Revision: 2628
Author: [email protected]
Date: Wed Aug  5 05:52:31 2009
Log: Add support to the CFG builder for non-short-circuited binary
expressions.  Add compilation support in fast mode (optimized for
compilation time and code size).

This breaks one debugger test each on ARM and IA32 (expectedly).
Review URL: http://codereview.chromium.org/160584
http://code.google.com/p/v8/source/detail?r=2628

Modified:
  /branches/bleeding_edge/src/arm/cfg-arm.cc
  /branches/bleeding_edge/src/arm/codegen-arm.cc
  /branches/bleeding_edge/src/arm/codegen-arm.h
  /branches/bleeding_edge/src/cfg.cc
  /branches/bleeding_edge/src/cfg.h
  /branches/bleeding_edge/src/ia32/cfg-ia32.cc
  /branches/bleeding_edge/src/ia32/codegen-ia32.cc
  /branches/bleeding_edge/src/ia32/codegen-ia32.h
  /branches/bleeding_edge/src/x64/cfg-x64.cc
  /branches/bleeding_edge/src/x64/codegen-x64.cc
  /branches/bleeding_edge/src/x64/codegen-x64.h

=======================================
--- /branches/bleeding_edge/src/arm/cfg-arm.cc  Mon Aug  3 00:55:48 2009
+++ /branches/bleeding_edge/src/arm/cfg-arm.cc  Wed Aug  5 05:52:31 2009
@@ -29,6 +29,7 @@

  #include "cfg.h"
  #include "codegen-inl.h"
+#include "codegen-arm.h"  // Include after codegen-inl.h.
  #include "macro-assembler-arm.h"

  namespace v8 {
@@ -42,6 +43,14 @@
    {
      Comment cmt(masm, "[ InstructionBlock");
      for (int i = 0, len = instructions_.length(); i < len; i++) {
+      // If the location of the current instruction is a temp, then the
+      // instruction cannot be in tail position in the block.  Allocate the
+      // temp based on peeking ahead to the next instruction.
+      Instruction* instr = instructions_[i];
+      Location* loc = instr->location();
+      if (loc->is_temporary()) {
+        instructions_[i+1]->FastAllocate(TempLocation::cast(loc));
+      }
        instructions_[i]->Compile(masm);
      }
    }
@@ -89,35 +98,125 @@
    __ add(sp, sp, Operand((count + 1) * kPointerSize));
    __ Jump(lr);
  }
+
+
+void BinaryOpInstr::Compile(MacroAssembler* masm) {
+  // The right-hand value should not be on the stack---if it is a
+  // compiler-generated temporary it is in the accumulator.
+  ASSERT(!val1_->is_on_stack());
+
+  Comment cmnt(masm, "[ BinaryOpInstr");
+  // We can overwrite one of the operands if it is a temporary.
+  OverwriteMode mode = NO_OVERWRITE;
+  if (val0_->is_temporary()) {
+    mode = OVERWRITE_LEFT;
+  } else if (val1_->is_temporary()) {
+    mode = OVERWRITE_RIGHT;
+  }
+
+  // Move left to r1 and right to r0.
+  val0_->Get(masm, r1);
+  val1_->Get(masm, r0);
+  GenericBinaryOpStub stub(op_, mode);
+  __ CallStub(&stub);
+  loc_->Set(masm, r0);
+}


  void ReturnInstr::Compile(MacroAssembler* masm) {
+  // The location should be 'Effect'.  As a side effect, move the value to
+  // the accumulator.
    Comment cmnt(masm, "[ ReturnInstr");
-  value_->ToRegister(masm, r0);
+  value_->Get(masm, r0);
  }


-void Constant::ToRegister(MacroAssembler* masm, Register reg) {
+void Constant::Get(MacroAssembler* masm, Register reg) {
    __ mov(reg, Operand(handle_));
  }


-void SlotLocation::ToRegister(MacroAssembler* masm, Register reg) {
-  switch (type_) {
+void Constant::Push(MacroAssembler* masm) {
+  __ mov(ip, Operand(handle_));
+  __ push(ip);
+}
+
+
+static MemOperand ToMemOperand(SlotLocation* loc) {
+  switch (loc->type()) {
      case Slot::PARAMETER: {
        int count = CfgGlobals::current()->fun()->scope()->num_parameters();
-      __ ldr(reg, MemOperand(fp, (1 + count - index_) * kPointerSize));
-      break;
+      return MemOperand(fp, (1 + count - loc->index()) * kPointerSize);
      }
      case Slot::LOCAL: {
        const int kOffset = JavaScriptFrameConstants::kLocal0Offset;
-      __ ldr(reg, MemOperand(fp, kOffset - index_ * kPointerSize));
-      break;
+      return MemOperand(fp, kOffset - loc->index() * kPointerSize);
      }
      default:
        UNREACHABLE();
+      return MemOperand(r0);
    }
  }
+
+
+void SlotLocation::Get(MacroAssembler* masm, Register reg) {
+  __ ldr(reg, ToMemOperand(this));
+}
+
+
+void SlotLocation::Set(MacroAssembler* masm, Register reg) {
+  __ str(reg, ToMemOperand(this));
+}
+
+
+void SlotLocation::Push(MacroAssembler* masm) {
+  __ ldr(ip, ToMemOperand(this));
+  __ push(ip);  // Push will not destroy ip.
+}
+
+
+void TempLocation::Get(MacroAssembler* masm, Register reg) {
+  switch (where_) {
+    case ACCUMULATOR:
+      if (!reg.is(r0)) __ mov(reg, r0);
+      break;
+    case STACK:
+      __ pop(reg);
+      break;
+    case NOWHERE:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
+void TempLocation::Set(MacroAssembler* masm, Register reg) {
+  switch (where_) {
+    case ACCUMULATOR:
+      if (!reg.is(r0)) __ mov(r0, reg);
+      break;
+    case STACK:
+      __ push(reg);
+      break;
+    case NOWHERE:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
+void TempLocation::Push(MacroAssembler* masm) {
+  switch (where_) {
+    case ACCUMULATOR:
+      __ push(r0);
+      break;
+    case STACK:
+    case NOWHERE:
+      UNREACHABLE();
+      break;
+  }
+}
+

  #undef __

=======================================
--- /branches/bleeding_edge/src/arm/codegen-arm.cc      Thu Jul 23 04:40:14 2009
+++ /branches/bleeding_edge/src/arm/codegen-arm.cc      Wed Aug  5 05:52:31 2009
@@ -697,96 +697,6 @@
  }


-class GenericBinaryOpStub : public CodeStub {
- public:
-  GenericBinaryOpStub(Token::Value op,
-                      OverwriteMode mode,
-                      int constant_rhs = CodeGenerator::kUnknownIntValue)
-      : op_(op),
-        mode_(mode),
-        constant_rhs_(constant_rhs),
-        specialized_on_rhs_(RhsIsOneWeWantToOptimizeFor(op, constant_rhs))  
{ }
-
- private:
-  Token::Value op_;
-  OverwriteMode mode_;
-  int constant_rhs_;
-  bool specialized_on_rhs_;
-
-  static const int kMaxKnownRhs = 0x40000000;
-
-  // Minor key encoding in 16 bits.
-  class ModeBits: public BitField<OverwriteMode, 0, 2> {};
-  class OpBits: public BitField<Token::Value, 2, 6> {};
-  class KnownIntBits: public BitField<int, 8, 8> {};
-
-  Major MajorKey() { return GenericBinaryOp; }
-  int MinorKey() {
-    // Encode the parameters in a unique 16 bit value.
-    return OpBits::encode(op_)
-           | ModeBits::encode(mode_)
-           | KnownIntBits::encode(MinorKeyForKnownInt());
-  }
-
-  void Generate(MacroAssembler* masm);
-  void HandleNonSmiBitwiseOp(MacroAssembler* masm);
-
-  static bool RhsIsOneWeWantToOptimizeFor(Token::Value op, int  
constant_rhs) {
-    if (constant_rhs == CodeGenerator::kUnknownIntValue) return false;
-    if (op == Token::DIV) return constant_rhs >= 2 && constant_rhs <= 3;
-    if (op == Token::MOD) {
-      if (constant_rhs <= 1) return false;
-      if (constant_rhs <= 10) return true;
-      if (constant_rhs <= kMaxKnownRhs && IsPowerOf2(constant_rhs)) return  
true;
-      return false;
-    }
-    return false;
-  }
-
-  int MinorKeyForKnownInt() {
-    if (!specialized_on_rhs_) return 0;
-    if (constant_rhs_ <= 10) return constant_rhs_ + 1;
-    ASSERT(IsPowerOf2(constant_rhs_));
-    int key = 12;
-    int d = constant_rhs_;
-    while ((d & 1) == 0) {
-      key++;
-      d >>= 1;
-    }
-    return key;
-  }
-
-  const char* GetName() {
-    switch (op_) {
-      case Token::ADD: return "GenericBinaryOpStub_ADD";
-      case Token::SUB: return "GenericBinaryOpStub_SUB";
-      case Token::MUL: return "GenericBinaryOpStub_MUL";
-      case Token::DIV: return "GenericBinaryOpStub_DIV";
-      case Token::MOD: return "GenericBinaryOpStub_MOD";
-      case Token::BIT_OR: return "GenericBinaryOpStub_BIT_OR";
-      case Token::BIT_AND: return "GenericBinaryOpStub_BIT_AND";
-      case Token::BIT_XOR: return "GenericBinaryOpStub_BIT_XOR";
-      case Token::SAR: return "GenericBinaryOpStub_SAR";
-      case Token::SHL: return "GenericBinaryOpStub_SHL";
-      case Token::SHR: return "GenericBinaryOpStub_SHR";
-      default:         return "GenericBinaryOpStub";
-    }
-  }
-
-#ifdef DEBUG
-  void Print() {
-    if (!specialized_on_rhs_) {
-      PrintF("GenericBinaryOpStub (%s)\n", Token::String(op_));
-    } else {
-      PrintF("GenericBinaryOpStub (%s by %d)\n",
-             Token::String(op_),
-             constant_rhs_);
-    }
-  }
-#endif
-};
-
-
  void CodeGenerator::GenericBinaryOperation(Token::Value op,
                                             OverwriteMode overwrite_mode,
                                             int constant_rhs) {
=======================================
--- /branches/bleeding_edge/src/arm/codegen-arm.h       Thu Jul 30 05:09:05 2009
+++ /branches/bleeding_edge/src/arm/codegen-arm.h       Wed Aug  5 05:52:31 2009
@@ -421,6 +421,96 @@
  };


+class GenericBinaryOpStub : public CodeStub {
+ public:
+  GenericBinaryOpStub(Token::Value op,
+                      OverwriteMode mode,
+                      int constant_rhs = CodeGenerator::kUnknownIntValue)
+      : op_(op),
+        mode_(mode),
+        constant_rhs_(constant_rhs),
+        specialized_on_rhs_(RhsIsOneWeWantToOptimizeFor(op, constant_rhs))  
{ }
+
+ private:
+  Token::Value op_;
+  OverwriteMode mode_;
+  int constant_rhs_;
+  bool specialized_on_rhs_;
+
+  static const int kMaxKnownRhs = 0x40000000;
+
+  // Minor key encoding in 16 bits.
+  class ModeBits: public BitField<OverwriteMode, 0, 2> {};
+  class OpBits: public BitField<Token::Value, 2, 6> {};
+  class KnownIntBits: public BitField<int, 8, 8> {};
+
+  Major MajorKey() { return GenericBinaryOp; }
+  int MinorKey() {
+    // Encode the parameters in a unique 16 bit value.
+    return OpBits::encode(op_)
+           | ModeBits::encode(mode_)
+           | KnownIntBits::encode(MinorKeyForKnownInt());
+  }
+
+  void Generate(MacroAssembler* masm);
+  void HandleNonSmiBitwiseOp(MacroAssembler* masm);
+
+  static bool RhsIsOneWeWantToOptimizeFor(Token::Value op, int  
constant_rhs) {
+    if (constant_rhs == CodeGenerator::kUnknownIntValue) return false;
+    if (op == Token::DIV) return constant_rhs >= 2 && constant_rhs <= 3;
+    if (op == Token::MOD) {
+      if (constant_rhs <= 1) return false;
+      if (constant_rhs <= 10) return true;
+      if (constant_rhs <= kMaxKnownRhs && IsPowerOf2(constant_rhs)) return  
true;
+      return false;
+    }
+    return false;
+  }
+
+  int MinorKeyForKnownInt() {
+    if (!specialized_on_rhs_) return 0;
+    if (constant_rhs_ <= 10) return constant_rhs_ + 1;
+    ASSERT(IsPowerOf2(constant_rhs_));
+    int key = 12;
+    int d = constant_rhs_;
+    while ((d & 1) == 0) {
+      key++;
+      d >>= 1;
+    }
+    return key;
+  }
+
+  const char* GetName() {
+    switch (op_) {
+      case Token::ADD: return "GenericBinaryOpStub_ADD";
+      case Token::SUB: return "GenericBinaryOpStub_SUB";
+      case Token::MUL: return "GenericBinaryOpStub_MUL";
+      case Token::DIV: return "GenericBinaryOpStub_DIV";
+      case Token::MOD: return "GenericBinaryOpStub_MOD";
+      case Token::BIT_OR: return "GenericBinaryOpStub_BIT_OR";
+      case Token::BIT_AND: return "GenericBinaryOpStub_BIT_AND";
+      case Token::BIT_XOR: return "GenericBinaryOpStub_BIT_XOR";
+      case Token::SAR: return "GenericBinaryOpStub_SAR";
+      case Token::SHL: return "GenericBinaryOpStub_SHL";
+      case Token::SHR: return "GenericBinaryOpStub_SHR";
+      default:         return "GenericBinaryOpStub";
+    }
+  }
+
+#ifdef DEBUG
+  void Print() {
+    if (!specialized_on_rhs_) {
+      PrintF("GenericBinaryOpStub (%s)\n", Token::String(op_));
+    } else {
+      PrintF("GenericBinaryOpStub (%s by %d)\n",
+             Token::String(op_),
+             constant_rhs_);
+    }
+  }
+#endif
+};
+
+
  } }  // namespace v8::internal

