[turbofan] Keep AstGraphBuilder context chain length in sync.

[turbofan] Keep AstGraphBuilder context chain length in sync.

This keeps the length of the context chain tracked by the environment
in sync even for local control flow commands. It removes the need to
guess the correct chain length at Environment::Merge points.

R=titzer@chromium.org

Committed: https://crrev.com/9596b36c1df3764daa07ca1afbbd1790389b0037
Cr-Commit-Position: refs/heads/master@{#27588}

[titzer, 2015-04-02 11:03:28]

LGTM other than naming suggestions.

https://codereview.chromium.org/1045703003/diff/20001/src/compiler/ast-graph-...
File src/compiler/ast-graph-builder.h (right):

https://codereview.chromium.org/1045703003/diff/20001/src/compiler/ast-graph-...
src/compiler/ast-graph-builder.h:402: void TrimContext(int trim_to_length) {
contexts()->resize(trim_to_length); }
TrimContextChain?

https://codereview.chromium.org/1045703003/diff/20001/src/compiler/ast-graph-...
src/compiler/ast-graph-builder.h:434: void Trim(int trim_to_height) {
Can we also rename this to TrimStack?

[Michael Starzinger, 2015-04-02 11:29:20]

https://codereview.chromium.org/1045703003/diff/20001/src/compiler/ast-graph-...
File src/compiler/ast-graph-builder.h (right):

https://codereview.chromium.org/1045703003/diff/20001/src/compiler/ast-graph-...
src/compiler/ast-graph-builder.h:402: void TrimContext(int trim_to_length) {
contexts()->resize(trim_to_length); }
On 2015/04/02 11:03:28, titzer wrote:
> TrimContextChain?

Done.

https://codereview.chromium.org/1045703003/diff/20001/src/compiler/ast-graph-...
src/compiler/ast-graph-builder.h:434: void Trim(int trim_to_height) {
On 2015/04/02 11:03:28, titzer wrote:
> Can we also rename this to TrimStack?

Done.

[Michael Starzinger, 2015-04-02 11:38:20]

The CQ bit was checked by mstarzinger@chromium.org

[Michael Starzinger, 2015-04-02 11:38:20]

The patchset sent to the CQ was uploaded after l-g-t-m from titzer@chromium.org
Link to the patchset: https://codereview.chromium.org/1045703003/#ps40001
(title: "Addressed comments.")

[commit-bot: I haz the power, 2015-04-02 11:38:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1045703003/40001

[commit-bot: I haz the power, 2015-04-02 11:49:11]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-04-02 11:49:18]

Patchset 3 (id:??) landed as
https://crrev.com/9596b36c1df3764daa07ca1afbbd1790389b0037
Cr-Commit-Position: refs/heads/master@{#27588}