Allocate the environment's location backing store during register allocation.

Allocate the environment's location backing store during register allocation.

The code relies on the addresses of elements in this backing store.  It was
correct but difficult to guarantee when it was a growable array's backing
store.

R=vegorov@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=10290

[Kevin Millikin (Google), 2012-08-06 14:59:18]

http://codereview.chromium.org/10831179/diff/1/runtime/vm/intermediate_langua...
File runtime/vm/intermediate_language.h (right):

http://codereview.chromium.org/10831179/diff/1/runtime/vm/intermediate_langua...
runtime/vm/intermediate_language.h:2699: return locations_[ix];
It's not bulletproof, but I think I'll assert ix is in the (current) range of 0
<= ix < values_.length().  Also just below.

[Vyacheslav Egorov (Google), 2012-08-06 15:06:49]

lgtm

[srdjan, 2012-08-06 22:49:25]

DBC

http://codereview.chromium.org/10831179/diff/4001/runtime/vm/flow_graph_alloc...
File runtime/vm/flow_graph_allocator.cc (right):

http://codereview.chromium.org/10831179/diff/4001/runtime/vm/flow_graph_alloc...
runtime/vm/flow_graph_allocator.cc:665: env->InitializeLocations();
I would move the loop below into InitializeLocation. Since InitializeLocations
only allocates locations, initialization is occurring below.

http://codereview.chromium.org/10831179/diff/4001/runtime/vm/intermediate_lan...
File runtime/vm/intermediate_language.h (right):

http://codereview.chromium.org/10831179/diff/4001/runtime/vm/intermediate_lan...
runtime/vm/intermediate_language.h:2695: location_count_ = values_.length();
ASSERT(locations_ == NULL), guaranteeing that we do not reallocate locations_ as
we use pointers into it (add that as comment as well).

http://codereview.chromium.org/10831179/diff/4001/runtime/vm/intermediate_lan...
runtime/vm/intermediate_language.h:2698:
Isolate::Current()->current_zone()->Alloc<Location>(location_count_);
Please initialize locations_ with default Location values.

http://codereview.chromium.org/10831179/diff/4001/runtime/vm/intermediate_lan...
runtime/vm/intermediate_language.h:2703: ASSERT((ix >= 0) && (ix <
location_count_));
ASSERT(locations_ != NULL) .

http://codereview.chromium.org/10831179/diff/4001/runtime/vm/intermediate_lan...
runtime/vm/intermediate_language.h:2708: ASSERT((ix >= 0) && (ix <
location_count_));
ditto