From patchwork Wed Feb 17 17:44:26 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Markus Armbruster X-Patchwork-Id: 8341771 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A5646C0553 for ; Wed, 17 Feb 2016 17:44:49 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 66502202F2 for ; Wed, 17 Feb 2016 17:44:48 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DFDBA2024D for ; Wed, 17 Feb 2016 17:44:46 +0000 (UTC) Received: from localhost ([::1]:60109 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aW69d-0001ux-W3 for patchwork-qemu-devel@patchwork.kernel.org; Wed, 17 Feb 2016 12:44:46 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45227) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aW69U-0001ud-6j for qemu-devel@nongnu.org; Wed, 17 Feb 2016 12:44:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aW69P-00017O-Cm for qemu-devel@nongnu.org; Wed, 17 Feb 2016 12:44:36 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45115) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aW69P-00017F-2j for qemu-devel@nongnu.org; Wed, 17 Feb 2016 12:44:31 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id D409DC00EB16; Wed, 17 Feb 2016 17:44:29 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-116-75.ams2.redhat.com [10.36.116.75]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u1HHiQHs021990 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 17 Feb 2016 12:44:28 -0500 Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 6BEB7303F903; Wed, 17 Feb 2016 18:44:26 +0100 (CET) From: Markus Armbruster To: Eric Blake References: <1455582057-27565-1-git-send-email-eblake@redhat.com> <1455582057-27565-12-git-send-email-eblake@redhat.com> Date: Wed, 17 Feb 2016 18:44:26 +0100 In-Reply-To: <1455582057-27565-12-git-send-email-eblake@redhat.com> (Eric Blake's message of "Mon, 15 Feb 2016 17:20:55 -0700") Message-ID: <877fi3s03p.fsf@blackfin.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Peter Crosthwaite , qemu-devel@nongnu.org, Michael Roth , Luiz Capitulino , Paolo Bonzini , Richard Henderson Subject: Re: [Qemu-devel] [PATCH v10 11/13] qapi: Don't box branches of flat unions X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Eric Blake writes: > There's no reason to do two malloc's for a flat union; let's just > inline the branch struct directly into the C union branch of the > flat union. > > Surprisingly, fewer clients were actually using explicit references > to the branch types in comparison to the number of flat unions > thus modified. > > This lets us reduce the hack in qapi-types:gen_variants() added in > the previous patch; we no longer need to distinguish between > alternates and flat unions. It also lets us get rid of all traces > of 'visit_type_implicit_FOO()' in qapi-visit, and reduce one (but > not all) special cases of simplie unions. simple > > Unfortunately, simple unions are not as easy to convert; because > we are special-casing the hidden implicit type with a single 'data' > member, we really DO need to keep calling another layer of > visit_start_struct(), with a second malloc. Hence, > gen_visit_fields_decl() has to special case implicit types (the > type for a simple union variant). Simple unions should be mere sugar for the equivalent flat union, as explained in qapi-code-gen.txt. That they aren't now on the C side is accidental complexity. I hope we can clean that up relatively soon. In the long run, I'd like to replace the whole struct / flat union / simple union mess by a variant record type. > Note that after this patch, the only remaining use of > visit_start_implicit_struct() is for alternate types; the next > couple of patches will do further cleanups based on that fact. Remind me, what makes alternates need visit_start_implicit_struct()? > Signed-off-by: Eric Blake > > --- > v10: new