[turbofan] Fix undefined behavior in Int64Lowering.

[turbofan] Fix undefined behavior in Int64Lowering.

This fixes undefined behavior introduced by extracting the const call
descriptor of a call node as non-const. Such an implicit cast between
constness is not safe and should be avoided.

R=ahaas@chromium.org
TEST=unittests/Int64LoweringTest.CallI64Parameter
BUG=v8:4924
LOG=n

Committed: https://crrev.com/dee91da817f3cf0ab373463cfa9c390de529c03d
Cr-Commit-Position: refs/heads/master@{#35569}

[Benedikt Meurer, 2016-04-18 09:20:12]

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

[Benedikt Meurer, 2016-04-18 09:20:13]

LGTM. Can we pretty please have CallDescriptorOf?

[Michael Starzinger, 2016-04-18 09:38:55]

On 2016/04/18 09:20:13, Benedikt Meurer wrote:
> LGTM. Can we pretty please have CallDescriptorOf?

Yes, CallDescriptorOf will be done next. We need it!

[ahaas, 2016-04-18 09:56:34]

lgtm

[Michael Starzinger, 2016-04-18 09:57:26]

The CQ bit was checked by mstarzinger@chromium.org

[Michael Starzinger, 2016-04-18 09:57:26]

The patchset sent to the CQ was uploaded after l-g-t-m from bmeurer@chromium.org
Link to the patchset: https://codereview.chromium.org/1900563002/#ps20001
(title: "Workaround with const-cast.")

[commit-bot: I haz the power, 2016-04-18 09:57:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1900563002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1900563002/20001

[commit-bot: I haz the power, 2016-04-18 09:59:37]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-04-18 10:01:19]

Description was changed from

==========
[turbofan] Fix undefined behavior in Int64Lowering.

This fixes undefined behavior introduced by extracting the const call
descriptor of a call node as non-const. Such an implicit cast between
constness is not safe and should be avoided.

R=ahaas@chromium.org
TEST=unittests/Int64LoweringTest.CallI64Parameter
BUG=v8:4924
LOG=n
==========

to

==========
[turbofan] Fix undefined behavior in Int64Lowering.

This fixes undefined behavior introduced by extracting the const call
descriptor of a call node as non-const. Such an implicit cast between
constness is not safe and should be avoided.

R=ahaas@chromium.org
TEST=unittests/Int64LoweringTest.CallI64Parameter
BUG=v8:4924
LOG=n

Committed: https://crrev.com/dee91da817f3cf0ab373463cfa9c390de529c03d
Cr-Commit-Position: refs/heads/master@{#35569}
==========

[commit-bot: I haz the power, 2016-04-18 10:01:20]

Patchset 2 (id:??) landed as
https://crrev.com/dee91da817f3cf0ab373463cfa9c390de529c03d
Cr-Commit-Position: refs/heads/master@{#35569}