Re: [PATCH] perf: fix wrong DEBUG configuration

[Martin LiÅka]

On 05/20/2015 03:17 PM, Arnaldo Carvalho de Melo wrote:
> Em Wed, May 20, 2015 at 03:07:39PM +0200, Martin LiÅka escreveu:
> > On 05/19/2015 04:04 PM, Arnaldo Carvalho de Melo wrote:
> > > Em Tue, May 19, 2015 at 03:41:03PM +0200, Martin LiÅka escreveu:
> > > > Following patch is fix for wrong DEBUG configuration.
> > >
> > > Can you please state, in the changelog, what you think is wrong and how
> > > your proposed change fixes it, so that after reading your intent I can
> > > go and look at the code to see if it matches that?
>
> Ok, that improved things, thanks! A question:
>
> > Currently, GCC optimizes -O6 same as -O3 level. Right optimize debugging
> > experience is given by passing -Og to compiler.
>
> Is this is this -Og available in old gcc versions? When was it
> introduced? Do you know?
>
> - Arnaldo

Hi

GCC 4.8.0 is the first version capable of the option: https://gcc.gnu.org/gcc-4.8/changes.html.
That can be problematic, which GCC version do you support in linux/perf?

Martin

> > Assign default value for pointers that are identified by compiler as
> > non-initialized.
> >
> > Signed-off-by: Martin Liska <mliska@xxxxxxx>
>
> > >From b5f2b42b279ab497e92d41e1f4021dd5cb6ae3ce Mon Sep 17 00:00:00 2001
> > From: mliska <mliska@xxxxxxx>
> > Date: Thu, 2 Apr 2015 15:24:49 +0200
> > Subject: [PATCH] perf: fix wrong DEBUG configuration
> >
> > Currently, GCC optimizes -O6 same as -O3 level. Right optimize debugging
> > experience is given by passing -Og to compiler.
> > Assign default value for pointers that are identified by compiler as
> > non-initialized.
> >
> > Signed-off-by: Martin Liska <mliska@xxxxxxx>
> > ---
> >   tools/perf/arch/common.c            | 2 +-
> >   tools/perf/config/Makefile          | 2 +-
> >   tools/perf/util/symbol.c            | 2 +-
> >   tools/perf/util/trace-event-parse.c | 2 +-
> >   4 files changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/arch/common.c b/tools/perf/arch/common.c
> > index 49776f1..b7bb42c 100644
> > --- a/tools/perf/arch/common.c
> > +++ b/tools/perf/arch/common.c
> > @@ -61,7 +61,7 @@ const char *const mips_triplets[] = {
> >   static bool lookup_path(char *name)
> >   {
> >   	bool found = false;
> > -	char *path, *tmp;
> > +	char *path, *tmp = NULL;
> >   	char buf[PATH_MAX];
> >   	char *env = getenv("PATH");
> >
> > diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
> > index e3b3724..ca8d3e3 100644
> > --- a/tools/perf/config/Makefile
> > +++ b/tools/perf/config/Makefile
> > @@ -129,7 +129,7 @@ ifndef DEBUG
> >   endif
> >
> >   ifeq ($(DEBUG),0)
> > -  CFLAGS += -O6
> > +  CFLAGS += -Og
> >   endif
> >
> >   ifdef PARSER_DEBUG
> > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> > index 82a31fd..a19fbd4 100644
> > --- a/tools/perf/util/symbol.c
> > +++ b/tools/perf/util/symbol.c
> > @@ -400,7 +400,7 @@ static struct symbol *symbols__find_by_name(struct rb_root *symbols,
> >   					    const char *name)
> >   {
> >   	struct rb_node *n;
> > -	struct symbol_name_rb_node *s;
> > +	struct symbol_name_rb_node *s = NULL;
> >
> >   	if (symbols == NULL)
> >   		return NULL;
> > diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c
> > index 25d6c73..d495741 100644
> > --- a/tools/perf/util/trace-event-parse.c
> > +++ b/tools/perf/util/trace-event-parse.c
> > @@ -173,7 +173,7 @@ void parse_ftrace_printk(struct pevent *pevent,
> >   	char *line;
> >   	char *next = NULL;
> >   	char *addr_str;
> > -	char *fmt;
> > +	char *fmt = NULL;
> >
> >   	line = strtok_r(file, "\n", &next);
> >   	while (line) {
> > --
> > 2.1.4

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