ZJIT: Decouple stats and side exit tracing (ruby#14688)

Author: Aiden Fox Ivey

doc/zjit.md

@@ -155,10 +155,10 @@ make -j
 
 ### Tracing side exits
 
-Through [Stackprof](https://github.com/tmm1/stackprof), detailed information about the methods that the JIT side-exits from can be displayed after some execution of a program. Note that the use of `--zjit-trace-exits` must be used alongside `--zjit-stats`.
+Through [Stackprof](https://github.com/tmm1/stackprof), detailed information about the methods that the JIT side-exits from can be displayed after some execution of a program.
 
 ```bash
-./miniruby --zjit-stats --zjit-trace-exits script.rb
+./miniruby --zjit-trace-exits script.rb
 ```
 
 A file called `zjit_exit_locations.dump` will be created in the same directory as `script.rb`. Viewing the side exited methods can be done with Stackprof:

zjit.rb

@@ -9,10 +9,10 @@
 module RubyVM::ZJIT
   # Avoid calling a Ruby method here to avoid interfering with compilation tests
   if Primitive.rb_zjit_print_stats_p
-    at_exit {
-      print_stats
-      dump_locations
-    }
+    at_exit { print_stats }
+  end
+  if Primitive.rb_zjit_trace_exit_locations_enabled_p
+    at_exit { dump_locations }
   end
 end
 

zjit/src/state.rs

@@ -392,7 +392,7 @@ pub extern "C" fn rb_zjit_record_exit_stack(exit_pc: *const VALUE) {
 /// Mark `raw_samples` so they can be used by rb_zjit_add_frame.
 pub fn gc_mark_raw_samples() {
     // Return if ZJIT is not enabled
-    if !zjit_enabled_p() || !get_option!(stats) || !get_option!(trace_side_exits) {
+    if !zjit_enabled_p() || !get_option!(trace_side_exits) {
         return;
     }
 

zjit/src/stats.rs

@@ -2,6 +2,7 @@
 
 use std::time::Instant;
 use std::sync::atomic::Ordering;
+use crate::options::OPTIONS;
 
 #[cfg(feature = "stats_allocator")]
 #[path = "../../jit/src/lib.rs"]
@@ -475,11 +476,11 @@ pub struct SideExitLocations {
 
 /// Primitive called in zjit.rb
 ///
-/// Check if trace_exits generation is enabled. Requires the stats feature
-/// to be enabled.
+/// Check if trace_exits generation is enabled.
 #[unsafe(no_mangle)]
 pub extern "C" fn rb_zjit_trace_exit_locations_enabled_p(_ec: EcPtr, _ruby_self: VALUE) -> VALUE {
-    if get_option!(stats) && get_option!(trace_side_exits) {
+    // Builtin zjit.rb calls this even if ZJIT is disabled, so OPTIONS may not be set.
+    if unsafe { OPTIONS.as_ref() }.is_some_and(|opts| opts.trace_side_exits) {
         Qtrue
     } else {
         Qfalse
@@ -490,7 +491,7 @@ pub extern "C" fn rb_zjit_trace_exit_locations_enabled_p(_ec: EcPtr, _ruby_self:
 /// into raw, lines, and frames hash for RubyVM::YJIT.exit_locations.
 #[unsafe(no_mangle)]
 pub extern "C" fn rb_zjit_get_exit_locations(_ec: EcPtr, _ruby_self: VALUE) -> VALUE {
-    if !zjit_enabled_p() || !get_option!(stats) || !get_option!(trace_side_exits) {
+    if !zjit_enabled_p() || !get_option!(trace_side_exits) {
         return Qnil;
     }