Kenneth Russell wrote:
> For interop, JS requires cross-browser (VM) NaN canonicalization to avoid
> observably different results on different browsers.
As long as NaN values loaded from Float32Array and Float64Array obey
ES6's semantics, such as returning true from isNaN(), then it should
not matter whether the ES6 implementation happens to support multiple
bit patterns for NaN.
That's at issue. By reading via an aliasing byte or wider integral-typed
array view, different results could be observed on two VMs for the exact
same code.
NaNs are an error condition and corner case in
floating-point algorithms, and it is important not to negatively
impact the performance of the common case in order to achieve
absolutely precise semantics for this error case.
I want "as close to the metal as safety and interop allow" performance.
I'm not sure we are actually in conflict here, given how aggressive JITs
work.
Have you measured the performance impact in any optimizing VM?
/be
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