People may recall that I was hoping to build thunderbird using gcc
and g++ a little while ago, but gave up on that because the build
was taking so much longer. This week I've looked at gentoo to see
what options they use.
First, some builds using 4 cores where everything in the system was
optimized and hardened. For rust, I'm not convinced that optimizing
makes a lot of difference, but the optimizations and hardening in
gcc and clang add time to the build. The builds of rust were NOT
using CFLAGS or CXXFLAGS other than what is in the book
(enable-optimize=-O2).
1. Exactly as the book :
4781 sec 43 SBU 11G build, 173M install
2. Add --disable-debug-symbols :
4010 sec 36 SBU 4.8G build, 173M install
Clearly, --disable-debug is NOT the same as --disable-debug-symbols.
3. Add --disable-debug-symbols and --enable-linker=gold
3858 sec 34 SBU 4.8G buld, 171M install
So, unlike my past experience with te gold linker in firefox, it is
beneficial with thunderbird, at least when using clang. In
particular, it saves time.
4. To the above, I tried droppig --disable-debug.
3942 sec 35 SBU 4.8G build, 171M install
The build was 5 MB smaller, but slower, maybe normal variation?
After this I wanted to try to use gcc and g++ (export CC, CXX).
I'll skip measurements from the initial builds because after I
thought I'd completed I noticed that my build time for
firefox-78.2.0 (remeasuring because of fresher toolchain) on my
skylake where I use -O2 and hardening was way out of order. I now
think that must have been swapping.
I also checked that with the best version (for speed) I could build
with my own CFLAGS including -fstack-clash-protection which
currently causes clang to barf but may be present in clang-11. This
succeeded, using my normal optimized system gcc -
3600 sec 32 SBU 4.9G build, 179M install
Anyway, I built binutils anf gcc without passing CFLAGS (i.e. they
used '-g -O2') in /opt/toolsO2 and put those at the front of my
PATH. I remeasured my SBU, it was a little faster. [ and firefox
seemed to consistently be 32 SBU both when the 4-core SBU was
measured with the system binutils and gcc, and with the default
versions.
5. gcc with --disable-debug-symbols and --enable-linker=gold
2743 sec (!) 26 SBU 4.9G build, 177M install
I've no idea whether this amount of timesaving will be typical, but
the approach looks worthwhile.
6. gcc with only added --disable-debug-symbols
3590 sec 34 SBU 4.9G build, 177M install
It seems that gold is equally beneficial (for time to build) with
gcc, which surprised me.
7. gcc with --disable-debug-symbols and --enable-linker=gold, but
without --disable-debug.
3627 sec 34 SBU 4.9G build, 177M install.
It is not clear if --disable-debug is doing anything useful (the
build was 4M bigger without it), but omitting it seems to slow down
the build.
Normally I would say this is 10.1 material, but with the space
savings as much as the time, I wonder.
ĸen
--
Juliet's version of cleanliness was next to godliness, which was to
say it was erratic, past all understanding and was seldom seen.
-- Unseen Academicals
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