diff mbox

[1/3] GCC plugin infrastructure

Message ID 20160207222844.dc001c6608c3f3f4cb7a8e22@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Emese Revfy Feb. 7, 2016, 9:28 p.m. UTC 
This patch allows to build the whole kernel with GCC plugins. It was ported from
grsecurity/PaX. The infrastructure supports building out-of-tree modules and
building in a separate directory. Cross-compilation is supported too but
currently only the x86 architecture enables plugins.

The directory of the gcc plugins is tools/gcc. You can use a file or a directory
there. The plugins compile with these options:
 * -fno-rtti: gcc is compiled with this option so the plugins must use it too
 * -fno-exceptions: this is inherited from gcc too
 * -fasynchronous-unwind-tables: this is inherited from gcc too
 * -ggdb: it is useful for debugging a plugin (better backtrace on internal
    errors)
 * -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h)
 * -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version
    variable, plugin-version.h)

The infrastructure introduces a new Makefile target called gcc-plugins. It
supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script
chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++).
This script also checks the availability of the included headers in
tools/gcc/gcc-common.h.

The gcc-common.h header contains frequently included headers for GCC plugins
and it has a compatibility layer for the supported gcc versions.

Note that 'make clean' keeps the *.so files (only the distclean or mrproper
targets clean all) because they are needed for out-of-tree modules.

---
 Documentation/dontdiff   |   1 +
 Makefile                 |  66 +++-
 arch/Kconfig             |  10 +
 arch/x86/Kconfig         |   1 +
 init/Makefile            |   3 +
 scripts/Makefile.build   |   2 +-
 scripts/Makefile.clean   |   3 +-
 scripts/Makefile.host    |  69 +++-
 scripts/gcc-plugin.sh    |  51 +++
 scripts/link-vmlinux.sh  |   2 +-
 scripts/package/builddeb |   1 +
 tools/gcc/Makefile       |  15 +
 tools/gcc/gcc-common.h   | 794 +++++++++++++++++++++++++++++++++++++++++++++++
 13 files changed, 1003 insertions(+), 15 deletions(-)
 create mode 100644 scripts/gcc-plugin.sh
 create mode 100644 tools/gcc/Makefile
 create mode 100644 tools/gcc/gcc-common.h

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Comments

Michal Marek Feb. 8, 2016, 8:28 p.m. UTC | #1 
Dne 7.2.2016 v 22:28 Emese Revfy napsal(a):
> This patch allows to build the whole kernel with GCC plugins. It was ported from
> grsecurity/PaX. The infrastructure supports building out-of-tree modules and
> building in a separate directory. Cross-compilation is supported too but
> currently only the x86 architecture enables plugins.
> 
> The directory of the gcc plugins is tools/gcc. You can use a file or a directory
> there. The plugins compile with these options:
>  * -fno-rtti: gcc is compiled with this option so the plugins must use it too
>  * -fno-exceptions: this is inherited from gcc too
>  * -fasynchronous-unwind-tables: this is inherited from gcc too
>  * -ggdb: it is useful for debugging a plugin (better backtrace on internal
>     errors)
>  * -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h)
>  * -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version
>     variable, plugin-version.h)
> 
> The infrastructure introduces a new Makefile target called gcc-plugins. It
> supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script
> chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++).
> This script also checks the availability of the included headers in
> tools/gcc/gcc-common.h.
> 
> The gcc-common.h header contains frequently included headers for GCC plugins
> and it has a compatibility layer for the supported gcc versions.

The changelog is missing an explanation as to why this needs to be part
of the kernel build system. To me it looks like building the kernel with
a modified build system and non-default compiler flags, which can be
achieved by doing make CC=my-gcc-wrapper or somesuch. But I'd love to be
corrected.

Michal
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Emese Revfy Feb. 8, 2016, 9:31 p.m. UTC | #2 
On Mon, 8 Feb 2016 21:28:13 +0100
Michal Marek <mmarek@suse.com> wrote:

> Dne 7.2.2016 v 22:28 Emese Revfy napsal(a):
> > This patch allows to build the whole kernel with GCC plugins. It was ported from
> > grsecurity/PaX. The infrastructure supports building out-of-tree modules and
> > building in a separate directory. Cross-compilation is supported too but
> > currently only the x86 architecture enables plugins.
> > 
> > The directory of the gcc plugins is tools/gcc. You can use a file or a directory
> > there. The plugins compile with these options:
> >  * -fno-rtti: gcc is compiled with this option so the plugins must use it too
> >  * -fno-exceptions: this is inherited from gcc too
> >  * -fasynchronous-unwind-tables: this is inherited from gcc too
> >  * -ggdb: it is useful for debugging a plugin (better backtrace on internal
> >     errors)
> >  * -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h)
> >  * -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version
> >     variable, plugin-version.h)
> > 
> > The infrastructure introduces a new Makefile target called gcc-plugins. It
> > supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script
> > chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++).
> > This script also checks the availability of the included headers in
> > tools/gcc/gcc-common.h.
> > 
> > The gcc-common.h header contains frequently included headers for GCC plugins
> > and it has a compatibility layer for the supported gcc versions.
> 
> The changelog is missing an explanation as to why this needs to be part
> of the kernel build system. To me it looks like building the kernel with
> a modified build system and non-default compiler flags, which can be
> achieved by doing make CC=my-gcc-wrapper or somesuch. But I'd love to be
> corrected.

These compiler options compile the gcc plugins not the kernel. The new gcc option
used for building the kernel is the -fplugin option.
diff mbox

Patch

diff --git a/Documentation/dontdiff b/Documentation/dontdiff
index 8ea834f..5385cba 100644
--- a/Documentation/dontdiff
+++ b/Documentation/dontdiff
@@ -3,6 +3,7 @@ 
 *.bc
 *.bin
 *.bz2
+*.c.[012]*.*
 *.cis
 *.cpio
 *.csp
diff --git a/Makefile b/Makefile
index c65fe37..96ce015 100644
--- a/Makefile
+++ b/Makefile
@@ -434,8 +434,8 @@  export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn \
 # Rules shared between *config targets and build targets
 
 # Basic helpers built in scripts/
-PHONY += scripts_basic
-scripts_basic:
+PHONY += scripts_basic gcc-plugins
+scripts_basic: gcc-plugins
 	$(Q)$(MAKE) $(build)=scripts/basic
 	$(Q)rm -f .tmp_quiet_recordmcount
 
@@ -622,6 +622,33 @@  endif
 # Tell gcc to never replace conditional load with a non-conditional one
 KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
 
