Re: [PATCH v9 3/4] Add Cyclomatic complexity GCC plugin

[Laura Abbott <labbott@redhat.com>]

On 05/23/2016 03:10 PM, Emese Revfy wrote:
> 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).
>

This has some weird interaction with ftrace. On x86

1) make mrproper
2) make defconfig
3) enable GCC_PLUGINS, GCC_PLUGIN_CYC_COMPLEXITY
4) enable FUNCTION_TRACER (it will select other options as well)
5) make && make modules

   MODPOST 18 modules
ERROR: "__fentry__" [net/netfilter/xt_nat.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_mark.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_addrtype.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_LOG.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_sip.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_irc.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_ftp.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_log_common.ko] undefined!
ERROR: "__fentry__" [net/ipv6/netfilter/nf_log_ipv6.ko] undefined!
ERROR: "__fentry__" [net/ipv4/netfilter/nf_nat_masquerade_ipv4.ko] undefined!
ERROR: "__fentry__" [net/ipv4/netfilter/nf_nat_ipv4.ko] undefined!
ERROR: "__fentry__" [net/ipv4/netfilter/nf_log_ipv4.ko] undefined!
ERROR: "__fentry__" [net/ipv4/netfilter/nf_log_arp.ko] undefined!
ERROR: "__fentry__" [net/ipv4/netfilter/iptable_nat.ko] undefined!
ERROR: "__fentry__" [net/ipv4/netfilter/ipt_MASQUERADE.ko] undefined!
ERROR: "__fentry__" [fs/efivarfs/efivarfs.ko] undefined!
ERROR: "__fentry__" [drivers/thermal/x86_pkg_temp_thermal.ko] undefined!
scripts/Makefile.modpost:91: recipe for target '__modpost' failed
make[1]: *** [__modpost] Error 1

Verified with gcc-5.3.1 and gcc-6.1.1. You need to do a clean build
with 'make mrproper' first to see this. Subsequent builds will
succeed oddly enough. I suspect this

Thanks,
Laura

> Signed-off-by: Emese Revfy <re.emese@gmail.com>
> ---
>  arch/Kconfig                                | 12 +++++
>  scripts/Makefile.gcc-plugins                |  1 +
>  scripts/gcc-plugins/Makefile                |  1 +
>  scripts/gcc-plugins/cyc_complexity_plugin.c | 73 +++++++++++++++++++++++++++++
>  4 files changed, 87 insertions(+)
>  create mode 100644 scripts/gcc-plugins/cyc_complexity_plugin.c
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 2821cfe..74f0d63 100644
> --- 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 bcc373d..b4a189c 100644
> --- 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 a4c9341..c60ba4b 100644
> --- 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
> 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;
> +}
>