Optimizing code generator expects that every AST node is traversed once, i.e., the nodes are not ...

Optimizing code generator expects that every AST node is traversed once, i.e., the nodes are not reused. Unfortunately this is not the case in  assignment operations with arrays (e.g. a[i] += 3).
The proper solution would be to clone array and index nodes but that would require too many changes. Long term we can't / won't use AST nodes for optimization purposes.
Short term fix is here: load array and index and release their CodeGenInfo before value is traversed so that the value computation can set its own CodeGenInfo on the same node.
Committed: https://code.google.com/p/dart/source/detail?r=4121

[hausner, 2012-02-09 21:51:48]

LGTM.

https://chromiumcodereview.appspot.com/9373025/diff/1/runtime/vm/opt_code_gen...
File runtime/vm/opt_code_generator_ia32.cc (right):

https://chromiumcodereview.appspot.com/9373025/diff/1/runtime/vm/opt_code_gen...
runtime/vm/opt_code_generator_ia32.cc:2492: known_array_class =
array_info.is_class()->raw();
Not sure why you call this the "known" array class. Isn't the known class the
one that the VM knows about, i.e. object_array_class?

[srdjan, 2012-02-10 07:13:11]

https://chromiumcodereview.appspot.com/9373025/diff/1/runtime/vm/opt_code_gen...
File runtime/vm/opt_code_generator_ia32.cc (right):

https://chromiumcodereview.appspot.com/9373025/diff/1/runtime/vm/opt_code_gen...
runtime/vm/opt_code_generator_ia32.cc:2492: known_array_class =
array_info.is_class()->raw();
On 2012/02/09 21:51:48, hausner wrote:
> Not sure why you call this the "known" array class. Isn't the known class the
> one that the VM knows about, i.e. object_array_class?

Changing it to class_of_this_array to avoid confusion. That class is computed
using type analysis and can be any of the classes including ObjectArray,
GrowableObjectArray, ImmutableArray or any user class.