From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH v2] net/core: Fix BUG to BUG_ON conditionals.
Date: Mon, 09 Oct 2017 16:17:08 -0700 (PDT)
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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date: Mon, 9 Oct 2017 16:06:20 -0700

>> For these archs, wouldn't it then be more efficient to use BUG_ON
>> rather than BUG()?
> 
> why more efficient? any data to prove that?

It can completely eliminate a branch.

For example on powerpc if you use BUG() then the code generated is:

	test condition
	branch_not_true	1f
	unconditional_trap
1:

Whereas with BUG_ON() it's just:

	test condition
	trap_if_true

Which is a lot better even when the branches in the first case are
well predicted.