+ifeq ($(call cc-ifversion, -ge, 0408, y), y)
+PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh "$(HOSTCXX)" "$(HOSTCXX)" "$(CC)")
+else
+PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh "$(HOSTCC)" "$(HOSTCXX)" "$(CC)")
+endif
+ifneq ($(PLUGINCC),)
+export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS
+ifeq ($(KBUILD_EXTMOD),)
+gcc-plugins:
+	$(Q)$(MAKE) $(build)=tools/gcc
+else
+gcc-plugins: ;
+endif
+else
+gcc-plugins:
+ifeq ($(call cc-ifversion, -ge, 0405, y), y)
+	$(Q)echo "warning, your gcc installation does not support plugins, perhaps the necessary headers are missing?"
+ifeq ($(call cc-ifversion, -ge, 0408, y), y)
+	$(CONFIG_SHELL) -x $(srctree)/scripts/gcc-plugin.sh "$(HOSTCXX)" "$(HOSTCXX)" "$(CC)"
+else
+	$(CONFIG_SHELL) -x $(srctree)/scripts/gcc-plugin.sh "$(HOSTCC)" "$(HOSTCXX)" "$(CC)"
+endif
+else
+	$(Q)echo "warning, your gcc version does not support plugins, you should upgrade it to gcc 4.5 at least"
+endif
+endif
+
 ifdef CONFIG_READABLE_ASM
 # Disable optimizations that make assembler listings hard to read.
 # reorder blocks reorders the control in the function
@@ -937,6 +964,8 @@  endif
 
 # The actual objects are generated when descending,
 # make sure no implicit rule kicks in
+$(filter-out $(init-y),$(vmlinux-deps)): KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+$(filter-out $(init-y),$(vmlinux-deps)): KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 $(sort $(vmlinux-deps)): $(vmlinux-dirs) ;
 
 # Handle descending into subdirectories listed in $(vmlinux-dirs)
@@ -946,7 +975,7 @@  $(sort $(vmlinux-deps)): $(vmlinux-dirs) ;
 # Error messages still appears in the original language
 
 PHONY += $(vmlinux-dirs)
-$(vmlinux-dirs): prepare scripts
+$(vmlinux-dirs): gcc-plugins prepare scripts
 	$(Q)$(MAKE) $(build)=$@
 
 define filechk_kernel.release
@@ -989,10 +1018,13 @@  prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
 
 archprepare: archheaders archscripts prepare1 scripts_basic
 
+prepare0: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+prepare0: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 prepare0: archprepare FORCE
 	$(Q)$(MAKE) $(build)=.
 
 # All the preparing..
+prepare: KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
 prepare: prepare0
 
 # Generate some files
@@ -1103,6 +1135,8 @@  all: modules
 # using awk while concatenating to the final file.
 
 PHONY += modules
+modules: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+modules: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux) modules.builtin
 	$(Q)$(AWK) '!x[$$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtree)/modules.order
 	@$(kecho) '  Building modules, stage 2.';
@@ -1118,7 +1152,7 @@  modules.builtin: $(vmlinux-dirs:%=%/modules.builtin)
 
 # Target to prepare building external modules
 PHONY += modules_prepare
-modules_prepare: prepare scripts
+modules_prepare: gcc-plugins prepare scripts
 
 # Target to install modules
 PHONY += modules_install
@@ -1223,7 +1257,7 @@  distclean: mrproper
 	@find $(srctree) $(RCS_FIND_IGNORE) \
 		\( -name '*.orig' -o -name '*.rej' -o -name '*~' \
 		-o -name '*.bak' -o -name '#*#' -o -name '.*.orig' \
-		-o -name '.*.rej' -o -name '*%'  -o -name 'core' \) \
+		-o -name '.*.rej' -o -name '*.so' -o -name '*%' -o -name 'core' \) \
 		-type f -print | xargs rm -f
 
 
@@ -1390,6 +1424,8 @@  PHONY += $(module-dirs) modules
 $(module-dirs): crmodverdir $(objtree)/Module.symvers
 	$(Q)$(MAKE) $(build)=$(patsubst _module_%,%,$@)
 
+modules: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+modules: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 modules: $(module-dirs)
 	@$(kecho) '  Building modules, stage 2.';
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
@@ -1531,17 +1567,21 @@  else
         target-dir = $(if $(KBUILD_EXTMOD),$(dir $<),$(dir $@))
 endif
 
-%.s: %.c prepare scripts FORCE
+%.s: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+%.s: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
+%.s: %.c gcc-plugins prepare scripts FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
 %.i: %.c prepare scripts FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.o: %.c prepare scripts FORCE
+%.o: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+%.o: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
+%.o: %.c gcc-plugins prepare scripts FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
 %.lst: %.c prepare scripts FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.s: %.S prepare scripts FORCE
+%.s: %.S gcc-plugins prepare scripts FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.o: %.S prepare scripts FORCE
+%.o: %.S gcc-plugins prepare scripts FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
 %.symtypes: %.c prepare scripts FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
@@ -1553,11 +1593,15 @@  endif
 	$(build)=$(build-dir)
 # Make sure the latest headers are built for Documentation
 Documentation/: headers_install
-%/: prepare scripts FORCE
+%/: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+%/: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
+%/: gcc-plugins prepare scripts FORCE
 	$(cmd_crmodverdir)
 	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
 	$(build)=$(build-dir)
-%.ko: prepare scripts FORCE
+%.ko: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+%.ko: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
+%.ko: gcc-plugins prepare scripts FORCE
 	$(cmd_crmodverdir)
 	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \
 	$(build)=$(build-dir) $(@:.ko=.o)
diff --git a/arch/Kconfig b/arch/Kconfig
index 155e6cd..a95e5b1 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -357,6 +357,16 @@  config SECCOMP_FILTER
 
 	  See Documentation/prctl/seccomp_filter.txt for details.
 
