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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Tue, 10 Jan 2023 11:08:57 -0800
Message-ID: <CAM9d7chS+91Nep8FtsJsOdTvMJ0HhkSD1_Fn70=hWPi7a1JpfQ@mail.gmail.com>
Subject: Re: [PATCH v1 1/2] perf tools: Remove HAVE_LIBTRACEEVENT_TEP_FIELD_IS_RELATIVE
To:     Ian Rogers <irogers@google.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Yang Jihong <yangjihong1@huawei.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Kim Phillips <kim.phillips@amd.com>,
        German Gomez <german.gomez@arm.com>,
        Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Eelco Chaudron <echaudro@redhat.com>,
        Leo Yan <leo.yan@linaro.org>,
        Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
        Stephane Eranian <eranian@google.com>,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
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On Mon, Jan 9, 2023 at 3:38 PM Ian Rogers <irogers@google.com> wrote:
>
> On Mon, Jan 9, 2023 at 2:57 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > Hi Ian,
> >
> > On Mon, Jan 9, 2023 at 2:31 PM Ian Rogers <irogers@google.com> wrote:
> > > diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
> > > index e188f74698dd..cfcc253239f0 100644
> > > --- a/tools/perf/util/sort.c
> > > +++ b/tools/perf/util/sort.c
> > > @@ -28,6 +28,7 @@
> > >  #include "time-utils.h"
> > >  #include "cgroup.h"
> > >  #include "machine.h"
> > > +#include "trace-event.h"
> > >  #include <linux/kernel.h>
> > >  #include <linux/string.h>
> > >
> > > @@ -2667,7 +2668,7 @@ static int64_t __sort__hde_cmp(struct perf_hpp_fmt *fmt,
> > >                 tep_read_number_field(field, a->raw_data, &dyn);
> > >                 offset = dyn & 0xffff;
> > >                 size = (dyn >> 16) & 0xffff;
> > > -#ifdef HAVE_LIBTRACEEVENT_TEP_FIELD_IS_RELATIVE
> > > +#if LIBTRACEEVENT_VERSION >= MAKE_LIBTRACEEVENT_VERSION(1, 5, 0)
> > >                 if (field->flags & TEP_FIELD_IS_RELATIVE)
> > >                         offset += field->offset + field->size;
> >
> > Maybe I missed the previous discussion.
> >
> > As it's only used in the bit test, can we have something like this
> > in the header file?
> >
> > #if LIBTRACE_EVENT_VERSION < ...(1, 5, 0)
> > # define TEP_FIELD_IS_RELATIVE  0
> > #endif
> >
> > Thanks,
> > Namhyung
>
> We could but I think we lose some of the intention revealing-ness that
> TEP_FIELD_IS_RELATIVE is only present with libtraceevent 1.5.0 or
> newer.

I'm not sure how important it is to reveal the intention.
I think we wanted to minimize #ifdef-ery in the .c file and
moved the conditionals to the header.  Maybe we can add
a wrapper like this.

#if LIBTRACEEVENT_VERSION >= ...(1, 5, 0)
static inline bool is_relative_field(field)
{
    return field->flags & TEP_FIELD_IS_RELATIVE;
}
#else
static inline bool is_relative_field(field)
{
    return false;
}
#endif

Thanks,
Namhyung