fix(math): correct Math.asinh for large finite inputs

[HiteshShonak]

This Pull Request fixes/closes #5239.

It changes the following:

• When the absolute value of the input is finite and greater than 1/√f64::EPSILON (67_108_864.0), fall back to n.signum() * (n.abs().ln() + LN_2) instead of calling f64::asinh() directly, avoiding an internal overflow that produces Infinity. threshold follows the Boost math library convention.
• Add regression tests for Math.asinh(1e308), Math.asinh(-1e308), and Math.asinh(Number.MAX_VALUE).

Testing:

cargo test -p boa_engine math -- --nocapture

Spec reference: https://tc39.es/ecma262/#sec-math.asinh

[Copilot]

Pull request overview

Fixes Math.asinh returning Infinity for very large finite inputs by introducing a large-input fallback formula consistent with common libm/Boost behavior, and adds regression tests to prevent recurrence.

Changes:

• Add a large-input threshold in Math.asinh to compute sign(x) * (ln(|x|) + LN_2) for large finite x, avoiding overflow in f64::asinh().
• Add regression tests for Math.asinh(1e308), Math.asinh(-1e308), and Math.asinh(Number.MAX_VALUE).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
core/engine/src/builtins/math/mod.rs	Adds a large-input branch to keep Math.asinh finite for extremely large finite numbers.
core/engine/src/builtins/math/tests.rs	Adds regression coverage for large finite inputs that previously overflowed to infinities.

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[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	50,545	50,545	0
Ignored	1,426	1,426	0
Failed	992	992	0
Panics	2	2	0
Conformance	95.43%	95.43%	0.00%

Tested main commit: 5b0f62ad860a2f5e2a4631ac2f280642cf7e21ea
Tested PR commit: 94fb037d70fb0330dd92c403a116c5f775a19d59
Compare commits: 5b0f62a...94fb037

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.83%. Comparing base (6ddc2b4) to head (94fb037).
⚠️ Report is 917 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5240       +/-   ##
===========================================
+ Coverage   47.24%   59.83%   +12.58%     
===========================================
  Files         476      582      +106     
  Lines       46892    63459    +16567     
===========================================
+ Hits        22154    37968    +15814     
- Misses      24738    25491      +753     

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[jedel1043]

Do we want to use the better approximation here? (ln |2x| + 1/(4x^2))

We can decompose it to avoid overflowing into infinity:

ln 2x + 1/(4x^2) = ln x + ln 2 + (1/2 * 1/x)(1/2 * 1/x)

[Veercodeprog]

could you check this:
i have made updates as you suggested
#5241

[jedel1043]

@Veercodeprog don't try to take over already assigned work, please.

[Veercodeprog]

are there any unassigned issues?

[HiteshShonak]

@jedel1043 updated to use the more accurate approximation ln(|x|) + ln(2) + 1/(4x²) as suggested, thanks