[llvmbuild] Add optional_libraries, i.e. a dependency iff the target is enabled

[dsanders]

Summary

Optional dependencies are promoted to required dependencies if the specified
library is enabled via --enable-optional-components or enabled_component = 1,
or dropped if the specified library is disabled. Of course, another mechanism
(such as preprocessor macros) needs to be used so that there are no unresolved
symbols.

It's a warning to specify a library that's not optional in optional_libraries.
Such a dependency will be treated as if it were provided via required_libraries.

llvm/test/LLVMBuild/optional-library/Input/LLVMBuild.txt

+;===- ./LLVMBuild.txt ------------------------------------------*- Conf -*--===;
+;
+; Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+; See https://llvm.org/LICENSE.txt for license information.
+; SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+;
+;===------------------------------------------------------------------------===;
+;
+; This is an LLVMBuild description file for the components in this subdirectory.
+;
+; For more information on the LLVMBuild system, please see:
+;
+;   http://llvm.org/docs/LLVMBuild.html
+;
+;===------------------------------------------------------------------------===;
+
+[common]
+subdirectories = lib
+
+[component_0]
+type = LibraryGroup
+name = Engine
+parent = $ROOT
+
+[component_1]
+type = Library
+name = Interpreter
+parent = $ROOT
+
+[component_2]
+type = Group
+name = Miscellaneous
+parent = $ROOT
+
+[component_3]
+type = LibraryGroup
+name = Native
+parent = $ROOT
+
+[component_4]
+type = LibraryGroup
+name = NativeCodeGen
+parent = $ROOT
+
+[component_5]
+type = LibraryGroup
+name = all-targets
+parent = $ROOT

llvm/test/LLVMBuild/optional-library/Input/lib/LLVMBuild.txt

+;===- ./LLVMBuild.txt ------------------------------------------*- Conf -*--===;
+;
+; Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+; See https://llvm.org/LICENSE.txt for license information.
+; SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+;
+;===------------------------------------------------------------------------===;
+;
+; This is an LLVMBuild description file for the components in this subdirectory.
+;
+; For more information on the LLVMBuild system, please see:
+;
+;   http://llvm.org/docs/LLVMBuild.html
+;
+;===------------------------------------------------------------------------===;
+
+[component_0]
+type = OptionalLibrary
+name = IncludeBecauseEnabled
+enabled_component = 1
+parent = $ROOT
+
+[component_1]
+type = OptionalLibrary
+name = IncludeBecauseRequired
+; OptionalLibrary being required via dependencies should be a warning though
+parent = $ROOT
+
+[component_2]
+type = Library
+name = IncludeBecauseNotOptional
+parent = $ROOT
+
+[component_3]
+type = OptionalLibrary
+name = ExcludeBecauseDisabled
+parent = $ROOT
+
+[component_4]
+type = Library
+name = Bar
+required_libraries = IncludeBecauseRequired IncludeBecauseNotOptional
+optional_libraries = IncludeBecauseEnabled ExcludeBecauseDisabled
+parent = $ROOT

llvm/test/LLVMBuild/optional-library/optional-library.test

+RUN: %llvmbuild --source-root=%S/Input --write-llvmbuild=%T 2>%T/stderr.txt
+RUN: FileCheck %s < %T/lib/LLVMBuild.txt
+RUN: FileCheck --check-prefix=STDERR %s < %T/stderr.txt
+
+CHECK:      [component_0]
+CHECK-NEXT: type = Library
+CHECK-NEXT: name = Bar
+CHECK-NEXT: parent = $ROOT
+CHECK-NEXT: required_libraries = IncludeBecauseRequired IncludeBecauseNotOptional IncludeBecauseEnabled
+CHECK-NEXT: optional_libraries = IncludeBecauseEnabled ExcludeBecauseDisabled
+
+CHECK:      [component_1]
+CHECK-NEXT: type = OptionalLibrary
+CHECK-NEXT: name = ExcludeBecauseDisabled
+CHECK-NEXT: parent = $ROOT
+
+CHECK:      [component_2]
+CHECK-NEXT: type = OptionalLibrary
+CHECK-NEXT: name = IncludeBecauseEnabled
+CHECK-NEXT: parent = $ROOT
+CHECK-NEXT: enabled_component = 1
+
+CHECK:      [component_3]
+CHECK-NEXT: type = Library
+CHECK-NEXT: name = IncludeBecauseNotOptional
+CHECK-NEXT: parent = $ROOT
+
+CHECK:      [component_4]
+CHECK-NEXT: type = OptionalLibrary
+CHECK-NEXT: name = IncludeBecauseRequired
+CHECK-NEXT: parent = $ROOT
+
+STDERR: llvm-build: warning: optional component IncludeBecauseRequired required by Bar

