Re: [Qemu-devel] [PATCH v2 2/6] softfloat: Honour default_nan_mode for float-to-float conversions

[Aurelien Jarno]

On Wed, Feb 09, 2011 at 04:27:26PM +0000, Peter Maydell wrote:
> From: Christophe Lyon <address@hidden>
> 
> Honour the default_nan_mode flag when doing conversions between
> different floating point formats, as well as when returning a NaN from
> a two-operand floating point function. This corrects the behaviour
> of float<->double conversions on both ARM and SH4.
> 
> Signed-off-by: Christophe Lyon <address@hidden>
> Reviewed-by: Peter Maydell <address@hidden>
> ---
>  fpu/softfloat-specialize.h |   29 +++++++++++++++++++++++++----
>  fpu/softfloat.c            |   24 ++++++++++++------------
>  2 files changed, 37 insertions(+), 16 deletions(-)

Reviewed-by: Aurelien Jarno <address@hidden>

> diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h
> index bc9a66c..2f65b9d 100644
> --- a/fpu/softfloat-specialize.h
> +++ b/fpu/softfloat-specialize.h
> @@ -203,9 +203,14 @@ static commonNaNT float32ToCommonNaN( float32 a 
> STATUS_PARAM )
>  | precision floating-point format.
>  
> *----------------------------------------------------------------------------*/
>  
> -static float32 commonNaNToFloat32( commonNaNT a )
> +static float32 commonNaNToFloat32( commonNaNT a STATUS_PARAM)
>  {
>      bits32 mantissa = a.high>>41;
> +
> +    if ( STATUS(default_nan_mode) ) {
> +        return float32_default_nan;
> +    }
> +
>      if ( mantissa )
>          return make_float32(
>              ( ( (bits32) a.sign )<<31 ) | 0x7F800000 | ( a.high>>41 ) );
> @@ -457,10 +462,14 @@ static commonNaNT float64ToCommonNaN( float64 a 
> STATUS_PARAM)
>  | precision floating-point format.
>  
> *----------------------------------------------------------------------------*/
>  
> -static float64 commonNaNToFloat64( commonNaNT a )
> +static float64 commonNaNToFloat64( commonNaNT a STATUS_PARAM)
>  {
>      bits64 mantissa = a.high>>12;
>  
> +    if ( STATUS(default_nan_mode) ) {
> +        return float64_default_nan;
> +    }
> +
>      if ( mantissa )
>          return make_float64(
>                ( ( (bits64) a.sign )<<63 )
> @@ -614,10 +623,16 @@ static commonNaNT floatx80ToCommonNaN( floatx80 a 
> STATUS_PARAM)
>  | double-precision floating-point format.
>  
> *----------------------------------------------------------------------------*/
>  
> -static floatx80 commonNaNToFloatx80( commonNaNT a )
> +static floatx80 commonNaNToFloatx80( commonNaNT a STATUS_PARAM)
>  {
>      floatx80 z;
>  
> +    if ( STATUS(default_nan_mode) ) {
> +        z.low = floatx80_default_nan_low;
> +        z.high = floatx80_default_nan_high;
> +        return z;
> +    }
> +
>      if (a.high)
>          z.low = a.high;
>      else
> @@ -762,10 +777,16 @@ static commonNaNT float128ToCommonNaN( float128 a 
> STATUS_PARAM)
>  | precision floating-point format.
