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Date: Wed, 10 Oct 2012 13:09:49 -0700
From: Richard Henderson <rth@twiddle.net>
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Subject: Re: [Qemu-devel] [PATCH 04/14] target-mips: use softfloat constants
 when possible
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To: Aurelien Jarno <aurelien@aurel32.net>
Cc: qemu-devel@nongnu.org

On 10/09/2012 01:27 PM, Aurelien Jarno wrote:
> softfloat already has a few constants defined, use them instead of
> redefining them in target-mips.
> 
> Rename FLOAT_SNAN32 and FLOAT_SNAN64 to FP_TO_INT32_OVERFLOW and
> FP_TO_INT64_OVERFLOW as even if they have the same value, they are
> technically different (and defined differently in the MIPS ISA).
> 
> Remove the unused constants.
> 
> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

Reviewed-by: Richard Henderson <rth@twiddle.net>

> @@ -2495,8 +2491,9 @@ uint64_t helper_float_cvtl_d(CPUMIPSState *env, uint64_t fdt0)
>      set_float_exception_flags(0, &env->active_fpu.fp_status);
>      dt2 = float64_to_int64(fdt0, &env->active_fpu.fp_status);
>      update_fcr31(env);
> -    if (GET_FP_CAUSE(env->active_fpu.fcr31) & (FP_OVERFLOW | FP_INVALID))
> -        dt2 = FLOAT_SNAN64;
> +    if (GET_FP_CAUSE(env->active_fpu.fcr31) & (FP_OVERFLOW | FP_INVALID)) {
> +        dt2 = FP_TO_INT64_OVERFLOW;
> +    }
>      return dt2;

That said, the existing code you're patching is incorrect.

This code will fold to OVERFLOW if any previous operation caused an overflow,
not checking that the *current* operation caused an overflow.


r~