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['required_libraries'] = items.get_list('required_libraries')
+        kwargs['optional_libraries'] = items.get_list('optional_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):
+                 required_libraries, optional_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
 
         # 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 components which are optional when linking
+        # with this component.
+        self.optional_libraries = list(optional_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)
 
         # Whether or not this library is installed.
         self.installed = installed
 
     def get_component_references(self):
         for r in ComponentInfo.get_component_references(self):
             yield r
         for r in self.required_libraries:
             yield ('required library', r)
+        for r in self.optional_libraries:
+            yield ('optional library', r)
         for r in self.add_to_library_groups:
             yield ('library group', r)
 
     def get_llvmbuild_fragment(self):
         result = """\
 type = %s
 name = %s
 parent = %s
 """ % (self.type_name, self.name, self.parent)
         if self.library_name is not None:
             result += 'library_name = %s\n' % self.library_name
         if self.required_libraries:
             result += 'required_libraries = %s\n' % ' '.join(
                 self.required_libraries)
+        if self.optional_libraries:
+            result += 'optional_libraries = %s\n' % ' '.join(
+                self.optional_libraries)
         if self.add_to_library_groups:
             result += 'add_to_library_groups = %s\n' % ' '.join(
                 self.add_to_library_groups)
         if not self.installed:
             result += 'installed = 0\n'
         return result
 
     def get_library_name(self):
class OptionalLibraryComponentInfo(LibraryComponentInfo):
     @staticmethod
     def parse(subpath, items):
       kwargs = LibraryComponentInfo.parse_items(items)
       kwargs['enabled_component'] = \
           items.get_optional_bool('enabled_component', False)
       return OptionalLibraryComponentInfo(subpath, **kwargs)
 
     def __init__(self, subpath, name, dependencies, parent, library_name,
-                 required_libraries, add_to_library_groups, installed,
-                 enabled_component):
+                 required_libraries, optional_libraries, add_to_library_groups,
+                 installed, enabled_component):
       LibraryComponentInfo.__init__(self, subpath, name, dependencies, parent,
                                     library_name, required_libraries,
-                                    add_to_library_groups, installed)
+                                    optional_libraries, add_to_library_groups,
+                                    installed)
       self.enabled_component = enabled_component
       self.optional_component = True
 
     def get_llvmbuild_fragment(self):
         result = super(OptionalLibraryComponentInfo,
                        self).get_llvmbuild_fragment()
         if self.enabled_component:
             result += 'enabled_component = 1\n'
         return result
 
 class LibraryGroupComponentInfo(ComponentInfo):
     type_name = 'LibraryGroup'
 
     @staticmethod
     def parse(subpath, items):
         kwargs = ComponentInfo.parse_items(items, has_dependencies = False)
         kwargs['required_libraries'] = items.get_list('required_libraries')
+        kwargs['optional_libraries'] = items.get_list('optional_libraries')
         kwargs['add_to_library_groups'] = items.get_list(
             'add_to_library_groups')
         return LibraryGroupComponentInfo(subpath, **kwargs)
 
     def __init__(self, subpath, name, parent, required_libraries = [],
-                 add_to_library_groups = []):
+                 optional_libraries = [], add_to_library_groups = []):
         ComponentInfo.__init__(self, subpath, name, [], parent)
 