>  
> *----------------------------------------------------------------------------*/
>  
> -static float128 commonNaNToFloat128( commonNaNT a )
> +static float128 commonNaNToFloat128( commonNaNT a STATUS_PARAM)
>  {
>      float128 z;
>  
> +    if ( STATUS(default_nan_mode) ) {
> +        z.low = float128_default_nan_low;
> +        z.high = float128_default_nan_high;
> +        return z;
> +    }
> +
>      shift128Right( a.high, a.low, 16, &z.high, &z.low );
>      z.high |= ( ( (bits64) a.sign )<<63 ) | LIT64( 0x7FFF000000000000 );
>      return z;
> diff --git a/fpu/softfloat.c b/fpu/softfloat.c
> index dc4492a..c3058f4 100644
> --- a/fpu/softfloat.c
> +++ b/fpu/softfloat.c
> @@ -1534,7 +1534,7 @@ float64 float32_to_float64( float32 a STATUS_PARAM )
>      aExp = extractFloat32Exp( a );
>      aSign = extractFloat32Sign( a );
>      if ( aExp == 0xFF ) {
> -        if ( aSig ) return commonNaNToFloat64( float32ToCommonNaN( a 
> STATUS_VAR ));
> +        if ( aSig ) return commonNaNToFloat64( float32ToCommonNaN( a 
> STATUS_VAR ) STATUS_VAR );
>          return packFloat64( aSign, 0x7FF, 0 );
>      }
>      if ( aExp == 0 ) {
> @@ -1566,7 +1566,7 @@ floatx80 float32_to_floatx80( float32 a STATUS_PARAM )
>      aExp = extractFloat32Exp( a );
>      aSign = extractFloat32Sign( a );
>      if ( aExp == 0xFF ) {
> -        if ( aSig ) return commonNaNToFloatx80( float32ToCommonNaN( a 
> STATUS_VAR ) );
> +        if ( aSig ) return commonNaNToFloatx80( float32ToCommonNaN( a 
> STATUS_VAR ) STATUS_VAR );
>          return packFloatx80( aSign, 0x7FFF, LIT64( 0x8000000000000000 ) );
>      }
>      if ( aExp == 0 ) {
> @@ -1600,7 +1600,7 @@ float128 float32_to_float128( float32 a STATUS_PARAM )
>      aExp = extractFloat32Exp( a );
>      aSign = extractFloat32Sign( a );
>      if ( aExp == 0xFF ) {
> -        if ( aSig ) return commonNaNToFloat128( float32ToCommonNaN( a 
> STATUS_VAR ) );
> +        if ( aSig ) return commonNaNToFloat128( float32ToCommonNaN( a 
> STATUS_VAR ) STATUS_VAR );
>          return packFloat128( aSign, 0x7FFF, 0, 0 );
>      }
>      if ( aExp == 0 ) {
> @@ -2689,7 +2689,7 @@ float32 float64_to_float32( float64 a STATUS_PARAM )
>      aExp = extractFloat64Exp( a );
>      aSign = extractFloat64Sign( a );
>      if ( aExp == 0x7FF ) {
> -        if ( aSig ) return commonNaNToFloat32( float64ToCommonNaN( a 
> STATUS_VAR ) );
> +        if ( aSig ) return commonNaNToFloat32( float64ToCommonNaN( a 
> STATUS_VAR ) STATUS_VAR );
>          return packFloat32( aSign, 0xFF, 0 );
>      }
>      shift64RightJamming( aSig, 22, &aSig );
> @@ -2861,7 +2861,7 @@ floatx80 float64_to_floatx80( float64 a STATUS_PARAM )
>      aExp = extractFloat64Exp( a );
>      aSign = extractFloat64Sign( a );
>      if ( aExp == 0x7FF ) {
> -        if ( aSig ) return commonNaNToFloatx80( float64ToCommonNaN( a 
> STATUS_VAR ) );
> +        if ( aSig ) return commonNaNToFloatx80( float64ToCommonNaN( a 
> STATUS_VAR ) STATUS_VAR );
>          return packFloatx80( aSign, 0x7FFF, LIT64( 0x8000000000000000 ) );
>      }
>      if ( aExp == 0 ) {
> @@ -2896,7 +2896,7 @@ float128 float64_to_float128( float64 a STATUS_PARAM )
