Further improve deopt reason output.

Further improve deopt reason output.

* Make the detailed deopt reason mandatory on x64, other platforms
  will follow in separate CLs.

* Extracted and improved jump table entry sharing logic: When
  --trace-deopt is on, we get separate entries for different deopt
  reasons. This enables us to distinguish the several reasons single
  instructions can have.

* Don't emit superfluous jump table comments: The bailout ID is still
  visible, and the jump table entry number is not interesting (but
  easy to determine if really needed).

* Unify the internal name of the jump table member across platforms.

R=jarin@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=24123

[Sven Panne, 2014-09-22 13:32:04]

svenpanne@chromium.org changed reviewers:
+ jarin@chromium.org

[Jarin, 2014-09-22 14:04:38]

lgtm. I like where this is going.

However, I am not too happy about using strings for the deopt reasons and for
the mnemonics. Have you thought about using enums or some such?

[Sven Panne, 2014-09-22 14:16:05]

On 2014/09/22 14:04:38, jarin wrote:
> lgtm. I like where this is going.
> 
> However, I am not too happy about using strings for the deopt reasons and for
> the mnemonics. Have you thought about using enums or some such?

As discussed offline, I thought about this, but first let's do the rest of the
platforms and collect all the reasons. Having enums would allow a more compact
runtime representation, because in the end we want to thread through all this
information back to C land in the deoptimizer.

[Sven Panne, 2014-09-22 14:17:03]

Committed patchset #1 (id:1) manually as 24123 (presubmit successful).