Fix issue 9744

runtime/vm/debugger.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/debugger.h"
 
 #include "include/dart_api.h"
 
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
@@ skipping 244 matching lines @@
 intptr_t ActivationFrame::TokenPos() {
   if (token_pos_ < 0) {
     GetPcDescriptors();
     for (int i = 0; i < pc_desc_.Length(); i++) {
       if (pc_desc_.PC(i) == pc_) {
         pc_desc_index_ = i;
         token_pos_ = pc_desc_.TokenPos(i);
         break;
       }
     }
-    ASSERT(token_pos_ >= 0);
   }
   return token_pos_;
 }
 
 
 intptr_t ActivationFrame::PcDescIndex() {
   if (pc_desc_index_ < 0) {
-    TokenPos();
-    ASSERT(pc_desc_index_ >= 0);
+    TokenPos();  // Sets pc_desc_index_ as a side effect.
   }
   return pc_desc_index_;
 }
 
 
 intptr_t ActivationFrame::TryIndex() {
   intptr_t desc_index = PcDescIndex();
-  return pc_desc_.TryIndex(desc_index);
+  if (desc_index < 0) {
+    return -1;
+  } else {
+    return pc_desc_.TryIndex(desc_index);
+  }
 }
 
 
 intptr_t ActivationFrame::LineNumber() {
   // Compute line number lazily since it causes scanning of the script.
-  if (line_number_ < 0) {
+  if ((line_number_ < 0) && (TokenPos() >= 0)) {
     const Script& script = Script::Handle(SourceScript());
     intptr_t ignore_column;
     script.GetTokenLocation(TokenPos(), &line_number_, &ignore_column);
   }
   return line_number_;
 }
 
 
 void ActivationFrame::GetVarDescriptors() {
   if (var_descriptors_.IsNull()) {
     var_descriptors_ = code().var_descriptors();
     ASSERT(!var_descriptors_.IsNull());
   }
 }
 
 
 // Calculate the context level at the current token index of the frame.
 intptr_t ActivationFrame::ContextLevel() {
   if (context_level_ < 0 && !ctx_.IsNull()) {
     ASSERT(!code_.is_optimized());
     context_level_ = 0;
     intptr_t pc_desc_idx = PcDescIndex();
+    // TODO(hausner): What to do if there is no descriptor entry
+    // for the code position of the frame? For now say we are at context
+    // level 0.
+    if (pc_desc_idx < 0) {
+      return context_level_;
+    }
     ASSERT(!pc_desc_.IsNull());
     if (pc_desc_.DescriptorKind(pc_desc_idx) == PcDescriptors::kReturn) {
       // Special case: the context chain has already been deallocated.
       // The context level is 0.
       return context_level_;
     }
     intptr_t innermost_begin_pos = 0;
     intptr_t activation_token_pos = TokenPos();
+    ASSERT(activation_token_pos >= 0);
     GetVarDescriptors();
     intptr_t var_desc_len = var_descriptors_.Length();
     for (int cur_idx = 0; cur_idx < var_desc_len; cur_idx++) {
       RawLocalVarDescriptors::VarInfo var_info;
       var_descriptors_.GetInfo(cur_idx, &var_info);
       if ((var_info.kind == RawLocalVarDescriptors::kContextLevel) &&
           (var_info.begin_pos <= activation_token_pos) &&
           (activation_token_pos < var_info.end_pos)) {
         // This var_descriptors_ entry is a context scope which is in scope
         // of the current token position. Now check whether it is shadowing
@@ skipping 70 matching lines @@
 
   // We don't trust variable descriptors in optimized code.
   // Rather than potentially displaying incorrect values, we
   // pretend that there are no variables in the frame.
   // We should be more clever about this in the future.
   if (code().is_optimized()) {
     vars_initialized_ = true;
     return;
   }
 
+  intptr_t activation_token_pos = TokenPos();
+  if (activation_token_pos < 0) {
+    // We don't have a token position for this frame, so can't determine
+    // which variables are visible.
+    vars_initialized_ = true;
+    return;
+  }
+
   GrowableArray<String*> var_names(8);
-  intptr_t activation_token_pos = TokenPos();
   intptr_t var_desc_len = var_descriptors_.Length();
   for (int cur_idx = 0; cur_idx < var_desc_len; cur_idx++) {
     ASSERT(var_names.length() == desc_indices_.length());
     RawLocalVarDescriptors::VarInfo var_info;
     var_descriptors_.GetInfo(cur_idx, &var_info);
     if ((var_info.kind != RawLocalVarDescriptors::kStackVar) &&
         (var_info.kind != RawLocalVarDescriptors::kContextVar)) {
       continue;
     }
     if ((var_info.begin_pos <= activation_token_pos) &&
@@ skipping 564 matching lines @@
   // We attempt to find the PC descriptor that is closest to the
   // beginning of the token range, in terms of native code address. If we
   // don't find a PC descriptor within the given range, we pick the
   // nearest one to the beginning of the range, in terms of token position.
   intptr_t best_fit_index = -1;
   intptr_t best_fit = INT_MAX;
   uword lowest_pc = kUwordMax;
   intptr_t lowest_pc_index = -1;
   for (int i = 0; i < desc.Length(); i++) {
     intptr_t desc_token_pos = desc.TokenPos(i);
+    ASSERT(desc_token_pos >= 0);
     if (desc_token_pos < first_token_pos) {
       continue;
     }
     PcDescriptors::Kind kind = desc.DescriptorKind(i);
     if ((kind == PcDescriptors::kIcCall) ||
         (kind == PcDescriptors::kFuncCall) ||
         (kind == PcDescriptors::kReturn)) {
       if ((desc_token_pos - first_token_pos) < best_fit) {
         best_fit = desc_token_pos - first_token_pos;
         ASSERT(best_fit >= 0);
@@ skipping 736 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart