed'] = items.get_optional_bool('installed', True)
         return kwargs
 
     @staticmethod
     def parse(subpath, items):
         kwargs = LibraryComponentInfo.parse_items(items)
         return LibraryComponentInfo(subpath, **kwargs)
 
     def __init__(self, subpath, name, dependencies, parent, library_name,
-                 required_libraries, add_to_library_groups, installed):
+                 prefix, required_libraries, add_to_library_groups, installed):
         ComponentInfo.__init__(self, subpath, name, dependencies, parent)
 
         # If given, the name to use for the library instead of deriving it from
         # the component name.
         self.library_name = library_name
 
+        # If given, override the default component prefix.
+        self.prefix = prefix
+
         # The names of the library components which are required when linking
         # with this component.
         self.required_libraries = list(required_libraries)
 
         # The names of the library group components this component should be
         # considered part of.
         self.add_to_library_groups = list(add_to_library_groups)
 
""" % (self.type_name, self.name, self.parent)
                 self.add_to_library_groups)
         if not self.installed:
             result += 'installed = 0\n'
         return result
 
     def get_library_name(self):
         return self.library_name or self.name
 
+    def get_library_prefix(self):
+        if self.prefix is None:
+            return 'LLVM'
+        else:
+            return self.prefix
+
     def get_prefixed_library_name(self):
         """
         get_prefixed_library_name() -> str
 
         Return the library name prefixed by the project name. This is generally
         what the library name will be on disk.
         """
 
         basename = self.get_library_name()
+        prefix = self.get_library_prefix()
 
-        # FIXME: We need to get the prefix information from an explicit project
-        # object, or something.
-        if basename in ('gtest', 'gtest_main'):
-            return basename
-
-        return 'LLVM%s' % basename
+        return '%s%s' % (prefix, basename)
 
     def get_llvmconfig_component_name(self):
         return self.get_library_name().lower()
 
 class OptionalLibraryComponentInfo(LibraryComponentInfo):
     type_name = "OptionalLibrary"
 
     @staticmethod
     def parse(subpath, items):
       kwargs = LibraryComponentInfo.parse_items(items)
       return OptionalLibraryComponentInfo(subpath, **kwargs)
 
     def __init__(self, subpath, name, dependencies, parent, library_name,
-                 required_libraries, add_to_library_groups, installed):
+                 prefix, required_libraries, add_to_library_groups, installed):
       LibraryComponentInfo.__init__(self, subpath, name, dependencies, parent,
-                                    library_name, required_libraries,
+                                    library_name, prefix, required_libraries,
                                     add_to_library_groups, installed)
 
 class LibraryGroupComponentInfo(ComponentInfo):
     type_name = 'LibraryGroup'
 
     @staticmethod
     def parse(subpath, items):
         kwargs = ComponentInfo.parse_items(items, has_dependencies = False)

llvm/utils/unittest/LLVMBuild.txt

 ;
 ;   http://llvm.org/docs/LLVMBuild.html
 ;
 ;===------------------------------------------------------------------------===;
 
 [component_0]
 type = Library
 name = gtest
+prefix =
 parent = Libraries
 required_libraries = Support
 installed = 0
 
 [component_1]
 type = Library
 name = gtest_main
+prefix =
 parent = Libraries
 required_libraries = gtest
 installed = 0