Testing gcc 5.2 and LTO

Lauri Kasanen curaga at operamail.com
Mon Aug 31 09:21:21 UTC 2015


Hi,

With my shiny new gcc 5.2 toy, I thought I'd test how its LTO worked for
bb,
and share the numbers. There were a few hundred new warnings, one
parenthesis
in ash, and all the rest about strict aliasing, mainly in minix and top.

All on x86_64, defconfig with sync_fancy and ubi* disabled.

busybox git 68acc0f8353

gcc 4.2.2: 849405 bytes 100%
gcc 5.2.0: 829369 bytes 97.6%
LTO 5.2.0: 828209 bytes 97.5%

So, the current best LTO saved a bit over a kb, that's pretty well done
for bb's manual tuning.

- Lauri

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