  #endif  // V8_ARM_CODEGEN_ARM_H_
=======================================
--- /branches/bleeding_edge/src/cfg.cc  Mon Aug  3 00:55:48 2009
+++ /branches/bleeding_edge/src/cfg.cc  Wed Aug  5 05:52:31 2009
@@ -42,8 +42,10 @@
  CfgGlobals::CfgGlobals(FunctionLiteral* fun)
      : global_fun_(fun),
        global_exit_(new ExitNode()),
+      effect_(new Effect()),
  #ifdef DEBUG
        node_counter_(0),
+      temp_counter_(0),
  #endif
        previous_(top_) {
    top_ = this;
@@ -73,6 +75,9 @@
    if (cfg == NULL) {
      BAILOUT("unsupported statement type");
    }
+  if (cfg->is_empty()) {
+    BAILOUT("function body produces empty cfg");
+  }
    if (cfg->has_exit()) {
      BAILOUT("control path without explicit return");
    }
@@ -90,8 +95,10 @@


  void Cfg::Append(Instruction* instr) {
-  ASSERT(has_exit());
-  ASSERT(!is_empty());
+  ASSERT(is_empty() || has_exit());
+  if (is_empty()) {
+    entry_ = exit_ = new InstructionBlock();
+  }
    InstructionBlock::cast(exit_)->Append(instr);
  }

@@ -102,6 +109,27 @@
    InstructionBlock::cast(exit_)->set_successor(global_exit);
    exit_ = NULL;
  }
+
+
+void Cfg::Concatenate(Cfg* other) {
+  ASSERT(is_empty() || has_exit());
+  if (other->is_empty()) return;
+
+  if (is_empty()) {
+    entry_ = other->entry();
+    exit_ = other->exit();
+  } else {
+    // We have a pair of nonempty fragments and this has an available exit.
+    // Destructively glue the fragments together.
+    InstructionBlock* first = InstructionBlock::cast(exit_);
+    InstructionBlock* second = InstructionBlock::cast(other->entry());
+    first->instructions()->AddAll(*second->instructions());
+    if (second->successor() != NULL) {
+      first->set_successor(second->successor());
+      exit_ = other->exit();
+    }
+  }
+}


  void InstructionBlock::Unmark() {
@@ -164,6 +192,26 @@

    return code;
  }
+
+
+void BinaryOpInstr::FastAllocate(TempLocation* temp) {
+  ASSERT(temp->where() == TempLocation::NOWHERE);
+  if (temp == val0_ || temp == val1_) {
+    temp->set_where(TempLocation::ACCUMULATOR);
+  } else {
+    temp->set_where(TempLocation::STACK);
+  }
+}
+
+
+void ReturnInstr::FastAllocate(TempLocation* temp) {
+  ASSERT(temp->where() == TempLocation::NOWHERE);
+  if (temp == value_) {
+    temp->set_where(TempLocation::ACCUMULATOR);
+  } else {
+    temp->set_where(TempLocation::STACK);
+  }
+}


  // The expression builder should not be used for declarations or  
statements.
@@ -178,12 +226,9 @@
  // Macros (temporarily) handling unsupported expression types.
  #define BAILOUT(reason)                         \
    do {                                          \
-    value_ = NULL;                              \
+    cfg_ = NULL;                                \
      return;                                     \
    } while (false)
-
-#define CHECK_BAILOUT()                         \
-  if (value_ == NULL) { return; } else {}

  void ExpressionBuilder::VisitFunctionLiteral(FunctionLiteral* expr) {
    BAILOUT("FunctionLiteral");
@@ -290,7 +335,46 @@


  void ExpressionBuilder::VisitBinaryOperation(BinaryOperation* expr) {
-  BAILOUT("BinaryOperation");
+  Token::Value op = expr->op();
+  switch (op) {
+    case Token::COMMA:
+    case Token::OR:
+    case Token::AND:
+      BAILOUT("unsupported binary operation");
+
+    case Token::BIT_OR:
+    case Token::BIT_XOR:
+    case Token::BIT_AND:
+    case Token::SHL:
+    case Token::SAR:
+    case Token::SHR:
+    case Token::ADD:
+    case Token::SUB:
+    case Token::MUL:
+    case Token::DIV:
+    case Token::MOD: {
+      ExpressionBuilder left, right;
+      left.Build(expr->left());
+      if (left.cfg() == NULL) {
+        BAILOUT("unsupported left subexpression in binop");
+      }
+      right.Build(expr->right());
+      if (right.cfg() == NULL) {
+        BAILOUT("unsupported right subexpression in binop");
+      }
+
+      Location* temp = new TempLocation();
+      cfg_ = left.cfg();
+      cfg_->Concatenate(right.cfg());
+      cfg_->Append(new BinaryOpInstr(temp, op, left.value(),  
right.value()));
+
+      value_ = temp;
+      return;
+    }
+
+    default:
+      UNREACHABLE();
+  }
  }


@@ -304,7 +388,6 @@
  }

  #undef BAILOUT
-#undef CHECK_BAILOUT


  // Macros (temporarily) handling unsupported statement types.
@@ -367,10 +450,13 @@

  void StatementBuilder::VisitReturnStatement(ReturnStatement* stmt) {
    ExpressionBuilder builder;
-  builder.Visit(stmt->expression());
-  Value* value = builder.value();
-  if (value == NULL) BAILOUT("unsupported expression type");
-  cfg_->AppendReturnInstruction(value);
+  builder.Build(stmt->expression());
+  if (builder.cfg() == NULL) {
+    BAILOUT("unsupported expression in return statement");
+  }
+
+  cfg_->Concatenate(builder.cfg());
+  cfg_->AppendReturnInstruction(builder.value());
  }


@@ -428,6 +514,11 @@
    handle_->Print();
    PrintF(")");
  }
+
+
+void Effect::Print() {
+  PrintF("Effect");
+}


  void SlotLocation::Print() {
@@ -443,12 +534,28 @@
        UNREACHABLE();
    }
  }
+
+
+void TempLocation::Print() {
+  PrintF("Temp(%d)", number());
+}
+
+
+void BinaryOpInstr::Print() {
+  PrintF("BinaryOp(");
+  loc_->Print();
+  PrintF(", %s, ", Token::Name(op_));
+  val0_->Print();
+  PrintF(", ");
+  val1_->Print();
+  PrintF(")\n");
+}


  void ReturnInstr::Print() {
-  PrintF("Return ");
+  PrintF("Return(");
    value_->Print();
-  PrintF("\n");
+  PrintF(")\n");
  }


=======================================
--- /branches/bleeding_edge/src/cfg.h   Mon Aug  3 00:55:48 2009
+++ /branches/bleeding_edge/src/cfg.h   Wed Aug  5 05:52:31 2009
@@ -34,6 +34,47 @@
  namespace internal {

  class ExitNode;
+class Location;
+
+// Translate a source AST into a control-flow graph (CFG).  The CFG  
contains
+// single-entry, single-exit blocks of straight-line instructions and
+// administrative nodes.
+//
+// Instructions are described by the following grammar.
+//
+// <Instruction> ::=
+//     BinaryOpInstr <Location> Token::Value <Value> <Value>
+//   | ReturnInstr Effect <Value>
+//
+// Values are trivial expressions:
+//
+// <Value> ::= Constant | <Location>
+//
+// Locations are storable values ('lvalues').  They can be slots,
+// compiler-generated temporaries, or the special location 'Effect'
+// indicating that no value is needed.
+//
+// <Location> ::=
+//     SlotLocation Slot::Type <Index>
+//   | TempLocation
+//   | Effect
+
+
+// Administrative nodes: There are several types of 'administrative' nodes
+// that do not contain instructions and do not necessarily have a single
+// predecessor and a single successor.
+//
+// EntryNode: there is a distinguished entry node that has no predecessors
+// and a single successor.
+//
+// ExitNode: there is a distinguished exit node that has arbitrarily many
+// predecessors and no successor.
+//
+// JoinNode: join nodes have multiple predecessors and a single successor.
+//
+// BranchNode: branch nodes have a single predecessor and multiple
+// successors.
+

