ZJIT: Count dynamic dispatch (SendWithoutBlock)

Author: tekknolagi

zjit.rb

@@ -56,6 +56,7 @@ def stats_string
       :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)

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.

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,