[es6] [interpreter] Add tail calls support to Ignition.

src/interpreter/bytecode-array-builder.cc

Index: src/interpreter/bytecode-array-builder.cc
diff --git a/src/interpreter/bytecode-array-builder.cc b/src/interpreter/bytecode-array-builder.cc
index c0abbc85889a2a9f6cfeb1b8abe9a6909d4ca74f..9d20a7dd4cada674d7652032730dfac7e30aa13b 100644
--- a/src/interpreter/bytecode-array-builder.cc
+++ b/src/interpreter/bytecode-array-builder.cc
@@ -1083,20 +1083,25 @@ void BytecodeArrayBuilder::EnsureReturn(FunctionLiteral* literal) {
 BytecodeArrayBuilder& BytecodeArrayBuilder::Call(Register callable,
                                                  Register receiver_args,
                                                  size_t receiver_args_count,
-                                                 int feedback_slot) {
+                                                 int feedback_slot,
+                                                 TailCallMode tail_call_mode) {
   if (FitsInReg8Operand(callable) && FitsInReg8Operand(receiver_args) &&
       FitsInIdx8Operand(receiver_args_count) &&
       FitsInIdx8Operand(feedback_slot)) {
-    Output(Bytecode::kCall, callable.ToRawOperand(),
-           receiver_args.ToRawOperand(),
+    Bytecode bytecode = tail_call_mode == TailCallMode::kAllow
+                            ? Bytecode::kTailCall
+                            : Bytecode::kCall;

[rmcilroy, 2016/02/16 17:16:58]

Could you move this to a BytecodeForTailCallMode() helper (
 down near the other helpers like BytecodeForCreateArguments) with a switch (to
ensure we know if any other modes are added to TailCallMode)

[Igor Sheludko, 2016/02/17 14:07:08]

Done.

+    Output(bytecode, callable.ToRawOperand(), receiver_args.ToRawOperand(),
            static_cast<uint8_t>(receiver_args_count),
            static_cast<uint8_t>(feedback_slot));
   } else if (FitsInReg16Operand(callable) &&
              FitsInReg16Operand(receiver_args) &&
              FitsInIdx16Operand(receiver_args_count) &&
              FitsInIdx16Operand(feedback_slot)) {
-    Output(Bytecode::kCallWide, callable.ToRawOperand(),
-           receiver_args.ToRawOperand(),
+    Bytecode bytecode = tail_call_mode == TailCallMode::kAllow
+                            ? Bytecode::kTailCallWide
+                            : Bytecode::kCallWide;
+    Output(bytecode, callable.ToRawOperand(), receiver_args.ToRawOperand(),

[rmcilroy, 2016/02/16 17:16:58]

Please add kCall and kTailCall to BytecodeForWideOperands and use that to
convert the bytecode here (moving the above declaration of Bytecode out of the
if block) 

[Igor Sheludko, 2016/02/17 14:07:08]

Done.

            static_cast<uint16_t>(receiver_args_count),
            static_cast<uint16_t>(feedback_slot));
   } else {