dart2js cps: Rewrite mutable variables to continuation parameters.

dart2js cps: Rewrite mutable variables to continuation parameters.

To assist basic block traversal, expressions now belong to one of three
categories:
- InteriorExpression
- CallExpression
- TailExpression

BUG=
R=karlklose@google.com

Committed: https://github.com/dart-lang/sdk/commit/562825e1610f59acf86bf13d91abee3e797c997e

[asgerf, 2015-07-13 13:46:57]

asgerf@google.com changed reviewers:
+ karlklose@google.com

[karlklose, 2015-07-14 08:39:45]

LGTM.

Could you add a small test to the js_backend_cps_ir... unit tests?

https://codereview.chromium.org/1234753003/diff/20001/pkg/compiler/lib/src/cp...
File pkg/compiler/lib/src/cps_ir/mutable_ssa.dart (right):

https://codereview.chromium.org/1234753003/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/mutable_ssa.dart:124: void merge(MutableVariable
variable, Primitive value) {
Maybe call this 'mergeHints.'

https://codereview.chromium.org/1234753003/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/mutable_ssa.dart:141: while (node is!
TailExpression) {
Consider using a for-loop instead to make the traversal step easier to spot.

https://codereview.chromium.org/1234753003/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/mutable_ssa.dart:143: // Put the new mutable
variable on the stack while processing the body.
Merge comment with comment below.

[asgerf, 2015-07-14 09:00:22]

Added two tests that rely on mutable variable elimination and are generally nice
basic tests to keep track of.

https://codereview.chromium.org/1234753003/diff/20001/pkg/compiler/lib/src/cp...
File pkg/compiler/lib/src/cps_ir/mutable_ssa.dart (right):

https://codereview.chromium.org/1234753003/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/mutable_ssa.dart:124: void merge(MutableVariable
variable, Primitive value) {
On 2015/07/14 08:39:44, karlklose wrote:
> Maybe call this 'mergeHints.'

Done.

https://codereview.chromium.org/1234753003/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/mutable_ssa.dart:141: while (node is!
TailExpression) {
On 2015/07/14 08:39:44, karlklose wrote:
> Consider using a for-loop instead to make the traversal step easier to spot.

Nice idea! Done.

https://codereview.chromium.org/1234753003/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/mutable_ssa.dart:143: // Put the new mutable
variable on the stack while processing the body.
On 2015/07/14 08:39:44, karlklose wrote:
> Merge comment with comment below.

Done.

[asgerf, 2015-07-14 09:19:02]

Committed patchset #4 (id:60001) manually as
562825e1610f59acf86bf13d91abee3e797c997e (presubmit successful).