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LibJS: Handle NaN/Infinity/Zero edge cases in Math.pow()

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This commit replaces the current simple call to LibM's pow with the
full implementation of 6.1.6.1.3 Number::exponentiate:
https://tc39.es/ecma262/#sec-numeric-types-number-exponentiate
This commit is contained in:
Idan Horowitz 2021-06-05 02:53:30 +03:00 committed by Linus Groh
parent 7507999230
commit 03255c1c53
Notes: sideshowbarker 2024-07-18 16:50:46 +09:00 
Author: https://github.com/IdanHo
Commit: https://github.com/SerenityOS/serenity/commit/03255c1c53b
Pull-request: https://github.com/SerenityOS/serenity/pull/7797
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/linusg
1 changed files with 53 additions and 1 deletions
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54
Userland/Libraries/LibJS/Runtime/MathObject.cpp
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@ -235,7 +235,59 @@ JS_DEFINE_NATIVE_FUNCTION(MathObject::tan)
JS_DEFINE_NATIVE_FUNCTION(MathObject::pow) JS_DEFINE_NATIVE_FUNCTION(MathObject::pow)
{ {
return JS::exp(global_object, vm.argument(0), vm.argument(1)); auto base = vm.argument(0).to_number(global_object);
if (vm.exception())
return {};
auto exponent = vm.argument(1).to_number(global_object);
if (vm.exception())
return {};
if (exponent.is_nan())
return js_nan();
if (exponent.is_positive_zero() || exponent.is_negative_zero())
return Value(1);
if (base.is_nan())
return js_nan();
if (base.is_positive_infinity())
return exponent.as_double() > 0 ? js_infinity() : Value(0);
if (base.is_negative_infinity()) {
auto is_odd_integral_number = exponent.is_integer() && (exponent.as_i32() % 2 != 0);
if (exponent.as_double() > 0)
return is_odd_integral_number ? js_negative_infinity() : js_infinity();
else
return is_odd_integral_number ? Value(-0.0) : Value(0);
}
if (base.is_positive_zero())
return exponent.as_double() > 0 ? Value(0) : js_infinity();
if (base.is_negative_zero()) {
auto is_odd_integral_number = exponent.is_integer() && (exponent.as_i32() % 2 != 0);
if (exponent.as_double() > 0)
return is_odd_integral_number ? Value(-0.0) : Value(0);
else
return is_odd_integral_number ? js_negative_infinity() : js_infinity();
}
VERIFY(base.is_finite_number() && !base.is_positive_zero() && !base.is_negative_zero());
if (exponent.is_positive_infinity()) {
auto absolute_base = fabs(base.as_double());
if (absolute_base > 1)
return js_infinity();
else if (absolute_base == 1)
return js_nan();
else if (absolute_base < 1)
return Value(0);
}
if (exponent.is_negative_infinity()) {
auto absolute_base = fabs(base.as_double());
if (absolute_base > 1)
return Value(0);
else if (absolute_base == 1)
return js_nan();
else if (absolute_base < 1)
return js_infinity();
}
VERIFY(exponent.is_finite_number() && !exponent.is_positive_zero() && !exponent.is_negative_zero());
if (base.as_double() < 0 && !exponent.is_integer())
return js_nan();
return Value(::pow(base.as_double(), exponent.as_double()));
} }
JS_DEFINE_NATIVE_FUNCTION(MathObject::exp) JS_DEFINE_NATIVE_FUNCTION(MathObject::exp)