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Mon, 8 Jun 2020 07:16:35 +0000 (UTC) Subject: Re: [PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org, =?UTF-8?Q?Martin_Li=c5=a1ka?= , Eric Blake References: <20200608071409.17024-1-philmd@redhat.com> From: Thomas Huth Openpgp: preference=signencrypt Message-ID: <976e5ec8-6cf5-bd45-c5ac-b02fed57598a@redhat.com> Date: Mon, 8 Jun 2020 09:16:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200608071409.17024-1-philmd@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=205.139.110.120; envelope-from=thuth@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/08 01:05:50 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Jia Liu , qemu-trivial@nongnu.org, Markus Armbruster , 1874073@bugs.launchpad.net, Christophe de Dinechin , Stafford Horne Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 08/06/2020 09.14, Philippe Mathieu-Daudé wrote: > When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get: > > CC or1k-softmmu/hw/openrisc/openrisc_sim.o > hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’: > hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized] > 87 | sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]); > | ~~~~~~~~^~~ > > While humans can tell smp_cpus will always be in the [1, 2] range, > (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler > can't. > > Add an assertion to give the compiler a hint there's no use of > uninitialized data. > > Buglink: https://bugs.launchpad.net/qemu/+bug/1874073 > Reported-by: Martin Liška > Suggested-by: Peter Maydell > Signed-off-by: Philippe Mathieu-Daudé > --- > hw/openrisc/openrisc_sim.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c > index d08ce61811..02f5259e5e 100644 > --- a/hw/openrisc/openrisc_sim.c > +++ b/hw/openrisc/openrisc_sim.c > @@ -134,6 +134,7 @@ static void openrisc_sim_init(MachineState *machine) > int n; > unsigned int smp_cpus = machine->smp.cpus; > > + assert(smp_cpus >= 1 && smp_cpus <= 2); > for (n = 0; n < smp_cpus; n++) { > cpu = OPENRISC_CPU(cpu_create(machine->cpu_type)); > if (cpu == NULL) { > Reviewed-by: Thomas Huth