Re: [PATCH 2/2] target/ppc: Bugfix FP when OE/UE are set

[Daniel Henrique Barboza <danielhb413@gmail.com>]

On 8/5/22 14:17, Richard Henderson wrote:
> On 8/5/22 07:15, Lucas Mateus Castro(alqotel) wrote:
>> From: "Lucas Mateus Castro (alqotel)" <lucas.araujo@eldorado.org.br>
>>
>> When an overflow exception occurs and OE is set the intermediate result
>> should be adjusted (by subtracting from the exponent) to avoid rounding
>> to inf. The same applies to an underflow exceptionion and UE (but adding
>> to the exponent). To do this set the fp_status.rebias_overflow when OE
>> is set and fp_status.rebias_underflow when UE is set as the FPU will
>> recalculate in case of a overflow/underflow if the according rebias* is
>> set.
>>
>> Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.araujo@eldorado.org.br>
>> ---
>>   target/ppc/cpu.c        | 2 ++
>>   target/ppc/fpu_helper.c | 2 --
>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/target/ppc/cpu.c b/target/ppc/cpu.c
>> index 401b6f9e63..0ebac04bc4 100644
>> --- a/target/ppc/cpu.c
>> +++ b/target/ppc/cpu.c
>> @@ -120,6 +120,8 @@ void ppc_store_fpscr(CPUPPCState *env, target_ulong val)
>>           val |= FP_FEX;
>>       }
>>       env->fpscr = val;
>> +    env->fp_status.rebias_overflow  = (FP_OE & env->fpscr) ? true : false;
>> +    env->fp_status.rebias_underflow = (FP_UE & env->fpscr) ? true : false;
> 
> No point in the ?: operator.
> 
> Otherwise,
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> 

Amended in the tree. No need to re-send.


diff --git a/target/ppc/cpu.c b/target/ppc/cpu.c
index 0ebac04bc4..947a4bfe1f 100644
--- a/target/ppc/cpu.c
+++ b/target/ppc/cpu.c
@@ -120,8 +120,8 @@ void ppc_store_fpscr(CPUPPCState *env, target_ulong val)
          val |= FP_FEX;
      }
      env->fpscr = val;
-    env->fp_status.rebias_overflow  = (FP_OE & env->fpscr) ? true : false;
-    env->fp_status.rebias_underflow = (FP_UE & env->fpscr) ? true : false;
+    env->fp_status.rebias_overflow  = FP_OE & env->fpscr;
+    env->fp_status.rebias_underflow = FP_UE & env->fpscr;
      if (tcg_enabled()) {
          fpscr_set_rounding_mode(env);
      }


Thanks,


Daniel

> 
> r~
> 
>>       if (tcg_enabled()) {
>>           fpscr_set_rounding_mode(env);
>>       }
>> diff --git a/target/ppc/fpu_helper.c b/target/ppc/fpu_helper.c
>> index 134804628b..c17575de5d 100644
>> --- a/target/ppc/fpu_helper.c
>> +++ b/target/ppc/fpu_helper.c
>> @@ -344,7 +344,6 @@ static inline int float_overflow_excp(CPUPPCState *env)
>>       bool overflow_enabled = !!(env->fpscr & FP_OE);
>>       if (overflow_enabled) {
>> -        /* XXX: should adjust the result */
>>           /* Update the floating-point enabled exception summary */
>>           env->fpscr |= FP_FEX;
>>           /* We must update the target FPR before raising the exception */
>> @@ -363,7 +362,6 @@ static inline void float_underflow_excp(CPUPPCState *env)
>>       /* Update the floating-point exception summary */
>>       env->fpscr |= FP_FX;
>>       if (env->fpscr & FP_UE) {
>> -        /* XXX: should adjust the result */
>>           /* Update the floating-point enabled exception summary */
>>           env->fpscr |= FP_FEX;
>>           /* We must update the target FPR before raising the exception */
>