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[Qemu-devel] [PULL 05/15] qapi: Emit implicit structs in generated C
From: |
Markus Armbruster |
Subject: |
[Qemu-devel] [PULL 05/15] qapi: Emit implicit structs in generated C |
Date: |
Fri, 18 Mar 2016 11:04:19 +0100 |
From: Eric Blake <address@hidden>
We already have several places that want to visit all the members
of an implicit object within a larger context (simple union variant,
event with anonymous data, command with anonymous arguments struct);
and will be adding another one soon (the ability to declare an
anonymous base for a flat union). Having a C struct declared for
these implicit types, along with a visit_type_FOO_members() helper
function, will make for fewer special cases in our generator.
We do not, however, need qapi_free_FOO() or visit_type_FOO()
functions for implicit types, because they should not be used
directly outside of the generated code. This is done by adding a
conditional in visit_object_type() for both qapi-types.py and
qapi-visit.py based on the object name. The comparison of
"name.startswith('q_')" is a bit hacky (it's basically duplicating
what .is_implicit() already uses), but beats changing the signature
of the visit_object_type() callback to pass a new 'implicit' flag.
The hack should be temporary: we are considering adding a future
patch that consolidates the narrow visit_object_type(..., base,
local_members, variants) and visit_object_type_flat(...,
all_members, variants) [where different sets of information are
already broken out, and the QAPISchemaObjectType is no longer
available] into a broader visit_object_type(obj_type) [where the
visitor can query the needed fields from obj_type directly].
Also, now that we WANT to output C code for implicits, we no longer
need the visit_needed() filter, leaving 'q_empty' as the only object
still needing a special case. Remember, 'q_empty' is the only
built-in generated object, which means that without a special case
it would be emitted in multiple files (the main qapi-types.h and in
qga-qapi-types.h) causing compilation failure due to redefinition.
But since it has no members, it's easier to just avoid an attempt to
visit that particular type; since gen_object() is called recursively,
we also prime the objects_seen set to cover any recursion into the
empty type.
The patch relies on the changed naming of implicit types in the
previous patch. It is a bit unfortunate that the generated struct
names and visit_type_FOO_members() don't match normal naming
conventions, but it's not too bad, since they will only be used in
generated code.
The generated code grows substantially in size: the implicit
'-wrapper' types must be emitted in qapi-types.h before any union
can include an unboxed member of that type. Arguably, the '-args'
types could be emitted in a private header for just qapi-visit.c
and qmp-marshal.c, rather than polluting qapi-types.h; but adding
complexity to the generator to split the output location according
to role doesn't seem worth the maintenance costs.
Signed-off-by: Eric Blake <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Markus Armbruster <address@hidden>
---
scripts/qapi-types.py | 19 +++++++++++--------
scripts/qapi-visit.py | 23 +++++++++++------------
scripts/qapi.py | 2 --
3 files changed, 22 insertions(+), 22 deletions(-)
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index f194bea..79416b2 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -61,8 +61,7 @@ def gen_object(name, base, members, variants):
ret = ''
if variants:
for v in variants.variants:
- if (isinstance(v.type, QAPISchemaObjectType) and
- not v.type.is_implicit()):
+ if isinstance(v.type, QAPISchemaObjectType):
ret += gen_object(v.type.name, v.type.base,
v.type.local_members, v.type.variants)
@@ -180,6 +179,8 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
self._btin = None
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)
self.decl = ''
self.defn = ''
self._fwdecl = ''
@@ -196,11 +197,6 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
self.decl = self._btin + self.decl
self._btin = None
- def visit_needed(self, entity):
- # Visit everything except implicit objects
- return not (entity.is_implicit() and
- isinstance(entity, QAPISchemaObjectType))
-
def _gen_type_cleanup(self, name):
self.decl += gen_type_cleanup_decl(name)
self.defn += gen_type_cleanup(name)
@@ -229,11 +225,18 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
self._gen_type_cleanup(name)
def visit_object_type(self, name, info, base, members, variants):
+ # Nothing to do for the special empty builtin
+ if name == 'q_empty':
+ return
self._fwdecl += gen_fwd_object_or_array(name)
self.decl += gen_object(name, base, members, variants)
if base:
self.decl += gen_upcast(name, base)
- self._gen_type_cleanup(name)
+ # TODO Worth changing the visitor signature, so we could
+ # directly use rather than repeat type.is_implicit()?