  // A convenient class to keep 'global' values when building a CFG.  Since
  // CFG construction can be invoked recursively, CFG globals are stacked.
@@ -48,40 +89,58 @@
      return top_;
    }

+  // The function currently being compiled.
    FunctionLiteral* fun() { return global_fun_; }

+  // The shared global exit node for all exits from the function.
    ExitNode* exit() { return global_exit_; }
+
+  // A singleton effect location.
+  Location* effect_location() { return effect_; }

  #ifdef DEBUG
-  int next_number() { return node_counter_++; }
+  int next_node_number() { return node_counter_++; }
+  int next_temp_number() { return temp_counter_++; }
  #endif

   private:
    static CfgGlobals* top_;
-
-  // Function literal currently compiling.
    FunctionLiteral* global_fun_;
-
-  // Shared global exit node for all returns from the same function.
    ExitNode* global_exit_;
+  Location* effect_;

  #ifdef DEBUG
-  // Used to number nodes when printing.
+  // Used to number nodes and temporaries when printing.
    int node_counter_;
+  int temp_counter_;
  #endif

    CfgGlobals* previous_;
  };


-// Values appear in instructions.  They represent trivial source
-// expressions: ones with no side effects and that do not require code to  
be
-// generated.
+// Values represent trivial source expressions: ones with no side effects
+// and that do not require code to be generated.
  class Value : public ZoneObject {
   public:
    virtual ~Value() {}

-  virtual void ToRegister(MacroAssembler* masm, Register reg) = 0;
+  // Predicates:
+
+  // True if the value is a temporary allocated to the stack in
+  // fast-compilation mode.
+  virtual bool is_on_stack() { return false; }
+
+  // True if the value is a compiler-generated temporary location.
+  virtual bool is_temporary() { return false; }
+
+  // Support for fast-compilation mode:
+
+  // Move the value into a register.
+  virtual void Get(MacroAssembler* masm, Register reg) = 0;
+
+  // Push the value on the stack.
+  virtual void Push(MacroAssembler* masm) = 0;

  #ifdef DEBUG
    virtual void Print() = 0;
@@ -96,7 +155,9 @@

    virtual ~Constant() {}

-  void ToRegister(MacroAssembler* masm, Register reg);
+  // Support for fast-compilation mode.
+  void Get(MacroAssembler* masm, Register reg);
+  void Push(MacroAssembler* masm);

  #ifdef DEBUG
    void Print();
@@ -112,7 +173,23 @@
   public:
    virtual ~Location() {}

-  virtual void ToRegister(MacroAssembler* masm, Register reg) = 0;
+  // Static factory function returning the singleton effect location.
+  static Location* Effect() {
+    return CfgGlobals::current()->effect_location();
+  }
+
+  // Support for fast-compilation mode:
+
+  // Assumes temporaries have been allocated.
+  virtual void Get(MacroAssembler* masm, Register reg) = 0;
+
+  // Store the value in a register to the location.  Assumes temporaries
+  // have been allocated.
+  virtual void Set(MacroAssembler* masm, Register reg) = 0;
+
+  // Assumes temporaries have been allocated, and if the value is a
+  // temporary it was not allocated to the stack.
+  virtual void Push(MacroAssembler* masm) = 0;

  #ifdef DEBUG
    virtual void Print() = 0;
@@ -120,13 +197,40 @@
  };


+// Effect is a special (singleton) location that indicates the value of a
+// computation is not needed (though its side effects are).
+class Effect : public Location {
+ public:
+  // We should not try to emit code to read or write to Effect.
+  void Get(MacroAssembler* masm, Register reg) { UNREACHABLE(); }
+  void Set(MacroAssembler* masm, Register reg) { UNREACHABLE(); }
+  void Push(MacroAssembler* masm) { UNREACHABLE(); }
+
+#ifdef DEBUG
+  void Print();
+#endif
+
+ private:
+  Effect() {}
+
+  friend class CfgGlobals;
+};
+
+
  // SlotLocations represent parameters and stack-allocated (i.e.,
  // non-context) local variables.
  class SlotLocation : public Location {
   public:
    SlotLocation(Slot::Type type, int index) : type_(type), index_(index) {}

-  void ToRegister(MacroAssembler* masm, Register reg);
+  // Accessors.
+  Slot::Type type() { return type_; }
+  int index() { return index_; }
+
+  // Support for fast-compilation mode.
+  void Get(MacroAssembler* masm, Register reg);
+  void Set(MacroAssembler* masm, Register reg);
+  void Push(MacroAssembler* masm);

  #ifdef DEBUG
    void Print();
@@ -138,29 +242,136 @@
  };


+// TempLocations represent compiler generated temporaries.  They are
+// allocated to registers or memory either before code generation (in the
+// optimized-for-speed compiler) or on the fly during code generation (in
+// the optimized-for-space compiler).
+class TempLocation : public Location {
+ public:
+  // Fast-compilation mode allocation decisions.
+  enum Where {
+    NOWHERE,      // Not yet allocated.
+    ACCUMULATOR,  // Allocated to the dedicated accumulator register.
+    STACK         //   "   "   "   "  stack.
+  };
+
+  TempLocation() : where_(NOWHERE) {
+#ifdef DEBUG
+    number_ = -1;
+#endif
+  }
+
+  // Cast accessor.
+  static TempLocation* cast(Location* loc) {
+    ASSERT(loc->is_temporary());
+    return reinterpret_cast<TempLocation*>(loc);
+  }
+
+  // Accessors.
+  Where where() { return where_; }
+  void set_where(Where where) { where_ = where; }
+
+  // Predicates.
+  bool is_on_stack() { return where_ == STACK; }
+  bool is_temporary() { return true; }
+
+  // Support for fast-compilation mode.  Assume the temp has been  
allocated.
+  void Get(MacroAssembler* masm, Register reg);
+  void Set(MacroAssembler* masm, Register reg);
+  void Push(MacroAssembler* masm);
+
+#ifdef DEBUG
+  int number() {
+    if (number_ == -1) number_ = CfgGlobals::current()->next_temp_number();
+    return number_;
+  }
+
+  void Print();
+#endif
+
+ private:
+  Where where_;
+
+#ifdef DEBUG
+  int number_;
+#endif
+};
+
+
  // Instructions are computations.  The represent non-trivial source
  // expressions: typically ones that have side effects and require code to
  // be generated.
  class Instruction : public ZoneObject {
   public:
+  // Every instruction has a location where its result is stored (which may
+  // be Effect).
+  explicit Instruction(Location* loc) : loc_(loc) {}
+
    virtual ~Instruction() {}

+  // Accessors.
+  Location* location() { return loc_; }
+
+  // Support for fast-compilation mode:
+
+  // Emit code to perform the instruction.
    virtual void Compile(MacroAssembler* masm) = 0;

