Re: [ubsan] f0996bc297: netperf.Throughput_total_tps -7.6% regression

From: Andrey Ryabinin
Date: Mon May 20 2019 - 05:52:45 EST

On 5/20/19 8:38 AM, kernel test robot wrote:
> Greeting,
> FYI, we noticed a -7.6% regression of netperf.Throughput_total_tps due to commit:
> commit: f0996bc2978e02d2ea898101462b960f6119b18f ("ubsan: Fix nasty -Wbuiltin-declaration-mismatch GCC-9 warnings")
> master

This can't be right. First of all the commit makes changes only lib/ubsan.c which is compiled only when CONFIG_UBSAN=y.
In your config:
# CONFIG_UBSAN is not set

But even in the case of enabled UBSAN that commit doesn't change the generated machine code at all.