compile.c: fix tailcall optimization

* compile.c (iseq_peephole_optimize): don't apply tailcall
  optimization to send/invokesuper instructions with blockiseq.
  This is a follow-up to the changes in r51903; blockiseq is now
  the third operand of send/invokesuper instructions.
  [ruby-core:73413] [Bug #12018]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53658 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,11 @@
+Tue Jan 26 15:14:01 2016  Kazuki Yamaguchi  <k@rhe.jp>
+
+	* compile.c (iseq_peephole_optimize): don't apply tailcall
+	  optimization to send/invokesuper instructions with blockiseq.
+	  This is a follow-up to the changes in r51903; blockiseq is now
+	  the third operand of send/invokesuper instructions.
+	  [ruby-core:73413] [Bug #12018]
+
 Tue Jan 26 14:26:46 2016  Eric Wong  <e@80x24.org>
 
 	* signal.c (sig_list): use fstring for hash key

compile.c

@@ -2248,8 +2248,12 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
 
 	if (piobj) {
 	    struct rb_call_info *ci = (struct rb_call_info *)piobj->operands[0];
-	    rb_iseq_t *blockiseq = (rb_iseq_t *)piobj->operands[1];
+	    if (piobj->insn_id == BIN(send) || piobj->insn_id == BIN(invokesuper)) {
-	    if (blockiseq == 0) {
+		if (piobj->operands[2] == 0) { /* no blockiseq */
+		    ci->flag |= VM_CALL_TAILCALL;
+		}
+	    }
+	    else {
 		ci->flag |= VM_CALL_TAILCALL;
 	    }
 	}

test/ruby/test_optimization.rb

@@ -275,6 +275,22 @@ class TestRubyOptimization < Test::Unit::TestCase
     assert_equal(123, delay { 123 }.call, bug6901)
   end
 
+  def just_yield
+    yield
+  end
+
+  def test_tailcall_inhibited_by_block
+    assert_separately([], <<~'end;')
+      def just_yield
+        yield
+      end
+      iseq = RubyVM::InstructionSequence
+      result = iseq.compile("just_yield {:ok}", __FILE__, __FILE__, __LINE__,
+                            tailcall_optimization: true).eval
+      assert_equal(:ok, result)
+    end;
+  end
+
   class Bug10557
     def [](_)
       block_given?