From 984e05a11b761186c50971d6ef40e6207669fc7e Mon Sep 17 00:00:00 2001
From: Max Bernstein <ruby@bernsteinbear.com>
Date: Wed, 27 Aug 2025 17:50:58 -0400
Subject: ZJIT: Count dynamic dispatch (SendWithoutBlock)

---
 zjit.rb             | 1 +
 zjit/src/codegen.rs | 4 ++++
 zjit/src/stats.rs   | 3 +++
 3 files changed, 8 insertions(+)

diff --git a/zjit.rb b/zjit.rb
index 3476c1cb38..86d6643df2 100644
--- a/zjit.rb
+++ b/zjit.rb
@@ -56,6 +56,7 @@ class << RubyVM::ZJIT
       :total_insn_count,
       :vm_insn_count,
       :zjit_insn_count,
+      :zjit_dynamic_dispatch,
       :ratio_in_zjit,
     ], buf:, stats:)
     print_counters_with_prefix(prefix: 'exit_', prompt: 'side exit reasons', buf:, stats:, limit: 20)
diff --git a/zjit/src/codegen.rs b/zjit/src/codegen.rs
index 2b71596a17..fd804e5a42 100644
--- a/zjit/src/codegen.rs
+++ b/zjit/src/codegen.rs
@@ -858,6 +858,10 @@ fn gen_send_without_block(
     cd: *const rb_call_data,
     state: &FrameState,
 ) -> lir::Opnd {
+    if get_option!(stats) {
+        gen_incr_counter(asm, Counter::zjit_dynamic_dispatch);
+    }
+
     // Note that it's incorrect to use this frame state to side exit because
     // the state might not be on the boundary of an interpreter instruction.
     // For example, `opt_str_uminus` pushes to the stack and then sends.
diff --git a/zjit/src/stats.rs b/zjit/src/stats.rs
index c6b1ed29d6..10692d83f5 100644
--- a/zjit/src/stats.rs
+++ b/zjit/src/stats.rs
@@ -72,6 +72,9 @@ make_counters! {
     // The number of times YARV instructions are executed on JIT code
     zjit_insn_count,
 
+    // The number of times we do a dynamic dispatch from JIT code
+    zjit_dynamic_dispatch,
+
     // failed_: Compilation failure reasons
     failed_iseq_stack_too_large,
     failed_hir_compile,
-- 
cgit v1.2.3