Experimental: the code to make a frame mergable is sometimes emitted...

Experimental: the code to make a frame mergable is sometimes emitted
between an instruction that sets the processor flags and an
instruction that tests them.  The flags must not be affected by the
make mergable code (mov and push is OK, xor is not).

Committed: http://code.google.com/p/v8/source/detail?r=1022

[Kevin Millikin (Chromium), 2008-12-30 12:54:29]

This is annoying and fragile.  We probably want to get the cc_reg inside the
virtual frame so we can preserve it when required.

Even better is to get rid of the requirement that frames be mergable (at least
for blocks reached by only forward CFG edges, and possibly forbid a value in
cc_reg on the backward ones).

[William Hesse, 2008-12-30 13:28:02]

LGTM, but don't we need a long-term fix that does not load immediate 32 bit
constants?