Re: [PATCH 07/25] hrtimer: Reduce conditional code (hres_active)

From: Peter Zijlstra
Date: Mon Sep 25 2017 - 09:55:54 EST


On Thu, Aug 31, 2017 at 12:23:36PM -0000, Anna-Maria Gleixner wrote:
> The hrtimer_cpu_base struct has the CONFIG_HIGH_RES_TIMERS conditional
> struct member hres_active. All related functions to this member are
> conditional as well.
>
> There is no functional change, when the hres_active member is unconditional
> with all related functions and is set to zero during initialization. This
> makes the code easier to read.

But you make what was a compile time dead-code-elimination into a
runtime load-and-branch.

Unless the compiler is overly clever and is able to deduce from the lack
of assignments that it must always be 0, is it?