[wasm] Do not used "undefined" for function signature padding.

[wasm] Do not used "undefined" for function signature padding.

Commit d0b8e7fb introduced some functionality to allocate additional
space in the function table, filled with an "undefined" function
signature. Use -1 instead of undefined_value() as the latter can have
the top bits cleared (which happens often for arm64) and causes
intermittent test failures.

BUG=

Committed: https://crrev.com/51f05798dfdcb69e249956a27436c6ed5591db4c
Cr-Commit-Position: refs/heads/master@{#37393}

[georgia.kouveli, 2016-06-29 11:21:47]

georgia.kouveli@arm.com changed reviewers:
+ ahaas@chromium.org, bradnelson@chromium.org

[titzer, 2016-06-29 11:32:52]

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

[titzer, 2016-06-29 11:32:52]

lgtm.

Does this also mean (elsewhere) we can do a RefEqual for comparing function
signatures, instead of doing a Smi conversion?

[georgia.kouveli, 2016-06-29 11:56:23]

The CQ bit was checked by georgia.kouveli@arm.com

[commit-bot: I haz the power, 2016-06-29 11:56:30]

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

[georgia.kouveli, 2016-06-29 12:08:35]

On 2016/06/29 11:32:52, titzer wrote:
> lgtm.
> 
> Does this also mean (elsewhere) we can do a RefEqual for comparing function
> signatures, instead of doing a Smi conversion?

I think that's what the code was doing before d0b8e7fb in CallIndirect. Since
the values in the function table were stored as SMIs and undefined is a pointer,
we couldn't have this issue (the signatures would never be equal to undefined).

[commit-bot: I haz the power, 2016-06-29 12:21:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-06-29 12:22:22]

Description was changed from

==========
[wasm] Do not used "undefined" for function signature padding.

Commit d0b8e7fb introduced some functionality to allocate additional
space in the function table, filled with an "undefined" function
signature. Use -1 instead of undefined_value() as the latter can have
the top bits cleared (which happens often for arm64) and causes
intermittent test failures.

BUG=
==========

to

==========
[wasm] Do not used "undefined" for function signature padding.

Commit d0b8e7fb introduced some functionality to allocate additional
space in the function table, filled with an "undefined" function
signature. Use -1 instead of undefined_value() as the latter can have
the top bits cleared (which happens often for arm64) and causes
intermittent test failures.

BUG=

Committed: https://crrev.com/51f05798dfdcb69e249956a27436c6ed5591db4c
Cr-Commit-Position: refs/heads/master@{#37393}
==========

[commit-bot: I haz the power, 2016-06-29 12:22:23]

Patchset 1 (id:??) landed as
https://crrev.com/51f05798dfdcb69e249956a27436c6ed5591db4c
Cr-Commit-Position: refs/heads/master@{#37393}

[bradnelson, 2016-06-29 15:11:22]

lgtm