Experimental: improve the code generated for possibly boolean-valued...

src/codegen-ia32.h

 // 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
@@ skipping 110 matching lines @@
   // Create an initial code generator state.  Destroying the initial state
   // leaves the code generator with a NULL state.
   explicit CodeGenState(CodeGenerator* owner);
 
   // Create a code generator state based on a code generator's current
   // state.  The new state may or may not be inside a typeof, and has its
   // own pair of branch targets.
   CodeGenState(CodeGenerator* owner,
                TypeofState typeof_state,
                JumpTarget* true_target,
-               JumpTarget* false_target);
+               JumpTarget* false_target,
+               JumpTarget* fall_through);
 
   // Destroy a code generator state and restore the owning code generator's
   // previous state.
   ~CodeGenState();
 
   // Accessors for the state.
   TypeofState typeof_state() const { return typeof_state_; }
   JumpTarget* true_target() const { return true_target_; }
   JumpTarget* false_target() const { return false_target_; }
+  JumpTarget* fall_through() const { return fall_through_; }
 
  private:
   // The owning code generator.
   CodeGenerator* owner_;
 
   // A flag indicating whether we are compiling the immediate subexpression
   // of a typeof expression.
   TypeofState typeof_state_;
 
   // A pair of jump targets in case the expression has a control-flow
   // effect.
   JumpTarget* true_target_;
   JumpTarget* false_target_;
 
+  JumpTarget* fall_through_;
+
   // The previous state of the owning code generator, restored when
   // this state is destroyed.
   CodeGenState* previous_;
 };
 
 
 
 
 // -------------------------------------------------------------------------
 // CodeGenerator
@@ skipping 52 matching lines @@
   Scope* scope() const { return scope_; }
 
   void ProcessDeferred();
 
   bool is_eval() { return is_eval_; }
 
   // State
   TypeofState typeof_state() const { return state_->typeof_state(); }
   JumpTarget* true_target() const  { return state_->true_target(); }
   JumpTarget* false_target() const  { return state_->false_target(); }
+  JumpTarget* fall_through() const { return state_->fall_through(); }
 
   // Track loop nesting level.
   int loop_nesting() const { return loop_nesting_; }
   void IncrementLoopNesting() { loop_nesting_++; }
   void DecrementLoopNesting() { loop_nesting_--; }
 
 
   // Node visitors.
   void VisitStatements(ZoneList<Statement*>* statements);
 
@@ skipping 50 matching lines @@
 
   // Expressions
   Operand GlobalObject() const {
     return ContextOperand(esi, Context::GLOBAL_INDEX);
   }
 
   void LoadCondition(Expression* x,
                      TypeofState typeof_state,
                      JumpTarget* true_target,
                      JumpTarget* false_target,
+                     JumpTarget* fall_through,
                      bool force_control);
   void Load(Expression* x, TypeofState typeof_state = NOT_INSIDE_TYPEOF);
   void LoadGlobal();
   void LoadGlobalReceiver();
 
   // Generate code to push the value of an expression on top of the frame
   // and then spill the frame fully to memory.  This function is used
   // temporarily while the code generator is being transformed.
   void LoadAndSpill(Expression* expression,
                     TypeofState typeof_state = NOT_INSIDE_TYPEOF) {
     ASSERT(in_spilled_code());
     set_in_spilled_code(false);
     Load(expression, typeof_state);
     frame_->SpillAll();
     set_in_spilled_code(true);
   }
 
   // Call LoadCondition and then spill the virtual frame unless control flow
   // cannot reach the end of the expression (ie, by emitting only
   // unconditional jumps to the control targets).
   void LoadConditionAndSpill(Expression* expression,
                              TypeofState typeof_state,
                              JumpTarget* true_target,
                              JumpTarget* false_target,
-                             bool force_cc) {
+                             JumpTarget* fall_through,
+                             bool force_control) {
     ASSERT(in_spilled_code());
     set_in_spilled_code(false);
     LoadCondition(expression, typeof_state, true_target, false_target,
-                  force_cc);
+                  fall_through, force_control);
     if (frame_ != NULL) {
       frame_->SpillAll();
     }
     set_in_spilled_code(true);
   }
 
   // Read a value from a slot and leave it on top of the expression stack.
   void LoadFromSlot(Slot* slot, TypeofState typeof_state);
 
   // Store the value on top of the expression stack into a slot, leaving the
   // value in place.
   void StoreToSlot(Slot* slot, InitState init_state);
 
   // 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);
 
-  void ToBoolean(JumpTarget* true_target, JumpTarget* false_target);
+  // Emit a branch to one of the true or false targets, and bind the
+  // other target.  The fall-through target is either the true or
+  // false target, and is the one that will be bound.  Because this
+  // binds the fall-through target, it should be emitted as the last
+  // thing when visiting an expression.
+  static void Branch(Condition cc,
+                     JumpTarget* true_target,
+                     JumpTarget* false_target,
+                     JumpTarget* fall_through);
+
+  // Branch based on the true and false targets and preferred
+  // fall-through in the code generator's state.
+  void Branch(Condition cc) {
+    Branch(cc, true_target(), false_target(), fall_through());
+  }
+
+  void ToBoolean(JumpTarget* true_target,
+                 JumpTarget* false_target,
+                 JumpTarget* fall_through);
 
   void GenericBinaryOperation(Token::Value op,
       StaticType* type,
       const OverwriteMode overwrite_mode = NO_OVERWRITE);
 
   void Comparison(Condition cc,
                   bool strict,
                   JumpTarget* true_target,
-                  JumpTarget* false_target);
+                  JumpTarget* false_target,
+                  JumpTarget* fall_through);
 
   // Inline small integer literals. To prevent long attacker-controlled byte
   // sequences, we only inline small Smis.
   static const int kMaxSmiInlinedBits = 16;
   bool IsInlineSmi(Literal* literal);
-  void SmiComparison(Condition cc,  Handle<Object> value, bool strict = false);
+  void SmiComparison(Condition cc,  Handle<Object> value, bool strict);
   void SmiOperation(Token::Value op,
                     StaticType* type,
                     Handle<Object> value,
                     bool reversed,
                     OverwriteMode overwrite_mode);
 
   void CallWithArguments(ZoneList<Expression*>* arguments, int position);
 
   void CheckStack();
   void CleanStack(int num_bytes);
@@ skipping 143 matching lines @@
   cgen_->set_in_spilled_code(false);
   GetValue(typeof_state);
   cgen_->frame()->SpillAll();
   cgen_->set_in_spilled_code(true);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_CODEGEN_IA32_H_