300047 - Use -dead_strip as a linker flag for mac builds

Status: RESOLVED FIXED

(Firefox Build System :: General, defect)

Description

[Brian Ryner (not reading)]

-dead_strip works similarly to MSVC's /OPT:REF in that it discards all functions
and data which are not reachable from the exported functions of a binary.  This
allows us to strip out some of the "extra" constructors and destructors that are
emitted for classes, as well as functions that are just never called.  In my
test, this yields a couple hundred KB savings for a static firefox-bin.

Comment 1

[Brian Ryner (not reading)]

Attachment: patch

Comment 2

[Mike Pinkerton (not reading bugmail)]

Comment on attachment 188638 [details] [diff] [review]
patch

looks good, can we add this to camino's LD_FLAGS somewhere? or is it a checkbox
we can flip in the project?

Comment 3

[Simon Fraser [no longer active]]

What does this do to C++ static ctors/dtors? We still have a few in the code.

Comment 4

[Brian Ryner (not reading)]

No idea.

Comment 5

[Chase Phillips]

Let's get this in at the beginning of the gecko 1.8b4 cycle.

Comment 6

[Brian Ryner (not reading)]

Comment on attachment 188638 [details] [diff] [review]
patch

I'd like to get this in after 1.1a2.

Comment 7

[Brian Ryner (not reading)]

checked in

Comment 8

[Simon Fraser [no longer active]]

What are the effects on code size? Also, did anyopne figure out comment #3?

Comment 9

[Mark Mentovai]

Some tinderboxen have older toolchains that don't know about -dead_strip.  This
should be backed out until the tinders are ready.  Adjusting blocking.

Comment 10

[Brian Ryner (not reading)]

Attachment: patch with configure check

Check that the linker flag is supported before enabling it

Comment 11

[ozjason_bugmail]

(In reply to comment #8)
> What are the effects on code size?

My optimized builds shrank from 24.4MB to 23.7MB with this patch. A nice result,
and no problems in my limited testing so far. (I built with -Os, disabled
SVG/canvas/mathml)

Comment 12

[Mike Pinkerton (not reading bugmail)]

Comment on attachment 189251 [details] [diff] [review]
patch with configure check

r=pink

Comment 13

[Brian Ryner (not reading)]

checked in. note that atlantia, which does firefox nightlies, has new enough
build tools to support this option.