patch > > If anything, we could match our simple union wire format more closely > by teaching qapi-types to expose implicit types inline, and write: > > struct SU { > SUKind type; > union { > struct { > Branch1 *data; > } branch1; > struct { > Branch2 *data; > } branch2; > } u; > }; > > where we would then access su.u.branch1.data->member instead of > the current su.u.branch1->member. Looks like the cleanup I mentioned above. > --- > scripts/qapi-types.py | 10 +-------- > scripts/qapi-visit.py | 45 +++++++---------------------------------- > cpus.c | 18 ++++++----------- > hmp.c | 12 +++++------ > tests/test-qmp-input-visitor.c | 2 +- > tests/test-qmp-output-visitor.c | 5 ++--- > 6 files changed, 23 insertions(+), 69 deletions(-) > > diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py > index aba2847..5071817 100644 > --- a/scripts/qapi-types.py > +++ b/scripts/qapi-types.py > @@ -116,14 +116,6 @@ static inline %(base)s *qapi_%(c_name)s_base(const %(c_name)s *obj) > > > def gen_variants(variants): > - # HACK: Determine if this is an alternate (at least one variant > - # is not an object); unions have all branches as objects. > - inline = False > - for v in variants.variants: > - if not isinstance(v.type, QAPISchemaObjectType): > - inline = True > - break > - > # FIXME: What purpose does data serve, besides preventing a union that > # has a branch named 'data'? We use it in qapi-visit.py to decide > # whether to bypass the switch statement if visiting the discriminator > @@ -144,7 +136,7 @@ def gen_variants(variants): for var in variants.variants: # Ugly special case for simple union TODO get rid of it typ = var.simple_union_type() or var.type > ret += mcgen(''' > %(c_type)s %(c_name)s; > ''', > - c_type=typ.c_type(is_member=inline), > + c_type=typ.c_type(is_member=not var.simple_union_type()), > c_name=c_name(var.name)) This is where we generate flat union members unboxed: is_member=True suppresses the pointer suffix. Still dislike the name is_member :) Perhaps: # Ugly special case for simple union TODO get rid of it simple_union_type = var.simple_union_type() typ = simple_union_type or var.type ret += mcgen(''' %(c_type)s %(c_name)s; ''', c_type=typ.c_type(is_member=not simple_union_type), c_name=c_name(var.name)) Slightly more readable, and makes it more clear that "ugly special case" applies to is_member=... as well. > > ret += mcgen(''' > diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py > index 948bde4..68354d8 100644 > --- a/scripts/qapi-visit.py > +++ b/scripts/qapi-visit.py > @@ -15,10 +15,6 @@ > from qapi import * > import re > > -# visit_type_implicit_FOO() is emitted as needed; track if it has already > -# been output. > -implicit_structs_seen = set() > - > # visit_type_alternate_FOO() is emitted as needed; track if it has already > # been output. > alternate_structs_seen = set() > @@ -39,40 +35,15 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_type)sobj, Error ** > > > def gen_visit_fields_decl(typ): > - ret = '' > - if typ.name not in struct_fields_seen: > - ret += mcgen(''' > + if typ.is_implicit() or typ.name in struct_fields_seen: > + return '' > + struct_fields_seen.add(typ.name) > + > + return mcgen(''' > > static void visit_type_%(c_type)s_fields(Visitor *v, %(c_type)s *obj, Error **errp); > ''', > - c_type=typ.c_name()) > - struct_fields_seen.add(typ.name) > - return ret Two changes squashed together. First step is mere style: The blank line before the return seems superfluous. Second step is the actual change: @@ -35,7 +39,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_type)sobj, Error ** def gen_visit_fields_decl(typ): - if typ.name in struct_fields_seen: + if typ.is_implicit() or typ.name in struct_fields_seen: return '' struct_fields_seen.add(typ.name) Much easier to see what's going on now. I