Improve and simplify removal of unreachable code

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index ba1de7aa2258a308927c90f937d5d1e6beccd841..0206584404ff477b1bb7c28d9c6b7b0ab9c539e2 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -93,6 +93,7 @@ HBasicBlock::HBasicBlock(HGraph* graph)
       deleted_phis_(4, graph->zone()),
       parent_loop_header_(NULL),
       inlined_entry_block_(NULL),
+      is_reachable_(true),
       is_inline_return_target_(false),
       is_deoptimizing_(false),
       dominates_loop_successors_(false),
@@ -104,6 +105,20 @@ Isolate* HBasicBlock::isolate() const {
 }
 
 
+void HBasicBlock::MarkUnreachable() {
+  if (!is_osr_entry()) {
+    is_reachable_ = false;
+    graph()->MarkHasUnreachableCode();
+  }
+}
+
+
+void HBasicBlock::MarkAsDeoptimizing() {
+  is_deoptimizing_ = true;
+  graph()->MarkHasUnreachableCode();
+}
+
+
 void HBasicBlock::AttachLoopInformation() {
   ASSERT(!IsLoopHeader());
   loop_information_ = new(zone()) HLoopInformation(this, zone());
@@ -2066,6 +2081,7 @@ HGraph::HGraph(CompilationInfo* info)
       osr_(NULL),
       info_(info),
       zone_(info->zone()),
+      has_unreachable_code_(false),
       is_recursive_(false),
       use_optimistic_licm_(false),
       has_soft_deoptimize_(false),
@@ -2729,16 +2745,6 @@ void TestContext::BuildBranch(HValue* value) {
   if (value != NULL && value->CheckFlag(HValue::kIsArguments)) {
     builder->Bailout(kArgumentsObjectValueInATestContext);
   }
-  if (value->IsConstant()) {
-    HConstant* constant_value = HConstant::cast(value);
-    if (constant_value->BooleanValue()) {
-      builder->current_block()->Goto(if_true(), builder->function_state());
-    } else {
-      builder->current_block()->Goto(if_false(), builder->function_state());
-    }
-    builder->set_current_block(NULL);
-    return;
-  }
   HBasicBlock* empty_true = builder->graph()->CreateBasicBlock();
   HBasicBlock* empty_false = builder->graph()->CreateBasicBlock();
   ToBooleanStub::Types expected(condition()->to_boolean_types());
@@ -8017,9 +8023,16 @@ void HOptimizedGraphBuilder::HandleLiteralCompareTypeof(CompareOperation* expr,
 static bool IsLiteralCompareBool(HValue* left,
                                  Token::Value op,
                                  HValue* right) {
-  return op == Token::EQ_STRICT &&
-      ((left->IsConstant() && HConstant::cast(left)->handle()->IsBoolean()) ||
-       (right->IsConstant() && HConstant::cast(right)->handle()->IsBoolean()));
+  if (op != Token::EQ_STRICT) return false;
+  if (left->IsConstant() && HConstant::cast(left)->handle()->IsBoolean()) {
+    return !right->IsConstant() ||

[Michael Starzinger, 2013/08/16 15:02:20]

nit: Should fit into one line.

[danno, 2013/10/01 10:43:18]

Done.

+        !HConstant::cast(right)->handle()->IsSmi();
+  }
+  if (right->IsConstant() && HConstant::cast(right)->handle()->IsBoolean()) {
+    return !left->IsConstant() ||

[Michael Starzinger, 2013/08/16 15:02:20]

nit: Should fit into one line.

[danno, 2013/10/01 10:43:18]

Done.

+        !HConstant::cast(left)->handle()->IsSmi();
+  }
+  return false;
 }