383607 - Add ARM pure endian double support to JS engine

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement)

Description

[Gavin Reaney]

Attachment: Add pure endian double support for ARM

Spidermonkey builds that target ARM processors assume that doubles are mixed endian (meaning that the low and high words don't match the natural CPU endian-ness).

This is true when targetting an FPA floating point unit (or soft FPA) on little endian ARMs. VFP (and soft VFP) use pure endian doubles so the macros in jsnum.h are incorrect for this case.

Affected architecture: ARM VFP and ARM soft VFP
Affects mobile devices OSes.

The attached diff should solve the issue. Note that the macro detects VFP rather than FPA so we don't risk breaking old compilers that may not set FPA - these behave as before (the wince ARM compiler comes to mind).

Comment 1

[Gavin Reaney]

Comment on attachment 267586 [details] [diff] [review]
Add pure endian double support for ARM

Brian, can you take a look?

I've tested this by running relevant ECMA tests on an arm linux PDA (soft FPA).

Also verified a VFP build on a symbian device.

Checked that building for wince 4 and 5 falls into the same branches of ifdefs as before.

Comment 2

[Brian Crowder]

Comment on attachment 267586 [details] [diff] [review]
Add pure endian double support for ARM

Thanks, Gavin, looks good to me.

Comment 3

[Doug Turner (:dougt)]

tested against wince5 arm and no problems found.

Comment 4

[Brian Crowder]

jsnum.h: 3.29