/*
   * 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/sancov
   *
   * This plugin inserts a __sanitizer_cov_trace_pc() call at the start of basic blocks.
   * It supports all gcc versions with plugin support (from gcc-4.5 on).
   * It is based on the commit "Add fuzzing coverage support" by Dmitry Vyukov <dvyukov@google.com>.
   *
   * You can read about it more here:
   *  https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296
   *  http://lwn.net/Articles/674854/
   *  https://github.com/google/syzkaller
   *  https://lwn.net/Articles/677764/
   *
   * Usage:
   * make run
   */
  
  #include "gcc-common.h"

  __visible int plugin_is_GPL_compatible;

  
  tree sancov_fndecl;
  
  static struct plugin_info sancov_plugin_info = {
  	.version	= "20160402",
  	.help		= "sancov plugin
  ",
  };
  
  static unsigned int sancov_execute(void)
  {
  	basic_block bb;
  
  	/* Remove this line when this plugin and kcov will be in the kernel.
  	if (!strcmp(DECL_NAME_POINTER(current_function_decl), DECL_NAME_POINTER(sancov_fndecl)))
  		return 0;
  	*/
  
  	FOR_EACH_BB_FN(bb, cfun) {
  		const_gimple stmt;
  		gcall *gcall;
  		gimple_stmt_iterator gsi = gsi_after_labels(bb);
  
  		if (gsi_end_p(gsi))
  			continue;
  
  		stmt = gsi_stmt(gsi);
  		gcall = as_a_gcall(gimple_build_call(sancov_fndecl, 0));
  		gimple_set_location(gcall, gimple_location(stmt));
  		gsi_insert_before(&gsi, gcall, GSI_SAME_STMT);
  	}
  	return 0;
  }
  
  #define PASS_NAME sancov
  
  #define NO_GATE
  #define TODO_FLAGS_FINISH TODO_dump_func | TODO_verify_stmts | TODO_update_ssa_no_phi | TODO_verify_flow
  
  #include "gcc-generate-gimple-pass.h"
  
  static void sancov_start_unit(void __unused *gcc_data, void __unused *user_data)
  {
  	tree leaf_attr, nothrow_attr;
  	tree BT_FN_VOID = build_function_type_list(void_type_node, NULL_TREE);
  
  	sancov_fndecl = build_fn_decl("__sanitizer_cov_trace_pc", BT_FN_VOID);
  
  	DECL_ASSEMBLER_NAME(sancov_fndecl);
  	TREE_PUBLIC(sancov_fndecl) = 1;
  	DECL_EXTERNAL(sancov_fndecl) = 1;
  	DECL_ARTIFICIAL(sancov_fndecl) = 1;
  	DECL_PRESERVE_P(sancov_fndecl) = 1;
  	DECL_UNINLINABLE(sancov_fndecl) = 1;
  	TREE_USED(sancov_fndecl) = 1;
  
  	nothrow_attr = tree_cons(get_identifier("nothrow"), NULL, NULL);
  	decl_attributes(&sancov_fndecl, nothrow_attr, 0);
  	gcc_assert(TREE_NOTHROW(sancov_fndecl));
  #if BUILDING_GCC_VERSION > 4005
  	leaf_attr = tree_cons(get_identifier("leaf"), NULL, NULL);
  	decl_attributes(&sancov_fndecl, leaf_attr, 0);
  #endif
  }

  __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)

  {
  	int i;

  	const char * const plugin_name = plugin_info->base_name;
  	const int argc = plugin_info->argc;
  	const struct plugin_argument * const argv = plugin_info->argv;
  	bool enable = true;
  
  	static const struct ggc_root_tab gt_ggc_r_gt_sancov[] = {
  		{
  			.base = &sancov_fndecl,
  			.nelt = 1,
  			.stride = sizeof(sancov_fndecl),
  			.cb = &gt_ggc_mx_tree_node,
  			.pchw = &gt_pch_nx_tree_node
  		},
  		LAST_GGC_ROOT_TAB
  	};
  
  	/* BBs can be split afterwards?? */

  #if BUILDING_GCC_VERSION >= 4009

  	PASS_INFO(sancov, "asan", 0, PASS_POS_INSERT_BEFORE);

  #else

  	PASS_INFO(sancov, "nrv", 1, PASS_POS_INSERT_BEFORE);

  #endif

  
  	if (!plugin_default_version_check(version, &gcc_version)) {
  		error(G_("incompatible gcc/plugin versions"));
  		return 1;
  	}
  
  	for (i = 0; i < argc; ++i) {
  		if (!strcmp(argv[i].key, "no-sancov")) {
  			enable = false;
  			continue;
  		}

  		error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);

  	}
  
  	register_callback(plugin_name, PLUGIN_INFO, NULL, &sancov_plugin_info);
  
  	if (!enable)
  		return 0;
  
  #if BUILDING_GCC_VERSION < 6000
  	register_callback(plugin_name, PLUGIN_START_UNIT, &sancov_start_unit, NULL);
  	register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, NULL, (void *)&gt_ggc_r_gt_sancov);

  	register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &sancov_pass_info);

  #endif
  
  	return 0;
  }