Disable aggressive optimizations on the last optimization attempt.

Disable aggressive optimizations on the last optimization attempt.

Only has effect on the loop invariant code motion and Check instructions
for now.

Committed: http://code.google.com/p/v8/source/detail?r=6363

[fschneider, 2011-01-18 10:45:51]

LGTM.

http://codereview.chromium.org/6321007/diff/1/src/hydrogen-instructions.h
File src/hydrogen-instructions.h (right):

http://codereview.chromium.org/6321007/diff/1/src/hydrogen-instructions.h#new...
src/hydrogen-instructions.h:778: virtual bool CanDeoptimize() const { return
false; }
I'd rather name this predicate IsCheckInstruction() because 
in the long run we want the logic for deciding if an instructions can deoptimize
factored out into a platform-specific part.

[Kevin Millikin (Chromium), 2011-01-18 11:18:39]

A couple of drive by comments.

http://codereview.chromium.org/6321007/diff/1/src/hydrogen-instructions.h
File src/hydrogen-instructions.h (right):

http://codereview.chromium.org/6321007/diff/1/src/hydrogen-instructions.h#new...
src/hydrogen-instructions.h:777: // deoptimize. Allowed to have false positives.
The comment is also confusing.  The predicate has false negatives (not every
instruction that can deoptimize says true).

http://codereview.chromium.org/6321007/diff/1/src/v8globals.h
File src/v8globals.h (right):

http://codereview.chromium.org/6321007/diff/1/src/v8globals.h#newcode110
src/v8globals.h:110: const int kDefaultMaxOptCount = 10;
This should probably go in class Compiler instead of here.

[Vitaly Repeshko, 2011-01-18 12:24:56]

http://codereview.chromium.org/6321007/diff/1/src/hydrogen-instructions.h
File src/hydrogen-instructions.h (right):

http://codereview.chromium.org/6321007/diff/1/src/hydrogen-instructions.h#new...
src/hydrogen-instructions.h:777: // deoptimize. Allowed to have false positives.
On 2011/01/18 11:18:39, Kevin Millikin wrote:
> The comment is also confusing.  The predicate has false negatives (not every
> instruction that can deoptimize says true).

I renamed the function and the comment is much clearer now.

http://codereview.chromium.org/6321007/diff/1/src/hydrogen-instructions.h#new...
src/hydrogen-instructions.h:778: virtual bool CanDeoptimize() const { return
false; }
On 2011/01/18 10:45:51, fschneider wrote:
> I'd rather name this predicate IsCheckInstruction() because 
> in the long run we want the logic for deciding if an instructions can
deoptimize
> factored out into a platform-specific part.

Done.

http://codereview.chromium.org/6321007/diff/1/src/v8globals.h
File src/v8globals.h (right):

http://codereview.chromium.org/6321007/diff/1/src/v8globals.h#newcode110
src/v8globals.h:110: const int kDefaultMaxOptCount = 10;
On 2011/01/18 11:18:39, Kevin Millikin wrote:
> This should probably go in class Compiler instead of here.

Done.