Improve representation inference for HUnknownOSRValue.

Use corresponding phi from the loop entry as a hint to infer proper representation for HUnkownOSRValue and dependent phis.

R=fschneider@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9704012

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11055 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -2262,7 +2262,15 @@ Representation HPhi::InferredRepresentation() {
   bool int32_occurred = false;
   for (int i = 0; i < OperandCount(); ++i) {
     HValue* value = OperandAt(i);
-    if (value->IsUnknownOSRValue()) continue;
+    if (value->IsUnknownOSRValue()) {
+      HPhi* hint_value = HUnknownOSRValue::cast(value)->incoming_value();
+      if (hint_value != NULL) {
+        Representation hint = hint_value->representation();
+        if (hint.IsDouble()) double_occurred = true;
+        if (hint.IsInteger32()) int32_occurred = true;
+      }
+      continue;
+    }
     if (value->representation().IsDouble()) double_occurred = true;
     if (value->representation().IsInteger32()) int32_occurred = true;
     if (value->representation().IsTagged()) {

src/hydrogen-instructions.h

@@ -3423,13 +3423,27 @@ class HCallStub: public HUnaryCall {
 
 class HUnknownOSRValue: public HTemplateInstruction<0> {
  public:
-  HUnknownOSRValue() { set_representation(Representation::Tagged()); }
+  HUnknownOSRValue()
+      : incoming_value_(NULL) {
+    set_representation(Representation::Tagged());
+  }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::None();
   }
 
+  void set_incoming_value(HPhi* value) {
+    incoming_value_ = value;
+  }
+
+  HPhi* incoming_value() {
+    return incoming_value_;
+  }
+
   DECLARE_CONCRETE_INSTRUCTION(UnknownOSRValue)
+
+ private:
+  HPhi* incoming_value_;
 };
 
 

src/hydrogen.cc

@@ -2520,6 +2520,14 @@ HGraph* HGraphBuilder::CreateGraph() {
   if (FLAG_eliminate_dead_phis) graph()->EliminateUnreachablePhis();
   graph()->CollectPhis();
 
+  if (graph()->has_osr_loop_entry()) {
+    const ZoneList<HPhi*>* phis = graph()->osr_loop_entry()->phis();
+    for (int j = 0; j < phis->length(); j++) {
+      HPhi* phi = phis->at(j);
+      graph()->osr_values()->at(phi->merged_index())->set_incoming_value(phi);
+    }
+  }
+
   HInferRepresentation rep(graph());
   rep.Analyze();
 
@@ -3092,8 +3100,8 @@ bool HGraphBuilder::HasOsrEntryAt(IterationStatement* statement) {
 }
 
 
-void HGraphBuilder::PreProcessOsrEntry(IterationStatement* statement) {
-  if (!HasOsrEntryAt(statement)) return;
+bool HGraphBuilder::PreProcessOsrEntry(IterationStatement* statement) {
+  if (!HasOsrEntryAt(statement)) return false;
 
   HBasicBlock* non_osr_entry = graph()->CreateBasicBlock();
   HBasicBlock* osr_entry = graph()->CreateBasicBlock();
@@ -3108,10 +3116,14 @@ void HGraphBuilder::PreProcessOsrEntry(IterationStatement* statement) {
   int osr_entry_id = statement->OsrEntryId();
   int first_expression_index = environment()->first_expression_index();
   int length = environment()->length();
+  ZoneList<HUnknownOSRValue*>* osr_values =
+      new(zone()) ZoneList<HUnknownOSRValue*>(length);
+
   for (int i = 0; i < first_expression_index; ++i) {
     HUnknownOSRValue* osr_value = new(zone()) HUnknownOSRValue;
     AddInstruction(osr_value);
     environment()->Bind(i, osr_value);
+    osr_values->Add(osr_value);
   }
 
   if (first_expression_index != length) {
@@ -3120,9 +3132,12 @@ void HGraphBuilder::PreProcessOsrEntry(IterationStatement* statement) {
       HUnknownOSRValue* osr_value = new(zone()) HUnknownOSRValue;
       AddInstruction(osr_value);
       environment()->Push(osr_value);
+      osr_values->Add(osr_value);
     }
   }
 
+  graph()->set_osr_values(osr_values);
+
   AddSimulate(osr_entry_id);
   AddInstruction(new(zone()) HOsrEntry(osr_entry_id));
   HContext* context = new(zone()) HContext;
@@ -3131,6 +3146,7 @@ void HGraphBuilder::PreProcessOsrEntry(IterationStatement* statement) {
   current_block()->Goto(loop_predecessor);
   loop_predecessor->SetJoinId(statement->EntryId());
   set_current_block(loop_predecessor);
+  return true;
 }
 
