557611 - Introduce a 'tweaks' system

Status: VERIFIED FIXED

(Tamarin Graveyard :: Virtual Machine, defect, P3)

Description

[Lars T Hansen]

Attachment: The tweaks system

The idea of a tweak is a mini-feature that has a default value that's usually right but that may be changed to compensate for some system bizarreness or bug.  Several of our AVMFEATURE_ names should probably become AVMTWEAK_ names because they fall into this category.

We want the same exposure for tweaks as for features, but we don't necessarily want to require every platform to worry about the available tweaks, which is why a default value is provided.  If the default value becomes abused - by using a tweak rather than a feature where a feature is called for - the default value facility may be removed in the future.

Comment 1

[Lars T Hansen]

It is probably also the case that numerous #ifdef nests in the source code can easily be converted to tweaks, for example in MathUtilsUnix.cpp we see this:

// MacOS X Intel 10.5 incorrectly make ceil(-0.5) -> 0.0 instead of -0.0
// special-case and correct.
#if defined(AVMPLUS_MAC) && (defined(AVMPLUS_IA32) || defined(AVMPLUS_AMD64))
  ...
#else
  ...
#endif

Comment 2

[Edwin Smith]

Comment on attachment 437367 [details] [diff] [review]
The tweaks system

Nothing obviously wrong, and since this blocks a 10.1 bug, i'm not applying any polishing compound to this review.

Comment 3

[Lars T Hansen]

tamarin-redux-argo changeset:   3944:a10b00432457

Comment 4

[Lars T Hansen]

Follow-up issues logged as bug #557629 and bug #557633.

Comment 5

[Brent Baker]

Marking as verified/fixed per conversation with Lars