[Interpreter] Add support for calling runtime functions which return a pair.

src/interpreter/bytecode-array-builder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-array-builder.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
@@ skipping 971 matching lines @@
   }
   DCHECK(FitsInIdx8Operand(arg_count));
   Output(Bytecode::kNew, constructor.ToOperand(), first_arg.ToOperand(),
          static_cast<uint8_t>(arg_count));
   return *this;
 }
 
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::CallRuntime(
     Runtime::FunctionId function_id, Register first_arg, size_t arg_count) {
+  DCHECK_EQ(1, Runtime::FunctionForId(function_id)->result_size);
   DCHECK(FitsInIdx16Operand(function_id));
   DCHECK(FitsInIdx8Operand(arg_count));
   if (!first_arg.is_valid()) {
     DCHECK_EQ(0u, arg_count);
     first_arg = Register(0);
   }
   Output(Bytecode::kCallRuntime, static_cast<uint16_t>(function_id),
          first_arg.ToOperand(), static_cast<uint8_t>(arg_count));
   return *this;
 }
 
 
+BytecodeArrayBuilder& BytecodeArrayBuilder::CallRuntimePair(

[oth, 2016/01/06 15:09:17]

This doesn't look like it's called except in tests. Is more required to hook it
up to the bytecode generator?

[rmcilroy, 2016/01/06 15:23:25]

Yup, as mentioned in the CL message, this is tested in the Eval CL:
https://codereview.chromium.org/1508293003/

+    Runtime::FunctionId function_id, Register first_arg, size_t arg_count,
+    Register first_return) {
+  DCHECK_EQ(2, Runtime::FunctionForId(function_id)->result_size);
+  DCHECK(FitsInIdx16Operand(function_id));
+  DCHECK(FitsInIdx8Operand(arg_count));
+  if (!first_arg.is_valid()) {
+    DCHECK_EQ(0u, arg_count);
+    first_arg = Register(0);
+  }
+  Output(Bytecode::kCallRuntimePair, static_cast<uint16_t>(function_id),
+         first_arg.ToOperand(), static_cast<uint8_t>(arg_count),
+         first_return.ToOperand());
+  return *this;
+}
+
+
 BytecodeArrayBuilder& BytecodeArrayBuilder::CallJSRuntime(int context_index,
                                                           Register receiver,
                                                           size_t arg_count) {
   DCHECK(FitsInIdx16Operand(context_index));
   DCHECK(FitsInIdx8Operand(arg_count));
   Output(Bytecode::kCallJSRuntime, static_cast<uint16_t>(context_index),
          receiver.ToOperand(), static_cast<uint8_t>(arg_count));
   return *this;
 }
 
@@ skipping 573 matching lines @@
   DCHECK_GT(next_consecutive_count_, 0);
   builder_->BorrowConsecutiveTemporaryRegister(next_consecutive_register_);
   allocated_.push_back(next_consecutive_register_);
   next_consecutive_count_--;
   return Register(next_consecutive_register_++);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8