+menu "GCC plugins"
+
+config HAVE_GCC_PLUGINS
+	bool
+	help
+	  An arch should select this symbol if it supports building with
+	  gcc plugins.
+
+endmenu # "GCC plugins"
+
 config HAVE_CC_STACKPROTECTOR
 	bool
 	help
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 152729c..e51ecd3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -156,6 +156,7 @@  config X86
 	select VIRT_TO_BUS
 	select X86_DEV_DMA_OPS			if X86_64
 	select X86_FEATURE_NAMES		if PROC_FS
+	select HAVE_GCC_PLUGINS
 
 config INSTRUCTION_DECODER
 	def_bool y
diff --git a/init/Makefile b/init/Makefile
index 7bc47ee..6da2dc7 100644
--- a/init/Makefile
+++ b/init/Makefile
@@ -2,6 +2,9 @@ 
 # Makefile for the linux kernel.
 #
 
+ccflags-y := $(GCC_PLUGINS_CFLAGS)
+asflags-y := $(GCC_PLUGINS_AFLAGS)
+
 obj-y                          := main.o version.o mounts.o
 ifneq ($(CONFIG_BLK_DEV_INITRD),y)
 obj-y                          += noinitramfs.o
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 2c47f9c..9d46008 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -60,7 +60,7 @@  endif
 endif
 
 # Do not include host rules unless needed
-ifneq ($(hostprogs-y)$(hostprogs-m),)
+ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),)
 include scripts/Makefile.host
 endif
 
diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
index 55c96cb..e4e88ab 100644
--- a/scripts/Makefile.clean
+++ b/scripts/Makefile.clean
@@ -38,7 +38,8 @@  subdir-ymn	:= $(addprefix $(obj)/,$(subdir-ymn))
 __clean-files	:= $(extra-y) $(extra-m) $(extra-)       \
 		   $(always) $(targets) $(clean-files)   \
 		   $(host-progs)                         \
-		   $(hostprogs-y) $(hostprogs-m) $(hostprogs-)
+		   $(hostprogs-y) $(hostprogs-m) $(hostprogs-) \
+		   $(hostlibs-y) $(hostlibs-m) $(hostlibs-)
 
 __clean-files   := $(filter-out $(no-clean-files), $(__clean-files))
 
diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index 133edfa..4d180d9 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -20,7 +20,25 @@ 
 # Will compile qconf as a C++ program, and menu as a C program.
 # They are linked as C++ code to the executable qconf
 
+# hostprogs-y := conf
+# conf-objs  := conf.o libkconfig.so
+# libkconfig-objs := expr.o type.o
+# Will create a shared library named libkconfig.so that consists of
+# expr.o and type.o (they are both compiled as C code and the object files
+# are made as position independent code).
+# conf.c is compiled as a C program, and conf.o is linked together with
+# libkconfig.so as the executable conf.
+# Note: Shared libraries consisting of C++ files are not supported
+
+# hostcc-option
+# Usage: cflags-y += $(call hostcc-option,-march=winchip-c6,-march=i586)
+
+hostcc-option = $(call try-run,\
+	$(HOSTCC) $(HOSTCFLAGS) $(HOST_EXTRACFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))
+
 __hostprogs := $(sort $(hostprogs-y) $(hostprogs-m))
+__hostlibs := $(sort $(hostlibs-y) $(hostlibs-m))
+__hostcxxlibs := $(sort $(hostcxxlibs-y) $(hostcxxlibs-m))
 
 # C code
 # Executables compiled from a single .c file
@@ -42,6 +60,19 @@  host-cxxmulti	:= $(foreach m,$(__hostprogs),$(if $($(m)-cxxobjs),$(m)))
 # C++ Object (.o) files compiled from .cc files
 host-cxxobjs	:= $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs)))
 
+# Shared libaries (only .c supported)
+# Shared libraries (.so) - all .so files referenced in "xxx-objs"
+host-cshlib	:= $(sort $(filter %.so, $(host-cobjs)))
+host-cshlib	+= $(sort $(filter %.so, $(__hostlibs)))
+host-cxxshlib	:= $(sort $(filter %.so, $(__hostcxxlibs)))
+# Remove .so files from "xxx-objs"
+host-cobjs	:= $(filter-out %.so,$(host-cobjs))
+host-cxxobjs	:= $(filter-out %.so,$(host-cxxobjs))
+
+# Object (.o) files used by the shared libaries
+host-cshobjs	:= $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs))))
+host-cxxshobjs	:= $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-objs))))
+
 # output directory for programs/.o files
 # hostprogs-y := tools/build may have been specified.
 # Retrieve also directory of .o files from prog-objs or prog-cxxobjs notation
@@ -56,6 +87,10 @@  host-cmulti	:= $(addprefix $(obj)/,$(host-cmulti))
 host-cobjs	:= $(addprefix $(obj)/,$(host-cobjs))
 host-cxxmulti	:= $(addprefix $(obj)/,$(host-cxxmulti))
 host-cxxobjs	:= $(addprefix $(obj)/,$(host-cxxobjs))
+host-cshlib	:= $(addprefix $(obj)/,$(host-cshlib))
+host-cxxshlib	:= $(addprefix $(obj)/,$(host-cxxshlib))
+host-cshobjs	:= $(addprefix $(obj)/,$(host-cshobjs))
+host-cxxshobjs	:= $(addprefix $(obj)/,$(host-cxxshobjs))
 host-objdirs    := $(addprefix $(obj)/,$(host-objdirs))
 
 obj-dirs += $(host-objdirs)
@@ -124,5 +159,37 @@  quiet_cmd_host-cxxobjs	= HOSTCXX $@
 $(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
 	$(call if_changed_dep,host-cxxobjs)
 
