Make Value not a subclass of Computation.

Make Value not a subclass of Computation.

Instead I introduce one new computation to materialize constants.

sizeof(UseVal) drops from 64 to 32.
sizeof(ConstantVal) drops from 48 to 16.
Committed: https://code.google.com/p/dart/source/detail?r=11041

[Kevin Millikin (Google), 2012-08-21 13:32:22]

LGTM, but it seems somewhere in the middle of:

1. Constants and variables are pure values and they can each be wrapped in some
sort of "unit" to become a computation, or else

2. Constants are not really pure values at all.

I think we should try to gravitate toward either of those options.

[srdjan, 2012-08-21 22:14:53]

DBC

https://chromiumcodereview.appspot.com/10829451/diff/2002/runtime/vm/flow_gra...
File runtime/vm/flow_graph_builder.h (right):

https://chromiumcodereview.appspot.com/10829451/diff/2002/runtime/vm/flow_gra...
runtime/vm/flow_graph_builder.h:120: // Build a computation for a constant
value.
s/Build/Builds/

https://chromiumcodereview.appspot.com/10829451/diff/2002/runtime/vm/intermed...
File runtime/vm/intermediate_language.h (right):

https://chromiumcodereview.appspot.com/10829451/diff/2002/runtime/vm/intermed...
runtime/vm/intermediate_language.h:332: FOR_EACH_VALUE(DECLARE_PREDICATE)
Is it worth going through all this for just two subclasses: UseVal and Constant?
Do you imagine we can have more subclasses of Value in near future?

[Florian Schneider, 2012-08-22 10:59:00]

https://chromiumcodereview.appspot.com/10829451/diff/2002/runtime/vm/intermed...
File runtime/vm/intermediate_language.h (right):

https://chromiumcodereview.appspot.com/10829451/diff/2002/runtime/vm/intermed...
runtime/vm/intermediate_language.h:332: FOR_EACH_VALUE(DECLARE_PREDICATE)
On 2012/08/21 22:14:53, srdjan wrote:
> Is it worth going through all this for just two subclasses: UseVal and
Constant?
> Do you imagine we can have more subclasses of Value in near future?

Yes, maybe we can get rid of ConstantVal completely and have only one class
UseValue?