codegen-ia32.cc.svn-base

Google浏览器V8内核代码

// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "v8.h"

#include "bootstrapper.h"
#include "codegen-inl.h"
#include "debug.h"
#include "prettyprinter.h"
#include "scopeinfo.h"
#include "scopes.h"
#include "runtime.h"

namespace v8 { namespace internal {

#define TOS (Operand(esp, 0))


class Ia32CodeGenerator;

// Mode to overwrite BinaryExpression values.
enum OverwriteMode { NO_OVERWRITE, OVERWRITE_LEFT, OVERWRITE_RIGHT };


// -----------------------------------------------------------------------------
// Reference support

// A reference is a C++ stack-allocated object that keeps an ECMA
// reference on the execution stack while in scope. For variables
// the reference is empty, indicating that it isn't necessary to
// store state on the stack for keeping track of references to those.
// For properties, we keep either one (named) or two (indexed) values
// on the execution stack to represent the reference.

class Reference BASE_EMBEDDED {
 public:
  enum Type { ILLEGAL = -1, EMPTY = 0, NAMED = 1, KEYED = 2 };
  Reference(Ia32CodeGenerator* cgen, Expression* expression);
  ~Reference();

  Expression* expression() const  { return expression_; }
  Type type() const  { return type_; }
  void set_type(Type value)  {
    ASSERT(type_ == ILLEGAL);
    type_ = value;
  }
  int size() const  { return type_; }

  bool is_illegal() const  { return type_ == ILLEGAL; }

 private:
  Ia32CodeGenerator* cgen_;
  Expression* expression_;
  Type type_;
};


// -------------------------------------------------------------------------
// Code generation state

// The state is passed down the AST by the code generator.  It is passed
// implicitly (in a member variable) to the non-static code generator member
// functions, and explicitly (as an argument) to the static member functions
// and the AST node member functions.
//
// The state is threaded through the call stack.  Constructing a state
// implicitly pushes it on the owning code generator's stack of states, and
// destroying one implicitly pops it.

class CodeGenState BASE_EMBEDDED {
 public:
  enum AccessType {
    UNDEFINED,
    LOAD,
    LOAD_TYPEOF_EXPR
  };

  // Create an initial code generator state.  Destroying the initial state
  // leaves the code generator with a NULL state.
  explicit CodeGenState(Ia32CodeGenerator* owner);

  // Create a code generator state based on a code generator's current
  // state.  The new state has its own access type and pair of branch
  // labels, and no reference.
  CodeGenState(Ia32CodeGenerator* owner,
               AccessType access,
               Label* true_target,
               Label* false_target);

  // Create a code generator state based on a code generator's current
  // state.  The new state has an access type of LOAD, its own reference,
  // and inherits the pair of branch labels of the current state.
  CodeGenState(Ia32CodeGenerator* owner, Reference* ref);

  // Destroy a code generator state and restore the owning code generator's
  // previous state.
  ~CodeGenState();

  AccessType access() const { return access_; }
  Reference* ref() const { return ref_; }
  Label* true_target() const { return true_target_; }
  Label* false_target() const { return false_target_; }

 private:
  Ia32CodeGenerator* owner_;
  AccessType access_;
  Reference* ref_;
  Label* true_target_;
  Label* false_target_;
  CodeGenState* previous_;
};


// -----------------------------------------------------------------------------
// Ia32CodeGenerator

class Ia32CodeGenerator: public CodeGenerator {
 public:
  static Handle<Code> MakeCode(FunctionLiteral* fun,
                               Handle<Script> script,
                               bool is_eval);

  MacroAssembler* masm()  { return masm_; }

  CodeGenState* state() { return state_; }
  void set_state(CodeGenState* state) { state_ = state; }

 private:
  // Assembler
  MacroAssembler* masm_;  // to generate code

  // Code generation state
  Scope* scope_;
  Condition cc_reg_;
  CodeGenState* state_;
  bool is_inside_try_;
  int break_stack_height_;

  // Labels
  Label function_return_;