+# Compile .c file, create position independent .o file
+# host-cshobjs -> .o
+quiet_cmd_host-cshobjs	= HOSTCC  -fPIC $@
+      cmd_host-cshobjs	= $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
+$(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE
+	$(call if_changed_dep,host-cshobjs)
+
+# Compile .c file, create position independent .o file
+# host-cxxshobjs -> .o
+quiet_cmd_host-cxxshobjs	= HOSTCXX -fPIC $@
+      cmd_host-cxxshobjs	= $(HOSTCXX) $(hostcxx_flags) -fPIC -c -o $@ $<
+$(host-cxxshobjs): $(obj)/%.o: $(src)/%.c FORCE
+	$(call if_changed_dep,host-cxxshobjs)
+
+# Link a shared library, based on position independent .o files
+# *.o -> .so shared library (host-cshlib)
+quiet_cmd_host-cshlib	= HOSTLLD -shared $@
+      cmd_host-cshlib	= $(HOSTCC) $(HOSTLDFLAGS) -shared -o $@ \
+			  $(addprefix $(obj)/,$($(@F:.so=-objs))) \
+			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
+$(host-cshlib): $(obj)/%: $(host-cshobjs) FORCE
+	$(call if_changed,host-cshlib)
+
+# Link a shared library, based on position independent .o files
+# *.o -> .so shared library (host-cxxshlib)
+quiet_cmd_host-cxxshlib	= HOSTLLD -shared $@
+      cmd_host-cxxshlib	= $(HOSTCXX) $(HOSTLDFLAGS) -shared -o $@ \
+			  $(addprefix $(obj)/,$($(@F:.so=-objs))) \
+			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
+$(host-cxxshlib): $(obj)/%: $(host-cxxshobjs) FORCE
+	$(call if_changed,host-cxxshlib)
+
 targets += $(host-csingle)  $(host-cmulti) $(host-cobjs)\
-	   $(host-cxxmulti) $(host-cxxobjs)
+	   $(host-cxxmulti) $(host-cxxobjs) $(host-cshlib) $(host-cshobjs) $(host-cxxshlib) $(host-cxxshobjs)
diff --git a/scripts/gcc-plugin.sh b/scripts/gcc-plugin.sh
new file mode 100644
index 0000000..eaa4fce
--- /dev/null
+++ b/scripts/gcc-plugin.sh
@@ -0,0 +1,51 @@ 
+#!/bin/sh
+srctree=$(dirname "$0")
+gccplugins_dir=$($3 -print-file-name=plugin)
+plugincc=$($1 -E -x c++ - -o /dev/null -I"${srctree}"/../tools/gcc -I"${gccplugins_dir}"/include 2>&1 <<EOF
+#include "gcc-common.h"
+#if BUILDING_GCC_VERSION >= 4008 || defined(ENABLE_BUILD_WITH_CXX)
+#warning $2 CXX
+#else
+#warning $1 CC
+#endif
+EOF
+)
+
+if [ $? -ne 0 ]
+then
+	exit 1
+fi
+
+case "$plugincc" in
+	*"$1 CC"*)
+		echo "$1"
+		exit 0
+		;;
+
+	*"$2 CXX"*)
+		# the c++ compiler needs another test, see below
+		;;
+
+	*)
+		exit 1
+		;;
+esac
+
+# we need a c++ compiler that supports the designated initializer GNU extension
+plugincc=$($2 -c -x c++ -std=gnu++98 - -fsyntax-only -I"${srctree}"/../tools/gcc -I"${gccplugins_dir}"/include 2>&1 <<EOF
+#include "gcc-common.h"
+class test {
+public:
+	int test;
+} test = {
+	.test = 1
+};
+EOF
+)
+
+if [ $? -eq 0 ]
+then
+	echo "$2"
+	exit 0
+fi
+exit 1
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index aae2473..5d62545 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -183,7 +183,7 @@  else
 fi;
 
 # final build of init/
-${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
+${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init GCC_PLUGINS_CFLAGS="${GCC_PLUGINS_CFLAGS}" GCC_PLUGINS_AFLAGS="${GCC_PLUGINS_AFLAGS}"
 
 kallsymso=""
 kallsyms_vmlinux=""
diff --git a/scripts/package/builddeb b/scripts/package/builddeb
index 6c3b038..54e0b5e 100755
--- a/scripts/package/builddeb
+++ b/scripts/package/builddeb
@@ -326,6 +326,7 @@  fi
 (cd $srctree; find arch/$SRCARCH -name module.lds -o -name Kbuild.platforms -o -name Platform) >> "$objtree/debian/hdrsrcfiles"
 (cd $srctree; find $(find arch/$SRCARCH -name include -o -name scripts -type d) -type f) >> "$objtree/debian/hdrsrcfiles"
 (cd $objtree; find arch/$SRCARCH/include Module.symvers include scripts -type f) >> "$objtree/debian/hdrobjfiles"
+(cd $objtree; find tools/gcc -name \*.so -o -name gcc-common.h) >> "$objtree/debian/hdrobjfiles"
 destdir=$kernel_headers_dir/usr/src/linux-headers-$version
 mkdir -p "$destdir"
 (cd $srctree; tar -c -f - -T -) < "$objtree/debian/hdrsrcfiles" | (cd $destdir; tar -xf -)
diff --git a/tools/gcc/Makefile b/tools/gcc/Makefile
new file mode 100644
index 0000000..b2d64af
--- /dev/null
+++ b/tools/gcc/Makefile
@@ -0,0 +1,15 @@ 
+GCC_PLUGINS_DIR := $(shell $(CC) -print-file-name=plugin)
+
+ifeq ($(PLUGINCC),$(HOSTCC))
+HOSTLIBS := hostlibs
+HOST_EXTRACFLAGS += -I$(GCC_PLUGINS_DIR)/include -I$(src) -std=gnu99 -ggdb
+export HOST_EXTRACFLAGS
+else
+HOSTLIBS := hostcxxlibs
+HOST_EXTRACXXFLAGS += -I$(GCC_PLUGINS_DIR)/include -I$(src) -std=gnu++98 -fno-rtti -fno-exceptions -fasynchronous-unwind-tables -ggdb -Wno-narrowing -Wno-unused-variable
+export HOST_EXTRACXXFLAGS
+endif
+
+export GCCPLUGINS_DIR HOSTLIBS
+
+always := $($(HOSTLIBS)-y)
diff --git a/tools/gcc/gcc-common.h b/tools/gcc/gcc-common.h
new file mode 100644
index 0000000..355bb1a
--- /dev/null
+++ b/tools/gcc/gcc-common.h
@@ -0,0 +1,794 @@ 
+#ifndef GCC_COMMON_H_INCLUDED
+#define GCC_COMMON_H_INCLUDED
+
+#include "bversion.h"
+#if BUILDING_GCC_VERSION >= 6000
+#include "gcc-plugin.h"
+#else
+#include "plugin.h"
+#endif
+#include "plugin-version.h"
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "line-map.h"
+#include "input.h"
+#include "tree.h"
+
+#include "tree-inline.h"
+#include "version.h"
+#include "rtl.h"
+#include "tm_p.h"
+#include "flags.h"
+#include "hard-reg-set.h"
+#include "output.h"
+#include "except.h"
+#include "function.h"
+#include "toplev.h"
+#include "basic-block.h"
+#include "intl.h"
+#include "ggc.h"
+#include "timevar.h"
+
+#include "params.h"
+
+#if BUILDING_GCC_VERSION <= 4009
+#include "pointer-set.h"
+#else
+#include "hash-map.h"
+#endif
+
+#include "emit-rtl.h"
+#include "debug.h"
+#include "target.h"
+#include "langhooks.h"
+#include "cfgloop.h"
+#include "cgraph.h"
+#include "opts.h"
+
+#if BUILDING_GCC_VERSION == 4005
+#include <sys/mman.h>
+#endif
+
+#if BUILDING_GCC_VERSION >= 4007
+#include "tree-pretty-print.h"
+#include "gimple-pretty-print.h"
+#endif
+
+#if BUILDING_GCC_VERSION >= 4006
+#include "c-family/c-common.h"
+#else
+#include "c-common.h"
+#endif
+
+#if BUILDING_GCC_VERSION <= 4008
+#include "tree-flow.h"
+#else
+#include "tree-cfgcleanup.h"
+#include "tree-ssa-operands.h"
+#include "tree-into-ssa.h"
+#endif
+
+#if BUILDING_GCC_VERSION >= 4008
+#include "is-a.h"
+#endif
+
+#include "diagnostic.h"
+#include "tree-dump.h"
+#include "tree-pass.h"
+#include "predict.h"
+#include "ipa-utils.h"
+
+#if BUILDING_GCC_VERSION >= 4009
+#include "attribs.h"
+#include "varasm.h"
+#include "stor-layout.h"
+#include "internal-fn.h"
+#include "gimple-expr.h"
+#include "gimple-fold.h"
+#include "context.h"
+#include "tree-ssa-alias.h"
+#include "tree-ssa.h"
+#include "stringpool.h"
+#include "tree-ssanames.h"
+#include "print-tree.h"
+#include "tree-eh.h"
+#include "stmt.h"
+#include "gimplify.h"
+#endif
+
+#include "gimple.h"
+
+#if BUILDING_GCC_VERSION >= 4009
+#include "tree-ssa-operands.h"
+#include "tree-phinodes.h"
+#include "tree-cfg.h"
+#include "gimple-iterator.h"
+#include "gimple-ssa.h"
+#include "ssa-iterators.h"
+#endif
+
+#if BUILDING_GCC_VERSION >= 4007
+#else
+#endif
+#if BUILDING_GCC_VERSION >= 5000
+#include "builtins.h"
+#endif
+
+//#include "expr.h" where are you...
+extern rtx emit_move_insn(rtx x, rtx y);
+
+// missing from basic_block.h...
+extern void debug_dominance_info(enum cdi_direction dir);
+extern void debug_dominance_tree(enum cdi_direction dir, basic_block root);
+
+#if BUILDING_GCC_VERSION == 4006
+extern void debug_gimple_stmt(gimple);
+extern void debug_gimple_seq(gimple_seq);
+extern void print_gimple_seq(FILE *, gimple_seq, int, int);
+extern void print_gimple_stmt(FILE *, gimple, int, int);
+extern void print_gimple_expr(FILE *, gimple, int, int);
+extern void dump_gimple_stmt(pretty_printer *, gimple, int, int);
+#endif
+
+#ifdef __cplusplus
+static inline void debug_tree(const_tree t)
+{
+	debug_tree(CONST_CAST_TREE(t));
+}
+
+static inline void debug_gimple_stmt(const_gimple s)
+{
+	debug_gimple_stmt(CONST_CAST_GIMPLE(s));
+}
+#else
+#define debug_tree(t) debug_tree(CONST_CAST_TREE(t))
+#define debug_gimple_stmt(s) debug_gimple_stmt(CONST_CAST_GIMPLE(s))
+#endif
+
+#define __unused __attribute__((__unused__))
+
+#define DECL_NAME_POINTER(node) IDENTIFIER_POINTER(DECL_NAME(node))
+#define DECL_NAME_LENGTH(node) IDENTIFIER_LENGTH(DECL_NAME(node))
+#define TYPE_NAME_POINTER(node) IDENTIFIER_POINTER(TYPE_NAME(node))
+#define TYPE_NAME_LENGTH(node) IDENTIFIER_LENGTH(TYPE_NAME(node))
+
+// should come from c-tree.h if only it were installed for gcc 4.5...
+#define C_TYPE_FIELDS_READONLY(TYPE) TREE_LANG_FLAG_1(TYPE)
+
+#if BUILDING_GCC_VERSION == 4005
+#define FOR_EACH_LOCAL_DECL(FUN, I, D) for (tree vars = (FUN)->local_decls, (I) = 0; vars && ((D) = TREE_VALUE(vars)); vars = TREE_CHAIN(vars), (I)++)
