qapi/types qapi/visit: Generate built-in stuff into separate files

Linking code from multiple separate QAPI schemata into the same
program is possible, but involves some weirdness around built-in
types:

* We generate code for built-in types into .c only with option
  --builtins.  The user is responsible for generating code for exactly
  one QAPI schema per program with --builtins.

* We generate code for built-in types into .h regardless of
  --builtins, but guarded by #ifndef QAPI_VISIT_BUILTIN.  Because all
  copies of this code are exactly the same, including any combination
  of these headers works.

Replace this contraption by something more conventional: generate code
for built-in types into their very own files: qapi-builtin-types.c,
qapi-builtin-visit.c, qapi-builtin-types.h, qapi-builtin-visit.h, but
only with --builtins.  Obey --output-dir, but ignore --prefix for
them.

Make qapi-types.h include qapi-builtin-types.h.  With multiple
schemata you now have multiple qapi-types.[ch], but only one
qapi-builtin-types.[ch].  Same for qapi-visit.[ch] and
qapi-builtin-visit.[ch].

Bonus: if all you need is built-in stuff, you can include a much
smaller header.  To be exploited shortly.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20180211093607.27351-21-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
[eblake: fix octal constant for python 3]
Signed-off-by: Eric Blake <eblake@redhat.com>

3 files changed, 102 insertions, 83 deletions

diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
index 23437b558f..547656c8b2 100644
--- a/scripts/qapi/common.py
+++ b/scripts/qapi/common.py
@@ -1531,11 +1531,10 @@ class QAPISchema(object):
 
     def _def_builtin_type(self, name, json_type, c_type):
         self._def_entity(QAPISchemaBuiltinType(name, json_type, c_type))
-        # TODO As long as we have QAPI_TYPES_BUILTIN to share multiple
-        # qapi-types.h from a single .c, all arrays of builtins must be
-        # declared in the first file whether or not they are used.  Nicer
-        # would be to use lazy instantiation, while figuring out how to
-        # avoid compilation issues with multiple qapi-types.h.
+        # Instantiating only the arrays that are actually used would
+        # be nice, but we can't as long as their generated code
+        # (qapi-builtin-types.[ch]) may be shared by some other
+        # schema.
         self._make_array_type(name, None)
 
     def _def_predefineds(self):
@@ -1992,14 +1991,15 @@ class QAPIGen(object):
         return ''
 
     def write(self, output_dir, fname):
-        if output_dir:
+        pathname = os.path.join(output_dir, fname)
+        dir = os.path.dirname(pathname)
+        if dir:
             try:
-                os.makedirs(output_dir)
+                os.makedirs(dir)
             except os.error as e:
                 if e.errno != errno.EEXIST:
                     raise
-        fd = os.open(os.path.join(output_dir, fname),
-                     os.O_RDWR | os.O_CREAT, 0o666)
+        fd = os.open(pathname, os.O_RDWR | os.O_CREAT, 0o666)
         f = os.fdopen(fd, 'r+')
         text = (self._top(fname) + self._preamble + self._body
                 + self._bottom(fname))
@@ -2063,3 +2063,45 @@ class QAPISchemaMonolithicCVisitor(QAPISchemaVisitor):
     def write(self, output_dir):
         self._genc.write(output_dir, self._prefix + self._what + '.c')
         self._genh.write(output_dir, self._prefix + self._what + '.h')
+
+
+class QAPISchemaModularCVisitor(QAPISchemaVisitor):
+
+    def __init__(self, prefix, what, blurb, pydoc):
+        self._prefix = prefix
+        self._what = what
+        self._blurb = blurb
+        self._pydoc = pydoc
+        self._module = {}
+
+    def _module_basename(self, what, name):
+        if name is None:
+            return re.sub(r'-', '-builtin-', what)
+        return self._prefix + what
+
+    def _add_module(self, name, blurb):
+        genc = QAPIGenC(blurb, self._pydoc)
+        genh = QAPIGenH(blurb, self._pydoc)
+        self._module[name] = (genc, genh)
+        self._set_module(name)
+
+    def _set_module(self, name):
+        self._genc, self._genh = self._module[name]
+
+    def write(self, output_dir, opt_builtins):
+        for name in self._module:
+            if name is None and not opt_builtins:
+                continue
+            basename = self._module_basename(self._what, name)
+            (genc, genh) = self._module[name]
+            genc.write(output_dir, basename + '.c')
+            genh.write(output_dir, basename + '.h')
+
+    def _begin_module(self, name):
+        pass
+
+    def visit_module(self, name):
+        if len(self._module) != 1:
+            return
+        self._add_module(name, self._blurb)
+        self._begin_module(name)
diff --git a/scripts/qapi/types.py b/scripts/qapi/types.py
index d2b8423479..59826b1162 100644
--- a/scripts/qapi/types.py
+++ b/scripts/qapi/types.py
@@ -167,64 +167,51 @@ void qapi_free_%(c_name)s(%(c_name)s *obj)
     return ret
 
