From e1be448840da9ac2db4eeeed5d07ae8a765bacce Mon Sep 17 00:00:00 2001
From: k0kubun <k0kubun@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Sat, 23 Jun 2018 14:11:19 +0000
Subject: mjit.c: disable calling JIT-ed code

when TracePoint is enabled. We're cancelling JIT-ed code execution AFTER
each instruction, but there is no guard before the first insn of method.

To prevent spoiling performance, I don't want to modify the JIT-ed code
to fix this. So this commit replaces `mjit_enabled` check with `mjit_call_p`
check.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63734 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 iseq.c     | 2 ++
 mjit.c     | 5 +++++
 mjit.h     | 5 +++--
 vm_trace.c | 4 ++++
 4 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/iseq.c b/iseq.c
index f64177dc5b..7744e3f54f 100644
--- a/iseq.c
+++ b/iseq.c
@@ -2899,6 +2899,8 @@ rb_iseq_trace_set_all(rb_event_flag_t turnon_events)
     rb_objspace_each_objects(trace_set_i, &turnon_events);
 }
 
+/* This is exported since Ruby 2.5 but not internally used for now. If you're going to use this, please
+   update `ruby_vm_event_enabled_flags` and set `mjit_call_p = FALSE` as well to cancel MJIT code. */
 void
 rb_iseq_trace_on_all(void)
 {
diff --git a/mjit.c b/mjit.c
index b760691459..5c6cf47cc7 100644
--- a/mjit.c
+++ b/mjit.c
@@ -171,6 +171,9 @@ struct rb_mjit_unit_list {
 
 /* TRUE if MJIT is enabled.  */
 int mjit_enabled = FALSE;
+/* TRUE if JIT-ed code should be called. When `ruby_vm_event_enabled_flags & ISEQ_TRACE_EVENTS`
+   and `mjit_call_p == FALSE`, any JIT-ed code execution is cancelled as soon as possible. */
+int mjit_call_p = FALSE;
 
 /* Priority queue of iseqs waiting for JIT compilation.
    This variable is a pointer to head unit of the queue. */
@@ -1410,6 +1413,7 @@ mjit_init(struct mjit_options *opts)
 
     mjit_opts = *opts;
     mjit_enabled = TRUE;
+    mjit_call_p = TRUE;
 
     /* Normalize options */
     if (mjit_opts.min_calls == 0)
@@ -1549,6 +1553,7 @@ mjit_finish(void)
     xfree(pch_file); pch_file = NULL;
     xfree(header_file); header_file = NULL;
 
+    mjit_call_p = FALSE;
     free_list(&unit_queue);
     free_list(&active_units);
     finish_conts();
diff --git a/mjit.h b/mjit.h
index 2f9ea85134..9460d7595f 100644
--- a/mjit.h
+++ b/mjit.h
@@ -51,9 +51,10 @@ struct mjit_options {
 
 typedef VALUE (*mjit_func_t)(rb_execution_context_t *, rb_control_frame_t *);
 
+extern int mjit_enabled;
 RUBY_SYMBOL_EXPORT_BEGIN
 extern struct mjit_options mjit_opts;
-extern int mjit_enabled;
+extern int mjit_call_p;
 
 extern void mjit_add_iseq_to_process(const rb_iseq_t *iseq);
 extern mjit_func_t mjit_get_iseq_func(struct rb_iseq_constant_body *body);
@@ -94,7 +95,7 @@ mjit_exec(rb_execution_context_t *ec)
     long unsigned total_calls;
     mjit_func_t func;
 
-    if (!mjit_enabled)
+    if (!mjit_call_p)
         return Qundef;
 
     iseq = ec->cfp->iseq;
diff --git a/vm_trace.c b/vm_trace.c
index 10ee1ca18e..fabb15be2f 100644
--- a/vm_trace.c
+++ b/vm_trace.c
@@ -25,6 +25,7 @@
 #include "ruby/debug.h"
 
 #include "vm_core.h"
+#include "mjit.h"
 #include "iseq.h"
 #include "eval_intern.h"
 
@@ -68,6 +69,9 @@ update_global_event_hook(rb_event_flag_t vm_events)
     rb_event_flag_t enabled_iseq_events = ruby_vm_event_enabled_flags & ISEQ_TRACE_EVENTS;
 
     if (new_iseq_events & ~enabled_iseq_events) {
+        /* Stop calling all JIT-ed code. Compiling trace insns is not supported for now. */
+        mjit_call_p = FALSE;
+
 	/* write all ISeqs iff new events are added */
 	rb_iseq_trace_set_all(new_iseq_events | enabled_iseq_events);
     }
-- 
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