+#define DECL_CHAIN(NODE) (TREE_CHAIN(DECL_MINIMAL_CHECK(NODE)))
+#define FOR_EACH_VEC_ELT(T, V, I, P) for (I = 0; VEC_iterate(T, (V), (I), (P)); ++(I))
+#define TODO_rebuild_cgraph_edges 0
+#define SCOPE_FILE_SCOPE_P(EXP) (!(EXP))
+
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
+
+typedef struct varpool_node *varpool_node_ptr;
+
+static inline bool gimple_call_builtin_p(gimple stmt, enum built_in_function code)
+{
+	tree fndecl;
+
+	if (!is_gimple_call(stmt))
+		return false;
+	fndecl = gimple_call_fndecl(stmt);
+	if (!fndecl || DECL_BUILT_IN_CLASS(fndecl) != BUILT_IN_NORMAL)
+		return false;
+	return DECL_FUNCTION_CODE(fndecl) == code;
+}
+
+static inline bool is_simple_builtin(tree decl)
+{
+	if (decl && DECL_BUILT_IN_CLASS(decl) != BUILT_IN_NORMAL)
+		return false;
+
+	switch (DECL_FUNCTION_CODE(decl)) {
+	/* Builtins that expand to constants. */
+	case BUILT_IN_CONSTANT_P:
+	case BUILT_IN_EXPECT:
+	case BUILT_IN_OBJECT_SIZE:
+	case BUILT_IN_UNREACHABLE:
+	/* Simple register moves or loads from stack. */
+	case BUILT_IN_RETURN_ADDRESS:
+	case BUILT_IN_EXTRACT_RETURN_ADDR:
+	case BUILT_IN_FROB_RETURN_ADDR:
+	case BUILT_IN_RETURN:
+	case BUILT_IN_AGGREGATE_INCOMING_ADDRESS:
+	case BUILT_IN_FRAME_ADDRESS:
+	case BUILT_IN_VA_END:
+	case BUILT_IN_STACK_SAVE:
+	case BUILT_IN_STACK_RESTORE:
+	/* Exception state returns or moves registers around. */
+	case BUILT_IN_EH_FILTER:
+	case BUILT_IN_EH_POINTER:
+	case BUILT_IN_EH_COPY_VALUES:
+	return true;
+
+	default:
+	return false;
+	}
+}
+
+static inline void add_local_decl(struct function *fun, tree d)
+{
+	gcc_assert(TREE_CODE(d) == VAR_DECL);
+	fun->local_decls = tree_cons(NULL_TREE, d, fun->local_decls);
+}
+#endif
+
+#if BUILDING_GCC_VERSION <= 4006
+#define ANY_RETURN_P(rtx) (GET_CODE(rtx) == RETURN)
+#define C_DECL_REGISTER(EXP) DECL_LANG_FLAG_4(EXP)
+#define EDGE_PRESERVE 0ULL
+#define HOST_WIDE_INT_PRINT_HEX_PURE "%" HOST_WIDE_INT_PRINT "x"
+#define flag_fat_lto_objects true
+
+#define get_random_seed(noinit) ({						\
+	unsigned HOST_WIDE_INT seed;						\
+	sscanf(get_random_seed(noinit), "%" HOST_WIDE_INT_PRINT "x", &seed);	\
+	seed * seed; })
+
+#define int_const_binop(code, arg1, arg2) int_const_binop((code), (arg1), (arg2), 0)
+
+static inline bool gimple_clobber_p(gimple s __unused)
+{
+	return false;
+}
+
+static inline bool gimple_asm_clobbers_memory_p(const_gimple stmt)
+{
+	unsigned i;
+
+	for (i = 0; i < gimple_asm_nclobbers(stmt); i++) {
+		tree op = gimple_asm_clobber_op(stmt, i);
+		if (!strcmp(TREE_STRING_POINTER(TREE_VALUE(op)), "memory"))
+			return true;
+	}
+
+	return false;
+}
+
+static inline tree builtin_decl_implicit(enum built_in_function fncode)
+{
+	return implicit_built_in_decls[fncode];
+}
+
+static inline int ipa_reverse_postorder(struct cgraph_node **order)
+{
+	return cgraph_postorder(order);
+}
+
+static inline struct cgraph_node *cgraph_get_create_node(tree decl)
+{
+	struct cgraph_node *node = cgraph_get_node(decl);
+
+	return node ? node : cgraph_node(decl);
+}
+
+static inline bool cgraph_function_with_gimple_body_p(struct cgraph_node *node)
+{
+	return node->analyzed && !node->thunk.thunk_p && !node->alias;
+}
+
+static inline struct cgraph_node *cgraph_first_function_with_gimple_body(void)
+{
+	struct cgraph_node *node;
+
+	for (node = cgraph_nodes; node; node = node->next)
+		if (cgraph_function_with_gimple_body_p(node))
+			return node;
+	return NULL;
+}
+
+static inline struct cgraph_node *cgraph_next_function_with_gimple_body(struct cgraph_node *node)
+{
+	for (node = node->next; node; node = node->next)
+		if (cgraph_function_with_gimple_body_p(node))
+			return node;
+	return NULL;
+}
+
+#define FOR_EACH_FUNCTION_WITH_GIMPLE_BODY(node) \
+	for ((node) = cgraph_first_function_with_gimple_body(); (node); \
+		(node) = cgraph_next_function_with_gimple_body(node))
+
+static inline void varpool_add_new_variable(tree decl)
+{
+	varpool_finalize_decl(decl);
+}
+#endif
+
+#if BUILDING_GCC_VERSION <= 4007
+#define FOR_EACH_FUNCTION(node) for (node = cgraph_nodes; node; node = node->next)
+#define FOR_EACH_VARIABLE(node) for (node = varpool_nodes; node; node = node->next)
+#define PROP_loops 0
+#define NODE_SYMBOL(node) (node)
+#define NODE_DECL(node) (node)->decl
+#define INSN_LOCATION(INSN) RTL_LOCATION(INSN)
+
+static inline int bb_loop_depth(const_basic_block bb)
+{
+	return bb->loop_father ? loop_depth(bb->loop_father) : 0;
+}
+
+static inline bool gimple_store_p(gimple gs)
+{
+	tree lhs = gimple_get_lhs(gs);
+	return lhs && !is_gimple_reg(lhs);
+}
+#endif
+
+#if BUILDING_GCC_VERSION == 4007 || BUILDING_GCC_VERSION == 4008
+static inline struct cgraph_node *cgraph_alias_target(struct cgraph_node *n)
+{
+	return cgraph_alias_aliased_node(n);
+}
+#endif
+
+#if BUILDING_GCC_VERSION >= 4007 && BUILDING_GCC_VERSION <= 4009
+#define cgraph_create_edge(caller, callee, call_stmt, count, freq, nest) \
+	cgraph_create_edge((caller), (callee), (call_stmt), (count), (freq))
+#define cgraph_create_edge_including_clones(caller, callee, old_call_stmt, call_stmt, count, freq, nest, reason) \
+	cgraph_create_edge_including_clones((caller), (callee), (old_call_stmt), (call_stmt), (count), (freq), (reason))
+#endif
+
+#if BUILDING_GCC_VERSION <= 4008
+#define ENTRY_BLOCK_PTR_FOR_FN(FN)	ENTRY_BLOCK_PTR_FOR_FUNCTION(FN)
+#define EXIT_BLOCK_PTR_FOR_FN(FN)	EXIT_BLOCK_PTR_FOR_FUNCTION(FN)
+#define basic_block_info_for_fn(FN)	((FN)->cfg->x_basic_block_info)
+#define n_basic_blocks_for_fn(FN)	((FN)->cfg->x_n_basic_blocks)
+#define n_edges_for_fn(FN)		((FN)->cfg->x_n_edges)
+#define last_basic_block_for_fn(FN)	((FN)->cfg->x_last_basic_block)
