v.util.timers: improve tracing by supporting `-d trace_timers_creation`

cmd/v/v.v

@@ -50,7 +50,7 @@ fn main() {
 	$if time_v ? {
 		timers_should_print = true
 	}
-	mut timers := util.new_timers(timers_should_print)
+	mut timers := util.new_timers(should_print: timers_should_print, label: 'main')
 	timers.start('v total')
 	defer {
 		timers.show('v total')

vlib/v/checker/checker.v

@@ -101,7 +101,7 @@ mut:
 	vweb_gen_types                   []ast.Type // vweb route checks
 	prevent_sum_type_unwrapping_once bool       // needed for assign new values to sum type, stopping unwrapping then
 	loop_label                       string     // set when inside a labelled for loop
-	timers                           &util.Timers = util.new_timers(false)
+	timers                           &util.Timers = util.get_timers()
 	comptime_fields_type             map[string]ast.Type
 	fn_scope                         &ast.Scope = voidptr(0)
 	main_fn_decl_node                ast.FnDecl
@@ -123,7 +123,7 @@ pub fn new_checker(table &ast.Table, pref &pref.Preferences) &Checker {
 	return &Checker{
 		table: table
 		pref: pref
-		timers: util.new_timers(timers_should_print)
+		timers: util.new_timers(should_print: timers_should_print, label: 'checker')
 		match_exhaustive_cutoff_limit: pref.checker_match_exhaustive_cutoff_limit
 	}
 }

vlib/v/gen/c/cgen.v

@@ -175,7 +175,7 @@ mut:
 	returned_var_name   string // to detect that a var doesn't need to be freed since it's being returned
 	branch_parent_pos   int    // used in BranchStmt (continue/break) for autofree stop position
 	infix_left_var_name string // a && if expr
-	timers              &util.Timers = util.new_timers(false)
+	timers              &util.Timers = util.get_timers()
 	force_main_console  bool // true when [console] used on fn main()
 	as_cast_type_names  map[string]string // table for type name lookup in runtime (for __as_cast)
 	obf_table           map[string]string
@@ -240,7 +240,7 @@ pub fn gen(files []&ast.File, table &ast.Table, pref &pref.Preferences) string {
 		indent: -1
 		module_built: module_built
 		timers_should_print: timers_should_print
-		timers: util.new_timers(timers_should_print)
+		timers: util.new_timers(should_print: timers_should_print, label: 'global_cgen')
 		inner_loop: &ast.EmptyStmt{}
 		field_data_type: ast.Type(table.find_type_idx('FieldData'))
 		init: strings.new_builder(100)
@@ -525,7 +525,10 @@ fn cgen_process_one_file_cb(p &pool.PoolProcessor, idx int, wid int) &Gen {
 		fn_decl: 0
 		indent: -1
 		module_built: global_g.module_built
-		timers: util.new_timers(global_g.timers_should_print)
+		timers: util.new_timers(
+			should_print: global_g.timers_should_print
+			label: 'cgen_process_one_file_cb idx: $idx, wid: $wid'
+		)
 		inner_loop: &ast.EmptyStmt{}
 		field_data_type: ast.Type(global_g.table.find_type_idx('FieldData'))
 		array_sort_fn: global_g.array_sort_fn

vlib/v/parser/parser.v

@@ -360,7 +360,7 @@ fn (mut q Queue) run() {
 }
 */
 pub fn parse_files(paths []string, table &ast.Table, pref &pref.Preferences) []&ast.File {
-	mut timers := util.new_timers(false)
+	mut timers := util.new_timers(should_print: false, label: 'parse_files: $paths')
 	$if time_parsing ? {
 		timers.should_print = true
 	}

vlib/v/util/timers.v

@@ -1,12 +1,16 @@
 // Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
 // Use of this source code is governed by an MIT license
 // that can be found in the LICENSE file.
+[has_globals]
 module util
 
 import time
 
+__global g_timers = new_timers(should_print: false, label: 'g_timers')
+
 [heap]
 pub struct Timers {
+	label string
 pub mut:
 	swatches     map[string]time.StopWatch
 	should_print bool
@@ -14,18 +18,26 @@ pub mut:
 	already_shown []string
 }
 
-pub fn new_timers(should_print bool) &Timers {
+[params]
+pub struct TimerParams {
+	should_print bool
+	label        string
+}
+
+pub fn new_timers(params TimerParams) &Timers {
+	$if trace_timers_creation ? {
+		eprintln('>>>> new_timers, should_print: $params.should_print | label: $params.label')
+	}
 	return &Timers{
+		label: params.label
 		swatches: map[string]time.StopWatch{}
-		should_print: should_print
+		should_print: params.should_print
 		already_shown: []string{cap: 100}
 	}
 }
 
-const timers = new_timers(false)
-
 pub fn get_timers() &Timers {
-	return util.timers
+	return g_timers
 }
 
 pub fn timing_start(label string) {
@@ -34,18 +46,15 @@ pub fn timing_start(label string) {
 }
 
 pub fn timing_measure(label string) {
-	mut t := get_timers()
-	t.show(label)
+	g_timers.show(label)
 }
 
 pub fn timing_measure_cumulative(label string) {
-	mut t := get_timers()
-	t.measure_cumulative(label)
+	g_timers.measure_cumulative(label)
 }
 
 pub fn timing_set_should_print(should_print bool) {
-	mut t := util.timers
-	t.should_print = should_print
+	g_timers.should_print = should_print
 }
 
 pub fn (mut t Timers) start(name string) {