[turbofan] Perform OSR deconstruction early and remove type propagation.

[turbofan] Perform OSR deconstruction early and remove type propagation.

This way we don't have to deal with dead pre-OSR code in the graph and
risk optimizing the wrong code, especially we don't make optimistic
assumptions in the dead code that leaks into the OSR code (i.e. deopt
guards are in dead code, but the types propagate to OSR code via the
OsrValue type back propagation).

BUG=v8:4273
LOG=n
R=jarin@chromium.org

Committed: https://crrev.com/cdbb6c485b8d07fd4ad1cb000d54a937507e3b3e
Cr-Commit-Position: refs/heads/master@{#29478}

[Benedikt Meurer, 2015-07-06 08:44:07]

Hey Jaro,

The next step in fixing the OSR. Removing the dangerous code and deconstructing
OSR immediately.
Please take a look.

Thanks,
Benedikt

[Jarin, 2015-07-06 08:54:04]

lgtm

[Benedikt Meurer, 2015-07-06 09:05:24]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-07-06 09:05:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1215333005/1

[titzer, 2015-07-06 09:12:33]

titzer@chromium.org changed reviewers:
+ titzer@chromium.org

[titzer, 2015-07-06 09:12:34]

https://codereview.chromium.org/1215333005/diff/1/src/compiler/osr.cc
File src/compiler/osr.cc (left):

https://codereview.chromium.org/1215333005/diff/1/src/compiler/osr.cc#oldcode253
src/compiler/osr.cc:253: Node* osr_loop) {

I don't think it's necessary to delete this code. We need to discuss the policy
for OSR'ing code further.

[Benedikt Meurer, 2015-07-06 09:15:03]

https://codereview.chromium.org/1215333005/diff/1/src/compiler/osr.cc
File src/compiler/osr.cc (left):

https://codereview.chromium.org/1215333005/diff/1/src/compiler/osr.cc#oldcode253
src/compiler/osr.cc:253: Node* osr_loop) {
This is the main cause for the bug. So we could only leave this static function
here without calling it; but then again there is no point in doing so with a
revision control system.

[commit-bot: I haz the power, 2015-07-06 09:15:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-06 09:15:40]

Patchset 1 (id:??) landed as
https://crrev.com/cdbb6c485b8d07fd4ad1cb000d54a937507e3b3e
Cr-Commit-Position: refs/heads/master@{#29478}