From 167773dd1c795cdd87ec8c17a3f6f8f8565c3dab Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Sat, 6 Feb 2021 09:34:01 +0200
Subject: [PATCH] checker: make -skip-unused process a list of root functions,
 not just main.main

---
 vlib/v/checker/mark_used.v               | 175 +++++++++++------------
 vlib/v/checker/mark_used_walker/walker.v |  15 +-
 vlib/v/gen/c/fn.v                        |   7 +-
 3 files changed, 98 insertions(+), 99 deletions(-)

diff --git a/vlib/v/checker/mark_used.v b/vlib/v/checker/mark_used.v
index aa9235a11a..3b3268101c 100644
--- a/vlib/v/checker/mark_used.v
+++ b/vlib/v/checker/mark_used.v
@@ -7,103 +7,102 @@ import v.checker.mark_used_walker
 
 // mark_used walks the AST, starting at main() and marks all used fns transitively
 fn (mut c Checker) mark_used(ast_files []ast.File) {
-	// println('walking the ast')
-	// c.is_recursive = true
-	// c.fn_decl(mut c.table2.main_fn_decl_node)
-
 	util.timing_start(@METHOD)
 	mut walker := mark_used_walker.Walker{
 		files: ast_files
 	}
 
-	// TODO: walking over the AST using roots != main.main, like `panic`
-	// for example, will potentially eliminate many cases where manual
-	// whitelisting is needed.
-	// TODO: use the full name of the functions in the map. For now the
-	// receiver type is skipped, so we can not distinguish between
-	// array.trim and string.trim etc.
-	for stmt in c.main_fn_decl_node.stmts {
-		walker.stmt(stmt)
+	mut allfns := map[string]ast.FnDecl{}
+	for i in 0 .. ast_files.len {
+		file := unsafe { &ast_files[i] }
+		for node in file.stmts {
+			if node is ast.FnDecl {
+				fkey := if node.is_method {
+					'${int(node.receiver.typ)}.$node.name'
+				} else {
+					node.name
+				}
+				allfns[fkey] = node
+			}
+		}
+	}
+	all_fn_root_names := [
+		'main.main',
+		'__new_array',
+		'__new_array_with_default',
+		'new_array_from_c_array',
+		'panic',
+		'memdup',
+		'vstrlen',
+		'tos2',
+		'tos',
+		'isnil',
+		'utf8_char_len',
+		'utf8_str_visible_length',
+		'builtin_init',
+		'print_backtrace_skipping_top_frames',
+		'print_backtrace_skipping_top_frames_mac',
+		'print_backtrace_skipping_top_frames_linux',
+		'print_backtrace_skipping_top_frames_freebsd',
+		'print_backtrace_skipping_top_frames_windows',
+		'print_backtrace_skipping_top_frames_mingw',
+		'print_backtrace_skipping_top_frames_msvc',
+		'print_backtrace_skipping_top_frames_tcc',
+		/* byteptr and charptr */
+		'3.vstring',
+		'3.vstring_with_len',
+		'4.vstring',
+		'4.vstring_with_len',
+		/* string. methods */
+		'18.add',
+		'18.all_after',
+		'18.all_before',
+		'18.trim_space',
+		'18.replace',
+		'18.clone',
+		'18.trim',
+		'18.substr',
+		'18.at',
+		'18.index_kmp',
+		/* string. ==, !=, etc... */
+		'18.eq',
+		'18.ne',
+		'18.lt',
+		'18.gt',
+		'18.le',
+		'18.ge',
+		/* ustring. ==, !=, etc... */
+		'19.eq',
+		'19.ne',
+		'19.lt',
+		'19.gt',
+		'19.le',
+		'19.ge',
+		'19.add',
+		/* other array methods */
+		'21.get',
+		'21.get_unsafe',
+		'59.get',
+		'65557.free',
+		'65557.push',
+		'65557.set',
+		'65557.set_unsafe',
+		/* TODO: process the _vinit const initializations automatically too */
+		'os.getwd',
+		'os.init_os_args',
+	]
+	// println( allfns.keys() )
+	for fn_name in all_fn_root_names {
+		walker.fn_decl(mut allfns[fn_name])
 	}
-	// walker.fn_decl(mut c.table2.main_fn_decl_node)
-	// println('time = ${time.ticks() - t}ms, nr used fns=$walker.used_fns.len')
 
