Re: [Qemu-devel] [PATCH v3 2/2] trace: Avoid implicit bool->integer conversions

["Daniel P. Berrange" <berrange@redhat.com>]

On Thu, Aug 11, 2016 at 06:11:29PM +0200, Lluís Vilanova wrote:
> An explicit if/else is clearer than arithmetic assuming #true is 1,
> while the compiler should be able to generate just as optimal code.
> 
> Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
> ---
>  stubs/trace-control.c  |    9 +++++++--
>  trace/control-target.c |   18 ++++++++++++++----
>  2 files changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/stubs/trace-control.c b/stubs/trace-control.c
> index 3740c38..099c2b5 100644
> --- a/stubs/trace-control.c
> +++ b/stubs/trace-control.c
> @@ -21,8 +21,13 @@ void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
>      TraceEventID id;
>      assert(trace_event_get_state_static(ev));
>      id = trace_event_get_id(ev);
> -    trace_events_enabled_count += state - trace_events_dstate[id];
> -    trace_events_dstate[id] = state;
> +    if (state) {
> +        trace_events_enabled_count++;
> +        trace_events_dstate[id] = 1;
> +    } else {
> +        trace_events_enabled_count--;

SHouldn't this be trace_events_enabled_count -= trace_events_dstate[id];
as it is possible to call this method for a trace event that is a per-vcpu
event

> +        trace_events_dstate[id] = 0;
> +    }
>  }
>  
>  void trace_event_set_vcpu_state_dynamic(CPUState *vcpu,
> diff --git a/trace/control-target.c b/trace/control-target.c
> index 4ee3733..4e2e727 100644
> --- a/trace/control-target.c
> +++ b/trace/control-target.c
> @@ -18,8 +18,13 @@ void trace_event_set_state_dynamic_init(TraceEvent *ev, bool state)
>      TraceEventID id = trace_event_get_id(ev);
>      assert(trace_event_get_state_static(ev));
>      /* Ignore "vcpu" property, since no vCPUs have been created yet */
> -    trace_events_enabled_count += state - trace_events_dstate[id];
> -    trace_events_dstate[id] = state;
> +    if (state) {
> +        trace_events_enabled_count++;
> +        trace_events_dstate[id] = 1;
> +    } else {
> +        trace_events_enabled_count--;
> +        trace_events_dstate[id] = 0;
> +    }


>  }
>  
>  void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
> @@ -32,8 +37,13 @@ void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
>          }
>      } else {
>          TraceEventID id = trace_event_get_id(ev);
> -        trace_events_enabled_count += state - trace_events_dstate[id];
> -        trace_events_dstate[id] = state;
> +        if (state) {
> +            trace_events_enabled_count++;
> +            trace_events_dstate[id] = 1;
> +        } else {
> +            trace_events_enabled_count--;
> +            trace_events_dstate[id] = 0;
> +        }
>      }
>  }
>  
> 

Regards,
Daniel
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