Enforce strict weak ordering on NaN frequencies

Enforce strict weak ordering on NaN frequencies

In crrev.com/2856103002 sentinel frequency values were introduced, using
NaN as the sentinel. However the comparison function was not *fully*
updated to support these - comparing two NaNs would give ambiguous
results. This caused test failures when building with VS 2017, probably
because of subtle changes in the arrangement of nodes in the tree.

This change uses the the node ID to break ties. An alternative would be
to use a non-NaN sentinel value.

R=bmeurer@chromium.org
BUG=chromium:722480
Review-Url: https://codereview.chromium.org/2894433004
Cr-Commit-Position: refs/heads/master@{#45415}
Committed: https://chromium.googlesource.com/v8/v8/+/58ba4cefe8aeb05479dfdd0ffb65e2774a7a07b8

[brucedawson, 2017-05-18 17:44:31]

The CQ bit was checked by brucedawson@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-05-18 17:44:41]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[brucedawson, 2017-05-18 18:12:56]

This fixes some undefined behavior that was introduced a few weeks ago. PTAL.

[commit-bot: I haz the power, 2017-05-18 18:18:27]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-05-18 18:18:27]

Dry run: This issue passed the CQ dry run.

[Benedikt Meurer, 2017-05-19 05:02:00]

Nice catch, thanks! LGTM

[brucedawson, 2017-05-19 06:08:46]

The CQ bit was checked by brucedawson@chromium.org

[commit-bot: I haz the power, 2017-05-19 06:08:49]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-19 06:10:23]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1495174126357820, "parent_rev":
"d652d06f887b9ab062a0ab1bb697beef4a823a81", "commit_rev":
"58ba4cefe8aeb05479dfdd0ffb65e2774a7a07b8"}

[commit-bot: I haz the power, 2017-05-19 06:10:29]

Description was changed from

==========
Enforce strict weak ordering on NaN frequencies

In crrev.com/2856103002 sentinel frequency values were introduced, using
NaN as the sentinel. However the comparison function was not *fully*
updated to support these - comparing two NaNs would give ambiguous
results. This caused test failures when building with VS 2017, probably
because of subtle changes in the arrangement of nodes in the tree.

This change uses the the node ID to break ties. An alternative would be
to use a non-NaN sentinel value.

R=bmeurer@chromium.org
BUG=chromium:722480
==========

to

==========
Enforce strict weak ordering on NaN frequencies

In crrev.com/2856103002 sentinel frequency values were introduced, using
NaN as the sentinel. However the comparison function was not *fully*
updated to support these - comparing two NaNs would give ambiguous
results. This caused test failures when building with VS 2017, probably
because of subtle changes in the arrangement of nodes in the tree.

This change uses the the node ID to break ties. An alternative would be
to use a non-NaN sentinel value.

R=bmeurer@chromium.org
BUG=chromium:722480

Review-Url: https://codereview.chromium.org/2894433004
Cr-Commit-Position: refs/heads/master@{#45415}
Committed:
https://chromium.googlesource.com/v8/v8/+/58ba4cefe8aeb05479dfdd0ffb65e2774a7...
==========

[commit-bot: I haz the power, 2017-05-19 06:10:30]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/58ba4cefe8aeb05479dfdd0ffb65e2774a7...