Testing out an optimized respond_to? instruction

Author: jpcamara

compile.c

@@ -3482,6 +3482,29 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
         }
     }
 
+    if (IS_INSN_ID(iobj, send)) {
+        const struct rb_callinfo *ci = (struct rb_callinfo *)OPERAND_AT(iobj, 0);
+        const rb_iseq_t *blockiseq = (rb_iseq_t *)OPERAND_AT(iobj, 1);
+
+        // == disasm: #<ISeq:<main>@../test.rb:2 (2,0)-(2,76)>
+        // 0000 getglobal                              :$stdout                  (   2)[Li]
+        // 0002 putobject                              :write
+        // 0004 opt_send_without_block                 <calldata!mid:respond_to?, argc:1, ARGS_SIMPLE>
+        // 0006 branchunless                           14
+        // 0008 putself
+        // 0009 putchilledstring                       "Did you know you can write to $stdout?"
+        // 0011 opt_send_without_block                 <calldata!mid:puts, argc:1, FCALL|ARGS_SIMPLE>
+        // 0013 leave
+        // 0014 putnil
+        // 0015 leave
+        if (vm_ci_simple(ci) && vm_ci_argc(ci) == 1 && blockiseq == NULL && vm_ci_mid(ci) == idRespond_to) {
+            iobj->insn_id = BIN(opt_respond_to);
+            iobj->operand_size = 1;
+            iobj->operands = compile_data_calloc2(iseq, iobj->operand_size, sizeof(VALUE));
+            iobj->operands[0] = (VALUE)ci;
+        }
+    }
+
     /*
      * newhash 0
      * send     <calldata!mid:freeze, argc:0, ARGS_SIMPLE>, nil

insns.def

@@ -949,6 +949,16 @@ opt_hash_freeze
     }
 }
 
+DEFINE_INSN
+opt_respond_to
+(CALL_DATA cd)
+(VALUE recv, VALUE mid)
+(VALUE val)
+{
+    val = vm_opt_respond_to(recv, mid);
+    CALL_SIMPLE_METHOD();
+}
+
 DEFINE_INSN
 opt_str_freeze
 (VALUE str, CALL_DATA cd)

vm_insnhelper.c

@@ -6133,6 +6133,18 @@ vm_opt_ary_freeze(VALUE ary, int bop, ID id)
     }
 }
 
+static VALUE
+vm_opt_respond_to(VALUE recv, VALUE mid)
+{
+    if (SYMBOL_P(mid)) {
+        printf("symbol:");
+    } else if (STRING_P(mid)) {
+        printf("string:");
+    }
+    printf("%s\n", rb_builtin_type_name(TYPE(recv)));
+    return Qundef;
+}
+
 static VALUE
 vm_opt_hash_freeze(VALUE hash, int bop, ID id)
 {