[B.A.T.M.A.N.] [PATCH 0/9] Adding size relevant build options

[B.A.T.M.A.N.] [PATCH 0/9] Adding size relevant build options

[Sven Eckelmann]

Hi,

I was talking with Marek and Simon about build options which may be size
relevant. The first change is to allow the linker to check for unused code
sections. The second change is to let the compiler use get the whole source
code instead of only one source file during the final compilation step (ok,
it is originally the link step).

These changes reduce the size on an amd64 (default Debian settings with -O2) by
around 25%. The size reduction on MIPSel (default OpenWRT settings with -Os)
were only by 6%-10%. Marek were still interested and asked me to submit the
changes.

Kind regards,
	Sven

[B.A.T.M.A.N.] [PATCH 1/9] alfred: Add CFLAGS to the linker step

[Sven Eckelmann]

The GCC manual states for different parameters that the options for compilation
must also be used when linking. The options for compilation are stored in
CFLAGS and added to LINK.o to fix the behavior.

Option which need this are for example -fPIC/-fPIE or -flto.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 Makefile     | 2 +-
 vis/Makefile | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 268a156..aeee2e8 100644
--- a/Makefile
+++ b/Makefile
@@ -42,7 +42,7 @@ RM ?= rm -f
 INSTALL ?= install
 MKDIR ?= mkdir -p
 COMPILE.c = $(Q_CC)$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
-LINK.o = $(Q_LD)$(CC) $(LDFLAGS) $(TARGET_ARCH)
+LINK.o = $(Q_LD)$(CC) $(CFLAGS) $(LDFLAGS) $(TARGET_ARCH)
 
 # standard install paths
 PREFIX = /usr/local
diff --git a/vis/Makefile b/vis/Makefile
index 5ec0423..8585f9a 100644
--- a/vis/Makefile
+++ b/vis/Makefile
@@ -42,7 +42,7 @@ RM ?= rm -f
 INSTALL ?= install
 MKDIR ?= mkdir -p
 COMPILE.c = $(Q_CC)$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
-LINK.o = $(Q_LD)$(CC) $(LDFLAGS) $(TARGET_ARCH)
+LINK.o = $(Q_LD)$(CC) $(CFLAGS) $(LDFLAGS) $(TARGET_ARCH)
 
 # standard install paths
 PREFIX = /usr/local
-- 
1.8.2.1

[B.A.T.M.A.N.] [PATCH 2/9] batctl: Add CFLAGS to the linker step

[Sven Eckelmann]

The GCC manual states for different parameters that the options for compilation
must also be used when linking. The options for compilation are stored in
CFLAGS and added to LINK.o to fix the behavior.

Option which need this are for example -fPIC/-fPIE or -flto.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 61b24c6..1961298 100755
--- a/Makefile
+++ b/Makefile
@@ -53,7 +53,7 @@ RM ?= rm -f
 INSTALL ?= install
 MKDIR ?= mkdir -p
 COMPILE.c = $(Q_CC)$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
-LINK.o = $(Q_LD)$(CC) $(LDFLAGS) $(TARGET_ARCH)
+LINK.o = $(Q_LD)$(CC) $(CFLAGS) $(LDFLAGS) $(TARGET_ARCH)
 
 # standard install paths
 PREFIX = /usr/local
-- 
1.8.2.1

[B.A.T.M.A.N.] [PATCH 3/9] batmand: Add CFLAGS to the linker step

[Sven Eckelmann]

The GCC manual states for different parameters that the options for compilation
must also be used when linking. The options for compilation are stored in
CFLAGS and added to LINK.o to fix the behavior.

Option which need this are for example -fPIC/-fPIE or -flto.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index ce1e198..721f20b 100755
--- a/Makefile
+++ b/Makefile
@@ -57,7 +57,7 @@ RM ?= rm -f
 INSTALL ?= install
 MKDIR ?= mkdir -p
 COMPILE.c = $(Q_CC)$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
-LINK.o = $(Q_LD)$(CC) $(LDFLAGS) $(TARGET_ARCH)
+LINK.o = $(Q_LD)$(CC) $(CFLAGS) $(LDFLAGS) $(TARGET_ARCH)
 
 # standard install paths
 PREFIX = /usr/local
-- 
1.8.2.1

[B.A.T.M.A.N.] [PATCH 4/9] vis: Add CFLAGS to the linker step

[Sven Eckelmann]

The GCC manual states for different parameters that the options for compilation
must also be used when linking. The options for compilation are stored in
CFLAGS and added to LINK.o to fix the behavior.