 
-class QAPISchemaGenTypeVisitor(QAPISchemaMonolithicCVisitor):
+class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
 
-    def __init__(self, prefix, opt_builtins):
-        QAPISchemaMonolithicCVisitor.__init__(
+    def __init__(self, prefix):
+        QAPISchemaModularCVisitor.__init__(
             self, prefix, 'qapi-types', ' * Schema-defined QAPI types',
             __doc__)
-        self._opt_builtins = opt_builtins
+        self._add_module(None, ' * Built-in QAPI types')
+        self._genc.preamble_add(mcgen('''
+#include "qemu/osdep.h"
+#include "qapi/dealloc-visitor.h"
+#include "qapi-builtin-types.h"
+#include "qapi-builtin-visit.h"
+'''))
+        self._genh.preamble_add(mcgen('''
+#include "qapi/util.h"
+'''))
+
+    def _begin_module(self, name):
         self._genc.preamble_add(mcgen('''
 #include "qemu/osdep.h"
 #include "qapi/dealloc-visitor.h"
 #include "%(prefix)sqapi-types.h"
 #include "%(prefix)sqapi-visit.h"
 ''',
-                                      prefix=prefix))
+                                      prefix=self._prefix))
         self._genh.preamble_add(mcgen('''
-#include "qapi/util.h"
+#include "qapi-builtin-types.h"
 '''))
-        self._btin = '\n' + guardstart('QAPI_TYPES_BUILTIN')
 
     def visit_begin(self, schema):
         # gen_object() is recursive, ensure it doesn't visit the empty type
         objects_seen.add(schema.the_empty_object_type.name)
 
-    def visit_end(self):
-        # To avoid header dependency hell, we always generate
-        # declarations for built-in types in our header files and
-        # simply guard them.  See also opt_builtins (command line
-        # option -b).
-        self._btin += guardend('QAPI_TYPES_BUILTIN')
-        self._genh.preamble_add(self._btin)
-        self._btin = None
-
     def _gen_type_cleanup(self, name):
         self._genh.add(gen_type_cleanup_decl(name))
         self._genc.add(gen_type_cleanup(name))
 
     def visit_enum_type(self, name, info, values, prefix):
-        # Special case for our lone builtin enum type
-        # TODO use something cleaner than existence of info
-        if not info:
-            self._btin += gen_enum(name, values, prefix)
-            if self._opt_builtins:
-                self._genc.add(gen_enum_lookup(name, values, prefix))
-        else:
-            self._genh.preamble_add(gen_enum(name, values, prefix))
-            self._genc.add(gen_enum_lookup(name, values, prefix))
+        self._genh.preamble_add(gen_enum(name, values, prefix))
+        self._genc.add(gen_enum_lookup(name, values, prefix))
 
     def visit_array_type(self, name, info, element_type):
-        if isinstance(element_type, QAPISchemaBuiltinType):
-            self._btin += gen_fwd_object_or_array(name)
-            self._btin += gen_array(name, element_type)
-            self._btin += gen_type_cleanup_decl(name)
-            if self._opt_builtins:
-                self._genc.add(gen_type_cleanup(name))
-        else:
-            self._genh.preamble_add(gen_fwd_object_or_array(name))
-            self._genh.add(gen_array(name, element_type))
-            self._gen_type_cleanup(name)
+        self._genh.preamble_add(gen_fwd_object_or_array(name))
+        self._genh.add(gen_array(name, element_type))
+        self._gen_type_cleanup(name)
 
     def visit_object_type(self, name, info, base, members, variants):
         # Nothing to do for the special empty builtin
@@ -248,6 +235,6 @@ class QAPISchemaGenTypeVisitor(QAPISchemaMonolithicCVisitor):
 
 
 def gen_types(schema, output_dir, prefix, opt_builtins):
-    vis = QAPISchemaGenTypeVisitor(prefix, opt_builtins)
+    vis = QAPISchemaGenTypeVisitor(prefix)
     schema.visit(vis)
-    vis.write(output_dir)
+    vis.write(output_dir, opt_builtins)
diff --git a/scripts/qapi/visit.py b/scripts/qapi/visit.py
index 3d09d44265..9b678e7263 100644
--- a/scripts/qapi/visit.py
+++ b/scripts/qapi/visit.py
@@ -263,13 +263,27 @@ out:
                  c_name=c_name(name))
 
