do not disable `trace_` prefix insns.

* vm.c: introduce `ruby_vm_event_enabled_flags` which represents which
  event flags are enabled before.

* vm_trace.c: do not turn off `trace_` prefix instructions because turn on
  overhead is a matter if a program repeats turn on and turn off frequently.

* iseq.c (finish_iseq_build): respect `ruby_vm_event_enabled_flags`.

* vm_insnhelper.c (vm_trace): check `ruby_vm_event_flags` and disable
  lazy trace-off technique (do not disable traces).


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61122 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

iseq.c

@@ -361,8 +361,8 @@ finish_iseq_build(rb_iseq_t *iseq)
     }
 
     iseq->aux.trace_events = 0;
-    if (ruby_vm_event_flags & ISEQ_TRACE_EVENTS) {
-	rb_iseq_trace_set(iseq, ruby_vm_event_flags & ISEQ_TRACE_EVENTS);
+    if (ruby_vm_event_enabled_flags & ISEQ_TRACE_EVENTS) {
+	rb_iseq_trace_set(iseq, ruby_vm_event_enabled_flags & ISEQ_TRACE_EVENTS);
     }
     return Qtrue;
 }

vm.c

@@ -320,6 +320,7 @@ VALUE ruby_vm_const_missing_count = 0;
 rb_vm_t *ruby_current_vm_ptr = NULL;
 rb_execution_context_t *ruby_current_execution_context_ptr = NULL;
 rb_event_flag_t ruby_vm_event_flags;
+rb_event_flag_t ruby_vm_event_enabled_flags;
 rb_serial_t ruby_vm_global_method_state = 1;
 rb_serial_t ruby_vm_global_constant_state = 1;
 rb_serial_t ruby_vm_class_serial = 1;

vm_core.h

@@ -1591,6 +1591,7 @@ RUBY_SYMBOL_EXPORT_BEGIN
 extern rb_vm_t *ruby_current_vm_ptr;
 extern rb_execution_context_t *ruby_current_execution_context_ptr;
 extern rb_event_flag_t ruby_vm_event_flags;
+extern rb_event_flag_t ruby_vm_event_enabled_flags;
 
 RUBY_SYMBOL_EXPORT_END
 

vm_insnhelper.c

@@ -3727,56 +3727,68 @@ NOINLINE(static void vm_trace(rb_execution_context_t *ec, rb_control_frame_t *re
 static void
 vm_trace(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, const VALUE *pc)
 {
-    const rb_iseq_t *iseq = reg_cfp->iseq;
-    size_t pos = pc - iseq->body->iseq_encoded;
     rb_event_flag_t vm_event_flags = ruby_vm_event_flags;
-    rb_event_flag_t events = rb_iseq_event_flags(iseq, pos);
-    rb_event_flag_t event;
 
-    if ((events & vm_event_flags) == 0) {
-	/* disable trace */
-	rb_iseq_trace_set(iseq, vm_event_flags & ISEQ_TRACE_EVENTS);
+    if (vm_event_flags == 0) {
 	return;
     }
+    else {
+	const rb_iseq_t *iseq = reg_cfp->iseq;
+	size_t pos = pc - iseq->body->iseq_encoded;
+	rb_event_flag_t events = rb_iseq_event_flags(iseq, pos);
+	rb_event_flag_t event;
 
-    if (ec->trace_arg != NULL) return;
+	if ((events & vm_event_flags) == 0) {
+#if 0
+	    /* disable trace */
+	    rb_iseq_trace_set(iseq, vm_event_flags & ISEQ_TRACE_EVENTS);
+#else
+	    /* do not disable trace because of performance problem
+	     * (re-enable overhead)
+	     */
+#endif
+	    return;
+	}
 
-    if (0) {
-	fprintf(stderr, "vm_trace>>%4d (%4x) - %s:%d %s\n",
-		(int)pos,
-		(int)events,
-		RSTRING_PTR(rb_iseq_path(iseq)),
-		(int)rb_iseq_line_no(iseq, pos),
-		RSTRING_PTR(rb_iseq_label(iseq)));
-    }
+	if (ec->trace_arg != NULL) return;
 
-    VM_ASSERT(reg_cfp->pc == pc);
-    VM_ASSERT(events != 0);
-    VM_ASSERT(vm_event_flags & events);
+	if (0) {
+	    fprintf(stderr, "vm_trace>>%4d (%4x) - %s:%d %s\n",
+		    (int)pos,
+		    (int)events,
+		    RSTRING_PTR(rb_iseq_path(iseq)),
+		    (int)rb_iseq_line_no(iseq, pos),
+		    RSTRING_PTR(rb_iseq_label(iseq)));
+	}
 
-    /* increment PC because source line is calculated with PC-1 */
-    if (event = (events & (RUBY_EVENT_CLASS | RUBY_EVENT_CALL | RUBY_EVENT_B_CALL))) {
-	VM_ASSERT(event == RUBY_EVENT_CLASS ||
-		  event == RUBY_EVENT_CALL  ||
-		  event == RUBY_EVENT_B_CALL);
-	reg_cfp->pc++;
-	vm_dtrace(event, ec);
-	EXEC_EVENT_HOOK(ec, event, GET_SELF(), 0, 0, 0, Qundef);
-	reg_cfp->pc--;
-    }
-    if (events & RUBY_EVENT_LINE) {
-	reg_cfp->pc++;
-	vm_dtrace(RUBY_EVENT_LINE, ec);
-	EXEC_EVENT_HOOK(ec, RUBY_EVENT_LINE, GET_SELF(), 0, 0, 0, Qundef);
-	reg_cfp->pc--;
-    }
-    if (event = (events & (RUBY_EVENT_END | RUBY_EVENT_RETURN | RUBY_EVENT_B_RETURN))) {
-	VM_ASSERT(event == RUBY_EVENT_END ||
-		  event == RUBY_EVENT_RETURN  ||
-		  event == RUBY_EVENT_B_RETURN);
-	reg_cfp->pc++;
-	vm_dtrace(RUBY_EVENT_LINE, ec);
-	EXEC_EVENT_HOOK(ec, event, GET_SELF(), 0, 0, 0, TOPN(0));
-	reg_cfp->pc--;
+	VM_ASSERT(reg_cfp->pc == pc);
+	VM_ASSERT(events != 0);
+	VM_ASSERT(vm_event_flags & events);
+
+	/* increment PC because source line is calculated with PC-1 */
+	if (event = (events & (RUBY_EVENT_CLASS | RUBY_EVENT_CALL | RUBY_EVENT_B_CALL))) {
+	    VM_ASSERT(event == RUBY_EVENT_CLASS ||
+		      event == RUBY_EVENT_CALL  ||
+		      event == RUBY_EVENT_B_CALL);
+	    reg_cfp->pc++;
+	    vm_dtrace(event, ec);
+	    EXEC_EVENT_HOOK(ec, event, GET_SELF(), 0, 0, 0, Qundef);
+	    reg_cfp->pc--;
+	}
+	if (events & RUBY_EVENT_LINE) {
+	    reg_cfp->pc++;
+	    vm_dtrace(RUBY_EVENT_LINE, ec);
+	    EXEC_EVENT_HOOK(ec, RUBY_EVENT_LINE, GET_SELF(), 0, 0, 0, Qundef);
+	    reg_cfp->pc--;
+	}
+	if (event = (events & (RUBY_EVENT_END | RUBY_EVENT_RETURN | RUBY_EVENT_B_RETURN))) {
+	    VM_ASSERT(event == RUBY_EVENT_END ||
+		      event == RUBY_EVENT_RETURN  ||
+		      event == RUBY_EVENT_B_RETURN);
+	    reg_cfp->pc++;
+	    vm_dtrace(RUBY_EVENT_LINE, ec);
+	    EXEC_EVENT_HOOK(ec, event, GET_SELF(), 0, 0, 0, TOPN(0));
+	    reg_cfp->pc--;
+	}
     }
 }

vm_trace.c

@@ -65,14 +65,15 @@ static void
 update_global_event_hook(rb_event_flag_t vm_events)
 {
     rb_event_flag_t new_iseq_events = vm_events & ISEQ_TRACE_EVENTS;
-    rb_event_flag_t cur_iseq_events = ruby_vm_event_flags & ISEQ_TRACE_EVENTS;
+    rb_event_flag_t enabled_iseq_events = ruby_vm_event_enabled_flags & ISEQ_TRACE_EVENTS;
 
-    if (new_iseq_events > cur_iseq_events) {
+    if (new_iseq_events & ~enabled_iseq_events) {
 	/* write all ISeqs iff new events are added */
-	rb_iseq_trace_set_all(new_iseq_events);
+	rb_iseq_trace_set_all(new_iseq_events | enabled_iseq_events);
     }
 
     ruby_vm_event_flags = vm_events;
+    ruby_vm_event_enabled_flags |= vm_events;
     rb_objspace_set_event_hook(vm_events);
 }