Option which need this are for example -fPIC/-fPIE or -flto.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index c4220f5..0d49c7e 100755
--- a/Makefile
+++ b/Makefile
@@ -43,7 +43,7 @@ RM ?= rm -f
 INSTALL ?= install
 MKDIR ?= mkdir -p
 COMPILE.c = $(Q_CC)$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
-LINK.o = $(Q_LD)$(CC) $(LDFLAGS) $(TARGET_ARCH)
+LINK.o = $(Q_LD)$(CC) $(CFLAGS) $(LDFLAGS) $(TARGET_ARCH)
 
 # standard install paths
 PREFIX = /usr/local
-- 
1.8.2.1

[B.A.T.M.A.N.] [PATCH 5/9] alfred: Use section garbage collection to reduce binary size

[Sven Eckelmann]

The linker can identify unused sections of a binary when each symbol is stored
in a separate section. This mostly removes the unused debugfs function and
reduces the size by ~5% on mipsel.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 alfred/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/alfred/Makefile b/alfred/Makefile
index 4578c3b..ab19325 100644
--- a/alfred/Makefile
+++ b/alfred/Makefile
@@ -44,6 +44,9 @@ endef
 MAKE_ALFRED_FLAGS=\
 	CONFIG_ALFRED_VIS=$(if $(CONFIG_PACKAGE_ALFRED_VIS),y,n)
 
+TARGET_CFLAGS  += -ffunction-sections -fdata-sections
+TARGET_LDFLAGS += -Wl,--gc-sections
+
 define Build/Compile
 	CFLAGS="$(TARGET_CPPFLAGS) $(TARGET_CFLAGS)" \
 	LDFLAGS="$(TARGET_LDFLAGS)" \
-- 
1.8.2.1

[B.A.T.M.A.N.] [PATCH 6/9] alfred: Enable Link-time optimization

[Sven Eckelmann]

Link-time optimization allows to move parts of the optimization from the single
source file to the global source view. This is done by emitting the GIMPLE
representation in each object file and analyzing it again during the link step.

This reduces the binary size by around 10% on mipsel (this includes parts which
were also removed by garbage collection).

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 alfred/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/alfred/Makefile b/alfred/Makefile
index ab19325..2656d1c 100644
--- a/alfred/Makefile
+++ b/alfred/Makefile
@@ -44,8 +44,8 @@ endef
 MAKE_ALFRED_FLAGS=\
 	CONFIG_ALFRED_VIS=$(if $(CONFIG_PACKAGE_ALFRED_VIS),y,n)
 
-TARGET_CFLAGS  += -ffunction-sections -fdata-sections
-TARGET_LDFLAGS += -Wl,--gc-sections
+TARGET_CFLAGS  += -ffunction-sections -fdata-sections -flto
+TARGET_LDFLAGS += -Wl,--gc-sections -fuse-linker-plugin
 
 define Build/Compile
 	CFLAGS="$(TARGET_CPPFLAGS) $(TARGET_CFLAGS)" \
-- 
1.8.2.1

[B.A.T.M.A.N.] [PATCH 7/9] batman-adv-devel: Add missing TARGET_* flags to batctl compile

[Sven Eckelmann]

The compilation step of batctl completely dropped the TARGET_CFLAGS,
TARGET_CPPFLAGS and TARGET_LDFLAGS and therefore weren't compiled and linked
with the flags given by the OpenWRT build environment.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 batman-adv-devel/Makefile | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/batman-adv-devel/Makefile b/batman-adv-devel/Makefile
index 0958f38..b9e2650 100644
--- a/batman-adv-devel/Makefile
+++ b/batman-adv-devel/Makefile
@@ -85,7 +85,9 @@ $(eval $(call Download,batctl))
 
 BATCTL_EXTRACT = tar xzf "$(DL_DIR)/$(PKG_BATCTL_FNAME)" -C "$(BUILD_DIR)/$(PKG_NAME)"
 BATCTL_PATCH = $(call Build/DoPatch,"$(PKG_BATCTL_BUILD_DIR)","$(PATCH_DIR)","*batctl*")
-BATCTL_BUILD = $(MAKE) -C $(PKG_BATCTL_BUILD_DIR) $(MAKE_BATCTL_ARGS)
+BATCTL_BUILD =	CPPFLAGS="$(TARGET_CPPFLAGS)" CFLAGS="$(TARGET_CFLAGS)" \
+		LDFLAGS="$(TARGET_LDFLAGS)" \
+		$(MAKE) -C $(PKG_BATCTL_BUILD_DIR) $(MAKE_BATCTL_ARGS)
 BATCTL_INSTALL = $(INSTALL_BIN) $(PKG_INSTALL_DIR)/usr/local/sbin/batctl $(1)/usr/sbin/
 endif
 
-- 
1.8.2.1

[B.A.T.M.A.N.] [PATCH 8/9] batman-adv-devel: Use section garbage collection to reduce binary size

[Sven Eckelmann]

The linker can identify unused sections of a binary when each symbol is stored
in a separate section. This mostly removes unused linker sections and reduces
the size by ~3% on mipsel.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 batman-adv-devel/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/batman-adv-devel/Makefile b/batman-adv-devel/Makefile
index b9e2650..6dc66b8 100644
--- a/batman-adv-devel/Makefile
+++ b/batman-adv-devel/Makefile
@@ -76,6 +76,9 @@ MAKE_BATCTL_ARGS += \
 	STRIP="/bin/true" \
 	batctl install
 
+TARGET_CFLAGS  += -ffunction-sections -fdata-sections
+TARGET_LDFLAGS += -Wl,--gc-sections
+
 ifneq ($(DEVELOPER)$(CONFIG_KMOD_BATMAN_ADV_DEVEL_BATCTL),)
 define Download/batctl
   FILE:=$(PKG_BATCTL_FNAME)
-- 
1.8.2.1

[B.A.T.M.A.N.] [PATCH 5/9] batman-adv-devel: Enable Link-time optimization

[Sven Eckelmann]

Link-time optimization allows to move parts of the optimization from the single
source file to the global source view. This is done by emitting the GIMPLE
representation in each object file and analyzing it again during the link step.

This reduces the binary size by around 6% on mipsel (this includes parts which
were also removed by garbage collection).

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 batman-adv-devel/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/batman-adv-devel/Makefile b/batman-adv-devel/Makefile
index 6dc66b8..cad95c6 100644
--- a/batman-adv-devel/Makefile
+++ b/batman-adv-devel/Makefile
@@ -76,8 +76,8 @@ MAKE_BATCTL_ARGS += \
 	STRIP="/bin/true" \
 	batctl install
 
-TARGET_CFLAGS  += -ffunction-sections -fdata-sections
-TARGET_LDFLAGS += -Wl,--gc-sections
+TARGET_CFLAGS  += -ffunction-sections -fdata-sections -flto
+TARGET_LDFLAGS += -Wl,--gc-sections -fuse-linker-plugin
 
 ifneq ($(DEVELOPER)$(CONFIG_KMOD_BATMAN_ADV_DEVEL_BATCTL),)
 define Download/batctl
-- 
1.8.2.1

Re: [B.A.T.M.A.N.] [PATCH 2/9] batctl: Add CFLAGS to the linker step

[Marek Lindner]

On Tuesday, May 07, 2013 20:51:02 Sven Eckelmann wrote:
> The GCC manual states for different parameters that the options for
> compilation must also be used when linking. The options for compilation
> are stored in CFLAGS and added to LINK.o to fix the behavior.
> 
> Option which need this are for example -fPIC/-fPIE or -flto.
> 
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  Makefile | 2 +-

Applied in revision b80d07f.

Thanks,
Marek

Re: [B.A.T.M.A.N.] [PATCH 7/9] batman-adv-devel: Add missing TARGET_* flags to batctl compile

[Marek Lindner]

On Tuesday, May 07, 2013 20:51:07 Sven Eckelmann wrote:
> The compilation step of batctl completely dropped the TARGET_CFLAGS,
> TARGET_CPPFLAGS and TARGET_LDFLAGS and therefore weren't compiled and
> linked with the flags given by the OpenWRT build environment.

It seems you missed the meaning of MAKE_BATCTL_ARGS ? This variable contains 
TARGET_CFLAGS already. We apparently are missing TARGET_CPPFLAGS and 
TARGET_LDFLAGS. Do you want to resend and make the necessary changes to 
MAKE_BATCTL_ARGS ?

Cheers,
Marek

Re: [B.A.T.M.A.N.] [PATCH 7/9] batman-adv-devel: Add missing TARGET_* flags to batctl compile

[Sven Eckelmann]

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On Wednesday 08 May 2013 13:11:57 Marek Lindner wrote:
> On Tuesday, May 07, 2013 20:51:07 Sven Eckelmann wrote:
> > The compilation step of batctl completely dropped the TARGET_CFLAGS,
> > TARGET_CPPFLAGS and TARGET_LDFLAGS and therefore weren't compiled and
> > linked with the flags given by the OpenWRT build environment.
> 
> It seems you missed the meaning of MAKE_BATCTL_ARGS ? This variable contains
> TARGET_CFLAGS already. We apparently are missing TARGET_CPPFLAGS and
> TARGET_LDFLAGS. Do you want to resend and make the necessary changes to
> MAKE_BATCTL_ARGS ?

