Add Cyclomatic complexity GCC plugin

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>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michal Marek <mmarek@suse.com>

diff --git a/arch/Kconfig b/arch/Kconfig
index 1b93632198fa4dd29bf6ca27ed9bba85d67c3f00..04ca45262ad1917f8a0df507328786385fee2eeb 100644 (file)
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -372,6 +372,18 @@ menuconfig GCC_PLUGINS
 
          See Documentation/gcc-plugins.txt for details.
 
+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 bcc373dcb3b54b95204bcdb0919faacdc7b714d7..b4a189c95a8a6ab628c93480e4a920a68768356b 100644 (file)
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -2,6 +2,7 @@ ifdef CONFIG_GCC_PLUGINS
   __PLUGINCC := $(call cc-ifversion, -ge, 0408, $(HOSTCXX), $(HOSTCC))
   PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh "$(__PLUGINCC)" "$(HOSTCXX)" "$(CC)")
 
+  gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY)       += cyc_complexity_plugin.so
   GCC_PLUGINS_CFLAGS := $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y))
 
   export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGIN

diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile
index a4c93419d5d1236c0d136d63a4874b22f9c4a8b1..c60ba4bef57ce56e49b379f94c2aeb9f8497978b 100644 (file)
--- a/scripts/gcc-plugins/Makefile
+++ b/scripts/gcc-plugins/Makefile
@@ -17,4 +17,5 @@ export GCCPLUGINS_DIR HOSTLIBS
 $(HOSTLIBS)-y := $(GCC_PLUGIN)
 always := $($(HOSTLIBS)-y)
 
+cyc_complexity_plugin-objs := cyc_complexity_plugin.o
 clean-files += *.so

diff --git a/scripts/gcc-plugins/cyc_complexity_plugin.c b/scripts/gcc-plugins/cyc_complexity_plugin.c
new file mode 100644 (file)
index 0000000..34df974
--- /dev/null
+++ b/scripts/gcc-plugins/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;
+}