>      aExp = extractFloat64Exp( a );
>      aSign = extractFloat64Sign( a );
>      if ( aExp == 0x7FF ) {
> -        if ( aSig ) return commonNaNToFloat128( float64ToCommonNaN( a 
> STATUS_VAR ) );
> +        if ( aSig ) return commonNaNToFloat128( float64ToCommonNaN( a 
> STATUS_VAR ) STATUS_VAR );
>          return packFloat128( aSign, 0x7FFF, 0, 0 );
>      }
>      if ( aExp == 0 ) {
> @@ -3843,7 +3843,7 @@ float32 floatx80_to_float32( floatx80 a STATUS_PARAM )
>      aSign = extractFloatx80Sign( a );
>      if ( aExp == 0x7FFF ) {
>          if ( (bits64) ( aSig<<1 ) ) {
> -            return commonNaNToFloat32( floatx80ToCommonNaN( a STATUS_VAR ) );
> +            return commonNaNToFloat32( floatx80ToCommonNaN( a STATUS_VAR ) 
> STATUS_VAR );
>          }
>          return packFloat32( aSign, 0xFF, 0 );
>      }
> @@ -3871,7 +3871,7 @@ float64 floatx80_to_float64( floatx80 a STATUS_PARAM )
>      aSign = extractFloatx80Sign( a );
>      if ( aExp == 0x7FFF ) {
>          if ( (bits64) ( aSig<<1 ) ) {
> -            return commonNaNToFloat64( floatx80ToCommonNaN( a STATUS_VAR ) );
> +            return commonNaNToFloat64( floatx80ToCommonNaN( a STATUS_VAR ) 
> STATUS_VAR );
>          }
>          return packFloat64( aSign, 0x7FF, 0 );
>      }
> @@ -3900,7 +3900,7 @@ float128 floatx80_to_float128( floatx80 a STATUS_PARAM )
>      aExp = extractFloatx80Exp( a );
>      aSign = extractFloatx80Sign( a );
>      if ( ( aExp == 0x7FFF ) && (bits64) ( aSig<<1 ) ) {
> -        return commonNaNToFloat128( floatx80ToCommonNaN( a STATUS_VAR ) );
> +        return commonNaNToFloat128( floatx80ToCommonNaN( a STATUS_VAR ) 
> STATUS_VAR );
>      }
>      shift128Right( aSig<<1, 0, 16, &zSig0, &zSig1 );
>      return packFloat128( aSign, aExp, zSig0, zSig1 );
> @@ -4863,7 +4863,7 @@ float32 float128_to_float32( float128 a STATUS_PARAM )
>      aSign = extractFloat128Sign( a );
>      if ( aExp == 0x7FFF ) {
>          if ( aSig0 | aSig1 ) {
> -            return commonNaNToFloat32( float128ToCommonNaN( a STATUS_VAR ) );
> +            return commonNaNToFloat32( float128ToCommonNaN( a STATUS_VAR ) 
> STATUS_VAR );
>          }
>          return packFloat32( aSign, 0xFF, 0 );
>      }
> @@ -4897,7 +4897,7 @@ float64 float128_to_float64( float128 a STATUS_PARAM )
>      aSign = extractFloat128Sign( a );
>      if ( aExp == 0x7FFF ) {
>          if ( aSig0 | aSig1 ) {
> -            return commonNaNToFloat64( float128ToCommonNaN( a STATUS_VAR ) );
> +            return commonNaNToFloat64( float128ToCommonNaN( a STATUS_VAR ) 
> STATUS_VAR );
>          }
>          return packFloat64( aSign, 0x7FF, 0 );
>      }
> @@ -4932,7 +4932,7 @@ floatx80 float128_to_floatx80( float128 a STATUS_PARAM )
>      aSign = extractFloat128Sign( a );
>      if ( aExp == 0x7FFF ) {
>          if ( aSig0 | aSig1 ) {
> -            return commonNaNToFloatx80( float128ToCommonNaN( a STATUS_VAR ) 
> );
> +            return commonNaNToFloatx80( float128ToCommonNaN( a STATUS_VAR ) 
> STATUS_VAR );
>          }
>          return packFloatx80( aSign, 0x7FFF, LIT64( 0x8000000000000000 ) );
>      }
> -- 
> 1.7.1
> 
> 
> 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net