[turbofan] Implement OSR for outer loops.

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"
 #include "src/compiler/operator.h"
 #include "src/zone.h"
 
 namespace v8 {
 namespace internal {
 
 class CallInterfaceDescriptor;
 
 namespace compiler {
 
+class OsrHelper;
+
 // Describes the location for a parameter or a return value to a call.
 class LinkageLocation {
  public:
   explicit LinkageLocation(int location) : location_(location) {}
 
-  static const int16_t ANY_REGISTER = 32767;
+  static const int16_t ANY_REGISTER = 1023;
+  static const int16_t MAX_STACK_SLOT = 32767;
 
   static LinkageLocation AnyRegister() { return LinkageLocation(ANY_REGISTER); }
 
  private:
   friend class CallDescriptor;
   friend class OperandGenerator;
-  int16_t location_;  // >= 0 implies register, otherwise stack slot.
+  //         location < 0     -> a stack slot on the caller frame
+  // 0    <= location < 1023  -> a specific machine register
+  // 1023 <= location < 1024  -> any machine register
+  // 1024 <= location         -> a stack slot in the callee frame
+  int16_t location_;
 };
 
 typedef Signature<LinkageLocation> LocationSignature;
 
 // Describes a call to various parts of the compiler. Every call has the notion
 // of a "target", which is the first input to the call.
 class CallDescriptor FINAL : public ZoneObject {
  public:
   // Describes the kind of this call, which determines the target.
   enum Kind {
@@ skipping 176 matching lines @@
 
   // 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. The {extra} parameter indicates an additional offset from
   // the frame offset, e.g. to index into part of a double slot.
   FrameOffset GetFrameOffset(int spill_slot, Frame* frame, int extra = 0) const;
 
   static bool NeedsFrameState(Runtime::FunctionId function);
 
+  // Get the location where an incoming OSR value is stored.
+  LinkageLocation GetOsrValueLocation(int index) const;
+
  private:
   Zone* const zone_;
   CallDescriptor* const incoming_;
 
   DISALLOW_COPY_AND_ASSIGN(Linkage);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_LINKAGE_H_