+#define label_to_block_map_for_fn(FN)	((FN)->cfg->x_label_to_block_map)
+#define profile_status_for_fn(FN)	((FN)->cfg->x_profile_status)
+#define BASIC_BLOCK_FOR_FN(FN, N)	BASIC_BLOCK_FOR_FUNCTION((FN), (N))
+#define NODE_IMPLICIT_ALIAS(node)	(node)->same_body_alias
+#define VAR_P(NODE)			(TREE_CODE(NODE) == VAR_DECL)
+
+static inline bool tree_fits_shwi_p(const_tree t)
+{
+	if (t == NULL_TREE || TREE_CODE(t) != INTEGER_CST)
+		return false;
+
+	if (TREE_INT_CST_HIGH(t) == 0 && (HOST_WIDE_INT)TREE_INT_CST_LOW(t) >= 0)
+		return true;
+
+	if (TREE_INT_CST_HIGH(t) == -1 && (HOST_WIDE_INT)TREE_INT_CST_LOW(t) < 0 && !TYPE_UNSIGNED(TREE_TYPE(t)))
+		return true;
+
+	return false;
+}
+
+static inline bool tree_fits_uhwi_p(const_tree t)
+{
+	if (t == NULL_TREE || TREE_CODE(t) != INTEGER_CST)
+		return false;
+
+	return TREE_INT_CST_HIGH(t) == 0;
+}
+
+static inline HOST_WIDE_INT tree_to_shwi(const_tree t)
+{
+	gcc_assert(tree_fits_shwi_p(t));
+	return TREE_INT_CST_LOW(t);
+}
+
+static inline unsigned HOST_WIDE_INT tree_to_uhwi(const_tree t)
+{
+	gcc_assert(tree_fits_uhwi_p(t));
+	return TREE_INT_CST_LOW(t);
+}
+
+static inline const char *get_tree_code_name(enum tree_code code)
+{
+	gcc_assert(code < MAX_TREE_CODES);
+	return tree_code_name[code];
+}
+
+#define ipa_remove_stmt_references(cnode, stmt)
+
+typedef union gimple_statement_d gasm;
+typedef union gimple_statement_d gassign;
+typedef union gimple_statement_d gcall;
+typedef union gimple_statement_d gcond;
+typedef union gimple_statement_d gdebug;
+typedef union gimple_statement_d gphi;
+typedef union gimple_statement_d greturn;
+
+static inline gasm *as_a_gasm(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const gasm *as_a_const_gasm(const_gimple stmt)
+{
+	return stmt;
+}
+
+static inline gassign *as_a_gassign(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const gassign *as_a_const_gassign(const_gimple stmt)
+{
+	return stmt;
+}
+
+static inline gcall *as_a_gcall(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const gcall *as_a_const_gcall(const_gimple stmt)
+{
+	return stmt;
+}
+
+static inline gcond *as_a_gcond(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const gcond *as_a_const_gcond(const_gimple stmt)
+{
+	return stmt;
+}
+
+static inline gdebug *as_a_gdebug(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const gdebug *as_a_const_gdebug(const_gimple stmt)
+{
+	return stmt;
+}
+
+static inline gphi *as_a_gphi(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const gphi *as_a_const_gphi(const_gimple stmt)
+{
+	return stmt;
+}
+
+static inline greturn *as_a_greturn(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const greturn *as_a_const_greturn(const_gimple stmt)
+{
+	return stmt;
+}
+#endif
+
+#if BUILDING_GCC_VERSION == 4008
+#define NODE_SYMBOL(node) (&(node)->symbol)
+#define NODE_DECL(node) (node)->symbol.decl
+#endif
+
+#if BUILDING_GCC_VERSION >= 4008
+#define add_referenced_var(var)
+#define mark_sym_for_renaming(var)
+#define varpool_mark_needed_node(node)
+#define create_var_ann(var)
+#define TODO_dump_func 0
+#define TODO_dump_cgraph 0
+#endif
+
+#if BUILDING_GCC_VERSION <= 4009
+#define TODO_verify_il 0
+#define AVAIL_INTERPOSABLE AVAIL_OVERWRITABLE
+
+#define section_name_prefix LTO_SECTION_NAME_PREFIX
+#define fatal_error(loc, gmsgid, ...) fatal_error((gmsgid), __VA_ARGS__)
+
+typedef struct rtx_def rtx_insn;
+
+static inline void set_decl_section_name(tree node, const char *value)
+{
+	DECL_SECTION_NAME(node) = build_string(strlen(value) + 1, value);
+}
+#endif
+
+#if BUILDING_GCC_VERSION == 4009
+typedef struct gimple_statement_asm gasm;
+typedef struct gimple_statement_base gassign;
+typedef struct gimple_statement_call gcall;
+typedef struct gimple_statement_base gcond;
+typedef struct gimple_statement_base gdebug;
+typedef struct gimple_statement_phi gphi;
+typedef struct gimple_statement_base greturn;
+
+static inline gasm *as_a_gasm(gimple stmt)
+{
+	return as_a<gasm>(stmt);
+}
+
+static inline const gasm *as_a_const_gasm(const_gimple stmt)
+{
+	return as_a<const gasm>(stmt);
+}
+
+static inline gassign *as_a_gassign(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const gassign *as_a_const_gassign(const_gimple stmt)
+{
+	return stmt;
+}
+
+static inline gcall *as_a_gcall(gimple stmt)
+{
+	return as_a<gcall>(stmt);
+}
+
+static inline const gcall *as_a_const_gcall(const_gimple stmt)
+{
+	return as_a<const gcall>(stmt);
+}
+
+static inline gcond *as_a_gcond(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const gcond *as_a_const_gcond(const_gimple stmt)
+{
+	return stmt;
+}
+
+static inline gdebug *as_a_gdebug(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const gdebug *as_a_const_gdebug(const_gimple stmt)
+{
+	return stmt;
+}
+
+static inline gphi *as_a_gphi(gimple stmt)
+{
+	return as_a<gphi>(stmt);
+}
+
+static inline const gphi *as_a_const_gphi(const_gimple stmt)
+{
+	return as_a<const gphi>(stmt);
+}
+
+static inline greturn *as_a_greturn(gimple stmt)
+{
+	return stmt;
+}
+
+static inline const greturn *as_a_const_greturn(const_gimple stmt)
+{
+	return stmt;
+}
+#endif
+
+#if BUILDING_GCC_VERSION >= 4009
+#define TODO_ggc_collect 0
+#define NODE_SYMBOL(node) (node)
+#define NODE_DECL(node) (node)->decl
+#define cgraph_node_name(node) (node)->name()
+#define NODE_IMPLICIT_ALIAS(node) (node)->cpp_implicit_alias
+#endif
+
+#if BUILDING_GCC_VERSION >= 5000 && BUILDING_GCC_VERSION < 6000
+// gimple related
+template <>
+template <>
+inline bool is_a_helper<const gassign *>::test(const_gimple gs)
+{
+	return gs->code == GIMPLE_ASSIGN;
+}
+#endif
