673262 - Determine startup impact of gold linking on Android

Status: RESOLVED INVALID

(Firefox Build System :: General, defect)

Description

[Benjamin Stover (:stechz)]

gold has the possibility of removing lots of our dead code paths, which should positively affect performance.

Comment 1

[Mike Hommey [:glandium]]

After a bit of a struggle with the NDK build system, binutils 2.20.1 not wanting to build at all, binutils 2.21.1 leading to a crash when enabling icf, I got a working setup with supposedly a checkout of the 2.21 branch from the 20th of july (but I have to double check what the tarball I got actually is, it might just be current HEAD, which is the future 2.22).

Linking with that gold with --gc-sections gets me a 15979712 bytes libxul.so.
Adding --icf=safe gets that down to 15463616, and --icf=all down to 15439040. Changing the number of icf iterations doesn't seem to have an impact.

Comment 2

[Mike Hommey [:glandium]]

(these are numbers with ndk r4c, though. I need to upgrade to ndk 5)

Comment 3

[Mike Hommey [:glandium]]

As for the impact on startup time, it has an obvious impact on the time spent uncompressing libxul.so from the apk when the libraries are not cached. Considering it takes somewhere between 500 and 600ms on my Nexus S for libxul.so alone, we'd be looking at 15 to 20ms, which is not a whole lot but can add up to all that can make libxul.so smaller.

Comment 4

[(dormant account)]

There is not much point in investigating this. Gold is required for a whole bunch of optimizations