Re: [PATCH v3 15/22] linux-user/hppa: fix -Werror=maybe-uninitialized false-positive

[Laurent Vivier <laurent@vivier.eu>]

Le 30/09/2024 à 15:26, Marc-André Lureau a écrit :
> Hi Laurent
> 
> On Mon, Sep 30, 2024 at 4:19 PM Laurent Vivier <laurent@vivier.eu> wrote:
>>
>> CC Helge Deller
>>
>> Le 30/09/2024 à 10:14, marcandre.lureau@redhat.com a écrit :
>>> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>>>
>>> ../linux-user/hppa/cpu_loop.c: In function ‘hppa_lws’:
>>> ../linux-user/hppa/cpu_loop.c:106:17: error: ‘ret’ may be used uninitialized [-Werror=maybe-uninitialized]
>>>     106 |     env->gr[28] = ret;
>>>
>>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
>>> ---
>>>    linux-user/hppa/cpu_loop.c | 10 +++++-----
>>>    1 file changed, 5 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/linux-user/hppa/cpu_loop.c b/linux-user/hppa/cpu_loop.c
>>> index bc093b8fe8..f4da95490e 100644
>>> --- a/linux-user/hppa/cpu_loop.c
>>> +++ b/linux-user/hppa/cpu_loop.c
>>> @@ -43,7 +43,7 @@ static abi_ulong hppa_lws(CPUHPPAState *env)
>>>            old = tswap32(old);
>>>            new = tswap32(new);
>>>            ret = qatomic_cmpxchg((uint32_t *)g2h(cs, addr), old, new);
>>> -        ret = tswap32(ret);
>>> +        env->gr[28] = tswap32(ret);
>>>            break;
>>>
>>>        case 2: /* elf32 atomic "new" cmpxchg */
>>> @@ -64,19 +64,19 @@ static abi_ulong hppa_lws(CPUHPPAState *env)
>>>                old = *(uint8_t *)g2h(cs, old);
>>>                new = *(uint8_t *)g2h(cs, new);
>>>                ret = qatomic_cmpxchg((uint8_t *)g2h(cs, addr), old, new);
>>> -            ret = ret != old;
>>> +            env->gr[28] = ret != old;
>>>                break;
>>>            case 1:
>>>                old = *(uint16_t *)g2h(cs, old);
>>>                new = *(uint16_t *)g2h(cs, new);
>>>                ret = qatomic_cmpxchg((uint16_t *)g2h(cs, addr), old, new);
>>> -            ret = ret != old;
>>> +            env->gr[28] = ret != old;
>>>                break;
>>>            case 2:
>>>                old = *(uint32_t *)g2h(cs, old);
>>>                new = *(uint32_t *)g2h(cs, new);
>>>                ret = qatomic_cmpxchg((uint32_t *)g2h(cs, addr), old, new);
>>> -            ret = ret != old;
>>> +            env->gr[28] = ret != old;
>>>                break;
>>>            case 3:
>>>                {
>>> @@ -97,13 +97,13 @@ static abi_ulong hppa_lws(CPUHPPAState *env)
>>>                    }
>>>                    end_exclusive();
>>>    #endif
>>> +                env->gr[28] = ret;
>>>                }
>>>                break;
>>>            }
>>>            break;
>>>        }
>>>
>>> -    env->gr[28] = ret;
>>>        return 0;
>>>    }
>>>
>>
>> Did you try to put a g_assert_not_reached() in a "default:" for "switch(size)"?
>> This should help the compiler to know that "env->gr[28] = ret;" will not be reached if ret is not set.
> 
> That works! I'll change the patch and include your r-b then?
> 
> 

Yes, you can

Thanks,
Laurent