Re: [PATCH 1/5] sim/cgen: mask uninitialized variable warning in cgen-run.c

Andrew Burgess via Gdb-patches
2022-10-27T15:54:07Z

Mike Frysinger <vapier@gentoo.org> writes:

> On 24 Oct 2022 16:57, Andrew Burgess wrote:
>> Mike Frysinger <vapier@gentoo.org> writes:
>> commit 79f4f1d82d1da482e223079deb453eda7b2d2323
>> Author: Andrew Burgess <aburgess@redhat.com>
>> Date: Mon Oct 24 16:55:07 2022 +0100
>>
>> sim/cgen: initialize variable at creation in engine_run_n
>>
>> Zero initialize engine_fns entirely at creation, then override those
>> fields we intend to use, rather than zero just initializing the unused
>> fields later on.
>>
>> There should be no user visible changes after this commit.
>>
>> diff --git a/sim/common/cgen-run.c b/sim/common/cgen-run.c
>> index a9a493c01b9..1ace067a395 100644
>> --- a/sim/common/cgen-run.c
>> +++ b/sim/common/cgen-run.c
>> @@ -229,7 +229,7 @@ static void
>> engine_run_n (SIM_DESC sd, int next_cpu_nr, int nr_cpus, int max_insns, int fast_p)
>> {
>> int i;
>> - ENGINE_FN *engine_fns[MAX_NR_PROCESSORS];
>> + ENGINE_FN *engine_fns[MAX_NR_PROCESSORS] = {};
>>
>> SIM_ASSERT (nr_cpus <= MAX_NR_PROCESSORS);
>> SIM_ASSERT (next_cpu_nr >= 0 && next_cpu_nr < nr_cpus);
>> @@ -242,11 +242,6 @@ engine_run_n (SIM_DESC sd, int next_cpu_nr, int nr_cpus, int max_insns, int fast
>> prime_cpu (cpu, max_insns);
>> }
>>
>> - /* Ensure the remaining engine_fns slots are initialized, this silences a
>> - compiler warning when engine_fns is used below. */
>
> this comment is useful, so i would retain it

I added a variant of this comment back, and pushed this patch.

Thanks,
Andrew

---

commit a09f33be653fb112586be126f3d5ab848aaed095
Author: Andrew Burgess <aburgess@redhat.com>
Date: Mon Oct 24 16:55:07 2022 +0100

sim/cgen: initialize variable at creation in engine_run_n

Zero initialize engine_fns entirely at creation, then override those
fields we intend to use, rather than zero just initializing the unused
fields later on.

There should be no user visible changes after this commit.

diff --git a/sim/common/cgen-run.c b/sim/common/cgen-run.c
index a9a493c01b9..b6400a69c13 100644
--- a/sim/common/cgen-run.c
+++ b/sim/common/cgen-run.c
@@ -229,7 +229,9 @@ static void
engine_run_n (SIM_DESC sd, int next_cpu_nr, int nr_cpus, int max_insns, int fast_p)
{
int i;
- ENGINE_FN *engine_fns[MAX_NR_PROCESSORS];
+ /* Ensure that engine_fns is fully initialized, this silences a compiler
+ warning when engine_fns is used below. */
+ ENGINE_FN *engine_fns[MAX_NR_PROCESSORS] = {};

SIM_ASSERT (nr_cpus <= MAX_NR_PROCESSORS);
SIM_ASSERT (next_cpu_nr >= 0 && next_cpu_nr < nr_cpus);
@@ -242,11 +244,6 @@ engine_run_n (SIM_DESC sd, int next_cpu_nr, int nr_cpus, int max_insns, int fast
prime_cpu (cpu, max_insns);
}

- /* Ensure the remaining engine_fns slots are initialized, this silences a
- compiler warning when engine_fns is used below. */
- for (i = nr_cpus; i < MAX_NR_PROCESSORS; ++i)
- engine_fns[i] = NULL;
-
while (1)
{
SIM_ENGINE_PREFIX_HOOK (sd);