fpu/softfloat: Define floatN_silence_nan in terms of parts_silence_nan

Isolate the target-specific choice to 3 functions instead of 6.

The code in floatx80_default_nan tried to be over-general.  There are
only two targets that support this format: x86 and m68k.  Thus there
is no point in inventing a mechanism for snan_bit_is_one.

Move routines that no longer have ifdefs out of softfloat-specialize.h.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

fpu/softfloat-specialize.h

@@ -278,24 +278,6 @@ int float16_is_signaling_nan(float16 a_, float_status *status)
 #endif
 }
 
-/*----------------------------------------------------------------------------
-| Returns a quiet NaN from a signalling NaN for the half-precision
-| floating point value `a'.
-*----------------------------------------------------------------------------*/
-
-float16 float16_silence_nan(float16 a, float_status *status)
-{
-#ifdef NO_SIGNALING_NANS
-    g_assert_not_reached();
-#else
-    if (snan_bit_is_one(status)) {
-        return float16_default_nan(status);
-    } else {
-        return a | (1 << 9);
-    }
-#endif
-}
-
 /*----------------------------------------------------------------------------
 | Returns 1 if the single-precision floating-point value `a' is a quiet
 | NaN; otherwise returns 0.
@@ -334,30 +316,6 @@ int float32_is_signaling_nan(float32 a_, float_status *status)
 #endif
 }
 
-/*----------------------------------------------------------------------------
-| Returns a quiet NaN from a signalling NaN for the single-precision
-| floating point value `a'.
-*----------------------------------------------------------------------------*/
-
-float32 float32_silence_nan(float32 a, float_status *status)
-{
-#ifdef NO_SIGNALING_NANS
-    g_assert_not_reached();
-#else
-    if (snan_bit_is_one(status)) {
-# ifdef TARGET_HPPA
-        a &= ~0x00400000;
-        a |=  0x00200000;
-        return a;
-# else
-        return float32_default_nan(status);
-# endif
-    } else {
-        return a | (1 << 22);
-    }
-#endif
-}
-
 /*----------------------------------------------------------------------------
 | Returns the result of converting the single-precision floating-point NaN
 | `a' to the canonical NaN format.  If `a' is a signaling NaN, the invalid
@@ -706,31 +664,6 @@ int float64_is_signaling_nan(float64 a_, float_status *status)
 #endif
 }
 
-/*----------------------------------------------------------------------------
-| Returns a quiet NaN from a signalling NaN for the double-precision
-| floating point value `a'.
-*----------------------------------------------------------------------------*/
-
-float64 float64_silence_nan(float64 a, float_status *status)
-{
-#ifdef NO_SIGNALING_NANS
-    g_assert_not_reached();
-#else
-    if (snan_bit_is_one(status)) {
-# ifdef TARGET_HPPA
-        a &= ~0x0008000000000000ULL;
-        a |=  0x0004000000000000ULL;
-        return a;
-# else
-        return float64_default_nan(status);
-# endif
-    } else {
-        return a | LIT64(0x0008000000000000);
-    }
-#endif
-}
-
-
 /*----------------------------------------------------------------------------
 | Returns the result of converting the double-precision floating-point NaN
 | `a' to the canonical NaN format.  If `a' is a signaling NaN, the invalid
@@ -886,16 +819,10 @@ int floatx80_is_signaling_nan(floatx80 a, float_status *status)
 
 floatx80 floatx80_silence_nan(floatx80 a, float_status *status)
 {
-#ifdef NO_SIGNALING_NANS
-    g_assert_not_reached();
-#else
-    if (snan_bit_is_one(status)) {
-        return floatx80_default_nan(status);
-    } else {
-        a.low |= LIT64(0xC000000000000000);
-        return a;
-    }
-#endif
+    /* None of the targets that have snan_bit_is_one use floatx80.  */
+    assert(!snan_bit_is_one(status));
+    a.low |= LIT64(0xC000000000000000);
+    return a;
 }
 
 /*----------------------------------------------------------------------------

fpu/softfloat.c

@@ -2134,6 +2134,37 @@ float128 float128_default_nan(float_status *status)
     return r;
 }
 
+/*----------------------------------------------------------------------------
+| Returns a quiet NaN from a signalling NaN for the floating point value `a'.
+*----------------------------------------------------------------------------*/
+
+float16 float16_silence_nan(float16 a, float_status *status)
+{
+    FloatParts p = float16_unpack_raw(a);
+    p.frac <<= float16_params.frac_shift;
+    p = parts_silence_nan(p, status);
+    p.frac >>= float16_params.frac_shift;
+    return float16_pack_raw(p);
+}
+
+float32 float32_silence_nan(float32 a, float_status *status)
+{
+    FloatParts p = float32_unpack_raw(a);
+    p.frac <<= float32_params.frac_shift;
+    p = parts_silence_nan(p, status);
+    p.frac >>= float32_params.frac_shift;
+    return float32_pack_raw(p);
+}
+
+float64 float64_silence_nan(float64 a, float_status *status)
+{
+    FloatParts p = float64_unpack_raw(a);
+    p.frac <<= float64_params.frac_shift;
+    p = parts_silence_nan(p, status);
+    p.frac >>= float64_params.frac_shift;
+    return float64_pack_raw(p);
+}
+
 /*----------------------------------------------------------------------------
 | Takes a 64-bit fixed-point value `absZ' with binary point between bits 6
 | and 7, and returns the properly rounded 32-bit integer corresponding to the