I didn't felt like fixing your other problems too, but sent two other patches 
resolving the MAKE_BATCTL_ARGS problem. See 
[Bonus-PATCH 10/9] batman-adv-devel: Don't overwrite batctl's CFLAGS
[Bonus-PATCH 11/9] batman-adv-devel: Remove unused parameters from 
MAKE_BATCTL_ARGS

Kind regards,
	Sven

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Re: [B.A.T.M.A.N.] [PATCH 7/9] batman-adv-devel: Add missing TARGET_* flags to batctl compile

[Marek Lindner]

On Wednesday, May 08, 2013 15:24:50 Sven Eckelmann wrote:
> On Wednesday 08 May 2013 13:11:57 Marek Lindner wrote:
> > On Tuesday, May 07, 2013 20:51:07 Sven Eckelmann wrote:
> > > The compilation step of batctl completely dropped the TARGET_CFLAGS,
> > > TARGET_CPPFLAGS and TARGET_LDFLAGS and therefore weren't compiled and
> > > linked with the flags given by the OpenWRT build environment.
> > 
> > It seems you missed the meaning of MAKE_BATCTL_ARGS ? This variable
> > contains TARGET_CFLAGS already. We apparently are missing
> > TARGET_CPPFLAGS and TARGET_LDFLAGS. Do you want to resend and make the
> > necessary changes to MAKE_BATCTL_ARGS ?
> 
> I didn't felt like fixing your other problems too, but sent two other
> patches resolving the MAKE_BATCTL_ARGS problem. See
> [Bonus-PATCH 10/9] batman-adv-devel: Don't overwrite batctl's CFLAGS
> [Bonus-PATCH 11/9] batman-adv-devel: Remove unused parameters from
> MAKE_BATCTL_ARGS

Applied with minor modifications in revision f41a85c.

Thanks for the explanations as to why that is helpful.

Thanks,
Marek

Re: [B.A.T.M.A.N.] [PATCH 8/9] batman-adv-devel: Use section garbage collection to reduce binary size

[Marek Lindner]

On Tuesday, May 07, 2013 20:51:08 Sven Eckelmann wrote:
> The linker can identify unused sections of a binary when each symbol is
> stored in a separate section. This mostly removes unused linker sections
> and reduces the size by ~3% on mipsel.
> 
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  batman-adv-devel/Makefile | 3 +++
>  1 file changed, 3 insertions(+)

Applied in revision 3e056f3.

Thanks,
Marek

Re: [B.A.T.M.A.N.] [PATCH 5/9] batman-adv-devel: Enable Link-time optimization

[Marek Lindner]

On Tuesday, May 07, 2013 20:51:09 Sven Eckelmann wrote:
> Link-time optimization allows to move parts of the optimization from the
> single source file to the global source view. This is done by emitting the
> GIMPLE representation in each object file and analyzing it again during
> the link step.
> 
> This reduces the binary size by around 6% on mipsel (this includes parts
> which were also removed by garbage collection).
> 
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  batman-adv-devel/Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Applied in revision e25de79.

Thanks,
Marek

Re: [B.A.T.M.A.N.] [PATCH 1/9] alfred: Add CFLAGS to the linker step

[Simon Wunderlich]

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On Tue, May 07, 2013 at 02:51:01PM +0200, Sven Eckelmann wrote:
> The GCC manual states for different parameters that the options for compilation
> must also be used when linking. The options for compilation are stored in
> CFLAGS and added to LINK.o to fix the behavior.
> 
> Option which need this are for example -fPIC/-fPIE or -flto.
> 
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  Makefile     | 2 +-
>  vis/Makefile | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)

Applied in revision c693d67.

Thanks,
	Simon

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Re: [B.A.T.M.A.N.] [PATCH 5/9] alfred: Use section garbage collection to reduce binary size

[Simon Wunderlich]

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On Tue, May 07, 2013 at 02:51:05PM +0200, Sven Eckelmann wrote:
> The linker can identify unused sections of a binary when each symbol is stored
> in a separate section. This mostly removes the unused debugfs function and
> reduces the size by ~5% on mipsel.
> 
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  alfred/Makefile | 3 +++
>  1 file changed, 3 insertions(+)

Applied in revision fa23641 (alfred package feed).

Thanks,
	Simon

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Re: [B.A.T.M.A.N.] [PATCH 6/9] alfred: Enable Link-time optimization

[Simon Wunderlich]

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On Tue, May 07, 2013 at 02:51:06PM +0200, Sven Eckelmann wrote:
> Link-time optimization allows to move parts of the optimization from the single
> source file to the global source view. This is done by emitting the GIMPLE
> representation in each object file and analyzing it again during the link step.
> 
> This reduces the binary size by around 10% on mipsel (this includes parts which
> were also removed by garbage collection).
> 
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  alfred/Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
Applied in revision bbc581c (alfred package feed).

Thanks,
    Simon


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