[v5,3/5] Add Cyclomatic complexity GCC plugin
diff mbox

Message ID 20160307000531.d43ae7df74bfa5e9e9e29087@gmail.com
State New
Headers show

Commit Message

Emese Revfy March 6, 2016, 11:05 p.m. UTC
Add a very simple plugin to demonstrate the GCC plugin infrastructure. This GCC
plugin computes the cyclomatic complexity of each function.

The complexity M of a function's control flow graph is defined as:
 M = E - N + 2P
where
 E = the number of edges
 N = the number of nodes
 P = the number of connected components (exit nodes).

Signed-off-by: Emese Revfy <re.emese@gmail.com>
---
 arch/Kconfig                      | 12 +++++++
 scripts/Makefile.gcc-plugins      |  6 +++-
 tools/gcc/Makefile                |  4 +++
 tools/gcc/cyc_complexity_plugin.c | 73 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 tools/gcc/cyc_complexity_plugin.c

Comments

Masahiro Yamada March 11, 2016, 6:26 a.m. UTC | #1
Hi Emese,


2016-03-07 8:05 GMT+09:00 Emese Revfy <re.emese@gmail.com>:
> Add a very simple plugin to demonstrate the GCC plugin infrastructure. This GCC
> plugin computes the cyclomatic complexity of each function.
>
> The complexity M of a function's control flow graph is defined as:
>  M = E - N + 2P
> where
>  E = the number of edges
>  N = the number of nodes
>  P = the number of connected components (exit nodes).
>
> Signed-off-by: Emese Revfy <re.emese@gmail.com>
> ---
>  arch/Kconfig                      | 12 +++++++
>  scripts/Makefile.gcc-plugins      |  6 +++-
>  tools/gcc/Makefile                |  4 +++
>  tools/gcc/cyc_complexity_plugin.c | 73 +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 94 insertions(+), 1 deletion(-)
>  create mode 100644 tools/gcc/cyc_complexity_plugin.c
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index e090642..59bde9b 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -370,6 +370,18 @@ menuconfig GCC_PLUGINS
>           GCC plugins are loadable modules that provide extra features to the
>           compiler. They are useful for runtime instrumentation and static analysis.
>
> +config GCC_PLUGIN_CYC_COMPLEXITY
> +       bool "Compute the cyclomatic complexity of a function"
> +       depends on GCC_PLUGINS
> +       help
> +         The complexity M of a function's control flow graph is defined as:
> +          M = E - N + 2P
> +         where
> +
> +         E = the number of edges
> +         N = the number of nodes
> +         P = the number of connected components (exit nodes).
> +
>  config HAVE_CC_STACKPROTECTOR
>         bool
>         help
> diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
> index 7c85bf2..dd7b56d 100644
> --- a/scripts/Makefile.gcc-plugins
> +++ b/scripts/Makefile.gcc-plugins
> @@ -5,7 +5,11 @@ else
>  PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh "$(HOSTCC)" "$(HOSTCXX)" "$(CC)")
>  endif
>  ifneq ($(PLUGINCC),)
> -export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS
> +ifdef CONFIG_GCC_PLUGIN_CYC_COMPLEXITY
> +GCC_PLUGIN_CYC_COMPLEXITY_CFLAGS := -fplugin=$(objtree)/tools/gcc/cyc_complexity_plugin.so
> +endif
> +GCC_PLUGINS_CFLAGS := $(GCC_PLUGIN_CYC_COMPLEXITY_CFLAGS)
> +export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS GCC_PLUGIN_CYC_COMPLEXITY


Do you need to export "GCC_PLUGIN_CYC_COMPLEXITY"?
I do not see any reference to it.

If we expect more and more plugins in the future,
is it better to do like this?

gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY)  += cyc_complexity_plugin.so
gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV)          += sancov_plugin.so
gcc-plugin-$(CONFIG_GCC_PLUGIN_FOO)             += foo_plugin.so


GCC_PLUGINS_CFLAGS := $(addprefix -fplugin=$(objtree)/tools/gcc/,
$(gcc-plugin-y))
Emese Revfy March 14, 2016, 9:02 p.m. UTC | #2
On Fri, 11 Mar 2016 15:26:39 +0900
Masahiro Yamada <yamada.masahiro@socionext.com> wrote:

> > diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
> > index 7c85bf2..dd7b56d 100644
> > --- a/scripts/Makefile.gcc-plugins
> > +++ b/scripts/Makefile.gcc-plugins
> > @@ -5,7 +5,11 @@ else
> >  PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh "$(HOSTCC)" "$(HOSTCXX)" "$(CC)")
> >  endif
> >  ifneq ($(PLUGINCC),)
> > -export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS
> > +ifdef CONFIG_GCC_PLUGIN_CYC_COMPLEXITY
> > +GCC_PLUGIN_CYC_COMPLEXITY_CFLAGS := -fplugin=$(objtree)/tools/gcc/cyc_complexity_plugin.so
> > +endif
> > +GCC_PLUGINS_CFLAGS := $(GCC_PLUGIN_CYC_COMPLEXITY_CFLAGS)
> > +export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS GCC_PLUGIN_CYC_COMPLEXITY
> 
> 
> Do you need to export "GCC_PLUGIN_CYC_COMPLEXITY"?
> I do not see any reference to it.

This is a demo plugin. I just want to demonstrate how to use this infrastructure but I can remove it.
In my project there would be other plugins which use the export.

