1116773 - BaldrMonkey: Support addresses with scaled indices

Status: RESOLVED INACTIVE

(Core :: JavaScript: WebAssembly, enhancement, P5)

Description

[Dan Gohman [:sunfish]]

Bug 986981 is adding support for folding constant offsets into addresses. For x64 at least, we can also support scaled-index addressing in the same way, by increasing the size of the guard region.

Comment 1

[Luke Wagner [:luke]]

Heh, yeah, for a while Odin mmap'd 35gb.  My only concern is the recent issues we've seen with OSes capping virtual address space far below the 47-bit theoretical limit.  Lars already added a mitigation for this:
  http://hg.mozilla.org/mozilla-central/diff/9756bf697be4/js/src/vm/SharedArrayObject.cpp#l1.13
so we might need to extend it to normal asm.js array buffers (since it will be so much easier to hit).

Comment 2

[Benjamin Bouvier [:bbouvier] (inactive)]

It seems like it would require matching JS patterns, and it doesn't seem to be planned for wasm as far as i can see. That being said, this could probably be made as part of the EEA or something, so let's keep it.

Comment 3

[BMO Automation]

Per policy at https://wiki.mozilla.org/Bug_Triage/Projects/Bug_Handling/Bug_Husbandry#Inactive_Bugs. If this bug is not an enhancement request or a bug not present in a supported release of Firefox, then it may be reopened.

Comment 4

[Lars T Hansen [:lth]]

We won't do this for asm.js but we might still want to do it for wasm.