Cleaned up nil comparisons in Hydrogen.

src/hydrogen.cc

 // Copyright 2013 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 1727 matching lines @@
   return object;
 }
 
 
 void HGraphBuilder::BuildCompareNil(
     HValue* value,
     Handle<Type> type,
     int position,
     HIfContinuation* continuation) {
   IfBuilder if_nil(this, position);
-  bool needs_or = false;
+  bool some_case_handled = false;
+  bool some_case_missing = false;
+
   if (type->Maybe(Type::Null())) {
-    if (needs_or) if_nil.Or();
+    if (some_case_handled) if_nil.Or();
     if_nil.If<HCompareObjectEqAndBranch>(value, graph()->GetConstantNull());
-    needs_or = true;
+    some_case_handled = true;
+  } else {
+    some_case_missing = true;
   }
+
   if (type->Maybe(Type::Undefined())) {
-    if (needs_or) if_nil.Or();
+    if (some_case_handled) if_nil.Or();
     if_nil.If<HCompareObjectEqAndBranch>(value,
                                          graph()->GetConstantUndefined());
-    needs_or = true;
+    some_case_handled = true;
+  } else {
+    some_case_missing = true;
   }
+
   if (type->Maybe(Type::Undetectable())) {
-    if (needs_or) if_nil.Or();
+    if (some_case_handled) if_nil.Or();
     if_nil.If<HIsUndetectableAndBranch>(value);
+    some_case_handled = true;
   } else {
+    some_case_missing = true;
+  }
+
+  if (some_case_missing) {
     if_nil.Then();
     if_nil.Else();
     if (type->NumClasses() == 1) {
       BuildCheckHeapObject(value);
       // For ICs, the map checked below is a sentinel map that gets replaced by
       // the monomorphic map when the code is used as a template to generate a
       // new IC. For optimized functions, there is no sentinel map, the map
       // emitted below is the actual monomorphic map.
       BuildCheckMap(value, type->Classes().Current());
     } else {
@@ skipping 6428 matching lines @@
 
 void HOptimizedGraphBuilder::HandleLiteralCompareNil(CompareOperation* expr,
                                                      Expression* sub_expr,
                                                      NilValue nil) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   ASSERT(expr->op() == Token::EQ || expr->op() == Token::EQ_STRICT);
   CHECK_ALIVE(VisitForValue(sub_expr));
   HValue* value = Pop();
-  HIfContinuation continuation;
   if (expr->op() == Token::EQ_STRICT) {
-    IfBuilder if_nil(this);
-    if_nil.If<HCompareObjectEqAndBranch>(
-        value, (nil == kNullValue) ? graph()->GetConstantNull()
-                                   : graph()->GetConstantUndefined());
-    if_nil.Then();
-    if_nil.Else();
-    if_nil.CaptureContinuation(&continuation);
+    HConstant* nil_constant = nil == kNullValue
+        ? graph()->GetConstantNull()
+        : graph()->GetConstantUndefined();
+    HCompareObjectEqAndBranch* instr =
+        New<HCompareObjectEqAndBranch>(value, nil_constant);
+    instr->set_position(expr->position());
+    return ast_context()->ReturnControl(instr, expr->id());
+  } else {
+    ASSERT_EQ(Token::EQ, expr->op());
+    Handle<Type> type = expr->combined_type()->Is(Type::None())
+        ? handle(Type::Any(), isolate_)
+        : expr->combined_type();
+    HIfContinuation continuation;
+    BuildCompareNil(value, type, expr->position(), &continuation);
     return ast_context()->ReturnContinuation(&continuation, expr->id());
   }
-  Handle<Type> type = expr->combined_type()->Is(Type::None())
-      ? handle(Type::Any(), isolate_) : expr->combined_type();
-  BuildCompareNil(value, type, expr->position(), &continuation);
-  return ast_context()->ReturnContinuation(&continuation, expr->id());
 }
 
 
 HInstruction* HOptimizedGraphBuilder::BuildThisFunction() {
   // If we share optimized code between different closures, the
   // this-function is not a constant, except inside an inlined body.
   if (function_state()->outer() != NULL) {
       return New<HConstant>(
           function_state()->compilation_info()->closure());
   } else {
@@ skipping 1613 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal