remove `trace_` prefix insns lazily.

* vm_trace.c (update_global_event_hook): set only when tracing is added.
  If tracing was off (event flags are decreased), then ignore them.
  Next `trace_` prefix instruction will trace off itself (lazy tracing off).

* vm_insnhelper.c (vm_trace): trace-off for when trace is not needed.

* iseq.c (rb_iseq_trace_set): fix trace-off process (it was never off tracing).


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60817 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

iseq.c

@@ -336,8 +336,6 @@ prepare_iseq_build(rb_iseq_t *iseq,
     return Qtrue;
 }
 
-static void rb_iseq_trace_set(const rb_iseq_t *iseq, rb_event_flag_t turnon_events);
-
 static VALUE
 finish_iseq_build(rb_iseq_t *iseq)
 {
@@ -2311,15 +2309,16 @@ rb_iseq_defined_string(enum defined_type type)
     return str;
 }
 
-#define TRACE_INSN_P(insn) ((insn) >= VM_INSTRUCTION_SIZE/2)
 
 #if OPT_DIRECT_THREADED_CODE || OPT_CALL_THREADED_CODE
 #define INSN_CODE(insn) ((VALUE)table[insn])
+#define TRACE_INSN_P(insn, insn_encoded)      ((VALUE)table[insn] != insn_encoded)
 #else
 #define INSN_CODE(insn) (insn)
+#define TRACE_INSN_P(insn, insn_encoded)      ((insn_encoded) >= VM_INSTRUCTION_SIZE/2)
 #endif
 
-static void
+void
 rb_iseq_trace_set(const rb_iseq_t *iseq, rb_event_flag_t turnon_events)
 {
     unsigned int i;
@@ -2335,17 +2334,17 @@ rb_iseq_trace_set(const rb_iseq_t *iseq, rb_event_flag_t turnon_events)
 	int insn = (int)code[i];
 	rb_event_flag_t events = rb_iseq_event_flags(iseq, i);
 
+	/* code represents before transformation */
+	VM_ASSERT(insn < VM_INSTRUCTION_SIZE/2);
+
 	if (events & turnon_events) {
-	    if (!TRACE_INSN_P(insn)) {
+	    if (!TRACE_INSN_P(insn, iseq_encoded[i])) {
 		iseq_encoded[i] = INSN_CODE(insn + VM_INSTRUCTION_SIZE/2);
 	    }
-	    else {
-		/* OK */
 	}
-	}
-	else if (TRACE_INSN_P(insn)) {
+	else if (TRACE_INSN_P(insn, iseq_encoded[i])) {
 	    VM_ASSERT(insn - VM_INSTRUCTION_SIZE/2 >= 0);
-	    iseq_encoded[i] = INSN_CODE(insn - VM_INSTRUCTION_SIZE/2);
+	    iseq_encoded[i] = INSN_CODE(insn);
 	}
 	i += insn_len(insn);
     }

iseq.h

@@ -116,6 +116,7 @@ VALUE rb_iseq_load(VALUE data, VALUE parent, VALUE opt);
 VALUE rb_iseq_parameters(const rb_iseq_t *iseq, int is_proc);
 struct st_table *ruby_insn_make_insn_table(void);
 unsigned int rb_iseq_line_no(const rb_iseq_t *iseq, size_t pos);
+void rb_iseq_trace_set(const rb_iseq_t *iseq, rb_event_flag_t turnon_events);
 void rb_iseq_trace_set_all(rb_event_flag_t turnon_events);
 void rb_iseq_trace_on_all(void);
 

vm_insnhelper.c

@@ -3729,9 +3729,16 @@ vm_trace(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, const VALUE *p
 {
     const rb_iseq_t *iseq = reg_cfp->iseq;
     size_t pos = pc - iseq->body->iseq_encoded;
+    rb_event_flag_t cur_event_flags = ruby_vm_event_flags;
     rb_event_flag_t events = rb_iseq_event_flags(iseq, pos);
     rb_event_flag_t event;
 
+    if ((events & cur_event_flags) == 0) {
+	/* disable trace */
+	rb_iseq_trace_set(iseq, cur_event_flags);
+	return;
+    }
+
     if (ec->trace_arg != NULL) return;
 
     if (0) {

vm_trace.c

@@ -72,10 +72,14 @@ rb_vm_trace_mark_event_hooks(rb_hook_list_t *hooks)
 static void
 update_global_event_hook(rb_event_flag_t vm_events)
 {
-    if ((vm_events & RUBY_EVENTS_TRACE_BY_ISEQ) !=
-	(ruby_vm_event_flags & RUBY_EVENTS_TRACE_BY_ISEQ)) {
+    rb_event_flag_t new_iseq_events = vm_events & RUBY_EVENTS_TRACE_BY_ISEQ;
+    rb_event_flag_t cur_iseq_events = ruby_vm_event_flags & RUBY_EVENTS_TRACE_BY_ISEQ;
+
+    if (new_iseq_events > cur_iseq_events) {
+	/* write all ISeqs iff new events are added */
 	rb_iseq_trace_set_all(vm_events); 
     }
+
     ruby_vm_event_flags = vm_events;
     rb_objspace_set_event_hook(vm_events);
 }