  // Construction/destruction
  Ia32CodeGenerator(int buffer_size,
                    Handle<Script> script,
                    bool is_eval);
  virtual ~Ia32CodeGenerator()  { delete masm_; }

  // Main code generation function
  void GenCode(FunctionLiteral* fun);

  // The following are used by class Reference.
  void LoadReference(Reference* ref);
  void UnloadReference(Reference* ref);

  // State
  bool has_cc() const  { return cc_reg_ >= 0; }
  CodeGenState::AccessType access() const  { return state_->access(); }
  Reference* ref() const  { return state_->ref(); }
  bool is_referenced() const { return state_->ref() != NULL; }
  Label* true_target() const  { return state_->true_target(); }
  Label* false_target() const  { return state_->false_target(); }

  // Expressions
  Operand GlobalObject() const {
    return ContextOperand(esi, Context::GLOBAL_INDEX);
  }

  // Support functions for accessing parameters.  Static versions can
  // require some code generator state to be passed in as arguments.
  static Operand ParameterOperand(Scope* scope, int index) {
    ASSERT(-2 <= index && index < scope->num_parameters());
    return Operand(ebp, (1 + scope->num_parameters() - index) * kPointerSize);
  }

  Operand ParameterOperand(int index) const {
    return ParameterOperand(scope_, index);
  }

  Operand ReceiverOperand() const { return ParameterOperand(-1); }

  Operand FunctionOperand() const {
    return Operand(ebp, JavaScriptFrameConstants::kFunctionOffset);
  }

  static Operand ContextOperand(Register context, int index) {
    return Operand(context, Context::SlotOffset(index));
  }

  static Operand SlotOperand(MacroAssembler* masm,
                             Scope* scope,
                             Slot* slot,
                             Register tmp);

  Operand SlotOperand(Slot* slot, Register tmp) {
    return SlotOperand(masm_, scope_, slot, tmp);
  }

  void LoadCondition(Expression* x,
                     CodeGenState::AccessType access,
                     Label* true_target,
                     Label* false_target,
                     bool force_cc);
  void Load(Expression* x,
            CodeGenState::AccessType access = CodeGenState::LOAD);
  void LoadGlobal();

  // Special code for typeof expressions: Unfortunately, we must
  // be careful when loading the expression in 'typeof'
  // expressions. We are not allowed to throw reference errors for
  // non-existing properties of the global object, so we must make it
  // look like an explicit property access, instead of an access
  // through the context chain.
  void LoadTypeofExpression(Expression* x);

  // References

  // Generate code to fetch the value of a reference.  The reference is
  // expected to be on top of the expression stack.  It is left in place and
  // its value is pushed on top of it.
  void GetValue(Reference* ref) {
    ASSERT(!has_cc());
    ASSERT(!ref->is_illegal());
    CodeGenState new_state(this, ref);
    Visit(ref->expression());
  }

  // Generate code to store a value in a reference.  The stored value is
  // expected on top of the expression stack, with the reference immediately
  // below it.  The expression stack is left unchanged.
  void SetValue(Reference* ref) {
    ASSERT(!has_cc());
    ASSERT(!ref->is_illegal());
    ref->expression()->GenerateStoreCode(masm_, scope_, ref, NOT_CONST_INIT);
  }

  // Same as SetValue, used to set the initial value of a constant.
  void InitConst(Reference* ref) {
    ASSERT(!has_cc());
    ASSERT(!ref->is_illegal());
    ref->expression()->GenerateStoreCode(masm_, scope_, ref, CONST_INIT);
  }

  // Generate code to fetch a value from a property of a reference.  The
  // reference is expected on top of the expression stack.  It is left in
  // place and its value is pushed on top of it.
  void GetReferenceProperty(Expression* key);

  // Generate code to store a value in a property of a reference.  The
  // stored value is expected on top of the expression stack, with the
  // reference immediately below it.  The expression stack is left
  // unchanged.
  static void SetReferenceProperty(MacroAssembler* masm,
                                   Reference* ref,
                                   Expression* key);

  void ToBoolean(Label* true_target, Label* false_target);

  void GenericBinaryOperation(
      Token::Value op,
      const OverwriteMode overwrite_mode = NO_OVERWRITE);
  void Comparison(Condition cc, bool strict = false);