+ if not name.startswith('q_'):
+ # implicit types won't be directly allocated/freed
+ self._gen_type_cleanup(name)
def visit_alternate_type(self, name, info, variants):
self._fwdecl += gen_fwd_object_or_array(name)
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index a712e9a..4923b2e 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -215,13 +215,11 @@ out:
def gen_visit_object(name, base, members, variants):
- ret = gen_visit_object_members(name, base, members, variants)
-
# FIXME: if *obj is NULL on entry, and visit_start_struct() assigns to
# *obj, but then visit_type_FOO_members() fails, we should clean up *obj
# rather than leaving it non-NULL. As currently written, the caller must
# call qapi_free_FOO() to avoid a memory leak of the partial FOO.
- ret += mcgen('''
+ return mcgen('''
void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj,
Error **errp)
{
@@ -245,8 +243,6 @@ out:
''',
c_name=c_name(name))
- return ret
-
class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
def __init__(self):
@@ -268,11 +264,6 @@ class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
self.decl = self._btin + self.decl
self._btin = None
- def visit_needed(self, entity):
- # Visit everything except implicit objects
- return not (entity.is_implicit() and
- isinstance(entity, QAPISchemaObjectType))
-
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
@@ -296,9 +287,17 @@ class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
self.defn += defn
def visit_object_type(self, name, info, base, members, variants):
+ # Nothing to do for the special empty builtin
+ if name == 'q_empty':
+ return
self.decl += gen_visit_members_decl(name)
- self.decl += gen_visit_decl(name)
- self.defn += gen_visit_object(name, base, members, variants)
+ self.defn += gen_visit_object_members(name, base, members, variants)
+ # TODO Worth changing the visitor signature, so we could
+ # directly use rather than repeat type.is_implicit()?
+ if not name.startswith('q_'):
+ # only explicit types need an allocating visit
+ self.decl += gen_visit_decl(name)
+ self.defn += gen_visit_object(name, base, members, variants)
def visit_alternate_type(self, name, info, variants):
self.decl += gen_visit_decl(name)
diff --git a/scripts/qapi.py b/scripts/qapi.py
index f6701f5..96fb216 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1000,7 +1000,6 @@ class QAPISchemaObjectType(QAPISchemaType):
return self.name.startswith('q_')
def c_name(self):
- assert not self.is_implicit()
return QAPISchemaType.c_name(self)
def c_type(self):
@@ -1008,7 +1007,6 @@ class QAPISchemaObjectType(QAPISchemaType):
return c_name(self.name) + pointer_suffix
def c_unboxed_type(self):
- assert not self.is_implicit()
return c_name(self.name)
def json_type(self):
--
2.4.3
- [Qemu-devel] [PULL 08/15] qapi-commands: Utilize implicit struct visits, (continued)
- [Qemu-devel] [PULL 08/15] qapi-commands: Utilize implicit struct visits, Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 06/15] qapi-event: Drop qmp_output_get_qobject() null check, Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 04/15] qapi: Adjust names of implicit types, Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 10/15] qapi: Inline gen_visit_members() into lone caller, Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 15/15] qapi: Use anonymous bases in QMP flat unions, Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 02/15] qapi: Fix command with named empty argument type, Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 11/15] qapi: Drop unused c_null(), Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 13/15] qapi: Make BlockdevOptions doc example closer to reality, Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 09/15] qapi-commands: Inline single-use helpers of gen_marshal(), Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 03/15] qapi: Make c_type() more OO-like, Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 05/15] qapi: Emit implicit structs in generated C,
Markus Armbruster <=
- [Qemu-devel] [PULL 07/15] qapi-event: Utilize implicit struct visits, Markus Armbruster, 2016/03/18
- [Qemu-devel] [PULL 12/15] qapi: Don't special-case simple union wrappers, Markus Armbruster, 2016/03/18
- Re: [Qemu-devel] [PULL 00/15] QAPI patches for 2016-03-18, Peter Maydell, 2016/03/18