Implement logical AND/OR.

Implement logical AND/OR.
Committed: https://code.google.com/p/dart/source/detail?r=5253

[Kevin Millikin (Google), 2012-03-09 12:29:14]

It needs a conversion of 'right' in value contexts (probably using strict
equality to true).

When it handles, e.g., print(true && 0) correctly, LGTM.

https://chromiumcodereview.appspot.com/9649012/diff/3001/runtime/vm/flow_grap...
File runtime/vm/flow_graph_builder.cc (right):

https://chromiumcodereview.appspot.com/9649012/diff/3001/runtime/vm/flow_grap...
runtime/vm/flow_graph_builder.cc:225: if (node->kind() == Token::kAND) {
Maybe too cute is to write:

EffectGraphVisitor for_right(owner(), temp_index());
node->right()->Visit(&for_right);
EffectGraphVisitor empty(owner(), temp_index());
if (node->kind() == Token::kAND) {
  Join(for_left, for_right, empty);
} else {
  Join(for_left, empty, for_right);
}

https://chromiumcodereview.appspot.com/9649012/diff/3001/runtime/vm/flow_grap...
runtime/vm/flow_graph_builder.cc:262: // AND:  left ? right : false;
right needs a conversion to boolean (e.g., right === true).  This translation
won't work for:

print(true && 0);

Then, in a test context, we can do better than testing the literal false when
left is not true---translate right in a test context as well.  (Not as an
optimization in the non-optimizing compiler, but because that's what we want in
the optimizing compiler and it's easier if we keep the graph with the same shape
early.)

[srdjan, 2012-03-09 19:47:40]

https://chromiumcodereview.appspot.com/9649012/diff/3001/runtime/vm/flow_grap...
File runtime/vm/flow_graph_builder.cc (right):

https://chromiumcodereview.appspot.com/9649012/diff/3001/runtime/vm/flow_grap...
runtime/vm/flow_graph_builder.cc:225: if (node->kind() == Token::kAND) {
On 2012/03/09 12:29:14, kmillikin wrote:
> Maybe too cute is to write:
> 
> EffectGraphVisitor for_right(owner(), temp_index());
> node->right()->Visit(&for_right);
> EffectGraphVisitor empty(owner(), temp_index());
> if (node->kind() == Token::kAND) {
>   Join(for_left, for_right, empty);
> } else {
>   Join(for_left, empty, for_right);
> }

Done.

https://chromiumcodereview.appspot.com/9649012/diff/3001/runtime/vm/flow_grap...
runtime/vm/flow_graph_builder.cc:262: // AND:  left ? right : false;
On 2012/03/09 12:29:14, kmillikin wrote:
> right needs a conversion to boolean (e.g., right === true).  This translation
> won't work for:
> 
> print(true && 0);
> 
> Then, in a test context, we can do better than testing the literal false when
> left is not true---translate right in a test context as well.  (Not as an
> optimization in the non-optimizing compiler, but because that's what we want
in
> the optimizing compiler and it's easier if we keep the graph with the same
shape
> early.)

Thanks for catching it. Added tests (separate CL). There are two possibilities:
one is to use StrictCompare to convert right to boolean, the other is to use the
test context. I assume you would prefer the second, and I agree that it would
better convey the intent. However, I gave up on it (could not understand the
visitor interaction after many attempts) and implemented the correct version
using StrictCompare test.