+  // Allocate a temporary which is the result of the immediate predecessor
+  // instruction.  It is allocated to the accumulator register if it is  
used
+  // as an operand to this instruction, otherwise to the stack.
+  virtual void FastAllocate(TempLocation* temp) = 0;
+
  #ifdef DEBUG
    virtual void Print() = 0;
  #endif
+
+ protected:
+  Location* loc_;
  };


-// Return a value.
+// Perform a (non-short-circuited) binary operation on a pair of values,
+// leaving the result in a location.
+class BinaryOpInstr : public Instruction {
+ public:
+  BinaryOpInstr(Location* loc, Token::Value op, Value* val0, Value* val1)
+      : Instruction(loc), op_(op), val0_(val0), val1_(val1) {
+  }
+
+  // Support for fast-compilation mode.
+  void Compile(MacroAssembler* masm);
+  void FastAllocate(TempLocation* temp);
+
+#ifdef DEBUG
+  void Print();
+#endif
+
+ private:
+  Token::Value op_;
+  Value* val0_;
+  Value* val1_;
+};
+
+
+// Return a value.  Has the side effect of moving its value into the return
+// value register.  Can only occur as the last instruction in an  
instruction
+// block, and implies that the block is closed (cannot have instructions
+// appended or graph fragments concatenated to the end) and that the  
block's
+// successor is the global exit node for the current function.
  class ReturnInstr : public Instruction {
   public:
-  explicit ReturnInstr(Value* value) : value_(value) {}
+  // Location is always Effect.
+  explicit ReturnInstr(Value* value)
+      : Instruction(CfgGlobals::current()->effect_location()),
+        value_(value) {
+  }

    virtual ~ReturnInstr() {}

+  // Support for fast-compilation mode.
    void Compile(MacroAssembler* masm);
+  void FastAllocate(TempLocation* temp);

  #ifdef DEBUG
    void Print();
@@ -171,9 +382,7 @@
  };


-// Nodes make up control-flow graphs.  They contain single-entry,
-// single-exit blocks of instructions and administrative nodes making up  
the
-// graph structure.
+// Nodes make up control-flow graphs.
  class CfgNode : public ZoneObject {
   public:
    CfgNode() : is_marked_(false) {
@@ -184,17 +393,26 @@

    virtual ~CfgNode() {}

+  // Because CFGs contain cycles, nodes support marking during traversal
+  // (e.g., for printing or compilation).  The traversal functions will  
mark
+  // unmarked nodes and backtrack if they encounter a marked one.  After a
+  // traversal, the graph should be explicitly unmarked by calling Unmark  
on
+  // the entry node.
    bool is_marked() { return is_marked_; }
-
+  virtual void Unmark() = 0;
+
+  // Predicates:
+
+  // True if the node is an instruction block.
    virtual bool is_block() { return false; }

-  virtual void Unmark() = 0;
-
+  // Support for fast-compilation mode.  Emit the instructions or control
+  // flow represented by the node.
    virtual void Compile(MacroAssembler* masm) = 0;

  #ifdef DEBUG
    int number() {
-    if (number_ == -1) number_ = CfgGlobals::current()->next_number();
+    if (number_ == -1) number_ = CfgGlobals::current()->next_node_number();
      return number_;
    }

@@ -217,22 +435,30 @@

    virtual ~InstructionBlock() {}

+  void Unmark();
+
+  // Cast accessor.
    static InstructionBlock* cast(CfgNode* node) {
      ASSERT(node->is_block());
      return reinterpret_cast<InstructionBlock*>(node);
    }
+
+  bool is_block() { return true; }
+
+  // Accessors.
+  CfgNode* successor() { return successor_; }

    void set_successor(CfgNode* succ) {
      ASSERT(successor_ == NULL);
      successor_ = succ;
    }

-  bool is_block() { return true; }
-
-  void Unmark();
-
+  ZoneList<Instruction*>* instructions() { return &instructions_; }
+
+  // Support for fast-compilation mode.
    void Compile(MacroAssembler* masm);

+  // Add an instruction to the end of the block.
    void Append(Instruction* instr) { instructions_.Add(instr); }

  #ifdef DEBUG
@@ -245,9 +471,7 @@
  };


-// The CFG for a function has a distinguished entry node.  It has no
-// predecessors and a single successor.  The successor is the block
-// containing the function's first instruction.
+// An entry node (one per function).
  class EntryNode : public CfgNode {
   public:
    explicit EntryNode(InstructionBlock* succ) : successor_(succ) {}
@@ -256,6 +480,7 @@

    void Unmark();

+  // Support for fast-compilation mode.
    void Compile(MacroAssembler* masm);

  #ifdef DEBUG
@@ -267,9 +492,7 @@
  };


-// The CFG for a function has a distinguished exit node.  It has no
-// successor and arbitrarily many predecessors.  The predecessors are all
-// the blocks returning from the function.
+// An exit node (one per function).
  class ExitNode : public CfgNode {
   public:
    ExitNode() {}
@@ -278,6 +501,7 @@

    void Unmark();

+  // Support for fast-compilation mode.
    void Compile(MacroAssembler* masm);

  #ifdef DEBUG
@@ -286,28 +510,36 @@
  };


-// A CFG consists of a linked structure of nodes.  It has a single entry
-// node and optionally an exit node.  There is a distinguished global exit
-// node that is used as the successor of all blocks that return from the
-// function.
+// A CFG consists of a linked structure of nodes.  Nodes are linked by
+// pointing to their successors, always beginning with a (single) entry  
node
+// (not necessarily of type EntryNode).  If it is still possible to add
+// nodes to the end of the graph (i.e., there is a (single) path that does
+// not end with the global exit node), then the CFG has an exit node as
+// well.
  //
-// Fragments of control-flow graphs, produced when traversing the  
statements
-// and expressions in the source AST, are represented by the same class.
-// They have instruction blocks as both their entry and exit (if there is
-// one).  Instructions can always be prepended or appended to fragments,  
and
-// fragments can always be concatenated.
+// The empty CFG is represented by a NULL entry and a NULL exit.
  //
-// A singleton CFG fragment (i.e., with only one node) has the same node as
-// both entry and exit (if the exit is available).
+// We use the term 'open fragment' to mean a CFG whose entry and exits are
+// both instruction blocks.  It is always possible to add instructions and
+// nodes to the beginning or end of an open fragment.
+//
+// We use the term 'closed fragment' to mean a CFG whose entry is an
+// instruction block and whose exit is NULL (all paths go to the global
+// exit).
+//
+// We use the term 'fragment' to refer to a CFG that is known to be an open
+// or closed fragment.
  class Cfg : public ZoneObject {
   public:
-  // Create a singleton CFG fragment.
-  explicit Cfg(InstructionBlock* block) : entry_(block), exit_(block) {}
-
-  // Build the CFG for a function.
+  // Create an empty CFG fragment.
+  Cfg() : entry_(NULL), exit_(NULL) {}
+
+  // Build the CFG for a function.  The returned CFG begins with an
+  // EntryNode and all paths end with the ExitNode.
    static Cfg* Build();

-  // The entry and exit nodes.
+  // The entry and exit nodes of the CFG (not necessarily EntryNode and
+  // ExitNode).
    CfgNode* entry() { return entry_; }
    CfgNode* exit() { return exit_; }

