Commit Graph

13 Commits

Author SHA1 Message Date
svenpanne@chromium.org
f03fd70d9e Added a simple dead code removal phase.
We iteratively remove all dead Hydrogen instruction until we reach a fixed point. We consider an instruction dead if it is unused, has no observable side effects and is deletable. The last part of the condition is currently not very nice: We basically have to whitelist "safe" instructions, because we are missing more detailed dependencies and/or more detailed tracking of side effects.

We disable dead code elimination for now in our test runners, because we have tons of poorly written tests which wouldn't test anymore what they are supposed to test with this phase enabled. To get test coverage for dead code elimination itself, we should enable it on a few build bots. This is not really a perfect state, but the best we can do for now.

This patch includes a few const-correctness fixes, most of them were necessary for this CL.

Review URL: https://codereview.chromium.org/11088027

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12697 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-10-11 10:52:58 +00:00
verwaest@chromium.org
efb53e1499 Make order of addition the primary order of descriptor arrays.
The order by name is maintained as secondary order by using unused bits in the property details.

This is preliminary work towards sharing descriptors arrays.

The change allows us
- to get rid of the LastAdded bits in the map, binding it to the number of valid descriptors for the given map
- to avoid resorting by enumeration index to create the cache
- (maybe in the future, depending on performance) to get rid of the enumeration cache altogether.

Although generally the number_of_descriptors equals the NumberOfOwnDescriptors in the current version, this is preliminary work towards sharing    descriptors, where maps may have more descriptors than are valid for the map.

Review URL: https://chromiumcodereview.appspot.com/10879013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12385 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-08-27 13:47:34 +00:00
verwaest@chromium.org
d7a5b7d5e2 Separating transitions from descriptors.
In this design maps contain descriptor arrays, which in turn can contain transition arrays. If transitions are needed when no descriptor array is present, a descriptor array without real descriptors is inserted just so it can point at the transition array.

The transition array does not contain details about the field it transitions to. In order to weed out transitions to FIELDs from CONSTANT_FUNCTION (what used to be MAP_TRANSITION vs CONSTANT_TRANSITION), the transition needs to be followed and the details need to be looked up in the target map. CALLBACKS transitions are still easy to recognize since the transition targets are stored as an AccessorPair containing the maps, rather than the maps directly.

Currently AccessorPairs containing a transition and an accessor are shared between the descriptor array and the transition array. This simplifies lookup since we only have to look in one of both arrays. This will change in subsequent revisions, when descriptor arrays will become shared between multiple maps, since transitions cannot be shared.

Review URL: https://chromiumcodereview.appspot.com/10697015

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11994 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-07-05 13:54:20 +00:00
verwaest@chromium.org
68c944c265 In-place shrinking of descriptor arrays with non-live transitions.
Instead of overwriting non-live transitions with NULL_DESCRIPTORs, we remove them from the array by compacting the array (shifting live values to the left) and in-place trimming the array. If the final descriptor array contains no live values (only contained transitions which are now all cleared), we move bit_field3 back from the descriptor array to the map. The descriptor array itself will be collected in the next GC.

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/10575032

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11922 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-06-25 13:10:54 +00:00
verwaest@chromium.org
41560e9f5f Separate stub types from property types.
Review URL: https://chromiumcodereview.appspot.com/10656018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11920 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-06-25 11:35:23 +00:00
verwaest@chromium.org
2b574ef580 Promoting elements transitions to their own field.
This is a first step towards separating all transitions from the property descriptions. If we link the property descriptions from the transition object, this will in allow the descriptor array (property descriptions) to become immutable.

Review URL: https://chromiumcodereview.appspot.com/10444055

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11750 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-06-11 06:59:56 +00:00
svenpanne@chromium.org
5033b9b6d1 Re-land CL 9466047.
Main change from the original CL: Call::ComputeTarget does not use IsProperty
anymore, because this would potentially need a holder, which we don't have
here. Using Map::LookupInDescriptors with a NULL holder is a bit fishy in
general, because one has to be *extremely* careful when using its LookupResult.

The original CL made Chrome's NetInternalsTest.netInternalsTourTabs browser test
fail, but it's a mystery how this could happen: We should never reach
Call::ComputeTarget via Call::RecordTypeFeedback with a CALLBACKS property,
because we never consider calls to them monomorphic, which is in turn because of
the stub cache leaving them in the pre-monomorphic state. Therefore, I don't
have a clue how to write a regression test for this...