-	/*
-	for key, _ in walker.used_fns {
-		println(key)
+	$if trace_skip_unused ? {
+		for key, _ in walker.used_fns {
+			println('> used fn key: $key')
+		}
 	}
-	*/
+
 	c.table.used_fns = walker.used_fns
-
-	// Whitelist some functions that are used by cgen directly:
-	c.table.used_fns['tos'] = true
-	c.table.used_fns['tos2'] = true
-	c.table.used_fns['v_panic'] = true
-	c.table.used_fns['panic'] = true
-	c.table.used_fns['eprintln'] = true
-	c.table.used_fns['print_backtrace_skipping_top_frames'] = true
-	c.table.used_fns['print_backtrace_skipping_top_frames_mac'] = true
-	c.table.used_fns['print_backtrace_skipping_top_frames_linux'] = true
-	c.table.used_fns['print_backtrace_skipping_top_frames_freebsd'] = true
-	c.table.used_fns['print_backtrace_skipping_top_frames_windows'] = true
-	c.table.used_fns['print_backtrace_skipping_top_frames_mingw'] = true
-	c.table.used_fns['print_backtrace_skipping_top_frames_msvc'] = true
-	c.table.used_fns['print_backtrace_skipping_top_frames_tcc'] = true
-	c.table.used_fns['is_atty'] = true
-	c.table.used_fns['add_unhandled_exception_handler'] = true
-	c.table.used_fns['add_vectored_exception_handler'] = true
-	c.table.used_fns['unhandled_exception_handler'] = true
-	c.table.used_fns['restore_codepage'] = true
-	c.table.used_fns['new_array_from_c_array'] = true
-	c.table.used_fns['__new_array_with_default'] = true
-	c.table.used_fns['__new_array'] = true
-	c.table.used_fns['vcalloc'] = true
-	c.table.used_fns['set_unsafe'] = true
-	c.table.used_fns['get_unsafe'] = true
-	c.table.used_fns['push'] = true
-	c.table.used_fns['ensure_cap'] = true
-	c.table.used_fns['v_realloc'] = true
-	c.table.used_fns['all_before'] = true
-	c.table.used_fns['all_after'] = true
-	c.table.used_fns['add'] = true
-	c.table.used_fns['isnil'] = true
-	c.table.used_fns['vstrlen'] = true
-	c.table.used_fns['trim_space'] = true
-	c.table.used_fns['malloc'] = true
-	c.table.used_fns['trim'] = true
-	c.table.used_fns['at'] = true
-	c.table.used_fns['replace'] = true
-	c.table.used_fns['index_'] = true
-	c.table.used_fns['index_after'] = true
-	c.table.used_fns['index_kmp'] = true
-	c.table.used_fns['substr'] = true
-	c.table.used_fns['clone'] = true
-	c.table.used_fns['free'] = true
-	c.table.used_fns['has_index'] = true
-	c.table.used_fns['key'] = true
-	c.table.used_fns['set'] = true
-	c.table.used_fns['get'] = true
-	c.table.used_fns['new_node'] = true
-	c.table.used_fns['eq'] = true
-	c.table.used_fns['ne'] = true
-	c.table.used_fns['lt'] = true
-	c.table.used_fns['gt'] = true
-	c.table.used_fns['le'] = true
-	c.table.used_fns['ge'] = true
-	c.table.used_fns['split_child'] = true
-	c.table.used_fns['bytes'] = true
-	c.table.used_fns['utf8_char_len'] = true
-	c.table.used_fns['utf8_str_visible_length'] = true
-	c.table.used_fns['main.main'] = true
-	c.table.used_fns['builtin_init'] = true
-	c.table.used_fns['memdup'] = true
-	c.table.used_fns['vstring'] = true
-	c.table.used_fns['vstring_with_len'] = true
-	c.table.used_fns['string'] = true // array.string
-	// c.table.used_fns['str'] = true // builtin .str() methods; They use strings.builder and strconv.ftoa_64 etc.
-	// whitelist common modules const initializers too:
-	c.table.used_fns['os.getwd'] = true
-	c.table.used_fns['os.init_os_args'] = true
 	//
 	c.table.used_fns['term.can_show_color_on_stdin'] = true
 	c.table.used_fns['term.can_show_color_on_stdout'] = true
diff --git a/vlib/v/checker/mark_used_walker/walker.v b/vlib/v/checker/mark_used_walker/walker.v
index 14d7b58fd9..24af677e43 100644
--- a/vlib/v/checker/mark_used_walker/walker.v
+++ b/vlib/v/checker/mark_used_walker/walker.v
@@ -31,9 +31,9 @@ pub fn (mut w Walker) stmt(node ast.Stmt) {
 		ast.ExprStmt {
 			w.expr(node.expr)
 		}
-		// ast.FnDecl {
-		// w.fn_decl(mut node)
-		//}
+		ast.FnDecl {
+			w.fn_decl(mut node)
+		}
 		ast.ForStmt {
 			w.expr(node.cond)
 			for stmt in node.stmts {
@@ -79,10 +79,9 @@ fn (mut w Walker) expr(node ast.Expr) {
 	}
 }
 
-/*
 pub fn (mut w Walker) fn_decl(mut node ast.FnDecl) {
-	fn_name := if node.is_method { node.receiver.typ.str() + '.' + node.name } else { node.name }
-	if w.used_fns[fn_name] {
+	fkey := if node.is_method { '${int(node.receiver.typ)}.$node.name' } else { node.name }
+	if w.used_fns[fkey] {
 		// This function is already known to be called, meaning it has been processed already.
 		// Save CPU time and do nothing.
 		return
@@ -90,13 +89,11 @@ pub fn (mut w Walker) fn_decl(mut node ast.FnDecl) {
 	if node.language == .c {
 		return
 	}
-	// println('fn decl $fn_name')
-	w.used_fns[fn_name] = true
+	w.used_fns[fkey] = true
 	for stmt in node.stmts {
 		w.stmt(stmt)
 	}
 }
-*/
 
 pub fn (mut w Walker) call_expr(mut node ast.CallExpr) {
 	fn_name := if node.is_method { node.receiver_type.str() + '.' + node.name } else { node.name }
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index dc103737f5..48576c25e6 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -28,8 +28,11 @@ fn (mut g Gen) gen_fn_decl(node ast.FnDecl, skip bool) {
 	}
 	*/
 	if g.pref.skip_unused {
-		is_used_by_main := g.table.used_fns[node.name]
-		// println('> is_used_by_main: $is_used_by_main | node.name: $node.name')
+		fkey := if node.is_method { '${int(node.receiver.typ)}.$node.name' } else { node.name }
+		is_used_by_main := g.table.used_fns[fkey]
+		$if trace_skip_unused ? {
+			println('> is_used_by_main: $is_used_by_main | node.name: $node.name | fkey: $fkey | node.is_method: $node.is_method')
+		}
 		if !is_used_by_main {
 			g.writeln('// fn $node.name UNUSED')
 			return