Move catch prediction into frontend.

src/ast/ast-numbering.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ast/ast-numbering.h"
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 
 namespace v8 {
 namespace internal {
 
 class AstNumberingVisitor final : public AstVisitor {
  public:
   AstNumberingVisitor(Isolate* isolate, Zone* zone)
       : AstVisitor(),
         isolate_(isolate),
         zone_(zone),
         next_id_(BailoutId::FirstUsable().ToInt()),
         yield_count_(0),
         properties_(zone),
         slot_cache_(zone),
-        dont_optimize_reason_(kNoReason) {
+        dont_optimize_reason_(kNoReason),
+        catch_predicted_(false) {
     InitializeAstVisitor(isolate);
   }
 
   bool Renumber(FunctionLiteral* node);
 
  private:
 // AST node visitor interface.
 #define DEFINE_VISIT(type) void Visit##type(type* node) override;
   AST_NODE_LIST(DEFINE_VISIT)
 #undef DEFINE_VISIT
@@ skipping 39 matching lines @@
   BailoutReason dont_optimize_reason() const { return dont_optimize_reason_; }
 
   Isolate* isolate_;
   Zone* zone_;
   int next_id_;
   int yield_count_;
   AstProperties properties_;
   // The slot cache allows us to reuse certain feedback vector slots.
   FeedbackVectorSlotCache slot_cache_;
   BailoutReason dont_optimize_reason_;
+  bool catch_predicted_;
 
   DEFINE_AST_VISITOR_SUBCLASS_MEMBERS();
   DISALLOW_COPY_AND_ASSIGN(AstNumberingVisitor);
 };
 
 
 void AstNumberingVisitor::VisitVariableDeclaration(VariableDeclaration* node) {
   IncrementNodeCount();
   VisitVariableProxy(node->proxy());
 }
@@ skipping 197 matching lines @@
   node->set_first_yield_id(yield_count_);
   Visit(node->cond());
   Visit(node->body());
   node->set_yield_count(yield_count_ - node->first_yield_id());
 }
 
 
 void AstNumberingVisitor::VisitTryCatchStatement(TryCatchStatement* node) {
   IncrementNodeCount();
   DisableCrankshaft(kTryCatchStatement);
-  Visit(node->try_block());
+  {
+    const bool old_catch_predicted = catch_predicted_;
+    // If the node's clear_pending_message flag is unset, we assume that the
+    // catch block is a ReThrow and hence predict uncaught (unless caught by
+    // outer handlers).  Otherwise, we predict caught.
+    const bool not_rethrow = node->clear_pending_message();
+    catch_predicted_ = catch_predicted_ || not_rethrow;
+    node->set_catch_predicted(catch_predicted_);
+    Visit(node->try_block());
+    catch_predicted_ = old_catch_predicted;
+  }
   Visit(node->catch_block());
 }
 
 
 void AstNumberingVisitor::VisitTryFinallyStatement(TryFinallyStatement* node) {
   IncrementNodeCount();
   DisableCrankshaft(kTryFinallyStatement);
+  // We can't know whether the finally block will override ("catch") an
+  // exception thrown in the try block, so we just adopt the outer prediction.
+  node->set_catch_predicted(catch_predicted_);
   Visit(node->try_block());
   Visit(node->finally_block());
 }
 
 
 void AstNumberingVisitor::VisitPropertyReference(Property* node) {
   IncrementNodeCount();
   node->set_base_id(ReserveIdRange(Property::num_ids()));
   Visit(node->key());
   Visit(node->obj());
@@ skipping 267 matching lines @@
 }
 
 
 bool AstNumbering::Renumber(Isolate* isolate, Zone* zone,
                             FunctionLiteral* function) {
   AstNumberingVisitor visitor(isolate, zone);
   return visitor.Renumber(function);
 }
 }  // namespace internal
 }  // namespace v8