ler-plugin: initial gcc plugin harness to be used in our build

Ideas and some code from https://github.com/mesonbuild/meson/issues/5090

This is just an example plugin that cold be used as a starting point.
Right now we find efl_super() with GIMPLE and add a efl_super2 call when
it was defined and in code before to allow linking.

meson.build

@@ -248,6 +248,11 @@ if get_option('tslib') == true
   config_h.set('HAVE_TSLIB', '1')
 endif
 
+#if get_option('compiler-plugins') == true
+  #gcc_plugin = dependency('gcc-plugin')
+  subdir(join_paths('src', 'compiler-plugins'))
+#endif
+
 subdir('header_checks')
 subdir('po')
 
@@ -313,7 +318,7 @@ subprojects = [
 ['evil'             ,[]                    , false,  true, false, false, false, false,  true, [], []],
 ['eina'             ,[]                    , false,  true,  true,  true,  true,  true,  true, [], []],
 ['eolian'           ,[]                    , false,  true,  true, false,  true, false, false, ['eina'], []],
-['eo'               ,[]                    , false,  true, false,  true,  true, false,  true, ['eina'], []],
+['eo'               ,[]                    , false,  true, false,  true,  true, false,  true,  ['eina', 'compiler_plugin'], []],
 ['efl'              ,[]                    , false,  true, false, false,  true, false,  true, ['eo'], []],
 ['emile'            ,[]                    , false,  true, false, false,  true,  true,  true, ['eina', 'efl'], ['lz4', 'rg_etc']],
 ['eet'              ,[]                    , false,  true,  true, false,  true,  true,  true, ['eina', 'emile', 'efl'], []],
@@ -420,6 +425,8 @@ foreach package : subprojects
       '-DNEED_RUN_IN_TREE=1',
       '-DEFL_BUILD=1',
     ]
+# '-fdump-passes',
+#'-fdump-tree-gimple',
     if (package[3])
       subdir(join_paths(local_lib, package_name))
       set_variable(package_name + '_eo_files', pub_eo_files)

src/compiler-plugins/meson.build

@@ -0,0 +1,25 @@
+cc = meson.get_compiler('c')
+plugin_dev_path_result = run_command(cc.cmd_array(), '-print-file-name=plugin')
+plugin_dev_path = plugin_dev_path_result.stdout().strip()
+plugin_inc = include_directories([join_paths(plugin_dev_path, 'include')])
+
+myplugin = shared_module('myplugin',
+	'myplugin.cc',
+	cpp_args: [ '-fno-rtti' ],
+	include_directories: plugin_inc
+)
+
+myplugin_dep = custom_target('myplugin',
+	input: myplugin,
+        output: 'myplugin_dep.h',
+        command: ['echo'],
+        capture: true
+)
+
+compiler_plugin = declare_dependency()
+
+test_1 = executable('test-1', 'test-1.c', myplugin_dep,
+	c_args: [ '-fdump-passes', '-fplugin=' + myplugin.full_path() ],
+	native: true,
+)
+test('test_1', test_1)