 
-class QAPISchemaGenVisitVisitor(QAPISchemaMonolithicCVisitor):
+class QAPISchemaGenVisitVisitor(QAPISchemaModularCVisitor):
 
-    def __init__(self, prefix, opt_builtins):
-        QAPISchemaMonolithicCVisitor.__init__(
+    def __init__(self, prefix):
+        QAPISchemaModularCVisitor.__init__(
             self, prefix, 'qapi-visit', ' * Schema-defined QAPI visitors',
             __doc__)
-        self._opt_builtins = opt_builtins
+        self._add_module(None, ' * Built-in QAPI visitors')
+        self._genc.preamble_add(mcgen('''
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qapi/error.h"
+#include "qapi-builtin-visit.h"
+'''))
+        self._genh.preamble_add(mcgen('''
+#include "qapi/visitor.h"
+#include "qapi-builtin-types.h"
+
+''',
+                                      prefix=prefix))
+
+    def _begin_module(self, name):
         self._genc.preamble_add(mcgen('''
 #include "qemu/osdep.h"
 #include "qemu-common.h"
@@ -277,45 +291,21 @@ class QAPISchemaGenVisitVisitor(QAPISchemaMonolithicCVisitor):
 #include "qapi/qmp/qerror.h"
 #include "%(prefix)sqapi-visit.h"
 ''',
-                                      prefix=prefix))
+                                      prefix=self._prefix))
         self._genh.preamble_add(mcgen('''
-#include "qapi/visitor.h"
+#include "qapi-builtin-visit.h"
 #include "%(prefix)sqapi-types.h"
 
 ''',
-                                      prefix=prefix))
-        self._btin = guardstart('QAPI_VISIT_BUILTIN')
-
-    def visit_end(self):
-        # To avoid header dependency hell, we always generate
-        # declarations for built-in types in our header files and
-        # simply guard them.  See also opt_builtins (command line
-        # option -b).
-        self._btin += guardend('QAPI_VISIT_BUILTIN')
-        self._genh.preamble_add(self._btin)
-        self._btin = None
+                                      prefix=self._prefix))
 
     def visit_enum_type(self, name, info, values, prefix):
-        # Special case for our lone builtin enum type
-        # TODO use something cleaner than existence of info
-        if not info:
-            self._btin += gen_visit_decl(name, scalar=True)
-            if self._opt_builtins:
-                self._genc.add(gen_visit_enum(name))
-        else:
-            self._genh.add(gen_visit_decl(name, scalar=True))
-            self._genc.add(gen_visit_enum(name))
+        self._genh.add(gen_visit_decl(name, scalar=True))
+        self._genc.add(gen_visit_enum(name))
 
     def visit_array_type(self, name, info, element_type):
-        decl = gen_visit_decl(name)
-        defn = gen_visit_list(name, element_type)
-        if isinstance(element_type, QAPISchemaBuiltinType):
-            self._btin += decl
-            if self._opt_builtins:
-                self._genc.add(defn)
-        else:
-            self._genh.add(decl)
-            self._genc.add(defn)
+        self._genh.add(gen_visit_decl(name))
+        self._genc.add(gen_visit_list(name, element_type))
 
     def visit_object_type(self, name, info, base, members, variants):
         # Nothing to do for the special empty builtin
@@ -336,6 +326,6 @@ class QAPISchemaGenVisitVisitor(QAPISchemaMonolithicCVisitor):
 
 
 def gen_visit(schema, output_dir, prefix, opt_builtins):
-    vis = QAPISchemaGenVisitVisitor(prefix, opt_builtins)
+    vis = QAPISchemaGenVisitVisitor(prefix)
     schema.visit(vis)
-    vis.write(output_dir)
+    vis.write(output_dir, opt_builtins)