@@ -318,18 +550,21 @@
    // concatenated to).
    bool has_exit() { return exit_ != NULL; }

-  // Add an entry node to a CFG fragment.  It is no longer a fragment
-  // (instructions cannot be prepended).
+  // Add an EntryNode to a CFG fragment.  It is no longer a fragment
+  // (instructions can no longer be prepended).
    void PrependEntryNode();

-  // Append an instruction to the end of a CFG fragment.  Assumes it has an
-  // available exit.
+  // Append an instruction to the end of an open fragment.
    void Append(Instruction* instr);

-  // Appends a return instruction to the end of a CFG fragment.  It no
-  // longer has an available exit node.
+  // Appends a return instruction to the end of an open fragment and make
+  // it a closed fragment (the exit's successor becomes global exit node).
    void AppendReturnInstruction(Value* value);

+  // Glue an other CFG fragment to the end of this (open) fragment.
+  void Concatenate(Cfg* other);
+
+  // Support for compilation.  Compile the entire CFG.
    Handle<Code> Compile(Handle<Script> script);

  #ifdef DEBUG
@@ -344,12 +579,24 @@
  };


-// An Expression Builder traverses a trivial expression and returns a  
value.
+// An ExpressionBuilder traverses an expression and returns an open CFG
+// fragment (currently a possibly empty list of instructions represented by
+// a singleton instruction block) and the expression's value.
+//
+// Failure is to build the CFG is indicated by a NULL CFG.
  class ExpressionBuilder : public AstVisitor {
   public:
-  ExpressionBuilder() : value_(new Constant(Handle<Object>::null())) {}
-
+  ExpressionBuilder() : value_(NULL), cfg_(NULL) {}
+
+  // Result accessors.
    Value* value() { return value_; }
+  Cfg* cfg() { return cfg_; }
+
+  void Build(Expression* expr) {
+    value_ = NULL;
+    cfg_ = new Cfg();
+    Visit(expr);
+  }

    // AST node visitors.
  #define DECLARE_VISIT(type) void Visit##type(type* node);
@@ -358,13 +605,16 @@

   private:
    Value* value_;
+  Cfg* cfg_;
  };


-// A StatementBuilder traverses a statement and returns a CFG.
+// A StatementBuilder maintains a CFG fragment accumulator.  When it visits
+// a statement, it concatenates the CFG for the statement to the end of the
+// accumulator.
  class StatementBuilder : public AstVisitor {
   public:
-  StatementBuilder() : cfg_(new Cfg(new InstructionBlock())) {}
+  StatementBuilder() : cfg_(new Cfg()) {}

    Cfg* cfg() { return cfg_; }

=======================================
--- /branches/bleeding_edge/src/ia32/cfg-ia32.cc        Mon Aug  3 00:55:48 2009
+++ /branches/bleeding_edge/src/ia32/cfg-ia32.cc        Wed Aug  5 05:52:31 2009
@@ -29,6 +29,7 @@

  #include "cfg.h"
  #include "codegen-inl.h"
+#include "codegen-ia32.h"
  #include "macro-assembler-ia32.h"

  namespace v8 {
@@ -42,6 +43,14 @@
    {
      Comment cmt(masm, "[ InstructionBlock");
      for (int i = 0, len = instructions_.length(); i < len; i++) {
+      // If the location of the current instruction is a temp, then the
+      // instruction cannot be in tail position in the block.  Allocate the
+      // temp based on peeking ahead to the next instruction.
+      Instruction* instr = instructions_[i];
+      Location* loc = instr->location();
+      if (loc->is_temporary()) {
+        instructions_[i+1]->FastAllocate(TempLocation::cast(loc));
+      }
        instructions_[i]->Compile(masm);
      }
    }
@@ -79,6 +88,7 @@
    }
    successor_->Compile(masm);
    if (FLAG_check_stack) {
+    Comment cmnt(masm, "[ Deferred Stack Check");
      __ bind(&deferred_enter);
      StackCheckStub stub;
      __ CallStub(&stub);
@@ -101,33 +111,122 @@
    int count = CfgGlobals::current()->fun()->scope()->num_parameters();
    __ ret((count + 1) * kPointerSize);
  }
+
+
+void BinaryOpInstr::Compile(MacroAssembler* masm) {
+  // The right-hand value should not be on the stack---if it is a
+  // compiler-generated temporary it is in the accumulator.
+  ASSERT(!val1_->is_on_stack());
+
+  Comment cmnt(masm, "[ BinaryOpInstr");
+  // We can overwrite one of the operands if it is a temporary.
+  OverwriteMode mode = NO_OVERWRITE;
+  if (val0_->is_temporary()) {
+    mode = OVERWRITE_LEFT;
+  } else if (val1_->is_temporary()) {
+    mode = OVERWRITE_RIGHT;
+  }
+
+  // Push both operands and call the specialized stub.
+  if (!val0_->is_on_stack()) {
+    val0_->Push(masm);
+  }
+  val1_->Push(masm);
+  GenericBinaryOpStub stub(op_, mode, SMI_CODE_IN_STUB);
+  __ CallStub(&stub);
+  loc_->Set(masm, eax);
+}


  void ReturnInstr::Compile(MacroAssembler* masm) {
+  // The location should be 'Effect'.  As a side effect, move the value to
+  // the accumulator.
    Comment cmnt(masm, "[ ReturnInstr");
-  value_->ToRegister(masm, eax);
+  value_->Get(masm, eax);
  }


-void Constant::ToRegister(MacroAssembler* masm, Register reg) {
+void Constant::Get(MacroAssembler* masm, Register reg) {
    __ mov(reg, Immediate(handle_));
  }


-void SlotLocation::ToRegister(MacroAssembler* masm, Register reg) {
-  switch (type_) {
+void Constant::Push(MacroAssembler* masm) {
+  __ push(Immediate(handle_));
+}
+
+
+static Operand ToOperand(SlotLocation* loc) {
+  switch (loc->type()) {
      case Slot::PARAMETER: {
        int count = CfgGlobals::current()->fun()->scope()->num_parameters();
-      __ mov(reg, Operand(ebp, (1 + count - index_) * kPointerSize));
-      break;
+      return Operand(ebp, (1 + count - loc->index()) * kPointerSize);
      }
      case Slot::LOCAL: {
        const int kOffset = JavaScriptFrameConstants::kLocal0Offset;
-      __ mov(reg, Operand(ebp, kOffset - index_ * kPointerSize));
-      break;
+      return Operand(ebp, kOffset - loc->index() * kPointerSize);
      }
      default:
        UNREACHABLE();
+      return Operand(eax);
+  }
+}
+
+
+void SlotLocation::Get(MacroAssembler* masm, Register reg) {
+  __ mov(reg, ToOperand(this));
+}
+
+
+void SlotLocation::Set(MacroAssembler* masm, Register reg) {
+  __ mov(ToOperand(this), reg);
+}
+
+
+void SlotLocation::Push(MacroAssembler* masm) {
+  __ push(ToOperand(this));
+}
+
+
+void TempLocation::Get(MacroAssembler* masm, Register reg) {
+  switch (where_) {
+    case ACCUMULATOR:
+      if (!reg.is(eax)) __ mov(reg, eax);
+      break;
+    case STACK:
+      __ pop(reg);
+      break;
+    case NOWHERE:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
+void TempLocation::Set(MacroAssembler* masm, Register reg) {
+  switch (where_) {
+    case ACCUMULATOR:
+      if (!reg.is(eax)) __ mov(eax, reg);
+      break;
+    case STACK:
+      __ push(reg);
+      break;
+    case NOWHERE:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
+void TempLocation::Push(MacroAssembler* masm) {
+  switch (where_) {
+    case ACCUMULATOR:
+      __ push(eax);
+      break;
+    case STACK:
+    case NOWHERE:
+      UNREACHABLE();
+      break;
    }
  }

