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From:   Michael Ellerman <patch-notifications@ellerman.id.au>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Paul Mackerras <paulus@samba.org>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
In-Reply-To: <b286e07fb771a664b631cd07a40b09c06f26e64b.1618331881.git.christophe.leroy@csgroup.eu>
References: <b286e07fb771a664b631cd07a40b09c06f26e64b.1618331881.git.christophe.leroy@csgroup.eu>
Subject: Re: [PATCH v2 1/2] powerpc/bug: Remove specific powerpc BUG_ON() and WARN_ON() on PPC32
Message-Id: <162929393381.3619265.1023243092279572637.b4-ty@ellerman.id.au>
Date:   Wed, 18 Aug 2021 23:38:53 +1000
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On Tue, 13 Apr 2021 16:38:09 +0000 (UTC), Christophe Leroy wrote:
> powerpc BUG_ON() and WARN_ON() are based on using twnei instruction.
> 
> For catching simple conditions like a variable having value 0, this
> is efficient because it does the test and the trap at the same time.
> But most conditions used with BUG_ON or WARN_ON are more complex and
> forces GCC to format the condition into a 0 or 1 value in a register.
> This will usually require 2 to 3 instructions.
> 
> [...]

Applied to powerpc/next.

[1/2] powerpc/bug: Remove specific powerpc BUG_ON() and WARN_ON() on PPC32
      https://git.kernel.org/powerpc/c/db87a7199229b75c9996bf78117eceb81854fce2
[2/2] powerpc/bug: Provide better flexibility to WARN_ON/__WARN_FLAGS() with asm goto
      https://git.kernel.org/powerpc/c/1e688dd2a3d6759d416616ff07afc4bb836c4213

cheers