Unify the handling of comparinsons against null and undefined.

src/hydrogen.cc

 // Copyright 2011 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 5650 matching lines @@
 
 Representation HGraphBuilder::ToRepresentation(TypeInfo info) {
   if (info.IsSmi()) return Representation::Integer32();
   if (info.IsInteger32()) return Representation::Integer32();
   if (info.IsDouble()) return Representation::Double();
   if (info.IsNumber()) return Representation::Double();
   return Representation::Tagged();
 }
 
 
-void HGraphBuilder::HandleLiteralCompareTypeof(CompareOperation* compare_expr,
-                                               Expression* expr,
+void HGraphBuilder::HandleLiteralCompareTypeof(CompareOperation* expr,
+                                               Expression* sub_expr,
                                                Handle<String> check) {
-  CHECK_ALIVE(VisitForTypeOf(expr));
-  HValue* expr_value = Pop();
-  HTypeofIsAndBranch* instr = new(zone()) HTypeofIsAndBranch(expr_value, check);
-  instr->set_position(compare_expr->position());
-  return ast_context()->ReturnControl(instr, compare_expr->id());
+  CHECK_ALIVE(VisitForTypeOf(sub_expr));
+  HValue* value = Pop();
+  HTypeofIsAndBranch* instr = new(zone()) HTypeofIsAndBranch(value, check);
+  instr->set_position(expr->position());
+  return ast_context()->ReturnControl(instr, expr->id());
 }
 
 
-void HGraphBuilder::HandleLiteralCompareUndefined(
-    CompareOperation* compare_expr, Expression* expr) {
-  CHECK_ALIVE(VisitForValue(expr));
-  HValue* lhs = Pop();
-  HValue* rhs = graph()->GetConstantUndefined();
-  HCompareObjectEqAndBranch* instr =
-      new(zone()) HCompareObjectEqAndBranch(lhs, rhs);
-  instr->set_position(compare_expr->position());
-  return ast_context()->ReturnControl(instr, compare_expr->id());
+bool HGraphBuilder::TryLiteralCompare(CompareOperation* expr) {
+  Expression *sub_expr;
+  Handle<String> check;
+  if (expr->IsLiteralCompareTypeof(&sub_expr, &check)) {
+    HandleLiteralCompareTypeof(expr, sub_expr, check);
+    return true;
+  }
+
+  if (expr->IsLiteralCompareUndefined(&sub_expr)) {
+    HandleLiteralCompareNil(expr, sub_expr, kUndefinedValue);
+    return true;
+  }
+
+  if (expr->IsLiteralCompareNull(&sub_expr)) {
+    HandleLiteralCompareNil(expr, sub_expr, kNullValue);
+    return true;
+  }
+
+  return false;
 }
 
 
 void HGraphBuilder::VisitCompareOperation(CompareOperation* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   if (IsClassOfTest(expr)) {
     CallRuntime* call = expr->left()->AsCallRuntime();
     ASSERT(call->arguments()->length() == 1);
     CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
     HValue* value = Pop();
     Literal* literal = expr->right()->AsLiteral();
     Handle<String> rhs = Handle<String>::cast(literal->handle());
     HClassOfTestAndBranch* instr =
         new(zone()) HClassOfTestAndBranch(value, rhs);
     instr->set_position(expr->position());
     return ast_context()->ReturnControl(instr, expr->id());
   }
 
   // Check for special cases that compare against literals.
-  Expression *sub_expr;
-  Handle<String> check;
-  if (expr->IsLiteralCompareTypeof(&sub_expr, &check)) {
-    HandleLiteralCompareTypeof(expr, sub_expr, check);
-    return;
-  }
-
-  if (expr->IsLiteralCompareUndefined(&sub_expr)) {
-    HandleLiteralCompareUndefined(expr, sub_expr);
-    return;
-  }
-
-  if (expr->IsLiteralCompareNull(&sub_expr)) {
-    HandleLiteralCompareNull(expr, sub_expr);
-    return;
-  }
+  if (TryLiteralCompare(expr)) return;
 
   TypeInfo type_info = oracle()->CompareType(expr);
   // Check if this expression was ever executed according to type feedback.
   if (type_info.IsUninitialized()) {
     AddInstruction(new(zone()) HSoftDeoptimize);
     current_block()->MarkAsDeoptimizing();
     type_info = TypeInfo::Unknown();
   }
 
   CHECK_ALIVE(VisitForValue(expr->left()));
@@ skipping 84 matching lines @@
       HCompareIDAndBranch* result =
           new(zone()) HCompareIDAndBranch(left, right, op);
       result->set_position(expr->position());
       result->SetInputRepresentation(r);
       return ast_context()->ReturnControl(result, expr->id());
     }
   }
 }
 
 
-void HGraphBuilder::HandleLiteralCompareNull(CompareOperation* compare_expr,
-                                             Expression* expr) {
+void HGraphBuilder::HandleLiteralCompareNil(CompareOperation* expr,
+                                            Expression* sub_expr,
+                                            NilValue nil) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
-  CHECK_ALIVE(VisitForValue(expr));
+  CHECK_ALIVE(VisitForValue(sub_expr));
   HValue* value = Pop();
-  bool is_strict = compare_expr->op() == Token::EQ_STRICT;
-  HIsNullAndBranch* instr = new(zone()) HIsNullAndBranch(value, is_strict);
-  return ast_context()->ReturnControl(instr, compare_expr->id());
+  EqualityKind kind =
+      expr->op() == Token::EQ_STRICT ? kStrictEquality : kNonStrictEquality;
+  HIsNilAndBranch* instr = new(zone()) HIsNilAndBranch(value, kind, nil);
+  instr->set_position(expr->position());
+  return ast_context()->ReturnControl(instr, expr->id());
 }
 
 
 void HGraphBuilder::VisitThisFunction(ThisFunction* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   HThisFunction* self = new(zone()) HThisFunction;
   return ast_context()->ReturnInstruction(self, expr->id());
 }
@@ skipping 969 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal