| Message ID | 20210603214131.629841-26-richard.henderson@linaro.org |
|---|---|
| State | Accepted |
| Commit | 572c4d862ff2b5f1525044639aa60ec5854c813d |
| Headers | show |
| Series | softfloat patch queue | expand |
On Thu, 3 Jun 2021 at 22:58, Richard Henderson <richard.henderson@linaro.org> wrote: > > Keep the intermediate results in FloatParts instead of > converting back and forth between float64. Use muladd > instead of separate mul+add. > > Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > fpu/softfloat.c | 53 +++++++++++++++++++++---------------------------- > 1 file changed, 23 insertions(+), 30 deletions(-) > > diff --git a/fpu/softfloat.c b/fpu/softfloat.c > index c32b1c7113..27306d6a93 100644 > --- a/fpu/softfloat.c > +++ b/fpu/softfloat.c > @@ -5210,47 +5210,40 @@ static const float64 float32_exp2_coefficients[15] = > > float32 float32_exp2(float32 a, float_status *status) > { > - bool aSign; > - int aExp; > - uint32_t aSig; > - float64 r, x, xn; > + FloatParts64 xp, xnp, tp, rp; Coverity points out that we declare tp here without initializing it... > int i; > - a = float32_squash_input_denormal(a, status); > > - aSig = extractFloat32Frac( a ); > - aExp = extractFloat32Exp( a ); > - aSign = extractFloat32Sign( a ); > - > - if ( aExp == 0xFF) { > - if (aSig) { > - return propagateFloat32NaN(a, float32_zero, status); > + float32_unpack_canonical(&xp, a, status); > + if (unlikely(xp.cls != float_class_normal)) { > + switch (xp.cls) { > + case float_class_snan: > + case float_class_qnan: > + parts_return_nan(&xp, status); > + return float32_round_pack_canonical(&xp, status); > + case float_class_inf: > + return xp.sign ? float32_zero : a; > + case float_class_zero: > + return float32_one; > + default: > + break; > } > - return (aSign) ? float32_zero : a; > - } > - if (aExp == 0) { > - if (aSig == 0) return float32_one; > + g_assert_not_reached(); > } > > float_raise(float_flag_inexact, status); > > - /* ******************************* */ > - /* using float64 for approximation */ > - /* ******************************* */ > - x = float32_to_float64(a, status); > - x = float64_mul(x, float64_ln2, status); > + float64_unpack_canonical(&xnp, float64_ln2, status); > + xp = *parts_mul(&xp, &tp, status); ...and then here we pass &tp to parts_mul() which looks at its various fields. Missing initializer of some sort ? (CID 1457457) thanks -- PMM
On 6/7/21 2:07 PM, Peter Maydell wrote: >> + FloatParts64 xp, xnp, tp, rp; > > Coverity points out that we declare tp here without initializing it... ... >> + float64_unpack_canonical(&xnp, float64_ln2, status); >> + xp = *parts_mul(&xp, &tp, status); > > ...and then here we pass &tp to parts_mul() which looks at > its various fields. Missing initializer of some sort ? Typo in the unpack; should have been tp. r~
diff --git a/fpu/softfloat.c b/fpu/softfloat.c index c32b1c7113..27306d6a93 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -5210,47 +5210,40 @@ static const float64 float32_exp2_coefficients[15] = float32 float32_exp2(float32 a, float_status *status) { - bool aSign; - int aExp; - uint32_t aSig; - float64 r, x, xn; + FloatParts64 xp, xnp, tp, rp; int i; - a = float32_squash_input_denormal(a, status); - aSig = extractFloat32Frac( a ); - aExp = extractFloat32Exp( a ); - aSign = extractFloat32Sign( a ); - - if ( aExp == 0xFF) { - if (aSig) { - return propagateFloat32NaN(a, float32_zero, status); + float32_unpack_canonical(&xp, a, status); + if (unlikely(xp.cls != float_class_normal)) { + switch (xp.cls) { + case float_class_snan: + case float_class_qnan: + parts_return_nan(&xp, status); + return float32_round_pack_canonical(&xp, status); + case float_class_inf: + return xp.sign ? float32_zero : a; + case float_class_zero: + return float32_one; + default: + break; } - return (aSign) ? float32_zero : a; - } - if (aExp == 0) { - if (aSig == 0) return float32_one; + g_assert_not_reached(); } float_raise(float_flag_inexact, status); - /* ******************************* */ - /* using float64 for approximation */ - /* ******************************* */ - x = float32_to_float64(a, status); - x = float64_mul(x, float64_ln2, status); + float64_unpack_canonical(&xnp, float64_ln2, status); + xp = *parts_mul(&xp, &tp, status); + xnp = xp; - xn = x; - r = float64_one; + float64_unpack_canonical(&rp, float64_one, status); for (i = 0 ; i < 15 ; i++) { - float64 f; - - f = float64_mul(xn, float32_exp2_coefficients[i], status); - r = float64_add(r, f, status); - - xn = float64_mul(xn, x, status); + float64_unpack_canonical(&tp, float32_exp2_coefficients[i], status); + rp = *parts_muladd(&tp, &xp, &rp, 0, status); + xnp = *parts_mul(&xnp, &xp, status); } - return float64_to_float32(r, status); + return float32_round_pack_canonical(&rp, status); } /*----------------------------------------------------------------------------