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LibJS: Correctly handle NaN and negative infinity in Math.atan2

Browse source 
The current implementation was missing an early return on a NaN
argument and mixed up a couple of the positive/negative infinity early
returns.
This commit is contained in:
Idan Horowitz 2021-06-05 03:40:28 +03:00 • committed by Linus Groh
parent 57a52094d1
commit e2fb7943f7
1 changed files with 55 additions and 35 deletions
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90
Userland/Libraries/LibJS/Runtime/MathObject.cpp
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@ -1,6 +1,7 @@
/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2020, Linus Groh <linusg@serenityos.org>
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -420,44 +421,63 @@ JS_DEFINE_NATIVE_FUNCTION(MathObject::cbrt)
JS_DEFINE_NATIVE_FUNCTION(MathObject::atan2)
{
auto y = vm.argument(0).to_number(global_object), x = vm.argument(1).to_number(global_object);
auto pi_4 = M_PI_2 / 2;
auto three_pi_4 = pi_4 + M_PI_2;
auto constexpr three_quarters_pi = M_PI_4 + M_PI_2;
auto y = vm.argument(0).to_number(global_object);
if (vm.exception())
return {};
auto x = vm.argument(1).to_number(global_object);
if (vm.exception())
return {};
if (x.is_positive_zero()) {
if (y.is_positive_zero() || y.is_negative_zero())
return y;
else
return (y.as_double() > 0) ? Value(M_PI_2) : Value(-M_PI_2);
}
if (x.is_negative_zero()) {
if (y.is_positive_zero())
return Value(M_PI);
else if (y.is_negative_zero())
return Value(-M_PI);
else
return (y.as_double() > 0) ? Value(M_PI_2) : Value(-M_PI_2);
}
if (x.is_positive_infinity()) {
if (y.is_infinity())
return (y.is_positive_infinity()) ? Value(pi_4) : Value(-pi_4);
else
return (y.as_double() > 0) ? Value(+0.0) : Value(-0.0);
}
if (x.is_negative_infinity()) {
if (y.is_infinity())
return (y.is_positive_infinity()) ? Value(three_pi_4) : Value(-three_pi_4);
else
return (y.as_double() > 0) ? Value(M_PI) : Value(-M_PI);
}
if (y.is_infinity())
return (y.is_positive_infinity()) ? Value(M_PI_2) : Value(-M_PI_2);
if (y.is_positive_zero())
return (x.as_double() > 0) ? Value(+0.0) : Value(M_PI);
if (y.is_negative_zero())
return (x.as_double() > 0) ? Value(-0.0) : Value(-M_PI);
if (y.is_nan() || x.is_nan())
return js_nan();
if (y.is_positive_infinity()) {
if (x.is_positive_infinity())
return Value(M_PI_4);
else if (x.is_negative_infinity())
return Value(three_quarters_pi);
else
return Value(M_PI_2);
}
if (y.is_negative_infinity()) {
if (x.is_positive_infinity())
return Value(-M_PI_4);
else if (x.is_negative_infinity())
return Value(-three_quarters_pi);
else
return Value(-M_PI_2);
}
if (y.is_positive_zero()) {
if (x.as_double() > 0 || x.is_positive_zero())
return Value(0.0);
else
return Value(M_PI);
}
if (y.is_negative_zero()) {
if (x.as_double() > 0 || x.is_positive_zero())
return Value(-0.0);
else
return Value(-M_PI);
}
VERIFY(y.is_finite_number() && !y.is_positive_zero() && !y.is_negative_zero());
if (y.as_double() > 0) {
if (x.is_positive_infinity())
return Value(0);
else if (x.is_negative_infinity())
return Value(M_PI);
else if (x.is_positive_zero() || x.is_negative_zero())
return Value(M_PI_2);
}
if (y.as_double() < 0) {
if (x.is_positive_infinity())
return Value(-0.0);
else if (x.is_negative_infinity())
return Value(-M_PI);
else if (x.is_positive_zero() || x.is_negative_zero())
return Value(-M_PI_2);
}
VERIFY(x.is_finite_number() && !x.is_positive_zero() && !x.is_negative_zero());
return Value(::atan2(y.as_double(), x.as_double()));
}