 
@@ -3154,10 +3170,11 @@ void HGraphBuilder::VisitDoWhileStatement(DoWhileStatement* stmt) {
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   ASSERT(current_block() != NULL);
-  PreProcessOsrEntry(stmt);
+  bool osr_entry = PreProcessOsrEntry(stmt);
   HBasicBlock* loop_entry = CreateLoopHeaderBlock();
   current_block()->Goto(loop_entry);
   set_current_block(loop_entry);
+  if (osr_entry) graph()->set_osr_loop_entry(loop_entry);
 
   BreakAndContinueInfo break_info(stmt);
   CHECK_BAILOUT(VisitLoopBody(stmt, loop_entry, &break_info));
@@ -3196,10 +3213,12 @@ void HGraphBuilder::VisitWhileStatement(WhileStatement* stmt) {
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   ASSERT(current_block() != NULL);
-  PreProcessOsrEntry(stmt);
+  bool osr_entry = PreProcessOsrEntry(stmt);
   HBasicBlock* loop_entry = CreateLoopHeaderBlock();
   current_block()->Goto(loop_entry);
   set_current_block(loop_entry);
+  if (osr_entry) graph()->set_osr_loop_entry(loop_entry);
+
 
   // If the condition is constant true, do not generate a branch.
   HBasicBlock* loop_successor = NULL;
@@ -3241,10 +3260,11 @@ void HGraphBuilder::VisitForStatement(ForStatement* stmt) {
     CHECK_ALIVE(Visit(stmt->init()));
   }
   ASSERT(current_block() != NULL);
-  PreProcessOsrEntry(stmt);
+  bool osr_entry = PreProcessOsrEntry(stmt);
   HBasicBlock* loop_entry = CreateLoopHeaderBlock();
   current_block()->Goto(loop_entry);
   set_current_block(loop_entry);
+  if (osr_entry) graph()->set_osr_loop_entry(loop_entry);
 
   HBasicBlock* loop_successor = NULL;
   if (stmt->cond() != NULL) {
@@ -3336,10 +3356,11 @@ void HGraphBuilder::VisitForInStatement(ForInStatement* stmt) {
   HForInCacheArray::cast(array)->set_index_cache(
       HForInCacheArray::cast(index_cache));
 
-  PreProcessOsrEntry(stmt);
+  bool osr_entry = PreProcessOsrEntry(stmt);
   HBasicBlock* loop_entry = CreateLoopHeaderBlock();
   current_block()->Goto(loop_entry);
   set_current_block(loop_entry);
+  if (osr_entry) graph()->set_osr_loop_entry(loop_entry);
 
   HValue* index = environment()->ExpressionStackAt(0);
   HValue* limit = environment()->ExpressionStackAt(1);

src/hydrogen.h

@@ -313,6 +313,26 @@ class HGraph: public ZoneObject {
   void Verify(bool do_full_verify) const;
 #endif
 
+  bool has_osr_loop_entry() {
+    return osr_loop_entry_.is_set();
+  }
+
+  HBasicBlock* osr_loop_entry() {
+    return osr_loop_entry_.get();
+  }
+
+  void set_osr_loop_entry(HBasicBlock* entry) {
+    osr_loop_entry_.set(entry);
+  }
+
+  ZoneList<HUnknownOSRValue*>* osr_values() {
+    return osr_values_.get();
+  }
+
+  void set_osr_values(ZoneList<HUnknownOSRValue*>* values) {
+    osr_values_.set(values);
+  }
+
  private:
   void Postorder(HBasicBlock* block,
                  BitVector* visited,
@@ -353,6 +373,9 @@ class HGraph: public ZoneObject {
   SetOncePointer<HConstant> constant_hole_;
   SetOncePointer<HArgumentsObject> arguments_object_;
 
+  SetOncePointer<HBasicBlock> osr_loop_entry_;
+  SetOncePointer<ZoneList<HUnknownOSRValue*> > osr_values_;
+
   DISALLOW_COPY_AND_ASSIGN(HGraph);
 };
 
@@ -886,7 +909,7 @@ class HGraphBuilder: public AstVisitor {
   void VisitLogicalExpression(BinaryOperation* expr);
   void VisitArithmeticExpression(BinaryOperation* expr);
 
-  void PreProcessOsrEntry(IterationStatement* statement);
+  bool PreProcessOsrEntry(IterationStatement* statement);
   // True iff. we are compiling for OSR and the statement is the entry.
   bool HasOsrEntryAt(IterationStatement* statement);
   void VisitLoopBody(IterationStatement* stmt,