Re: [PATCH] perf: fix wrong DEBUG configuration

["Martin Liška" <mliska@suse.cz>]

[-- Attachment #1: Type: text/plain, Size: 1998 bytes --]

On 05/22/2015 09:02 AM, Ingo Molnar wrote:
>
> * Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>
>> Em Wed, May 20, 2015 at 06:16:51PM +0200, Martin Liška escreveu:
>>> On 05/20/2015 04:55 PM, Ingo Molnar wrote:
>>>> * Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>>>>> So the rule has been: What are the kernel requirements for the
>>>>> toolchain? tools/perf/ should build with that.
>>>>
>>>> So we could use -Og if it works, like Kbuild does it:
>>>>
>>>>          KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
>>>>
>>>> the 'cc-option' Make function does some magic of silently calling GCC
>>>> with that option and observing the result.
>>
>>>> See:
>>
>>>>    scripts/Kbuild.include:cc-option = $(call try-run,\
>>
>>> I am sorry, I did mistake in understanding of DEBUG variable.
>>> Following patch should be fixed, except missing auto-detection
>>> of -Og option.
>>>
>>> Unfortunately, following hunk does not work, no -Ox is added to CFLAGS?
>>>
>>> --  CFLAGS += -Og
>>> ++  CFLAGS += $(call cc-option,-Og,-O0)
>>
>> I don't know if we have this cc-option, perhaps Ingo is suggesting
>> we get it in tools/build/? Or include scripts/Kbuild.include and
>> then use it?
>>
>> I.e. we have checks to see if we can use, for instance
>> -fstack-protector-all, see tools/build/feature/Makefile, using this
>> cc-option thing, importing it from Kbuild would solve the issue at
>> hand in a definitive way and in line with what we have been
>> pursuing: to make the tools/ build system be based on Kbuild.
>
> So I'd suggest copying any necessary functions instead of outright
> including all of Kbuild in the tooling build system which creates
> non-trivial dependencies that is not necessarily tested as thoroughly
> on the kbuild side as on the tooling side.
>
> Thanks,
>
> 	Ingo
>

Hi.

Thanks for advice, I copied necessary functions to include/utilities.mak.
Following patch works for, tested both with a compiler capable of -Og and
a not capable one.

Thanks,
Martin

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Currently, GCC optimizes -O6 same as -O3 level, thus change the value
to -O6.
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@suse.cz>
---
 tools/perf/arch/common.c            |  2 +-
 tools/perf/config/Makefile          |  4 +++-
 tools/perf/config/utilities.mak     | 19 +++++++++++++++++++
 tools/perf/util/symbol.c            |  2 +-
 tools/perf/util/trace-event-parse.c |  2 +-
 5 files changed, 25 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..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))
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