Re: [PATCH v6 18/20] target/arm: Rebuild hflags at CPSR writes

[Richard Henderson]

On 10/14/19 12:08 PM, Alex Bennée wrote:
> 
> Richard Henderson <address@hidden> writes:
> 
>> Continue setting, but not relying upon, env->hflags.
>>
>> Signed-off-by: Richard Henderson <address@hidden>
>> ---
>>  target/arm/op_helper.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
>> index ccc2cecb46..b529d6c1bf 100644
>> --- a/target/arm/op_helper.c
>> +++ b/target/arm/op_helper.c
>> @@ -224,6 +224,7 @@ uint32_t HELPER(usat16)(CPUARMState *env, uint32_t x, 
>> uint32_t shift)
>>  void HELPER(setend)(CPUARMState *env)
>>  {
>>      env->uncached_cpsr ^= CPSR_E;
>> +    arm_rebuild_hflags(env);
>>  }
>>
>>  /* Function checks whether WFx (WFI/WFE) instructions are set up to be 
>> trapped.
>> @@ -387,6 +388,8 @@ uint32_t HELPER(cpsr_read)(CPUARMState *env)
>>  void HELPER(cpsr_write)(CPUARMState *env, uint32_t val, uint32_t mask)
>>  {
>>      cpsr_write(env, val, mask, CPSRWriteByInstr);
>> +    /* TODO: Not all cpsr bits are relevant to hflags.  */
> 
> Do you mean by this we could check which bits changed and avoid a
> re-compute if we wanted to? Is it likely to be anything other than the
> SS_ACTIVE bit?

Yes.  Well, there's also NZCV.  But neither case happens particularly often, so
it's probably not worth worrying about.


r~