Use constants from the frame at OSR entry.

Use constants from the frame at OSR entry.

The code for reserving stack slots for OSR entry values is shared with the
code for reserving stack slots for try/catch. It does not handle them
optimally (reserving slots above the desired ones and copying them down,
instead of directly reserving the desired one). This CL simplifies allocation
of spill slots for try-catch as well.

This is an rebased version of Kevin's original CL
(https://codereview.chromium.org/102173003/).
I removed an invalid assertion and removed more code that became unnecessary
with this change.

R=srdjan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=31601

[Kevin Millikin (Google), 2014-01-07 14:09:19]

I like it.

https://codereview.chromium.org/125943002/diff/1/runtime/vm/flow_graph.cc
File runtime/vm/flow_graph.cc (right):

https://codereview.chromium.org/125943002/diff/1/runtime/vm/flow_graph.cc#new...
runtime/vm/flow_graph.cc:712: definition = new ParameterInstr(env->length(),
graph_entry());
I know you've already thought of this, but here you could record the original
value (e.g., to query its class) but just not emit it in code.

https://codereview.chromium.org/125943002/diff/1/runtime/vm/flow_graph.cc#new...
runtime/vm/flow_graph.cc:728: intptr_t count = num_non_copied_params();
I guess there should be a comment here that it's important to initialize them
from 'left to right' (parameters first, then other stack locals, in environment
order) because the counter is used to assign indexes.

[srdjan, 2014-01-07 18:51:20]

LGTM with Kevin's comments.

https://codereview.chromium.org/125943002/diff/1/runtime/vm/flow_graph.cc
File runtime/vm/flow_graph.cc (right):

https://codereview.chromium.org/125943002/diff/1/runtime/vm/flow_graph.cc#new...
runtime/vm/flow_graph.cc:707: Object& value = Object::ZoneHandle(base[-i]);
const Object&

[Florian Schneider, 2014-01-08 10:48:03]

https://codereview.chromium.org/125943002/diff/1/runtime/vm/flow_graph.cc
File runtime/vm/flow_graph.cc (right):

https://codereview.chromium.org/125943002/diff/1/runtime/vm/flow_graph.cc#new...
runtime/vm/flow_graph.cc:707: Object& value = Object::ZoneHandle(base[-i]);
On 2014/01/07 18:51:20, srdjan wrote:
> const Object&

Done.

https://codereview.chromium.org/125943002/diff/1/runtime/vm/flow_graph.cc#new...
runtime/vm/flow_graph.cc:712: definition = new ParameterInstr(env->length(),
graph_entry());
On 2014/01/07 14:09:19, kmillikin wrote:
> I know you've already thought of this, but here you could record the original
> value (e.g., to query its class) but just not emit it in code.

Good point. I'll do this in a separate CL since adding the type information
triggers another bug in our specialization of ICData.

https://codereview.chromium.org/125943002/diff/1/runtime/vm/flow_graph.cc#new...
runtime/vm/flow_graph.cc:728: intptr_t count = num_non_copied_params();
On 2014/01/07 14:09:19, kmillikin wrote:
> I guess there should be a comment here that it's important to initialize them
> from 'left to right' (parameters first, then other stack locals, in
environment
> order) because the counter is used to assign indexes.

Done.

[Florian Schneider, 2014-01-08 11:27:18]

Committed patchset #3 manually as r31601 (presubmit successful).