softfloat: Honour default_nan_mode for float-to-float conversions

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: NChristophe Lyon <christophe.lyon@st.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

fpu/softfloat-specialize.h

@@ -207,9 +207,14 @@ 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 ) );
@@ -461,10 +466,14 @@ 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 )
@@ -618,10 +627,16 @@ 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
@@ -766,10 +781,16 @@ 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;

fpu/softfloat.c

@@ -1561,7 +1561,7 @@ 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 ) {
@@ -1593,7 +1593,7 @@ 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 ) {
@@ -1627,7 +1627,7 @@ 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 ) {
@@ -2716,7 +2716,7 @@ 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 );
@@ -2889,7 +2889,7 @@ 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 ) {
@@ -2924,7 +2924,7 @@ 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 ) {
@@ -3871,7 +3871,7 @@ 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 );
     }
@@ -3899,7 +3899,7 @@ 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 );
     }
@@ -3928,7 +3928,7 @@ 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 );
@@ -4891,7 +4891,7 @@ 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 );
     }
@@ -4925,7 +4925,7 @@ 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 );
     }
@@ -4960,7 +4960,7 @@ 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 ) );
     }