Group property assignments in top-level blocks.

Group property assignments in top-level blocks.

This patch enables insertion of To{Slow,Fast}Properties around a group
of assigments to the same object even when they are put in a block
(e.g. try-catch, if, etc.). Catching exceptions and disabling parts of
code based on some config vars is rather common in top-level code.


R=vegorov@chromium.org

Committed: http://code.google.com/p/v8/source/detail?r=8558

[Vyacheslav Egorov (Chromium), 2011-07-06 13:06:00]

LGTM

[Vyacheslav Egorov (Chromium), 2011-07-06 13:07:51]

nit

http://codereview.chromium.org/7314002/diff/1/src/parser.cc
File src/parser.cc (right):

http://codereview.chromium.org/7314002/diff/1/src/parser.cc#newcode1486
src/parser.cc:1486: if (top_scope_->is_global_scope()) {
I think this if needs the same kind of comment it has in ParseSourceElements.

Maybe you can even make a method (e.g. on InitializationBlockFinder) that
accepts scope and checks it.

[Kevin Millikin (Chromium), 2011-07-06 13:15:03]

http://codereview.chromium.org/7314002/diff/1/src/parser.cc
File src/parser.cc (right):

http://codereview.chromium.org/7314002/diff/1/src/parser.cc#newcode1486
src/parser.cc:1486: if (top_scope_->is_global_scope()) {
I think it needs to be top_scope_->DeclarationScope()->is_global_scope().

[Vitaly Repeshko, 2011-07-06 13:43:13]

Thanks for the comments! I addressed them and made one more change to avoid
transforming properties in top-level loops. Unfortunately, the parser doesn't
track whether we're in a loop or not, so doing this required small tweaks to the
codegens. Please take another look.


-- Vitaly

[Vyacheslav Egorov (Chromium), 2011-07-06 13:55:46]

Changes in codegens look hairy. 

Is it hard to track loop nesting in parser instead?

[Vitaly Repeshko, 2011-07-06 14:12:55]

On 2011/07/06 13:55:46, Vyacheslav Egorov wrote:
> Changes in codegens look hairy. 
> 
> Is it hard to track loop nesting in parser instead?

PTAL.

[Vyacheslav Egorov (Chromium), 2011-07-06 14:19:05]

LGTM

http://codereview.chromium.org/7314002/diff/5003/src/parser.cc
File src/parser.cc (right):

http://codereview.chromium.org/7314002/diff/5003/src/parser.cc#newcode828
src/parser.cc:828: // so it should be used only for code that will only be run
once.
Comment should mention that we do not apply this opt to loops.