         # 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 components which are optional when linking
+        # with this component.
+        self.optional_libraries = list(optional_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)
 
     def get_component_references(self):
         for r in ComponentInfo.get_component_references(self):
             yield r
         for r in self.required_libraries:
             yield ('required library', r)
+        for r in self.optional_libraries:
+            yield ('optional library', r)
         for r in self.add_to_library_groups:
             yield ('library group', r)
 
     def get_llvmbuild_fragment(self):
         result = """\
 type = %s
 name = %s
 parent = %s
 """ % (self.type_name, self.name, self.parent)
         if self.required_libraries and not self._is_special_group:
             result += 'required_libraries = %s\n' % ' '.join(
                 self.required_libraries)
+        if self.optional_libraries and not self._is_special_group:
+            result += 'optional_libraries = %s\n' % ' '.join(
+                self.optional_libraries)
         if self.add_to_library_groups:
             result += 'add_to_library_groups = %s\n' % ' '.join(
                 self.add_to_library_groups)
         return result
 
     def get_llvmconfig_component_name(self):
         return self.name.lower()
 
 class TargetGroupComponentInfo(ComponentInfo):
     type_name = 'TargetGroup'
 
     @staticmethod
     def parse(subpath, items):
         kwargs = ComponentInfo.parse_items(items, has_dependencies = False)
         kwargs['required_libraries'] = items.get_list('required_libraries')
+        kwargs['optional_libraries'] = items.get_list('optional_libraries')
         kwargs['add_to_library_groups'] = items.get_list(
             'add_to_library_groups')
         kwargs['has_jit'] = items.get_optional_bool('has_jit', False)
         kwargs['has_asmprinter'] = items.get_optional_bool('has_asmprinter',
                                                            False)
         kwargs['has_asmparser'] = items.get_optional_bool('has_asmparser',
                                                           False)
         kwargs['has_disassembler'] = items.get_optional_bool('has_disassembler',
                                                              False)
         return TargetGroupComponentInfo(subpath, **kwargs)
 
     def __init__(self, subpath, name, parent, required_libraries = [],
-                 add_to_library_groups = [], has_jit = False,
-                 has_asmprinter = False, has_asmparser = False,
+                 optional_libraries = [], add_to_library_groups = [],
+                 has_jit = False, has_asmprinter = False, has_asmparser = False,
                  has_disassembler = False):
         ComponentInfo.__init__(self, subpath, name, [], parent)
 
         # 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 components which are optional when linking
+        # with this component.
+        self.optional_libraries = list(optional_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)
 
         # Whether or not this target supports the JIT.
         self.has_jit = bool(has_jit)
 
         # Whether or not this target defines an assembly printer.
def __init__(self, subpath, name, parent, required_libraries = [],
         # configuration parameters.
         self.enabled = False
 
     def get_component_references(self):
         for r in ComponentInfo.get_component_references(self):
             yield r
         for r in self.required_libraries:
             yield ('required library', r)
+        for r in self.optional_libraries:
+            yield ('optional library', r)
         for r in self.add_to_library_groups:
             yield ('library group', r)
 
     def get_llvmbuild_fragment(self):
         result = """\
 type = %s
 name = %s
 parent = %s
 """ % (self.type_name, self.name, self.parent)
         if self.required_libraries:
             result += 'required_libraries = %s\n' % ' '.join(
                 self.required_libraries)
+        if self.optional_libraries:
+            result += 'optional_libraries = %s\n' % ' '.join(
+                self.optional_libraries)
         if self.add_to_library_groups:
             result += 'add_to_library_groups = %s\n' % ' '.join(
                 self.add_to_library_groups)
         for bool_key in ('has_asmparser', 'has_asmprinter', 'has_disassembler',
                          'has_jit'):
             if getattr(self, bool_key):
                 result += '%s = 1\n' % (bool_key,)
         return result
 
     def get_llvmconfig_component_name(self):
         return self.name.lower()
 
 class ToolComponentInfo(ComponentInfo):
     type_name = 'Tool'
 
     @staticmethod
     def parse(subpath, items):
         kwargs = ComponentInfo.parse_items(items)
         kwargs['required_libraries'] = items.get_list('required_libraries')
+        kwargs['optional_libraries'] = items.get_list('optional_libraries')
         return ToolComponentInfo(subpath, **kwargs)
 
     def __init__(self, subpath, name, dependencies, parent,
-                 required_libraries):
+                 required_libraries, optional_libraries):
         ComponentInfo.__init__(self, subpath, name, dependencies, parent)
 
