Fix finally clause inlining for forward jumps

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 #include "vm/flags.h"
 
 #ifndef DART_PRECOMPILED_RUNTIME
 
 #include "lib/invocation_mirror.h"
@@ skipping 347 matching lines @@
   TryStack* outer_try() const { return outer_try_; }
   Block* try_block() const { return try_block_; }
   intptr_t try_index() const { return try_index_; }
   bool inside_catch() const { return inside_catch_; }
   void enter_catch() { inside_catch_ = true; }
   bool inside_finally() const { return inside_finally_; }
   void enter_finally() { inside_finally_ = true; }
   void exit_finally() { inside_finally_ = false; }
 
   void AddNodeForFinallyInlining(AstNode* node);
+  void RemoveJumpToLabel(SourceLabel *label);
   AstNode* GetNodeToInlineFinally(int index) {
     if (0 <= index && index < inlined_finally_nodes_.length()) {
       return inlined_finally_nodes_[index];
     }
     return NULL;
   }
 
  private:
   Block* try_block_;
   GrowableArray<AstNode*> inlined_finally_nodes_;
   TryStack* outer_try_;
   const intptr_t try_index_;
   bool inside_catch_;  // True when parsing a catch clause of this try.
   bool inside_finally_;  // True when parsing a finally clause of an inner try
                          // of this try.
 
   DISALLOW_COPY_AND_ASSIGN(TryStack);
 };
 
 
 void Parser::TryStack::AddNodeForFinallyInlining(AstNode* node) {
   inlined_finally_nodes_.Add(node);
 }
 
 
+void Parser::TryStack::RemoveJumpToLabel(SourceLabel *label) {
+  int i = 0;
+  while (i < inlined_finally_nodes_.length()) {
+    if (inlined_finally_nodes_[i]->IsJumpNode()) {
+      JumpNode* jump = inlined_finally_nodes_[i]->AsJumpNode();
+      if (jump->label() == label) {
+        for (int j = i + 1; j < inlined_finally_nodes_.length(); j++) {
+          inlined_finally_nodes_[i] = inlined_finally_nodes_[j];

[regis, 2016/06/02 01:13:25]

Did you mean j-1 instead of i, which is not incremented?

[hausner, 2016/06/02 15:38:51]

Ahem, yes. Good catch, thank you!

+        }
+        inlined_finally_nodes_.RemoveLast();
+        continue;
+      }
+    }
+    i++;
+  }
+}
+
+
 // For parsing a compilation unit.
 Parser::Parser(const Script& script,
                const Library& library,
                TokenPosition token_pos)
     : thread_(Thread::Current()),
       isolate_(thread()->isolate()),
       script_(Script::Handle(zone(), script.raw())),
       tokens_iterator_(zone(),
                        TokenStream::Handle(zone(), script.tokens()),
                        token_pos),
@@ skipping 8031 matching lines @@
       case_label = current_block_->scope->LocalLookupLabel(*label_name);
       if (case_label == NULL) {
         // Label does not exist yet. Add it to scope of switch statement.
         case_label = new(Z) SourceLabel(
             label_pos, *label_name, SourceLabel::kCase);
         current_block_->scope->AddLabel(case_label);
       } else if (case_label->kind() == SourceLabel::kForward) {
         // We have seen a 'continue' with this label name. Resolve
         // the forward reference.
         case_label->ResolveForwardReference();
+        RemoveNodesForFinallyInlining(case_label);
       } else {
         ReportError(label_pos, "label '%s' already exists in scope",
                     label_name->ToCString());
       }
       ASSERT(case_label->kind() == SourceLabel::kCase);
     }
     if (CurrentToken() == Token::kCASE ||
         CurrentToken() == Token::kDEFAULT) {
       if (default_seen) {
         ReportError("no case clauses allowed after default clause");
@@ skipping 888 matching lines @@
     // For continue and break node check if the target label is in scope.
     if (node->IsJumpNode()) {
       SourceLabel* label = node->AsJumpNode()->label();
       ASSERT(label != NULL);
       LocalScope* try_scope = iterator->try_block()->scope;
       // If the label is defined in a scope which is a child (nested scope)
       // of the try scope then we are not breaking out of this try block
       // so we do not need to inline the finally code. Otherwise we need
       // to inline the finally code of this try block and then move on to the
       // next outer try block.
-      if (label->owner()->IsNestedWithin(try_scope)) {
+      // For unresolved forward jumps to switch cases, we don't yet know
+      // to which scope the label will be resolved. Tentatively add the
+      // jump to all nested try statements and remove the outermost ones
+      // when we know the exact jump target. (See
+      // RemoveNodesForFinallyInlining below.)
+      if (!label->IsUnresolved() && label->owner()->IsNestedWithin(try_scope)) {
         break;
       }
     }
     iterator->AddNodeForFinallyInlining(node);
     iterator = iterator->outer_try();
   }
 }
 
 
+void Parser::RemoveNodesForFinallyInlining(SourceLabel* label) {
+  TryStack* iterator = try_stack_;
+  const intptr_t func_level = FunctionLevel();
+  while ((iterator != NULL) &&
+         (iterator->try_block()->scope->function_level() == func_level)) {
+    iterator->RemoveJumpToLabel(label);
+    iterator = iterator->outer_try();
+  }
+}
+
+
 // Add the inlined finally clause to the specified node.
 void Parser::AddFinallyClauseToNode(bool is_async,
                                     AstNode* node,
                                     InlinedFinallyNode* finally_clause) {
   ReturnNode* return_node = node->AsReturnNode();
   if (return_node != NULL) {
     if (FunctionLevel() == 0) {
       parsed_function()->EnsureFinallyReturnTemp(is_async);
     }
     return_node->AddInlinedFinallyNode(finally_clause);
@@ skipping 5202 matching lines @@
     const ArgumentListNode& function_args,
     const LocalVariable* temp_for_last_arg,
     bool is_super_invocation) {
   UNREACHABLE();
   return NULL;
 }
 
 }  // namespace dart
 
 #endif  // DART_PRECOMPILED_RUNTIME