Re: [PATCH] perf: fix wrong DEBUG configuration

[Martin LiÅka]

On 05/25/2015 08:32 PM, Ingo Molnar wrote:
> * Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> > Em Mon, May 25, 2015 at 01:12:44PM +0200, Martin LiÅka escreveu:
> > > On 05/25/2015 01:09 PM, Ingo Molnar wrote:
> > > > * Martin LiÅka <mliska@xxxxxxx> wrote:
> > > >
> > > > > > > Right optimize debugging experience is given by passing -Og to
> > > > > > > compiler. Assign default value for pointers that are identified by
> > > > > > > compiler as non-initialized.
> > > > > >
> > > > > > s/Right optimize debugging experience is given/
> > > > > >    Correct debugging experience is given/
> > > >
> > > > > Right debugging experience is given by passing -Og to compiler.
> > > >
> > > > So I fixed the spelling here once already :-/ If you want to use
> > > > 'right' in this context then use it like this:
> > > >
> > > >    The right debugging experience is given by ...
> > > >
> > > > Or you can use what I suggested first:
> > > >
> > > >    Correct debugging experience is given by ...
> > > >
> > > > Thanks,
> > > >
> > > > 	Ingo
> > >
> > > Sorry Ingo for that, I overlooked that correction :)
> >
> > Are you ok with this Ingo?
>
> Yeah, certainly!
>
> > I can apply, but there seems to be two patches folded here, one that
> > sets the possibly unitiliazed variables to NULL, and could be the
> > first in the series, and the other, that deals with multiple
> > versions of gcc and how should we ask something from them.
>
> Yeah.
>
> Thanks,
>
> 	Ingo

Hello.

As Arnaldo pointed, I split the patch to following 2 smaller patches.

Thanks,
Martin
Assign default value for pointers that are identified by the compiler as
non-initialized.

Signed-off-by: Martin Liska <mliska@xxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 tools/perf/arch/common.c            | 2 +-
 tools/perf/util/symbol.c            | 2 +-
 tools/perf/util/trace-event-parse.c | 2 +-
 3 files changed, 3 insertions(+), 3 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/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

Currently, GCC optimizes -O6 same as -O3 level, thus change the value
to -O3.
Correct debugging experience is given by passing -Og to compiler.

Signed-off-by: Martin Liska <mliska@xxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 tools/perf/config/Makefile      |  4 +++-
 tools/perf/config/utilities.mak | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
index e3b3724..47e4ae1 100644
--- a/tools/perf/config/Makefile
+++ b/tools/perf/config/Makefile
@@ -129,7 +129,9 @@ ifndef DEBUG
 endif
 
 ifeq ($(DEBUG),0)
-  CFLAGS += -O6
+  CFLAGS += -O3
+else
+  CFLAGS += $(call cc-option,-Og,-O0)
 endif
 
 ifdef PARSER_DEBUG
diff --git a/tools/perf/config/utilities.mak b/tools/perf/config/utilities.mak
index c16ce83..0ebef09 100644
--- a/tools/perf/config/utilities.mak
+++ b/tools/perf/config/utilities.mak
@@ -177,3 +177,22 @@ $(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2)))
 endef
 _ge_attempt = $(if $(get-executable),$(get-executable),$(call _gea_err,$(2)))
 _gea_err  = $(if $(1),$(error Please set '$(1)' appropriately))
+
+# try-run
+# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
+# Exit code chooses option. "$$TMP" is can be used as temporary file and
+# is automatically cleaned up.
+try-run = $(shell set -e;		\
+	TMP="$(TMPOUT).$$$$.tmp";	\
+	TMPO="$(TMPOUT).$$$$.o";	\
+	if ($(1)) >/dev/null 2>&1;	\
+	then echo "$(2)";		\
+	else echo "$(3)";		\
+	fi;				\
+	rm -f "$$TMP" "$$TMPO")
+
+# cc-option
+# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
+
+cc-option = $(call try-run,\
+	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))
-- 
2.1.4