Initialize tags back to 0 before using it.

vm/object.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/object.h"
 
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
@@ skipping 6108 matching lines @@
   const String& name = String::Handle(target_name());
   intptr_t len = OS::SNPrint(NULL, 0, kFormat, name.ToCString()) + 1;
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len));
   OS::SNPrint(chars, len, kFormat, name.ToCString());
   return chars;
 }
 
 
 void ICData::set_function(const Function& value) const {
-  raw_ptr()->function_ = value.raw();
+  StorePointer(&raw_ptr()->function_, value.raw());
 }
 
 
 void ICData::set_target_name(const String& value) const {
-  raw_ptr()->target_name_ = value.raw();
+  StorePointer(&raw_ptr()->target_name_, value.raw());
 }
 
 
 void ICData::set_id(intptr_t value) const {
   raw_ptr()->id_ = value;
 }
 
 
 void ICData::set_num_args_tested(intptr_t value) const {
   raw_ptr()->num_args_tested_ = value;
 }
 
 
 void ICData::set_ic_data(const Array& value) const {
-  raw_ptr()->ic_data_ = value.raw();
+  StorePointer(&raw_ptr()->ic_data_, value.raw());
 }
 
 
 intptr_t ICData::TestEntryLength() const {
   return num_args_tested() + 1 /* target function*/;
 }
 
 
 intptr_t ICData::NumberOfChecks() const {
   // Do not count the sentinel;
@@ skipping 2369 matching lines @@
   growable_array.SetData(new_array);
 
   // If there is any left over space fill it with either an Array object or
   // just a plain object (depending on the amount of left over space) so
   // that it can be traversed over successfully during garbage collection.
   if (capacity_size != used_size) {
     ASSERT(capacity_len > used_len);
     intptr_t leftover_size = capacity_size - used_size;
 
     uword addr = RawObject::ToAddr(array.raw()) + used_size;
+    tags = 0;

[cshapiro, 2012/04/18 20:52:00]

This seems like a strange idiom but I may not understand what is actually going
on.  Rather than doing this

  tag = 0
  tag = DoSomething(tag)
  raw->ptr()->tags_ = tags

Why not just do

  uword tag = DoSomething(0)
  raw->ptr()->tags_ = tag

It was unclear to me what the effect of the tags = 0 assignment was when I
looked at this code.  Keeping the def and use as close together as possible
would be great.

[siva, 2012/04/18 21:21:17]

This is in preparation for merging the tags fields and the header field into one
word.

The pattern at that point will look as:

header_bits = 0;
header_bits = UpdateTag info...
header_bits = UpdateSize...
header_bits = UpdateClassId ...
raw->ptr()->header_ = header_bits;


On 2012/04/18 20:52:00, cshapiro wrote:

     if (leftover_size >= Array::InstanceSize(0)) {
       // As we have enough space to use an array object, update the leftover
       // space as an Array object.
       RawArray* raw = reinterpret_cast<RawArray*>(RawObject::FromAddr(addr));
       raw->ptr()->class_ = isolate->object_store()->array_class();
       tags = RawObject::SizeTag::update(leftover_size, tags);
       raw->ptr()->tags_ = tags;
       intptr_t leftover_len =
           ((leftover_size - Array::InstanceSize(0)) / kWordSize);
       raw->ptr()->tags_ = tags;
@@ skipping 580 matching lines @@
   const String& str = String::Handle(pattern());
   const char* format = "JSRegExp: pattern=%s flags=%s";
   intptr_t len = OS::SNPrint(NULL, 0, format, str.ToCString(), Flags());
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len + 1));
   OS::SNPrint(chars, (len + 1), format, str.ToCString(), Flags());
   return chars;
 }
 
 }  // namespace dart