  // Inline small integer literals. To prevent long attacker-controlled byte
  // sequences, we only inline small Smi:s.
  static const int kMaxSmiInlinedBits = 16;
  bool IsInlineSmi(Literal* literal);
  void SmiComparison(Condition cc,  Handle<Object> value, bool strict = false);
  void SmiOperation(Token::Value op,
                    Handle<Object> value,
                    bool reversed,
                    OverwriteMode overwrite_mode);

  void CallWithArguments(ZoneList<Expression*>* arguments, int position);

  // Declare global variables and functions in the given array of
  // name/value pairs.
  virtual void DeclareGlobals(Handle<FixedArray> pairs);

  // Instantiate the function boilerplate.
  void InstantiateBoilerplate(Handle<JSFunction> boilerplate);

  // Control flow
  void Branch(bool if_true, Label* L);
  void CheckStack();
  void CleanStack(int num_bytes);

  // Node visitors
#define DEF_VISIT(type)                         \
  virtual void Visit##type(type* node);
  NODE_LIST(DEF_VISIT)
#undef DEF_VISIT

  // Only allow fast-case switch if the range of labels is at most
  // this factor times the number of case labels.
  // Value is derived from comparing the size of code generated by the normal
  // switch code for Smi-labels to the size of a single pointer. If code
  // quality increases this number should be decreased to match.
  static const int kFastSwitchMaxOverheadFactor = 5;

  // Minimal number of switch cases required before we allow jump-table
  // optimization.
  static const int kFastSwitchMinCaseCount = 5;

  // Create fast switch implementation if all labels are small integers
  // in a limited range. Returns false if this is not the case, and no
  // code has been generated (i.e., the default implementation should be used).
  bool TryFastCaseSwitchStatement(SwitchStatement *switchStmt);

  // Generate a computed jump with an empty jump table.
  // Binds a label to the start of the jump table. This table must
  // be populated later when the adresses of the targets are known.
  // Used by GenerateFastCaseSwitchStatement.
  void GenerateFastCaseSwitchJumpTable(
      int min_index, int range, Label *fail_label, Label &table_start);

  // Populate an empty jump table with the adresses of bound labels.
  // Used by GenerateFastCaseSwitchStatement.
  void PopulateFastCaseSwitchJumpTable(
      Label &table_start, SmartPointer<Label*> &case_targets, int table_size);

  // Generates a fast-case switch statement for a switch with all-Smi labels
  // in a limited range.
  // Used by TryFastCaseSwitchStatement.
  void GenerateFastCaseSwitchStatement(
      SwitchStatement *node, int min_index, int range, int default_index);

  void RecordStatementPosition(Node* node);

  // Activation frames.
  void EnterJSFrame();
  void ExitJSFrame();

  virtual void GenerateIsSmi(ZoneList<Expression*>* args);
  virtual void GenerateIsNonNegativeSmi(ZoneList<Expression*>* args);
  virtual void GenerateIsArray(ZoneList<Expression*>* args);

  virtual void GenerateArgumentsLength(ZoneList<Expression*>* args);
  virtual void GenerateArgumentsAccess(ZoneList<Expression*>* args);

  virtual void GenerateValueOf(ZoneList<Expression*>* args);
  virtual void GenerateSetValueOf(ZoneList<Expression*>* args);

  virtual void GenerateFastCharCodeAt(ZoneList<Expression*>* args);

  virtual void GenerateObjectEquals(ZoneList<Expression*>* args);

  friend class Reference;
  friend class Property;
  friend class VariableProxy;
  friend class Slot;
};


// -------------------------------------------------------------------------
// CodeGenState implementation.

CodeGenState::CodeGenState(Ia32CodeGenerator* owner)
    : owner_(owner),
      access_(UNDEFINED),