Cleanup the handling of control flow in the toplevel code generator....

src/fast-codegen.cc

 // Copyright 2009 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 208 matching lines @@
       expected = (expr->op() == Token::OR)
           ? Expression::kTest
           : Expression::kTestValue;
       break;
   }
   ASSERT_EQ(expected, expr->left()->context());
   ASSERT_EQ(expr->context(), expr->right()->context());
 #endif
 
   Label eval_right, done;
-  Label* saved_true = true_label_;
-  Label* saved_false = false_label_;
 
-  // Set up the appropriate context for the left subexpression based on the
-  // operation and our own context.
+  // Set up the appropriate context for the left subexpression based
+  // on the operation and our own context.  Initially assume we can
+  // inherit both true and false labels from our context.
+  Label* if_true = true_label_;
+  Label* if_false = false_label_;
   if (expr->op() == Token::OR) {
-    // If there is no usable true label in the OR expression's context, use
-    // the end of this expression, otherwise inherit the same true label.
+    // If we are not in some kind of a test context, we did not inherit a
+    // true label from our context.  Use the end of the expression.
     if (expr->context() == Expression::kEffect ||
         expr->context() == Expression::kValue) {
-      true_label_ = &done;
+      if_true = &done;
     }
-    // The false label is the label of the second subexpression.
-    false_label_ = &eval_right;
+    // The false label is the label of the right subexpression.
+    if_false = &eval_right;
   } else {
     ASSERT_EQ(Token::AND, expr->op());
-    // The true label is the label of the second subexpression.
-    true_label_ = &eval_right;
-    // If there is no usable false label in the AND expression's context,
-    // use the end of the expression, otherwise inherit the same false
-    // label.
+    // The true label is the label of the right subexpression.
+    if_true = &eval_right;
+    // If we are not in some kind of a test context, we did not inherit a
+    // false label from our context.  Use the end of the expression.
     if (expr->context() == Expression::kEffect ||
         expr->context() == Expression::kValue) {
-      false_label_ = &done;
+      if_false = &done;
     }
   }
-
-  Visit(expr->left());
-  true_label_ = saved_true;
-  false_label_ = saved_false;
+  VisitForControl(expr->left(), if_true, if_false);
 
   __ bind(&eval_right);
   Visit(expr->right());
 
   __ bind(&done);
 }
 
 
 void FastCodeGenerator::VisitBlock(Block* stmt) {
   Comment cmnt(masm_, "[ Block");
@@ skipping 12 matching lines @@
 
 
 void FastCodeGenerator::VisitEmptyStatement(EmptyStatement* stmt) {
   Comment cmnt(masm_, "[ EmptyStatement");
   SetStatementPosition(stmt);
 }
 
 
 void FastCodeGenerator::VisitIfStatement(IfStatement* stmt) {
   Comment cmnt(masm_, "[ IfStatement");
-  // Expressions cannot recursively enter statements, there are no labels in
-  // the state.
-  ASSERT_EQ(NULL, true_label_);
-  ASSERT_EQ(NULL, false_label_);
   Label then_part, else_part, done;
 
   // Do not worry about optimizing for empty then or else bodies.
-  true_label_ = &then_part;
-  false_label_ = &else_part;
-  ASSERT(stmt->condition()->context() == Expression::kTest);
-  Visit(stmt->condition());
-  true_label_ = NULL;
-  false_label_ = NULL;
+  VisitForControl(stmt->condition(), &then_part, &else_part);
 
   __ bind(&then_part);
   Visit(stmt->then_statement());
   __ jmp(&done);
 
   __ bind(&else_part);
   Visit(stmt->else_statement());
 
   __ bind(&done);
 }
@@ skipping 97 matching lines @@
   Iteration loop_statement(this, stmt);
   increment_loop_depth();
 
   __ bind(&body);
   Visit(stmt->body());
 
   // Check stack before looping.
   __ StackLimitCheck(&stack_limit_hit);
   __ bind(&stack_check_success);
 
-  // We are not in an expression context because we have been compiling
-  // statements.  Set up a test expression context for the condition.
   __ bind(loop_statement.continue_target());
-  ASSERT_EQ(NULL, true_label_);
-  ASSERT_EQ(NULL, false_label_);
-  true_label_ = &body;
-  false_label_ = loop_statement.break_target();
-  ASSERT(stmt->cond()->context() == Expression::kTest);
-  Visit(stmt->cond());
-  true_label_ = NULL;
-  false_label_ = NULL;
+  VisitForControl(stmt->cond(), &body, loop_statement.break_target());
 
   __ bind(&stack_limit_hit);
   StackCheckStub stack_stub;
   __ CallStub(&stack_stub);
   __ jmp(&stack_check_success);
 
   __ bind(loop_statement.break_target());
 
   decrement_loop_depth();
 }
@@ skipping 10 matching lines @@
   __ jmp(loop_statement.continue_target());
 
   __ bind(&body);
   Visit(stmt->body());
 
   __ bind(loop_statement.continue_target());
   // Check stack before looping.
   __ StackLimitCheck(&stack_limit_hit);
   __ bind(&stack_check_success);
 
-  // We are not in an expression context because we have been compiling
-  // statements.  Set up a test expression context for the condition.
-  ASSERT_EQ(NULL, true_label_);
-  ASSERT_EQ(NULL, false_label_);
-  true_label_ = &body;
-  false_label_ = loop_statement.break_target();
-  ASSERT(stmt->cond()->context() == Expression::kTest);
-  Visit(stmt->cond());
-  true_label_ = NULL;
-  false_label_ = NULL;
+  VisitForControl(stmt->cond(), &body, loop_statement.break_target());
 
   __ bind(&stack_limit_hit);
   StackCheckStub stack_stub;
   __ CallStub(&stack_stub);
   __ jmp(&stack_check_success);
 
   __ bind(loop_statement.break_target());
   decrement_loop_depth();
 }
 
@@ skipping 133 matching lines @@
 
 
 void FastCodeGenerator::VisitConditional(Conditional* expr) {
   Comment cmnt(masm_, "[ Conditional");
   ASSERT_EQ(Expression::kTest, expr->condition()->context());
   ASSERT_EQ(expr->context(), expr->then_expression()->context());
   ASSERT_EQ(expr->context(), expr->else_expression()->context());
 
 
   Label true_case, false_case, done;
-  Label* saved_true = true_label_;
-  Label* saved_false = false_label_;
-
-  true_label_ = &true_case;
-  false_label_ = &false_case;
-  Visit(expr->condition());
-  true_label_ = saved_true;
-  false_label_ = saved_false;
+  VisitForControl(expr->condition(), &true_case, &false_case);
 
   __ bind(&true_case);
   Visit(expr->then_expression());
   // If control flow falls through Visit, jump to done.
   if (expr->context() == Expression::kEffect ||
       expr->context() == Expression::kValue) {
     __ jmp(&done);
   }
 
   __ bind(&false_case);
@@ skipping 139 matching lines @@
   __ Drop(stack_depth);
   __ PopTryHandler();
   return 0;
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal