1212861 - SIMD: Implement the behavior of MaybeFlushDenormal

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine: JIT, defect, P5)

Description

[Benjamin Bouvier [:bbouvier] (inactive)]

MaybeFlushDenormal is defined there:
http://tc39.github.io/ecmascript_simd/#maybe-flush-denormal

On NEON (SIMD under ARM), denormals are flushed to zero, and we don't get to get a choice. To be consistent, the interpreter needs to flush to zero as well, in this case. On x86, we don't have this issue.

I don't know if this is an issue on MIPS as well.

There are two ways of fixing this:

- either implement a platform-specific MaybeFlushDenormal that's called in the interpreter in the different functions,
- or, and this is more a crazy random idea, have a self-hosted implementation of SIMD that would be done in asm.js. That would ensure the interpreter has the same exact behavior as the platform, at least. But it means that we need a JIT backend for all platforms, which includes ARM, ARM64 (and MIPS).

Comment 1

[Benjamin Bouvier [:bbouvier] (inactive)]

SIMD.js is being removed.