As an additional tiny bonus, the --trace-opt output for deoptimizations has been
improved.

Review URL: https://chromiumcodereview.appspot.com/9584003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10906 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-03-02 14:03:59 +00:00
jkummerow@chromium.org
ea62dca70e Revert "Handle CALLBACKS correctly in IsProperty functions."
This reverts r10847.

Review URL: https://chromiumcodereview.appspot.com/9536010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10868 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-02-29 13:29:17 +00:00
svenpanne@chromium.org
18ba22168e Handle CALLBACKS correctly in IsProperty functions.
With transitions in AccessorPairs, it is not enough to look at the PropertyType
alone to decide whether we look at a property or not: For objects with
JavaScript accessors, we have to look into the AccessorPair itself and see if
one of its 2 parts is actually a JavaScript accessor. Therefore, a predicate
with a PropertyType argument alone doesn't make sense anymore, we might need the
associated value, too.

Things are complicated by the fact that the holder in a LookupResult can be
NULL, so we must be careful to retrieve its value only when it is really
needed. To achieve the needed call-by-name semantics, a new Entry is introduced,
which is basically a closure over a DescriptorArray and an index into this array
(C++0x to the rescue!). GCC is clever enough to inline this class, so we pay no
runtime penalty for this abstraction.

It's all a bit ugly, but this is caused by the current structure of Descriptor,
DescriptorArray and LookupResult: Things would be much easier if DescriptorArray
were, well, an array of Descriptors, and LookupResult were a 'Maybe Descriptor'
(in Haskell-terms).

Review URL: https://chromiumcodereview.appspot.com/9466047

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10847 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-02-28 07:16:50 +00:00
svenpanne@chromium.org
ba6825012c Removed PropertyDetails::IsProperty.
This is just an intermediate step to remove IsRealProperty.

Review URL: https://chromiumcodereview.appspot.com/9325060

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10610 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-02-06 12:11:40 +00:00
svenpanne@chromium.org
b34e202b20 Removed IsTransitionType predicate.
With the upcoming changes to CALLBACKS properties, a predicate on the transition
type alone doesn't make sense anymore: For CALLBACKS one has to look into the
property's value to decide, and there is even the possibility of having a an
accessor function *and* a transition in the same property.

I am not completely happy with some parts of this CL, because they contain
redundant code, but given the various representations we currently have for
property type/value pairs, I can see no easy way around that. Perhaps one can
improve this a bit in a different CL, the current diversity really, really hurts
productivity...

As a bonus, this CL includes a few minor things:

 * CaseClause::RecordTypeFeedback has been cleaned up and it handles the
   NULL_DESCRIPTOR case correctly now. Under some (very unlikely) circumstances,
   we previously missed some opportunities for monomorphic calls. In general, it
   is rather unfortunate that NULL_DESCRIPTOR "shines through", it is just a
   hack for the inability to remove a descriptor entry during GC, something
   callers shouldn't have to be aware of.

 * DescriptorArray::CopyInsert has been cleaned up a bit, preparing it for later
   CALLBACKS-related changes.

 * LookupResult::Print is now more informative for CONSTANT_TRANSITION.

Review URL: https://chromiumcodereview.appspot.com/9320066

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10600 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-02-03 13:37:13 +00:00
svenpanne@chromium.org
b16e02e823 Made PropertyType handling even more explicit.
Replaced FIRST_PHANTOM_PROPERTY_TYPE by a predicate. Removed the (hopefully)
last default cases for switches on PropertyType. Benchmarks show that both
changes are performace-neutral.

Now every value of PropertyType should either be handled by an explicit case in
a switch or by an equality operator. Therefore, the C++ compiler should finally
be able to tell us which places to touch when changing PropertyType.

Review URL: http://codereview.chromium.org/8506004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9930 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2011-11-09 12:47:15 +00:00
svenpanne@chromium.org
fbc0a9cd6f Disentangle header dependecies a bit by moving PropertyDetails-related types into a separate header
This moves PropertyType and its related predicate out of v8globals.h, where it didn't belong.

Review URL: http://codereview.chromium.org/8501006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9907 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2011-11-08 10:43:25 +00:00