Make scoping more prominent in the CPS IR's printed representation.

Make scoping more prominent in the CPS IR's printed representation.

Before: LetPrim and LetCont had "internal define" scoping, extending to
the end of the body they were in.  After: they have "let" scoping, with a
body as a subexpression.

This change makes it easier to see scoping in the printed representation.
It also makes the printed representation more closely resemble the
internal representation.  Finally, it is an advantage if writing the IR
by hand because expressions are balanced (Emacs, for example, can copy or
cut a balances S-expression).

Argument lists are changed to be always nested (enclosed by parentheses).
The basic rule of thumb is that the syntactic forms of the IR should all
have fixed arity (matching the internal representation), so that variable
arity parts such as arguments are represented as a single list.

BUG=
R=asgerf@google.com, floitsch@google.com, sigurdm@google.com

Committed: https://code.google.com/p/dart/source/detail?r=42630

[Kevin Millikin (Google), 2015-01-06 08:01:52]

kmillikin@google.com changed reviewers:
+ asgerf@google.com, floitsch@google.com, karlklose@google.com,
sigurdm@google.com

[Kevin Millikin (Google), 2015-01-06 08:01:53]

Improved (?) printed representation, comments welcome.

https://codereview.chromium.org/833353002/diff/1/pkg/analyzer2dart/test/sexpr...
File pkg/analyzer2dart/test/sexpr_data.dart (right):

https://codereview.chromium.org/833353002/diff/1/pkg/analyzer2dart/test/sexpr...
pkg/analyzer2dart/test/sexpr_data.dart:552: (InvokeMethod v0 == (v1) k0)))))
This is a pretty good example of the difference between the new and old style
printed representation.

https://codereview.chromium.org/833353002/diff/1/pkg/analyzer2dart/test/sexpr...
pkg/analyzer2dart/test/sexpr_data.dart:935: (InvokeContinuation return
(v9)))))))))))))
And here is an expression that runs away to the right.

https://codereview.chromium.org/833353002/diff/1/pkg/compiler/lib/src/cps_ir/...
File pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart (right):

https://codereview.chromium.org/833353002/diff/1/pkg/compiler/lib/src/cps_ir/...
pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart:87: indentBlock(() =>
indentBlock(() => visit(node.continuation.body)));
I'd actually like to align these bodies, but that's not so easy.  As a hack, I'm
indenting them twice this way.

[sigurdm, 2015-01-06 08:19:00]

lgtm
I think this representation is nicer, it much more clearly shows how the
IR-expressions are built.

[floitsch, 2015-01-06 09:59:08]

LGTM.

[asgerf, 2015-01-06 12:46:07]

I like it. LGTM

https://codereview.chromium.org/833353002/diff/1/pkg/analyzer2dart/test/sexpr...
File pkg/analyzer2dart/test/sexpr_data.dart (right):

https://codereview.chromium.org/833353002/diff/1/pkg/analyzer2dart/test/sexpr...
pkg/analyzer2dart/test/sexpr_data.dart:935: (InvokeContinuation return
(v9)))))))))))))
On 2015/01/06 08:01:52, kmillikin wrote:
> And here is an expression that runs away to the right.

I think it's OK since we have the IR tracer to see linearized output.

[Kevin Millikin (Google), 2015-01-06 12:49:39]

Committed patchset #1 (id:1) manually as 42630 (presubmit successful).