guess you add .is_implicit() here so that gen_visit_object() can call it unconditionally. It's odd; other gen_ functions don't check .is_implicit(). > - > - > -def gen_visit_implicit_struct(typ): > - if typ in implicit_structs_seen: > - return '' > - implicit_structs_seen.add(typ) > - > - ret = gen_visit_fields_decl(typ) > - > - ret += mcgen(''' > - > -static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error **errp) > -{ > - Error *err = NULL; > - > - visit_start_implicit_struct(v, (void **)obj, sizeof(%(c_type)s), &err); > - if (!err) { > - visit_type_%(c_type)s_fields(v, *obj, errp); > - visit_end_implicit_struct(v); > - } > - error_propagate(errp, err); > -} > -''', > c_type=typ.c_name()) > - return ret > > > def gen_visit_alternate_struct(typ): > @@ -250,9 +221,7 @@ def gen_visit_object(name, base, members, variants): > > 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) > + ret += gen_visit_fields_decl(var.type) Before: if this is a flat union member of type FOO, we're going to call visit_type_implicit_FOO(), as you can see in the next hunk. Ensure it's in scope by generating it unless it's been generated already. After: we're going to call visit_type_FOO_fields() instead. Generate a forward declaration unless either the function or the forward declaration has been generated already. Except don't generate it when FOO is an implicit type, because then the member is simple rather than flat. Doesn't this unduly hide the ugly special case? To keep it in view, I'd write # 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_fields_decl(var.type) and drop the .is_implicit() from gen_visit_fields_decl(). Would this work? > > # 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 > @@ -300,7 +269,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error > c_name=c_name(var.name)) > else: > ret += mcgen(''' > - visit_type_implicit_%(c_type)s(v, &(*obj)->u.%(c_name)s, &err); > + visit_type_%(c_type)s_fields(v, &(*obj)->u.%(c_name)s, &err); > ''', > c_type=var.type.c_name(), > c_name=c_name(var.name)) Before: we call visit_type_implicit_FOO() to visit the *boxed* member in C and the *inlined* member in QMP. visit_type_implicit_FOO() looks like this: static void visit_type_implicit_FOO(Visitor *v, FOO **obj, Error **errp) { Error *err = NULL; visit_start_implicit_struct(v, (void **)obj, sizeof(FOO), &err); if (!err) { visit_type_FOO_fields(v, *obj, errp); visit_end_implicit_struct(v); } error_propagate(errp, err); } After: we skip visit_start_implicit_struct() and visit_end_implicit_struct(), i.e. the memory allocation stuff, and pass &(*obj)->u.MEMBER instead of (*obj)->u.MEMBER to visit_type_FOO_fields(). Okay. Every time I come across "implicit" structs, I get confused, and have to dig to unconfuse myself. Good to get rid of one. > diff --git a/cpus.c b/cpus.c > index 898426c..9592163 100644 > --- a/cpus.c > +++ b/cpus.c > @@ -1568,28 +1568,22 @@ CpuInfoList *qmp_query_cpus(Error **errp) > info->value->thread_id = cpu->thread_id; > #if defined(TARGET_I386) > info->value->arch = CPU_INFO_ARCH_X86; > - info->value->u.x86 = g_new0(CpuInfoX86, 1); > - info->value->u.x86->pc = env->eip + env->segs[R_CS].base; > + info->value->u.x86.pc = env->eip + env->segs[R_CS].base; > #elif defined(TARGET_PPC) > info->value->arch = CPU_INFO_ARCH_PPC; > - info->value->u.ppc = g_new0(CpuInfoPPC, 1); > - info->value->u.ppc->nip = env->nip; > + info->value->u.ppc.nip = env->nip; > #elif defined(TARGET_SPARC) > info->value->arch = CPU_INFO_ARCH_SPARC; > - info->value->u.q_sparc = g_new0(CpuInfoSPARC, 1); > - info->value->u.q_sparc->pc = env->pc; > - info->value->u.q_sparc->npc = env->npc; > + info->value->u.q_sparc.pc = env->pc; > + info->value->u.q_sparc.npc = env->npc; > #elif defined(TARGET_MIPS) > info->value->arch = CPU_INFO_ARCH_MIPS; > - info->value->u.q_mips = g_new0(CpuInfoMIPS, 1); > - info->value->u.q_mips->PC = env->active_tc.PC; > + info->value->u.q_mips.PC = env->active_tc.PC; > #elif defined(TARGET_TRICORE) > info->value->arch = CPU_INFO_ARCH_TRICORE; > - info->value->u.tricore = g_new0(CpuInfoTricore, 1); > - info->value->u.tricore->PC = env->PC; > + info->value->u.tricore.PC = env->PC; > #else > info->value->arch = CPU_INFO_ARCH_OTHER; > - info->value->u.other = g_new0(CpuInfoOther, 1); > #endif > > /* XXX: waiting for the qapi to support GSList */ > diff --git a/hmp.c b/hmp.c > index c6419da..1c16ed9 100644 > --- a/hmp.c > +++ b/hmp.c > @@ -313,22 +313,22 @@ void hmp_info_cpus(Monitor *mon, const QDict *qdict) > > switch (cpu->value->arch) { > case CPU_INFO_ARCH_X86: > - monitor_printf(mon, " pc=0x%016" PRIx64, cpu->value->u.x86->pc); > + monitor_printf(mon, " pc=0x%016" PRIx64, cpu->value->u.x86.pc); > break; > case CPU_INFO_ARCH_PPC: > - monitor_printf(mon, " nip=0x%016" PRIx64, cpu->value->u.ppc->nip); > + monitor_printf(mon, " nip=0x%016" PRIx64, cpu->value->u.ppc.nip); > break; > case CPU_INFO_ARCH_SPARC: > monitor_printf(mon, " pc=0x%016" PRIx64, > - cpu->value->u.q_sparc->pc); > + cpu->value->u.q_sparc.pc); > monitor_printf(mon, " npc=0x%016" PRIx64, > - cpu->value->u.q_sparc->npc); > + cpu->value->u.q_sparc.npc); > break; > case CPU_INFO_ARCH_MIPS: > - monitor_printf(mon, " PC=0x%016" PRIx64, cpu->value->u.q_mips->PC); > + monitor_printf(mon, " PC=0x%016" PRIx64, cpu->value->u.q_mips.PC); > break; > case CPU_INFO_ARCH_TRICORE: > - monitor_printf(mon, " PC=0x%016" PRIx64, cpu->value->u.tricore->PC); > + monitor_printf(mon, " PC=0x%016" PRIx64, cpu->value->u.tricore.PC); > break; > default: > break; That's not bad at all. > diff --git a/tests/test-qmp-input-visitor.c b/tests/test-qmp-input-visitor.c > index 139ff7d..27e5ab9 100644 > --- a/tests/test-qmp-input-visitor.c > +++ b/tests/test-qmp-input-visitor.c > @@ -295,7 +295,7 @@ static void test_visitor_in_union_flat(TestInputVisitorData *data, > g_assert_cmpint(tmp->enum1, ==, ENUM_ONE_VALUE1); > g_assert_cmpstr(tmp->string, ==, "str"); > g_assert_cmpint(tmp->integer, ==, 41); > - g_assert_cmpint(tmp->u.value1->boolean, ==, true); > + g_assert_cmpint(tmp->u.value1.boolean, ==, true); > > base = qapi_UserDefFlatUnion_base(tmp); > g_assert(&base->enum1 == &tmp->enum1); > diff --git a/tests/test-qmp-output-visitor.c b/tests/test-qmp-output-visitor.c > index 965f298..c5514a1 100644 > --- a/tests/test-qmp-output-visitor.c > +++ b/tests/test-qmp-output-visitor.c > @@ -1,7 +1,7 @@ > /* > * QMP Output Visitor unit-tests. > * > - * Copyright (C) 2011, 2015 Red Hat Inc. > + * Copyright (C) 2011-2016 Red Hat Inc. > * > * Authors: > * Luiz Capitulino > @@ -403,9 +403,8 @@ static void test_visitor_out_union_flat(TestOutputVisitorData *data, > UserDefFlatUnion *tmp = g_malloc0(sizeof(UserDefFlatUnion)); > tmp->enum1 = ENUM_ONE_VALUE1; > tmp->string = g_strdup("str"); > - tmp->u.value1 = g_malloc0(sizeof(UserDefA)); > tmp->integer = 41; > - tmp->u.value1->boolean = true; > + tmp->u.value1.boolean = true; > > visit_type_UserDefFlatUnion(data->ov, NULL, &tmp, &error_abort); > arg = qmp_output_get_qobject(data->qov); diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py index 948bde4..ac7d504 100644 --- a/scripts/qapi-visit.py +++ b/scripts/qapi-visit.py @@ -39,15 +39,14 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_type)sobj, Error ** def gen_visit_fields_decl(typ): - ret = '' - if typ.name not in struct_fields_seen: - ret += mcgen(''' + if typ.name in struct_fields_seen: + return '' + struct_fields_seen.add(typ.name) + + return mcgen(''' static void visit_type_%(c_type)s_fields(Visitor *v, %(c_type)s *obj, Error **errp); ''', c_type=typ.c_name()) - struct_fields_seen.add(typ.name) - return ret def gen_visit_implicit_struct(typ):