=======================================
--- /branches/bleeding_edge/src/ia32/codegen-ia32.cc    Fri Jul 31 04:07:05  
2009
+++ /branches/bleeding_edge/src/ia32/codegen-ia32.cc    Wed Aug  5 05:52:31  
2009
@@ -778,57 +778,6 @@
  };


-// Flag that indicates whether or not the code that handles smi arguments
-// should be placed in the stub, inlined, or omitted entirely.
-enum GenericBinaryFlags {
-  SMI_CODE_IN_STUB,
-  SMI_CODE_INLINED
-};
-
-
-class GenericBinaryOpStub: public CodeStub {
- public:
-  GenericBinaryOpStub(Token::Value op,
-                      OverwriteMode mode,
-                      GenericBinaryFlags flags)
-      : op_(op), mode_(mode), flags_(flags) {
-    ASSERT(OpBits::is_valid(Token::NUM_TOKENS));
-  }
-
-  void GenerateSmiCode(MacroAssembler* masm, Label* slow);
-
- private:
-  Token::Value op_;
-  OverwriteMode mode_;
-  GenericBinaryFlags flags_;
-
-  const char* GetName();
-
-#ifdef DEBUG
-  void Print() {
-    PrintF("GenericBinaryOpStub (op %s), (mode %d, flags %d)\n",
-           Token::String(op_),
-           static_cast<int>(mode_),
-           static_cast<int>(flags_));
-  }
-#endif
-
-  // Minor key encoding in 16 bits FOOOOOOOOOOOOOMM.
-  class ModeBits: public BitField<OverwriteMode, 0, 2> {};
-  class OpBits: public BitField<Token::Value, 2, 13> {};
-  class FlagBits: public BitField<GenericBinaryFlags, 15, 1> {};
-
-  Major MajorKey() { return GenericBinaryOp; }
-  int MinorKey() {
-    // Encode the parameters in a unique 16 bit value.
-    return OpBits::encode(op_)
-           | ModeBits::encode(mode_)
-           | FlagBits::encode(flags_);
-  }
-  void Generate(MacroAssembler* masm);
-};
-
-
  const char* GenericBinaryOpStub::GetName() {
    switch (op_) {
      case Token::ADD: return "GenericBinaryOpStub_ADD";
=======================================
--- /branches/bleeding_edge/src/ia32/codegen-ia32.h     Fri Jul 31 04:07:05 2009
+++ /branches/bleeding_edge/src/ia32/codegen-ia32.h     Wed Aug  5 05:52:31 2009
@@ -609,6 +609,57 @@
  };


+// Flag that indicates whether or not the code that handles smi arguments
+// should be placed in the stub, inlined, or omitted entirely.
+enum GenericBinaryFlags {
+  SMI_CODE_IN_STUB,
+  SMI_CODE_INLINED
+};
+
+
+class GenericBinaryOpStub: public CodeStub {
+ public:
+  GenericBinaryOpStub(Token::Value op,
+                      OverwriteMode mode,
+                      GenericBinaryFlags flags)
+      : op_(op), mode_(mode), flags_(flags) {
+    ASSERT(OpBits::is_valid(Token::NUM_TOKENS));
+  }
+
+  void GenerateSmiCode(MacroAssembler* masm, Label* slow);
+
+ private:
+  Token::Value op_;
+  OverwriteMode mode_;
+  GenericBinaryFlags flags_;
+
+  const char* GetName();
+
+#ifdef DEBUG
+  void Print() {
+    PrintF("GenericBinaryOpStub (op %s), (mode %d, flags %d)\n",
+           Token::String(op_),
+           static_cast<int>(mode_),
+           static_cast<int>(flags_));
+  }
+#endif
+
+  // Minor key encoding in 16 bits FOOOOOOOOOOOOOMM.
+  class ModeBits: public BitField<OverwriteMode, 0, 2> {};
+  class OpBits: public BitField<Token::Value, 2, 13> {};
+  class FlagBits: public BitField<GenericBinaryFlags, 15, 1> {};
+
+  Major MajorKey() { return GenericBinaryOp; }
+  int MinorKey() {
+    // Encode the parameters in a unique 16 bit value.
+    return OpBits::encode(op_)
+           | ModeBits::encode(mode_)
+           | FlagBits::encode(flags_);
+  }
+  void Generate(MacroAssembler* masm);
+};
+
+
  } }  // namespace v8::internal

  #endif  // V8_IA32_CODEGEN_IA32_H_
=======================================
--- /branches/bleeding_edge/src/x64/cfg-x64.cc  Mon Aug  3 00:55:48 2009
+++ /branches/bleeding_edge/src/x64/cfg-x64.cc  Wed Aug  5 05:52:31 2009
@@ -29,6 +29,7 @@

  #include "cfg.h"
  #include "codegen-inl.h"
+#include "codegen-x64.h"
  #include "debug.h"
  #include "macro-assembler-x64.h"

@@ -43,6 +44,14 @@
    {
      Comment cmt(masm, "[ InstructionBlock");
      for (int i = 0, len = instructions_.length(); i < len; i++) {
+      // If the location of the current instruction is a temp, then the
+      // instruction cannot be in tail position in the block.  Allocate the
+      // temp based on peeking ahead to the next instruction.
+      Instruction* instr = instructions_[i];
+      Location* loc = instr->location();
+      if (loc->is_temporary()) {
+        instructions_[i+1]->FastAllocate(TempLocation::cast(loc));
+      }
        instructions_[i]->Compile(masm);
      }
    }
@@ -82,6 +91,7 @@
    }
    successor_->Compile(masm);
    if (FLAG_check_stack) {
+    Comment cmnt(masm, "[ Deferred Stack Check");
      __ bind(&deferred_enter);
      StackCheckStub stub;
      __ CallStub(&stub);
@@ -111,35 +121,125 @@
      __ int3();
    }
  }
+
+
+void BinaryOpInstr::Compile(MacroAssembler* masm) {
+  // The right-hand value should not be on the stack---if it is a
+  // compiler-generated temporary it is in the accumulator.
+  ASSERT(!val1_->is_on_stack());
+
+  Comment cmnt(masm, "[ BinaryOpInstr");
+  // We can overwrite one of the operands if it is a temporary.
+  OverwriteMode mode = NO_OVERWRITE;
+  if (val0_->is_temporary()) {
+    mode = OVERWRITE_LEFT;
+  } else if (val1_->is_temporary()) {
+    mode = OVERWRITE_RIGHT;
+  }
+
+  // Push both operands and call the specialized stub.
+  if (!val0_->is_on_stack()) {
+    val0_->Push(masm);
+  }
+  val1_->Push(masm);
+  GenericBinaryOpStub stub(op_, mode, SMI_CODE_IN_STUB);
+  __ CallStub(&stub);
+  loc_->Set(masm, rax);
+}


  void ReturnInstr::Compile(MacroAssembler* masm) {
+  // The location should be 'Effect'.  As a side effect, move the value to
+  // the accumulator.
    Comment cmnt(masm, "[ ReturnInstr");
-  value_->ToRegister(masm, rax);
+  value_->Get(masm, rax);
  }


