tailcall optimization again (#2528)

This is follow up of r67315.

1 files changed, 34 insertions, 3 deletions

diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index f9c825c272..8e4e02ee90 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -1872,6 +1872,30 @@ vm_call_iseq_setup_normal_opt_start(rb_execution_context_t *ec, rb_control_frame
     return vm_call_iseq_setup_normal(ec, cfp, calling, cc->me, opt_pc, param - delta, local);
 }
 
+static VALUE
+vm_call_iseq_setup_tailcall_opt_start(rb_execution_context_t *ec, rb_control_frame_t *cfp,
+                                      struct rb_calling_info *calling,
+                                      const struct rb_call_info *ci, struct rb_call_cache *cc)
+{
+    const rb_iseq_t *iseq = def_iseq_ptr(cc->me->def);
+    const int lead_num = iseq->body->param.lead_num;
+    const int opt = calling->argc - lead_num;
+    const int opt_pc = (int)iseq->body->param.opt_table[opt];
+
+    RB_DEBUG_COUNTER_INC(ccf_iseq_opt);
+
+#if USE_OPT_HIST
+    if (opt_pc < OPT_HIST_MAX) {
+        opt_hist[opt]++;
+    }
+    else {
+        opt_hist[OPT_HIST_MAX]++;
+    }
+#endif
+
+    return vm_call_iseq_setup_tailcall(ec, cfp, calling, ci, cc, opt_pc);
+}
+
 static void
 args_setup_kw_parameters(rb_execution_context_t *const ec, const rb_iseq_t *const iseq,
                          VALUE *const passed_values, const int passed_keyword_len, const VALUE *const passed_keywords,
@@ -1958,9 +1982,16 @@ vm_callee_setup_arg(rb_execution_context_t *ec, struct rb_calling_info *calling,
                 argument_arity_error(ec, iseq, argc, lead_num, lead_num + opt_num);
             }
 
-            CC_SET_FASTPATH(cc, vm_call_iseq_setup_normal_opt_start,
-                            !IS_ARGS_SPLAT(ci) && !IS_ARGS_KEYWORD(ci) &&
-                            !(METHOD_ENTRY_VISI(cc->me) == METHOD_VISI_PROTECTED));
+            if (LIKELY(!(ci->flag & VM_CALL_TAILCALL))) {
+                CC_SET_FASTPATH(cc, vm_call_iseq_setup_normal_opt_start,
+                                !IS_ARGS_SPLAT(ci) && !IS_ARGS_KEYWORD(ci) &&
+                                !(METHOD_ENTRY_VISI(cc->me) == METHOD_VISI_PROTECTED));
+            }
+            else {
+                CC_SET_FASTPATH(cc, vm_call_iseq_setup_tailcall_opt_start,
+                                !IS_ARGS_SPLAT(ci) && !IS_ARGS_KEYWORD(ci) &&
+                                !(METHOD_ENTRY_VISI(cc->me) == METHOD_VISI_PROTECTED));
+            }
 
             /* initialize opt vars for self-references */
             VM_ASSERT((int)iseq->body->param.size == lead_num + opt_num);