Fix unaligned accesses in back_edge tables.

src/deoptimizer.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2349 matching lines @@
                                      Code* replacement_code) {
   // Iterate over the back edge table and patch every interrupt
   // call to an unconditional call to the replacement code.
   ASSERT(unoptimized_code->kind() == Code::FUNCTION);
   int loop_nesting_level = unoptimized_code->allow_osr_at_loop_nesting_level();
   Address back_edge_cursor = unoptimized_code->instruction_start() +
       unoptimized_code->back_edge_table_offset();
   uint32_t table_length = Memory::uint32_at(back_edge_cursor);
   back_edge_cursor += kIntSize;
   for (uint32_t i = 0; i < table_length; ++i) {
-    uint8_t loop_depth = Memory::uint8_at(back_edge_cursor + 2 * kIntSize);
-    if (loop_depth == loop_nesting_level) {
+    uint32_t loop_depth = Memory::uint32_at(back_edge_cursor + 2 * kIntSize);
+    if (static_cast<int>(loop_depth) == loop_nesting_level) {
       // Loop back edge has the loop depth that we want to patch.
       uint32_t pc_offset = Memory::uint32_at(back_edge_cursor + kIntSize);
       Address pc_after = unoptimized_code->instruction_start() + pc_offset;
       PatchInterruptCodeAt(unoptimized_code,
                            pc_after,
                            interrupt_code,
                            replacement_code);
     }
     back_edge_cursor += FullCodeGenerator::kBackEdgeEntrySize;
   }
@@ skipping 10 matching lines @@
                                       Code* replacement_code) {
   // Iterate over the back edge table and revert the patched interrupt calls.
   ASSERT(unoptimized_code->kind() == Code::FUNCTION);
   ASSERT(unoptimized_code->back_edges_patched_for_osr());
   int loop_nesting_level = unoptimized_code->allow_osr_at_loop_nesting_level();
   Address back_edge_cursor = unoptimized_code->instruction_start() +
       unoptimized_code->back_edge_table_offset();
   uint32_t table_length = Memory::uint32_at(back_edge_cursor);
   back_edge_cursor += kIntSize;
   for (uint32_t i = 0; i < table_length; ++i) {
-    uint8_t loop_depth = Memory::uint8_at(back_edge_cursor + 2 * kIntSize);
-    if (loop_depth <= loop_nesting_level) {
+    uint32_t loop_depth = Memory::uint32_at(back_edge_cursor + 2 * kIntSize);
+    if (static_cast<int>(loop_depth) <= loop_nesting_level) {
       uint32_t pc_offset = Memory::uint32_at(back_edge_cursor + kIntSize);
       Address pc_after = unoptimized_code->instruction_start() + pc_offset;
       RevertInterruptCodeAt(unoptimized_code,
                             pc_after,
                             interrupt_code,
                             replacement_code);
     }
     back_edge_cursor += FullCodeGenerator::kBackEdgeEntrySize;
   }
   unoptimized_code->set_back_edges_patched_for_osr(false);
@@ skipping 10 matching lines @@
 void Deoptimizer::VerifyInterruptCode(Code* unoptimized_code,
                                       Code* interrupt_code,
                                       Code* replacement_code,
                                       int loop_nesting_level) {
   CHECK(unoptimized_code->kind() == Code::FUNCTION);
   Address back_edge_cursor = unoptimized_code->instruction_start() +
       unoptimized_code->back_edge_table_offset();
   uint32_t table_length = Memory::uint32_at(back_edge_cursor);
   back_edge_cursor += kIntSize;
   for (uint32_t i = 0; i < table_length; ++i) {
-    uint8_t loop_depth = Memory::uint8_at(back_edge_cursor + 2 * kIntSize);
+    int32_t loop_depth = Memory::int32_at(back_edge_cursor + 2 * kIntSize);

[kisg, 2013/07/18 15:46:52]

Instead of int32_t, use uint32_t and static_cast<int> in the CHECK to fix debug
builds

[kilvadyb, 2013/07/18 18:22:43]

Done.

     CHECK_LE(loop_depth, Code::kMaxLoopNestingMarker);
     // Assert that all back edges for shallower loops (and only those)
     // have already been patched.
     uint32_t pc_offset = Memory::uint32_at(back_edge_cursor + kIntSize);
     Address pc_after = unoptimized_code->instruction_start() + pc_offset;
     CHECK_EQ((loop_depth <= loop_nesting_level),
              InterruptCodeIsPatched(unoptimized_code,
                                     pc_after,
                                     interrupt_code,
                                     replacement_code));
@@ skipping 647 matching lines @@
 
 void DeoptimizedFrameInfo::Iterate(ObjectVisitor* v) {
   v->VisitPointer(BitCast<Object**>(&function_));
   v->VisitPointers(parameters_, parameters_ + parameters_count_);
   v->VisitPointers(expression_stack_, expression_stack_ + expression_count_);
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal