unicorn/qemu/scripts
Markus Armbruster 428eadd9e0
qapi-visit: Simplify how we visit common union members
For a simple union SU, gen_visit_union() generates a visit of its
single tag member, like this:

visit_type_SUKind(v, "type", &(*obj)->type, &err);

For a flat union FU with base B, it generates a visit of its base
fields:

visit_type_B_fields(v, (B **)obj, &err);

Instead, we can simply visit the common members using the same fields
visit function we use for structs, generated with
gen_visit_struct_fields(). This function visits the base if any, then
the local members.

For a simple union SU, visit_type_SU_fields() contains exactly the old
tag member visit, because there is no base, and the tag member is the
only member. For instance, the code generated for qapi-schema.json's
KeyValue changes like this:

+static void visit_type_KeyValue_fields(Visitor *v, KeyValue **obj, Error **errp)
+{
+ Error *err = NULL;
+
+ visit_type_KeyValueKind(v, "type", &(*obj)->type, &err);
+ if (err) {
+ goto out;
+ }
+
+out:
+ error_propagate(errp, err);
+}
+
void visit_type_KeyValue(Visitor *v, const char *name, KeyValue **obj, Error **errp)
{
Error *err = NULL;
@@ -4863,7 +4911,7 @@ void visit_type_KeyValue(Visitor *v, con
if (!*obj) {
goto out_obj;
}
- visit_type_KeyValueKind(v, "type", &(*obj)->type, &err);
+ visit_type_KeyValue_fields(v, obj, &err);
if (err) {
goto out_obj;
}

For a flat union FU, visit_type_FU_fields() contains exactly the old
base fields visit, because there is a base, but no members. For
instance, the code generated for qapi-schema.json's CpuInfo changes
like this:

static void visit_type_CpuInfoBase_fields(Visitor *v, CpuInfoBase **obj, Error **errp);

+static void visit_type_CpuInfo_fields(Visitor *v, CpuInfo **obj, Error **errp)
+{
+ Error *err = NULL;
+
+ visit_type_CpuInfoBase_fields(v, (CpuInfoBase **)obj, &err);
+ if (err) {
+ goto out;
+ }
+
+out:
+ error_propagate(errp, err);
+}
+
static void visit_type_CpuInfoX86_fields(Visitor *v, CpuInfoX86 **obj, Error **errp)
...
@@ -3485,7 +3509,7 @@ void visit_type_CpuInfo(Visitor *v, cons
if (!*obj) {
goto out_obj;
}
- visit_type_CpuInfoBase_fields(v, (CpuInfoBase **)obj, &err);
+ visit_type_CpuInfo_fields(v, obj, &err);
if (err) {
goto out_obj;
}

As you see, the generated code grows a bit, but in practice, it's lost
in the noise: qapi-schema.json's qapi-visit.c gains roughly 1%.

This simplification became possible with commit 441cbac "qapi-visit:
Convert to QAPISchemaVisitor, fixing bugs". It's a step towards
unifying gen_struct() and gen_union().

Backports commit d7445b57f4342d50c25b5bc1746048fa3720511b from qemu
2018-02-20 15:48:54 -05:00
..
create_config
make_device_config.sh
ordereddict.py
qapi-event.py qapi: Drop unused 'kind' for struct/enum visit 2018-02-19 23:43:54 -05:00
qapi-types.py qapi: Swap visit_* arguments for consistent 'name' placement 2018-02-19 22:45:07 -05:00
qapi-visit.py qapi-visit: Simplify how we visit common union members 2018-02-20 15:48:54 -05:00
qapi.py qapi: Forbid 'any' inside an alternate 2018-02-20 15:47:16 -05:00