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fpu: convert float[16/32/64]_squash_denormal to new modern style

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This also allows us to remove the extractFloat16exp/frac helpers. We
avoid using the floatXX_pack_raw functions as they are slight overkill
for masking out all but the top bit of the number. The generated code
is almost exactly the same as makes no difference to the
pre-conversion code.

Backports commit e6b405fe00d8e6424a58492b37a1656d1ef0929b from qemu
This commit is contained in:
Alex Bennée 2019-11-18 20:42:04 -05:00 committed by Lioncash
parent e5c799cd3c
commit 0d573763c9
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GPG key ID: 4E3C3CC1031BA9C7
1 changed files with 48 additions and 63 deletions
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111
qemu/fpu/softfloat.c
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@ -415,24 +415,6 @@ float64_gen2(float64 xa, float64 xb, float_status *s,
return soft(ua.s, ub.s, s);
}
/*----------------------------------------------------------------------------
| Returns the fraction bits of the half-precision floating-point value `a'.
*----------------------------------------------------------------------------*/
static inline uint32_t extractFloat16Frac(float16 a)
{
return float16_val(a) & 0x3ff;
}
/*----------------------------------------------------------------------------
| Returns the exponent bits of the half-precision floating-point value `a'.
*----------------------------------------------------------------------------*/
static inline int extractFloat16Exp(float16 a)
{
return (float16_val(a) >> 10) & 0x1f;
}
/*----------------------------------------------------------------------------
| Returns the fraction bits of the single-precision floating-point value `a'.
*----------------------------------------------------------------------------*/
@ -3285,6 +3267,54 @@ float64 float64_silence_nan(float64 a, float_status *status)
return float64_pack_raw(p);
}
/*----------------------------------------------------------------------------
| If `a' is denormal and we are in flush-to-zero mode then set the
| input-denormal exception and return zero. Otherwise just return the value.
*----------------------------------------------------------------------------*/
static bool parts_squash_denormal(FloatParts p, float_status *status)
{
if (p.exp == 0 && p.frac != 0) {
float_raise(float_flag_input_denormal, status);
return true;
}
return false;
}
float16 float16_squash_input_denormal(float16 a, float_status *status)
{
if (status->flush_inputs_to_zero) {
FloatParts p = float16_unpack_raw(a);
if (parts_squash_denormal(p, status)) {
return float16_set_sign(float16_zero, p.sign);
}
}
return a;
}
float32 float32_squash_input_denormal(float32 a, float_status *status)
{
if (status->flush_inputs_to_zero) {
FloatParts p = float32_unpack_raw(a);
if (parts_squash_denormal(p, status)) {
return float32_set_sign(float32_zero, p.sign);
}
}
return a;
}
float64 float64_squash_input_denormal(float64 a, float_status *status)
{
if (status->flush_inputs_to_zero) {
FloatParts p = float64_unpack_raw(a);
if (parts_squash_denormal(p, status)) {
return float64_set_sign(float64_zero, p.sign);
}
}
return a;
}
/*----------------------------------------------------------------------------
| 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
@ -3461,21 +3491,6 @@ static int64_t roundAndPackUint64(flag zSign, uint64_t absZ0,
return absZ0;
}
/*----------------------------------------------------------------------------
| If `a' is denormal and we are in flush-to-zero mode then set the
| input-denormal exception and return zero. Otherwise just return the value.
*----------------------------------------------------------------------------*/
float32 float32_squash_input_denormal(float32 a, float_status *status)
{
if (status->flush_inputs_to_zero) {
if (extractFloat32Exp(a) == 0 && extractFloat32Frac(a) != 0) {
float_raise(float_flag_input_denormal, status);
return make_float32(float32_val(a) & 0x80000000);
}
}
return a;
}
/*----------------------------------------------------------------------------
| Normalizes the subnormal single-precision floating-point value represented
| by the denormalized significand `aSig'. The normalized exponent and
@ -3614,21 +3629,6 @@ static float32
}
/*----------------------------------------------------------------------------
| If `a' is denormal and we are in flush-to-zero mode then set the
| input-denormal exception and return zero. Otherwise just return the value.
*----------------------------------------------------------------------------*/
float64 float64_squash_input_denormal(float64 a, float_status *status)
{
if (status->flush_inputs_to_zero) {
if (extractFloat64Exp(a) == 0 && extractFloat64Frac(a) != 0) {
float_raise(float_flag_input_denormal, status);
return make_float64(float64_val(a) & (1ULL << 63));
}
}
return a;
}
/*----------------------------------------------------------------------------
| Normalizes the subnormal double-precision floating-point value represented
| by the denormalized significand `aSig'. The normalized exponent and
@ -4961,21 +4961,6 @@ int float32_unordered_quiet(float32 a, float32 b, float_status *status)
return 0;
}
/*----------------------------------------------------------------------------
| If `a' is denormal and we are in flush-to-zero mode then set the
| input-denormal exception and return zero. Otherwise just return the value.
*----------------------------------------------------------------------------*/
float16 float16_squash_input_denormal(float16 a, float_status *status)
{
if (status->flush_inputs_to_zero) {
if (extractFloat16Exp(a) == 0 && extractFloat16Frac(a) != 0) {
float_raise(float_flag_input_denormal, status);
return make_float16(float16_val(a) & 0x8000);
}
}
return a;
}
/*----------------------------------------------------------------------------
| Returns the result of converting the double-precision floating-point value
| `a' to the extended double-precision floating-point format. The conversion