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qapi: Visit variants in visit_type_FOO_fields()

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We initially created the static visit_type_FOO_fields() helper
function for reuse of code - we have cases where the initial
setup for a visit has different allocation (depending on whether
the fields represent a stand-alone type or are embedded as part
of a larger type), but where the actual field visits are
identical once a pointer is available.

Up until the previous patch, visit_type_FOO_fields() was only
used for structs (no variants), so it was covering every field
for each type where it was emitted.

Meanwhile, the code for visiting unions looks like:

static visit_type_U_fields() {
visit base;
visit local_members;
}
visit_type_U() {
visit_start_struct();
visit_type_U_fields();
visit variants;
visit_end_struct();
}

which splits the fields of the union visit across two functions.
Move the code to visit variants to live inside visit_type_U_fields(),
while making it conditional on having variants so that all other
instances of the helper function remain unchanged. This is also
a step closer towards unifying struct and union visits, and towards
allowing one union type to be the branch of another flat union.

The resulting diff to the generated code is a bit hard to read,
but it can be verified that it touches only union types, and that
the end result is the following general structure:

static visit_type_U_fields() {
visit base;
visit local_members;
visit variants;
}
visit_type_U() {
visit_start_struct();
visit_type_U_fields();
visit_end_struct();
}

Backports commit 9a5cd424d5f06fb5293eb264456d89343c557558 from qemu
This commit is contained in:
Eric Blake 2018-02-20 15:50:47 -05:00 committed by Lioncash
parent 428eadd9e0
commit 155c507ed4
No known key found for this signature in database
GPG key ID: 4E3C3CC1031BA9C7
1 changed files with 54 additions and 54 deletions
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108
qemu/scripts/qapi-visit.py
View file

@ -68,11 +68,16 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *
c_type=typ.c_name())
return ret
def gen_visit_struct_fields(name, base, members):
def gen_visit_struct_fields(name, base, members, variants):
ret = ''
if base:
ret += gen_visit_fields_decl(base)
if variants:
for var in variants.variants:
# Ugly special case for simple union TODO get rid of it
if not var.simple_union_type():
ret += gen_visit_implicit_struct(var.type)
struct_fields_seen.add(name)
ret += mcgen('''
@ -93,8 +98,49 @@ static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s **obj, Error **e
ret += gen_visit_fields(members, prefix='(*obj)->')
# 'goto out' produced for base, and by gen_visit_fields() for each member
if base or members:
if variants:
ret += mcgen('''
if (!visit_start_union(v, !!(*obj)->u.data, &err) || err) {
goto out;
}
switch ((*obj)->%(c_name)s) {
''',
c_name=c_name(variants.tag_member.name))
for var in variants.variants:
# TODO ugly special case for simple union
simple_union_type = var.simple_union_type()
ret += mcgen('''
case %(case)s:
''',
case=c_enum_const(variants.tag_member.type.name,
var.name,
variants.tag_member.type.prefix))
if simple_union_type:
ret += mcgen('''
visit_type_%(c_type)s(v, "data", &(*obj)->u.%(c_name)s, &err);
''',
c_type=simple_union_type.c_name(),
c_name=c_name(var.name))
else:
ret += mcgen('''
visit_type_implicit_%(c_type)s(v, &(*obj)->u.%(c_name)s, &err);
''',
c_type=var.type.c_name(),
c_name=c_name(var.name))
ret += mcgen('''
break;
''')
ret += mcgen('''
default:
abort();
}
''')
# 'goto out' produced for base, by gen_visit_fields() for each member,
# and if variants were present
if base or members or variants:
ret += mcgen('''
out:
@ -107,7 +153,7 @@ out:
def gen_visit_struct(name, base, members):
ret = gen_visit_struct_fields(name, base, members)
ret = gen_visit_struct_fields(name, base, members, None)
# FIXME: if *obj is NULL on entry, and visit_start_struct() assigns to
# *obj, but then visit_type_FOO_fields() fails, we should clean up *obj
@ -240,12 +286,7 @@ out:
def gen_visit_union(name, base, members, variants):
ret = gen_visit_struct_fields(name, base, members)
for var in variants.variants:
# Ugly special case for simple union TODO get rid of it
if not var.simple_union_type():
ret += gen_visit_implicit_struct(var.type)
ret = gen_visit_struct_fields(name, base, members, variants)
ret += mcgen('''
@ -261,56 +302,15 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
goto out_obj;
}
visit_type_%(c_name)s_fields(v, obj, &err);
''',
c_name=c_name(name))
ret += gen_err_check(label='out_obj')
ret += mcgen('''
if (!visit_start_union(v, !!(*obj)->u.data, &err) || err) {
goto out_obj;
}
switch ((*obj)->%(c_name)s) {
''',
c_name=c_name(variants.tag_member.name))
for var in variants.variants:
# TODO ugly special case for simple union
simple_union_type = var.simple_union_type()
ret += mcgen('''
case %(case)s:
''',
case=c_enum_const(variants.tag_member.type.name,
var.name,
variants.tag_member.type.prefix))
if simple_union_type:
ret += mcgen('''
visit_type_%(c_type)s(v, "data", &(*obj)->u.%(c_name)s, &err);
''',
c_type=simple_union_type.c_name(),
c_name=c_name(var.name))
else:
ret += mcgen('''
visit_type_implicit_%(c_type)s(v, &(*obj)->u.%(c_name)s, &err);
''',
c_type=var.type.c_name(),
c_name=c_name(var.name))
ret += mcgen('''
break;
''')
ret += mcgen('''
default:
abort();
}
out_obj:
error_propagate(errp, err);
err = NULL;
out_obj:
visit_end_struct(v, &err);
out:
error_propagate(errp, err);
}
''')
''',
c_name=c_name(name))
return ret