[turbofan] Support for %_DoubleHi, %_DoubleLo and %_ConstructDouble.

src/compiler/machine-operator.h

 // Copyright 2013 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_MACHINE_OPERATOR_H_
 #define V8_COMPILER_MACHINE_OPERATOR_H_
 
 #include "src/base/flags.h"
 #include "src/compiler/machine-type.h"
 
@@ skipping 159 matching lines @@
   // Floating point rounding.
   const Operator* Float64Floor();
   const Operator* Float64Ceil();
   const Operator* Float64RoundTruncate();
   const Operator* Float64RoundTiesAway();
   bool HasFloat64Floor() { return flags_ & kFloat64Floor; }
   bool HasFloat64Ceil() { return flags_ & kFloat64Ceil; }
   bool HasFloat64RoundTruncate() { return flags_ & kFloat64RoundTruncate; }
   bool HasFloat64RoundTiesAway() { return flags_ & kFloat64RoundTiesAway; }
 
+  // Floating point bit representation.
+  const Operator* Float64ExtractWord32(int location);

[Sven Panne, 2015/03/05 07:40:12]

If I see this correctly, location == 0 means "Low" and location == 1 means
"High", and there are no other allowed values. Using int and the name "location"
is a bit confusing here, it is *not* really an offset. A separate enum class
might be more appropriate IMHO.

[Benedikt Meurer, 2015/03/05 08:51:46]

Turned into dedicated opcodes instead, as per offline dicussion.

+  const Operator* Float64InsertWord32(int location);
+
   // load [base + index]
   const Operator* Load(LoadRepresentation rep);
 
   // store [base + index], value
   const Operator* Store(StoreRepresentation rep);
 
   // Access to the machine stack.
   const Operator* LoadStackPointer();
 
   // checked-load heap, index, length
@@ skipping 29 matching lines @@
   V(Uint, Mod)
 #define PSEUDO_OP(Prefix, Suffix)                                \
   const Operator* Prefix##Suffix() {                             \
     return Is32() ? Prefix##32##Suffix() : Prefix##64##Suffix(); \
   }
   PSEUDO_OP_LIST(PSEUDO_OP)
 #undef PSEUDO_OP
 #undef PSEUDO_OP_LIST
 
  private:
-  Zone* zone_;
-  const MachineOperatorGlobalCache& cache_;
-  const MachineType word_;
-  const Flags flags_;
+  Zone* const zone_;
+  MachineOperatorGlobalCache const& cache_;
+  MachineType const word_;
+  Flags const flags_;
 
   DISALLOW_COPY_AND_ASSIGN(MachineOperatorBuilder);
 };
 
 
 DEFINE_OPERATORS_FOR_FLAGS(MachineOperatorBuilder::Flags)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_MACHINE_OPERATOR_H_