         # The names of the library components which are required to link this
         # tool.
         self.required_libraries = list(required_libraries)
 
+        # The names of the library components which are required to link this
+        # tool.
+        self.optional_libraries = list(optional_libraries)
+
     def get_component_references(self):
         for r in ComponentInfo.get_component_references(self):
             yield r
         for r in self.required_libraries:
             yield ('required library', r)
+        for r in self.optional_libraries:
+            yield ('optional library', r)
 
     def get_llvmbuild_fragment(self):
-        return """\
+        result = """\
 type = %s
 name = %s
 parent = %s
 required_libraries = %s
 """ % (self.type_name, self.name, self.parent,
        ' '.join(self.required_libraries))
+        if self.optional_libraries:
+            result += 'optional_libraries = %s\n' % ' '.join(
+                self.optional_libraries)
+        return result
 
 class BuildToolComponentInfo(ToolComponentInfo):
     type_name = 'BuildTool'
 
     @staticmethod
     def parse(subpath, items):
         kwargs = ComponentInfo.parse_items(items)
         kwargs['required_libraries'] = items.get_list('required_libraries')
+        kwargs['optional_libraries'] = items.get_list('optional_libraries')
         return BuildToolComponentInfo(subpath, **kwargs)
 
 ###
 
 class IniFormatParser(dict):
     def get_list(self, key):
         # Check if the value is defined.
         value = self.get(key)

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

 from __future__ import absolute_import
 import filecmp
 import os
 import sys
 
 import llvmbuild.componentinfo as componentinfo
 
-from llvmbuild.util import fatal, note
+from llvmbuild.util import fatal, warning, note
 
 ###
 
 def space_or_semicolon_list(x):
     # We support both space separated and semi-colon separated lists.
     if x == '':
         return []
     elif ' ' in x:
class LLVMProjectInfo(object):
 
     def __init__(self, source_root, component_infos):
         # Store our simple ivars.
         self.source_root = source_root
         self.component_infos = list(component_infos)
         self.component_info_map = None
         self.ordered_component_infos = None
 
+    def warn_if_optional_component_required(self):
+        """warn_if_optional_component_required() -> None
+
+        Warn if optional components are not actually optional because they're
+        included in required_libraries.
+        """
+        component_map = dict((ci.name, ci) for ci in self.component_infos)
+        for ci in self.component_infos:
+            if not hasattr(ci, 'required_libraries'):
+                continue
+            for libname in ci.required_libraries:
+                if component_map[libname].optional_component:
+                    warning('optional component %s required by %s' % (libname,
+                                                                      ci.name))
+
+    def promote_optional_dependencies(self):
+        """promote_optional_dependencies() -> None
+
+        Optional dependencies that are satisfied are promoted to required
+        dependencies when emitting the generated outputs
+        """
+        component_map = dict((ci.name, ci) for ci in self.component_infos)
+        for ci in self.component_infos:
+            if not hasattr(ci, 'optional_libraries'):
+                continue
+            libnames = list(ci.optional_libraries)
+            for libname in libnames:
+                if component_map[libname].enabled_component:
+                    if libname not in ci.required_libraries:
+                        ci.required_libraries.append(libname)
+                else:
+                    ci.optional_libraries.append(libname)
+
     def validate_components(self):
         """validate_components() -> None
 
         Validate that the project components are well-defined. Among other
         things, this checks that:
           - Components have valid references.
           - Components references do not form cycles.
 
for c in project_info.component_infos:
             else:
                 parser.error('component `%s` is not optional' % c.name)
         if c.name in opts.disable_optional_components:
             if c.optional_component:
                 c.enabled_component = False
             else:
                 parser.error('component `%s` is not optional' % c.name)
 
+    project_info.warn_if_optional_component_required()
+    project_info.promote_optional_dependencies()
+
     # Validate the project component info.
     project_info.validate_components()
 
     # Print the component tree, if requested.
     if opts.print_tree:
         project_info.print_tree()
 
     # Write out the components, if requested. This is useful for auto-upgrading