717311 - gfxUnicodePropertyData.cpp:sCatEAWValues takes up more space than it should

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Nathan Froyd [:froydnj]]

gfxUnicodePropertyData.cpp:sCatEAWValues is an array of:

struct {
  unsigned int mEAW:3;
  unsigned int mCategory:5;
}

Unfortunately, this actually winds up wasting space because of structure padding inserted to maintain alignment.

Patch coming up.

Comment 1

[Nathan Froyd [:froydnj]]

Attachment: pack bits manually

Instead of using a structure with bitfields, pack things manually.

Saves a little over 70K of data.

Comment 2

[Jonathan Kew [:jfkthame]]

Hmm... you're right, it does end up wasting space. :( However, wouldn't a simpler patch be to declare the fields as unsigned char (with the appropriate field widths)? That would avoid the need for manually packing/unpacking the fields, which just makes the code more opaque.

Comment 3

[Nathan Froyd [:froydnj]]

Attachment: change bitfield datatype

Indeed, that works just as well and produces a much smaller patch. :)

Comment 4

[Jonathan Kew [:jfkthame]]

Comment on attachment 587875 [details] [diff] [review]
change bitfield datatype

Great, let's go with this - thanks.

Comment 5

[Jonathan Kew [:jfkthame]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/6bf51f18e69e

Comment 6

[Ed Morley [:emorley]]

Backed out of inbound, since that push caused test crashes, though presumably just bug 708075:
https://tbpl.mozilla.org/?tree=Mozilla-Inbound&rev=f94f83c7f2df

https://hg.mozilla.org/integration/mozilla-inbound/rev/76fc8cdd2a31

Comment 7

[Jonathan Kew [:jfkthame]]

Re-landed on inbound, as this wasn't responsible for the problems on the previous push:
https://hg.mozilla.org/integration/mozilla-inbound/rev/9e52edb8a534

Comment 8

[Marco Bonardo [:mak] (Away 10-21 August)]

https://hg.mozilla.org/mozilla-central/rev/9e52edb8a534