linux-kernel - Re: [PATCH] drm/i915: Remove unreachable code

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Date:   Sat, 30 Jan 2021 12:45:10 +0000
From:   Chris Wilson <chris@...is-wilson.co.uk>
To:     Vinicius Tinti <viniciustinti@...il.com>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH] drm/i915: Remove unreachable code

Quoting Vinicius Tinti (2021-01-30 12:34:11)
> On Fri, Jan 29, 2021 at 08:55:54PM +0000, Chris Wilson wrote:
> > Quoting Vinicius Tinti (2021-01-29 18:15:19)
> > > By enabling -Wunreachable-code-aggressive on Clang the following code
> > > paths are unreachable.
> > 
> > That code exists as commentary and, especially for sdvo, library
> > functions that we may need in future.
> 
> I would argue that this code could be removed since it is in git history.
> It can be restored when needed.
> 
> This will make the code cleaner.

It doesn't change the control flow, so no complexity argument. It
removes documentation from the code, so I have the opposite opinion.

> > The ivb-gt1 case => as we now set the gt level for ivb, should we not
> > enable the optimisation for ivb unaffected by the w/a? Just no one has
> > taken the time to see if it causes a regression.
> 
> I don't know. I just found out that the code is unreachable.
> 
> > For error state, the question remains whether we should revert to
> > uncompressed data if the compressed stream is larger than the original.
> 
> I don't know too.
> 
> In this last two cases the code could be commented and the decisions
> and problems explained in the comment section.

They already are, that is the point.
-Chris