src/compiler-plugins/myplugin.cc

@@ -0,0 +1,104 @@
+#include <stdio.h>
+#include "gcc-common.h"
+
+/* TODO:
+ * Find all efl_super calls
+ * Traverse back to find function calling it (foo)
+ * Calculate the private data pointer diff
+ * Replace foo(efl_super(obj, MY_CLASS),...) calls with the next lower level function for foo and
+ * adjust private data with diff
+ * Make eolian more expressive (We need the implemented methods of classes, accross the tree)
+ */
+
+__visible int plugin_is_GPL_compatible;
+
+static const char super2_function[] = "efl_super2";
+static GTY(()) tree super2_function_decl;
+
+static void super2_add(gimple_stmt_iterator *gsi)
+{
+	gimple stmt;
+	gcall *super2_func;
+	cgraph_node_ptr node;
+	int frequency;
+	basic_block bb;
+
+	stmt = gimple_build_call(super2_function_decl, 0);
+	super2_func = as_a_gcall(stmt);
+	gsi_insert_after(gsi, super2_func, GSI_CONTINUE_LINKING);
+
+	/* Update the cgraph */
+	bb = gimple_bb(super2_func);
+	node = cgraph_get_create_node(super2_function_decl);
+	gcc_assert(node);
+	frequency = compute_call_stmt_bb_frequency(current_function_decl, bb);
+	cgraph_create_edge(cgraph_get_node(current_function_decl), node,
+			super2_func, bb->count, frequency);
+}
+
+static unsigned int eo_execute(void)
+{
+  basic_block bb, entry_bb;
+  gimple_stmt_iterator gsi;
+
+  //fprintf(stderr, "Function %s called\n", get_name(cfun->decl));
+
+  gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
+  entry_bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun));
+
+  FOR_EACH_BB_FN(bb, cfun) {
+    const_gimple stmt;
+    for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi))
+      {
+        stmt = gsi_stmt(gsi);
+        if (is_gimple_call(stmt)){
+	  tree current_fn_decl = gimple_call_fndecl(stmt);
+	  if (!current_fn_decl)
+	     continue;
+          const char* name = IDENTIFIER_POINTER(DECL_NAME(current_fn_decl));
+          if (!strncmp(name, "efl_super", 9)) {
+            fprintf(stderr, "Found function %s\n", name);
+            super2_add(&gsi);
+	  }
+        }
+      }
+    }
+  return 0;
+}
+
+static void super2_start_unit(void *gcc_data __unused,
+				 void *user_data __unused)
+{
+	/* void efl_super2(void) */
+	tree fntype = build_function_type_list(void_type_node, NULL_TREE);
+	super2_function_decl = build_fn_decl(super2_function, fntype);
+	DECL_ASSEMBLER_NAME(super2_function_decl); /* for LTO */
+	TREE_PUBLIC(super2_function_decl) = 1;
+	TREE_USED(super2_function_decl) = 1;
+	DECL_EXTERNAL(super2_function_decl) = 1;
+	DECL_ARTIFICIAL(super2_function_decl) = 1;
+	DECL_PRESERVE_P(super2_function_decl) = 1;
+}
+
+#define PASS_NAME eo
+#define NO_GATE
+#include "gcc-generate-gimple-pass.h"
+
+__visible int plugin_init(struct plugin_name_args *plugin_info,
+		struct plugin_gcc_version *version)
+{
+	const char *plugin_name = plugin_info->base_name;
+
+	if (!plugin_default_version_check (version, &gcc_version))
+		return 1;
+
+        PASS_INFO(eo, "cfg", 1, PASS_POS_INSERT_AFTER);
+
+	/* Register to be called before processing a translation unit */
+	register_callback(plugin_name, PLUGIN_START_UNIT,
+					&super2_start_unit, NULL);
+
+        register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &eo_pass_info);
+
+	return 0;
+}

src/compiler-plugins/test-1.c

@@ -0,0 +1,11 @@
+#include <stdio.h>
+void efl_super2(void){}
+
+int efl_super(void) {
+}
+
+int main(void)
+{
+	efl_super();
+	return 0;
+}

src/lib/eo/Eo.h

@@ -1458,6 +1458,7 @@ EAPI Eo * _efl_add_end(Eo *obj, Eina_Bool is_ref, Eina_Bool is_fallback);
  * @see efl_cast
  */
 EAPI Eo *efl_super(const Eo *obj, const Efl_Class *cur_klass);
+EAPI void efl_super2(void);
 
 /**
  * @brief Prepare a call to cast to a parent class implementation of a function.

src/lib/eo/eo.c

@@ -529,6 +529,10 @@ efl_super(const Eo *eo_id, const Efl_Class *cur_klass)
 {
    return _efl_super_cast(eo_id, cur_klass, EINA_TRUE);
 }
+EAPI void
+efl_super2(void)
+{
+}
 
 EAPI Eo *
 efl_cast(const Eo *eo_id, const Efl_Class *cur_klass)

src/lib/eo/meson.build

@@ -1,4 +1,4 @@
-eo_deps = []
+eo_deps = [compiler_plugin]
 eo_pub_deps = [eina]
 eo_ext_deps = [valgrind, dl, execinfo]