> If we expect more and more plugins in the future,
> is it better to do like this?
> 
> gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY)  += cyc_complexity_plugin.so
> gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV)          += sancov_plugin.so
> gcc-plugin-$(CONFIG_GCC_PLUGIN_FOO)             += foo_plugin.so
> 
> 
> GCC_PLUGINS_CFLAGS := $(addprefix -fplugin=$(objtree)/tools/gcc/,
> $(gcc-plugin-y))

Yes, it is better, I will do it.

Patch
diff mbox

diff --git a/arch/Kconfig b/arch/Kconfig
index e090642..59bde9b 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -370,6 +370,18 @@  menuconfig GCC_PLUGINS
 	  GCC plugins are loadable modules that provide extra features to the
 	  compiler. They are useful for runtime instrumentation and static analysis.
 
+config GCC_PLUGIN_CYC_COMPLEXITY
+	bool "Compute the cyclomatic complexity of a function"
+	depends on GCC_PLUGINS
+	help
+	  The complexity M of a function's control flow graph is defined as:
+	   M = E - N + 2P
+	  where
+
+	  E = the number of edges
+	  N = the number of nodes
+	  P = the number of connected components (exit nodes).
+
 config HAVE_CC_STACKPROTECTOR
 	bool
 	help
diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
index 7c85bf2..dd7b56d 100644
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -5,7 +5,11 @@  else
 PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh "$(HOSTCC)" "$(HOSTCXX)" "$(CC)")
 endif
 ifneq ($(PLUGINCC),)
-export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS
+ifdef CONFIG_GCC_PLUGIN_CYC_COMPLEXITY
+GCC_PLUGIN_CYC_COMPLEXITY_CFLAGS := -fplugin=$(objtree)/tools/gcc/cyc_complexity_plugin.so
+endif
+GCC_PLUGINS_CFLAGS := $(GCC_PLUGIN_CYC_COMPLEXITY_CFLAGS)
+export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS GCC_PLUGIN_CYC_COMPLEXITY
 ifeq ($(KBUILD_EXTMOD),)
 gcc-plugins:
 	$(Q)$(MAKE) $(build)=tools/gcc
diff --git a/tools/gcc/Makefile b/tools/gcc/Makefile
index b2d64af..31c72bf 100644
--- a/tools/gcc/Makefile
+++ b/tools/gcc/Makefile
@@ -12,4 +12,8 @@  endif
 
 export GCCPLUGINS_DIR HOSTLIBS
 
+$(HOSTLIBS)-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) := cyc_complexity_plugin.so
+
 always := $($(HOSTLIBS)-y)
+
+cyc_complexity_plugin-objs := cyc_complexity_plugin.o
diff --git a/tools/gcc/cyc_complexity_plugin.c b/tools/gcc/cyc_complexity_plugin.c
new file mode 100644
index 0000000..34df974
--- /dev/null
+++ b/tools/gcc/cyc_complexity_plugin.c
@@ -0,0 +1,73 @@ 
+/*
+ * Copyright 2011-2016 by Emese Revfy <re.emese@gmail.com>
+ * Licensed under the GPL v2, or (at your option) v3
+ *
+ * Homepage:
+ * https://github.com/ephox-gcc-plugins/cyclomatic_complexity
+ *
+ * http://en.wikipedia.org/wiki/Cyclomatic_complexity
+ * The complexity M is then defined as:
+ * M = E - N + 2P
+ * where
+ *
+ *  E = the number of edges of the graph
+ *  N = the number of nodes of the graph
+ *  P = the number of connected components (exit nodes).
+ *
+ * Usage (4.5 - 5):
+ * $ make clean; make run
+ */
+
+#include "gcc-common.h"
+
+int plugin_is_GPL_compatible;
+
+static struct plugin_info cyc_complexity_plugin_info = {
+	.version	= "20160225",
+	.help		= "Cyclomatic Complexity\n",
+};
+
+static unsigned int cyc_complexity_execute(void)
+{
+	int complexity;
+	expanded_location xloc;
+
+	/* M = E - N + 2P */
+	complexity = n_edges_for_fn(cfun) - n_basic_blocks_for_fn(cfun) + 2;
+
+	xloc = expand_location(DECL_SOURCE_LOCATION(current_function_decl));
+	fprintf(stderr, "Cyclomatic Complexity %d %s:%s\n", complexity,
+		xloc.file, DECL_NAME_POINTER(current_function_decl));
+
+	return 0;
+}
+
+#define PASS_NAME cyc_complexity
+
+#define NO_GATE
+#define TODO_FLAGS_FINISH TODO_dump_func
+
+#include "gcc-generate-gimple-pass.h"
+
+int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
+{
+	const char * const plugin_name = plugin_info->base_name;
+	struct register_pass_info cyc_complexity_pass_info;
+
+	cyc_complexity_pass_info.pass				= make_cyc_complexity_pass();
+	cyc_complexity_pass_info.reference_pass_name		= "ssa";
+	cyc_complexity_pass_info.ref_pass_instance_number	= 1;
+	cyc_complexity_pass_info.pos_op				= PASS_POS_INSERT_AFTER;
+
+	if (!plugin_default_version_check(version, &gcc_version)) {
+		error(G_("incompatible gcc/plugin versions"));
+		return 1;
+	}
+
+	register_callback(plugin_name, PLUGIN_INFO, NULL,
+				&cyc_complexity_plugin_info);
+	register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL,
+				&cyc_complexity_pass_info);
+
+	return 0;
+}