-void Constant::ToRegister(MacroAssembler* masm, Register reg) {
+void Constant::Get(MacroAssembler* masm, Register reg) {
    __ Move(reg, handle_);
  }


-void SlotLocation::ToRegister(MacroAssembler* masm, Register reg) {
-  switch (type_) {
+void Constant::Push(MacroAssembler* masm) {
+  __ Push(handle_);
+}
+
+
+static Operand ToOperand(SlotLocation* loc) {
+  switch (loc->type()) {
      case Slot::PARAMETER: {
        int count = CfgGlobals::current()->fun()->scope()->num_parameters();
-      __ movq(reg, Operand(rbp, (1 + count - index_) * kPointerSize));
-      break;
+      return Operand(rbp, (1 + count - loc->index()) * kPointerSize);
      }
      case Slot::LOCAL: {
        const int kOffset = JavaScriptFrameConstants::kLocal0Offset;
-      __ movq(reg, Operand(rbp, kOffset - index_ * kPointerSize));
-      break;
+      return Operand(rbp, kOffset - loc->index() * kPointerSize);
      }
      default:
        UNREACHABLE();
+      return Operand(rax, 0);
    }
  }
+
+
+void SlotLocation::Get(MacroAssembler* masm, Register reg) {
+  __ movq(reg, ToOperand(this));
+}
+
+
+void SlotLocation::Set(MacroAssembler* masm, Register reg) {
+  __ movq(ToOperand(this), reg);
+}
+
+
+void SlotLocation::Push(MacroAssembler* masm) {
+  __ push(ToOperand(this));
+}
+
+
+void TempLocation::Get(MacroAssembler* masm, Register reg) {
+  switch (where_) {
+    case ACCUMULATOR:
+      if (!reg.is(rax)) __ movq(reg, rax);
+      break;
+    case STACK:
+      __ pop(reg);
+      break;
+    case NOWHERE:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
+void TempLocation::Set(MacroAssembler* masm, Register reg) {
+  switch (where_) {
+    case ACCUMULATOR:
+      if (!reg.is(rax)) __ movq(rax, reg);
+      break;
+    case STACK:
+      __ push(reg);
+      break;
+    case NOWHERE:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
+void TempLocation::Push(MacroAssembler* masm) {
+  switch (where_) {
+    case ACCUMULATOR:
+      __ push(rax);
+      break;
+    case STACK:
+    case NOWHERE:
+      UNREACHABLE();
+      break;
+  }
+}
+

  #undef __

=======================================
--- /branches/bleeding_edge/src/x64/codegen-x64.cc      Tue Aug  4 06:46:58 2009
+++ /branches/bleeding_edge/src/x64/codegen-x64.cc      Wed Aug  5 05:52:31 2009
@@ -4532,14 +4532,6 @@
      }
    }
  }
-
-
-// Flag that indicates whether or not the code that handles smi arguments
-// should be placed in the stub, inlined, or omitted entirely.
-enum GenericBinaryFlags {
-  SMI_CODE_IN_STUB,
-  SMI_CODE_INLINED
-};


  class FloatingPointHelper : public AllStatic {
@@ -4593,49 +4585,6 @@
  };


-class GenericBinaryOpStub: public CodeStub {
- public:
-  GenericBinaryOpStub(Token::Value op,
-                      OverwriteMode mode,
-                      GenericBinaryFlags flags)
-      : op_(op), mode_(mode), flags_(flags) {
-    ASSERT(OpBits::is_valid(Token::NUM_TOKENS));
-  }
-
-  void GenerateSmiCode(MacroAssembler* masm, Label* slow);
-
- private:
-  Token::Value op_;
-  OverwriteMode mode_;
-  GenericBinaryFlags flags_;
-
-  const char* GetName();
-
-#ifdef DEBUG
-  void Print() {
-    PrintF("GenericBinaryOpStub (op %s), (mode %d, flags %d)\n",
-           Token::String(op_),
-           static_cast<int>(mode_),
-           static_cast<int>(flags_));
-  }
-#endif
-
-  // Minor key encoding in 16 bits FOOOOOOOOOOOOOMM.
-  class ModeBits: public BitField<OverwriteMode, 0, 2> {};
-  class OpBits: public BitField<Token::Value, 2, 13> {};
-  class FlagBits: public BitField<GenericBinaryFlags, 15, 1> {};
-
-  Major MajorKey() { return GenericBinaryOp; }
-  int MinorKey() {
-    // Encode the parameters in a unique 16 bit value.
-    return OpBits::encode(op_)
-           | ModeBits::encode(mode_)
-           | FlagBits::encode(flags_);
-  }
-  void Generate(MacroAssembler* masm);
-};
-
-
  class DeferredInlineBinaryOperation: public DeferredCode {
   public:
    DeferredInlineBinaryOperation(Token::Value op,
=======================================
--- /branches/bleeding_edge/src/x64/codegen-x64.h       Fri Jul 31 04:07:05 2009
+++ /branches/bleeding_edge/src/x64/codegen-x64.h       Wed Aug  5 05:52:31 2009
@@ -601,6 +601,57 @@
  };


+// Flag that indicates whether or not the code that handles smi arguments
+// should be placed in the stub, inlined, or omitted entirely.
+enum GenericBinaryFlags {
+  SMI_CODE_IN_STUB,
+  SMI_CODE_INLINED
+};
+
+
+class GenericBinaryOpStub: public CodeStub {
+ public:
+  GenericBinaryOpStub(Token::Value op,
+                      OverwriteMode mode,
+                      GenericBinaryFlags flags)
+      : op_(op), mode_(mode), flags_(flags) {
+    ASSERT(OpBits::is_valid(Token::NUM_TOKENS));
+  }
+
+  void GenerateSmiCode(MacroAssembler* masm, Label* slow);
+
+ private:
+  Token::Value op_;
+  OverwriteMode mode_;
+  GenericBinaryFlags flags_;
+
+  const char* GetName();
+
+#ifdef DEBUG
+  void Print() {
+    PrintF("GenericBinaryOpStub (op %s), (mode %d, flags %d)\n",
+           Token::String(op_),
+           static_cast<int>(mode_),
+           static_cast<int>(flags_));
+  }
+#endif
+
+  // Minor key encoding in 16 bits FOOOOOOOOOOOOOMM.
+  class ModeBits: public BitField<OverwriteMode, 0, 2> {};
+  class OpBits: public BitField<Token::Value, 2, 13> {};
+  class FlagBits: public BitField<GenericBinaryFlags, 15, 1> {};
+
+  Major MajorKey() { return GenericBinaryOp; }
+  int MinorKey() {
+    // Encode the parameters in a unique 16 bit value.
+    return OpBits::encode(op_)
+           | ModeBits::encode(mode_)
+           | FlagBits::encode(flags_);
+  }
+  void Generate(MacroAssembler* masm);
+};
+
+
  } }  // namespace v8::internal

  #endif  // V8_X64_CODEGEN_X64_H_

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