Experimental: improve the code generated for possibly boolean-valued...

Experimental: improve the code generated for possibly boolean-valued
expressions.

Instead of branching to the true control target and jumping to the
false one, track which one is the preferred fall-through.  Use this to
branch to the non-fall-through and bind the fall-through.  This avoids
a jump to the next instruction or else a branch around a jump.

It becomes more difficult to tell if we have compiled an expression
into control flow or not.

Committed: http://code.google.com/p/v8/source/detail?r=1235

[Kevin Millikin (Chromium), 2009-02-05 10:43:14]

This is a little complicated.

As another change, I plan to abstract the triple of jump targets into a single
class with the branching behavior and the state to tell if they've been used.