+
+#if BUILDING_GCC_VERSION >= 5000
+#define TODO_verify_ssa TODO_verify_il
+#define TODO_verify_flow TODO_verify_il
+#define TODO_verify_stmts TODO_verify_il
+#define TODO_verify_rtl_sharing TODO_verify_il
+
+#define INSN_DELETED_P(insn) (insn)->deleted()
+
+// symtab/cgraph related
+#define debug_cgraph_node(node) (node)->debug()
+#define cgraph_get_node(decl) cgraph_node::get(decl)
+#define cgraph_get_create_node(decl) cgraph_node::get_create(decl)
+#define cgraph_n_nodes symtab->cgraph_count
+#define cgraph_max_uid symtab->cgraph_max_uid
+#define varpool_get_node(decl) varpool_node::get(decl)
+
+#define cgraph_create_edge(caller, callee, call_stmt, count, freq, nest) \
+	(caller)->create_edge((callee), (call_stmt), (count), (freq))
+#define cgraph_create_edge_including_clones(caller, callee, old_call_stmt, call_stmt, count, freq, nest, reason) \
+	(caller)->create_edge_including_clones((callee), (old_call_stmt), (call_stmt), (count), (freq), (reason))
+
+typedef struct cgraph_node *cgraph_node_ptr;
+typedef struct cgraph_edge *cgraph_edge_p;
+typedef struct varpool_node *varpool_node_ptr;
+
+static inline void change_decl_assembler_name(tree decl, tree name)
+{
+	symtab->change_decl_assembler_name(decl, name);
+}
+
+static inline void varpool_finalize_decl(tree decl)
+{
+	varpool_node::finalize_decl(decl);
+}
+
+static inline void varpool_add_new_variable(tree decl)
+{
+	varpool_node::add(decl);
+}
+
+static inline unsigned int rebuild_cgraph_edges(void)
+{
+	return cgraph_edge::rebuild_edges();
+}
+
+static inline cgraph_node_ptr cgraph_function_node(cgraph_node_ptr node, enum availability *availability)
+{
+	return node->function_symbol(availability);
+}
+
+static inline cgraph_node_ptr cgraph_function_or_thunk_node(cgraph_node_ptr node, enum availability *availability = NULL)
+{
+	return node->ultimate_alias_target(availability);
+}
+
+static inline bool cgraph_only_called_directly_p(cgraph_node_ptr node)
+{
+	return node->only_called_directly_p();
+}
+
+static inline enum availability cgraph_function_body_availability(cgraph_node_ptr node)
+{
+	return node->get_availability();
+}
+
+static inline cgraph_node_ptr cgraph_alias_target(cgraph_node_ptr node)
+{
+	return node->get_alias_target();
+}
+
+static inline struct cgraph_node_hook_list *cgraph_add_function_insertion_hook(cgraph_node_hook hook, void *data)
+{
+	return symtab->add_cgraph_insertion_hook(hook, data);
+}
+
+static inline void cgraph_remove_function_insertion_hook(struct cgraph_node_hook_list *entry)
+{
+	symtab->remove_cgraph_insertion_hook(entry);
+}
+
+static inline struct cgraph_node_hook_list *cgraph_add_node_removal_hook(cgraph_node_hook hook, void *data)
+{
+	return symtab->add_cgraph_removal_hook(hook, data);
+}
+
+static inline void cgraph_remove_node_removal_hook(struct cgraph_node_hook_list *entry)
+{
+	symtab->remove_cgraph_removal_hook(entry);
+}
+
+static inline struct cgraph_2node_hook_list *cgraph_add_node_duplication_hook(cgraph_2node_hook hook, void *data)
+{
+	return symtab->add_cgraph_duplication_hook(hook, data);
+}
+
+static inline void cgraph_remove_node_duplication_hook(struct cgraph_2node_hook_list *entry)
+{
+	symtab->remove_cgraph_duplication_hook(entry);
+}
+
+#if BUILDING_GCC_VERSION >= 6000
+typedef gimple *gimple_ptr;
+typedef const gimple *const_gimple;
+#define gimple gimple_ptr
+#endif
+
+// gimple related
+static inline gimple gimple_build_assign_with_ops(enum tree_code subcode, tree lhs, tree op1, tree op2 MEM_STAT_DECL)
+{
+	return gimple_build_assign(lhs, subcode, op1, op2 PASS_MEM_STAT);
+}
+
+template <>
+template <>
+inline bool is_a_helper<const greturn *>::test(const_gimple gs)
+{
+	return gs->code == GIMPLE_RETURN;
+}
+
+static inline gasm *as_a_gasm(gimple stmt)
+{
+	return as_a<gasm *>(stmt);
+}
+
+static inline const gasm *as_a_const_gasm(const_gimple stmt)
+{
+	return as_a<const gasm *>(stmt);
+}
+
+static inline gassign *as_a_gassign(gimple stmt)
+{
+	return as_a<gassign *>(stmt);
+}
+
+static inline const gassign *as_a_const_gassign(const_gimple stmt)
+{
+	return as_a<const gassign *>(stmt);
+}
+
+static inline gcall *as_a_gcall(gimple stmt)
+{
+	return as_a<gcall *>(stmt);
+}
+
+static inline const gcall *as_a_const_gcall(const_gimple stmt)
+{
+	return as_a<const gcall *>(stmt);
+}
+
+static inline gphi *as_a_gphi(gimple stmt)
+{
+	return as_a<gphi *>(stmt);
+}
+
+static inline const gphi *as_a_const_gphi(const_gimple stmt)
+{
+	return as_a<const gphi *>(stmt);
+}
+
+static inline greturn *as_a_greturn(gimple stmt)
+{
+	return as_a<greturn *>(stmt);
+}
+
+static inline const greturn *as_a_const_greturn(const_gimple stmt)
+{
+	return as_a<const greturn *>(stmt);
+}
+
+// IPA/LTO related
+#define ipa_ref_list_referring_iterate(L,I,P) (L)->referring.iterate((I), &(P))
+#define ipa_ref_list_reference_iterate(L,I,P) (L)->reference.iterate((I), &(P))
+
+static inline cgraph_node_ptr ipa_ref_referring_node(struct ipa_ref *ref)
+{
+	return dyn_cast<cgraph_node_ptr>(ref->referring);
+}
+
+static inline void ipa_remove_stmt_references(symtab_node *referring_node, gimple stmt)
+{
+	referring_node->remove_stmt_references(stmt);
+}
+#endif
+
+#if BUILDING_GCC_VERSION < 6000
+#define get_inner_reference(exp, pbitsize, pbitpos, poffset, pmode, punsignedp, preversep, pvolatilep, keep_aligning) get_inner_reference(exp, pbitsize, pbitpos, poffset, pmode, punsignedp, pvolatilep, keep_aligning)
+#define gen_rtx_set(ARG0, ARG1) gen_rtx_SET(VOIDmode, (ARG0), (ARG1))
+#endif
+
+#if BUILDING_GCC_VERSION >= 6000
+#define gen_rtx_set(ARG0, ARG1) gen_rtx_SET((ARG0), (ARG1))
+#endif
+
+#endif