llvm-build: Switch to using the common subdirectory list instead of

autodiscovery.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146437 91177308-0d34-0410-b5e6-96231b3b80d8

docs/LLVMBuild.html

@@ -147,7 +147,7 @@ $ROOT of project trees for things which can be checked out separately. -->
 <i>; Comments start with a semi-colon.</i>
 
 <i>; Sections are declared using square brackets.</i>
-[component 0]
+[component_0]
 
 <i>; Properties are declared using '=' and are contained in the previous section.
 ;
@@ -160,7 +160,7 @@ boolean_property_name = 1 <em>(or 0)</em>
 </pre>
   </div>
 
-  <p>LLVMBuild files are expected to define a strict set of section and
+  <p>LLVMBuild files are expected to define a strict set of sections and
   properties. An typical component description file for a library
   component would look typically look like the following example:</p>
   <div class="doc_code">
@@ -176,14 +176,22 @@ required_libraries = Archive BitReader Core Support TransformUtils
   <p>A full description of the exact sections and properties which are allowed
  follows.</p>
 
+  <p>Each file may define exactly one common component, named "common". The
+  common component may define the following properties:</p>
+  <ul>
+    <li><i>subdirectories</i> <b>[optional]</b>
+      <p>If given, a list of the names of the subdirectories from the current
+        subpath to search for additional LLVMBuild files.</p></li>
+  </ul>
+
   <p>Each file may define multiple components. Each component is described by a
   section who name starts with "component". The remainder of the section name is
   ignored, but each section name must be unique. Typically components are just
   number in order for files with multiple components ("component_0",
   "component_1", and so on).<p>
 
-  <p><b>Section names not matches this format are currently
-  unused and are disallowed.</b></p>
+  <p><b>Section names not matches this format (or the "common" section) are
+  currently unused and are disallowed.</b></p>
 
   <p>Every component is defined by the properties in the section. The exact list
   of properties that are allowed depends on the component

utils/llvm-build/llvmbuild/componentinfo.py

@@ -381,6 +381,16 @@ def load_from_path(path, subpath):
     parser = ConfigParser.RawConfigParser()
     parser.read(path)
 
+    # Extract the common section.
+    if parser.has_section("common"):
+        common = IniFormatParser(parser.items("common"))
+        parser.remove_section("common")
+    else:
+        common = IniFormatParser({})
+
+    return common, _read_components_from_parser(parser, path, subpath)
+
+def _read_components_from_parser(parser, path, subpath):
     # We load each section which starts with 'component' as a distinct component
     # description (so multiple components can be described in one file).
     for section in parser.sections():

utils/llvm-build/llvmbuild/main.py

@@ -64,32 +64,26 @@ def make_install_dir(path):
 class LLVMProjectInfo(object):
     @staticmethod
     def load_infos_from_path(llvmbuild_source_root):
-        # FIXME: Implement a simple subpath file list cache, so we don't restat
-        # directories we have already traversed.
+        def recurse(subpath):
+            # Load the LLVMBuild file.
+            llvmbuild_path = os.path.join(llvmbuild_source_root + subpath,
+                                          'LLVMBuild.txt')
+            if not os.path.exists(llvmbuild_path):
+                fatal("missing LLVMBuild.txt file at: %r" % (llvmbuild_path,))
 
-        # First, discover all the LLVMBuild.txt files.
-        #
-        # FIXME: We would like to use followlinks=True here, but that isn't
-        # compatible with Python 2.4. Instead, we will either have to special
-        # case projects we would expect to possibly be linked to, or implement
-        # our own walk that can follow links. For now, it doesn't matter since
-        # we haven't picked up the LLVMBuild system in any other LLVM projects.
-        for dirpath,dirnames,filenames in os.walk(llvmbuild_source_root):
-            # If there is no LLVMBuild.txt file in a directory, we don't recurse
-            # past it. This is a simple way to prune our search, although it
-            # makes it easy for users to add LLVMBuild.txt files in places they
-            # won't be seen.
-            if 'LLVMBuild.txt' not in filenames:
-                del dirnames[:]
-                continue
-
-            # Otherwise, load the LLVMBuild file in this directory.
-            assert dirpath.startswith(llvmbuild_source_root)
-            subpath = '/' + dirpath[len(llvmbuild_source_root)+1:]
-            llvmbuild_path = os.path.join(dirpath, 'LLVMBuild.txt')
-            for info in componentinfo.load_from_path(llvmbuild_path, subpath):
+            # Parse the components from it.
+            common,info_iter = componentinfo.load_from_path(llvmbuild_path,
+                                                            subpath)
+            for info in info_iter:
                 yield info
 
+            # Recurse into the specified subdirectories.
+            for subdir in common.get_list("subdirectories"):
+                for item in recurse(os.path.join(subpath, subdir)):
+                    yield item
+
+        return recurse("/")
+
     @staticmethod
     def load_from_path(source_root, llvmbuild_source_root):
         infos = list(