Adding support for multiple returns in compiled functions.

src/compiler/linkage.h

 // Copyright 2014 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.
 
 #ifndef V8_COMPILER_LINKAGE_H_
 #define V8_COMPILER_LINKAGE_H_
 
 #include "src/base/flags.h"
 #include "src/compiler/frame.h"
 #include "src/compiler/machine-type.h"
@@ skipping 286 matching lines @@
   LinkageLocation GetParameterLocation(int index) const {
     return incoming_->GetInputLocation(index + 1);  // + 1 to skip target.
   }
 
   // Get the machine type of an (incoming) parameter to this function.
   MachineType GetParameterType(int index) const {
     return incoming_->GetInputType(index + 1);  // + 1 to skip target.
   }
 
   // Get the location where this function should place its return value.
-  LinkageLocation GetReturnLocation() const {
-    return incoming_->GetReturnLocation(0);
+  LinkageLocation GetReturnLocation(size_t index = 0) const {
+    return incoming_->GetReturnLocation(index);
   }
 
   // Get the machine type of this function's return value.
-  MachineType GetReturnType() const { return incoming_->GetReturnType(0); }
+  MachineType GetReturnType(size_t index = 0) const {
+    return incoming_->GetReturnType(index);
+  }
 
   // Get the frame offset for a given spill slot. The location depends on the
   // calling convention and the specific frame layout, and may thus be
   // architecture-specific. Negative spill slots indicate arguments on the
   // caller's frame.
   FrameOffset GetFrameOffset(int spill_slot, Frame* frame) const;
 
   static int FrameStateInputCount(Runtime::FunctionId function);
 
   // Get the location where an incoming OSR value is stored.
@@ skipping 18 matching lines @@
   CallDescriptor* const incoming_;
 
   DISALLOW_COPY_AND_ASSIGN(Linkage);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_LINKAGE_H_