* Hash code is now just done with a private own symbol instead of the hidden string, which predates symbols.
* In the long run we should do all hidden properties this way and get rid of the
hidden magic 0-length string with the zero hash code. The advantages include
less complexity and being able to do things from JS in a natural way.
* Initially, the performance of weak set regressed, because it's a little harder
to do the lookup in C++. Instead of heroics in C++ to make things faster I
moved some functionality into JS and got the performance back. JS is supposed to be good at looking up named properties on objects.
* This also changes hash codes of Smis so that they are always Smis.
Performance figures are in the comments to the code review. Summary: Most of js-perf-test/Collections is neutral. Set and Map with object keys are 40-50% better. WeakMap is -5% and WeakSet is +9%. After the measurements, I fixed global proxies, which cost 1% on most tests and 5% on the weak ones :-(.
In the code review comments is a patch with an example of the heroics we could do in C++ to make lookup faster (I hope we don't have to do this. Instead of checking for the property, then doing a new lookup to insert it, we could do one lookup and handle the addition immediately). With the current benchmarks above this buys us nothing, but if we go back to doing more lookups in C++ instead of in stubs and JS then it's a win.
In a similar vein we could give the magic zero hash code to the hash code
symbol. Then when we look up the hash code we would sometimes see the table
with all the hidden properties. This dual use of the field for either the hash
code or the table with all hidden properties and the hash code is rather ugly,
and this CL gets rid of it. I'd be loath to bring it back. On the benchmarks quoted above it's slightly slower than moving the hash code lookup to JS like in this CL.
One worry is that the benchmark results above are more monomorphic than real
world code, so may be overstating the performance benefits of moving to JS. I
think this is part of a general issue we have with handling polymorphic code in
JS and any solutions there will benefit this solution, which boils down to
regular property access. Any improvement there will lift all boats.
R=adamk@chromium.org, verwaest@chromium.org
BUG=
Review URL: https://codereview.chromium.org/1149863005
Cr-Commit-Position: refs/heads/master@{#28622}
Alas, this involved quite a bit of copy-n-paste between the
architectures, but this is caused by the very convoluted
relationships, lifetimes and distribution of responsibilities. This
should really be cleaned up by moving code around and using STL maps,
but that's not really a priority right now.
Bonus: Fixed leaks in the ARM64 disassembler tests.
Review URL: https://codereview.chromium.org/1132943007
Cr-Commit-Position: refs/heads/master@{#28496}
The functions of strong classes are born non extensible. But, when
the class is created we need to add an own private symbol representing
the [[HomeObject]] slot in the spec.
Like for the hidden_string property, we allow adding private own
symbols to non extensible objects.
BUG=v8:4077
LOG=N
R=rossberg@chromium.org
Review URL: https://codereview.chromium.org/1138603003
Cr-Commit-Position: refs/heads/master@{#28447}
When we preprocess stack traces, we turn code pointer and offset to
source position, and store it in place of code pointer as smi.
Preprocessing stack traces is currently disabled due to issue 4065.
R=jkummerow@chromium.org
Review URL: https://codereview.chromium.org/1125723002
Cr-Commit-Position: refs/heads/master@{#28213}
If the array's map is the initial FastHoley array map, and the array prototype
chain is undisturbed and empty of elements, then keyed loads can convert the
load of a hole to undefined.
BUG=
Review URL: https://codereview.chromium.org/1100083002
Cr-Commit-Position: refs/heads/master@{#28056}
Reason for revert:
This was probably an infrastructure problem caused by the mac ninja/goma switch.
Original issue's description:
> Revert of Protect the emptiness of Array prototype elements with a PropertyCell. (patchset #7 id:120001 of https://codereview.chromium.org/1092043002/)
>
> Reason for revert:
> MAC GCSTRESS failure on new test.
>
> Original issue's description:
> > Protect the emptiness of Array prototype elements with a PropertyCell.
> >
> > Not just emptiness, but also a particular structure.
> >
> > BUG=v8:4044
> > LOG=N
>
> TBR=jkummerow@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=v8:4044
TBR=jkummerow@chromium.org,mvstanton@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4044
Review URL: https://codereview.chromium.org/1052253003
Cr-Commit-Position: refs/heads/master@{#28000}
Reason for revert:
MAC GCSTRESS failure on new test.
Original issue's description:
> Protect the emptiness of Array prototype elements with a PropertyCell.
>
> Not just emptiness, but also a particular structure.
>
> BUG=v8:4044
> LOG=N
TBR=jkummerow@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4044
Review URL: https://codereview.chromium.org/1099203004
Cr-Commit-Position: refs/heads/master@{#27998}
Not just emptiness, but also a particular structure.
BUG=v8:4044
LOG=N
Review URL: https://codereview.chromium.org/1092043002
Cr-Commit-Position: refs/heads/master@{#27993}
This fixes a race where
- mutator changes the fixed array length by trimming it,
- sweeper thread reads the length of the fixed array.
Also rename FROM_GC and FROM_MUTATOR to be more precise.
BUG=chromium:462908
LOG=NO
Review URL: https://codereview.chromium.org/1034163002
Cr-Commit-Position: refs/heads/master@{#27869}
The embedder can control how many threads it wants to use via the
v8::Platform implementation. V8 internally doesn't spin up threads
anymore. If the embedder doesn't want to use any threads at all, it's
v8::Platform implementation must either run the background jobs on
the foreground thread, or the embedder should specify --predictable
BUG=none
R=yangguo@chromium.org
LOG=y
Review URL: https://codereview.chromium.org/1064723005
Cr-Commit-Position: refs/heads/master@{#27833}
The motivation is that we prefer to avoid creating internal properties, and we have a usable field on maps ("transitions", which is not used for prototype maps).
This CL also ensures the invariant that prototype maps are never shared, even if they are in dictionary mode.
Review URL: https://codereview.chromium.org/1033653002
Cr-Commit-Position: refs/heads/master@{#27617}
This switches full-codegen to no longer push and pop StackHandler
markers onto the operand stack, but relies on a range-based handler
table instead. We only use StackHandlers in JSEntryStubs to mark the
transition from C to JS code.
Note that this makes deoptimization and OSR from within any try-block
work out of the box, makes the non-exception paths faster and should
overall be neutral on the memory footprint (pros).
On the other hand it makes the exception paths slower and actually
throwing and exception more expensive (cons).
R=yangguo@chromium.org
TEST=cctest/test-run-jsexceptions/DeoptTry
Review URL: https://codereview.chromium.org/1010883002
Cr-Commit-Position: refs/heads/master@{#27440}
Reason for revert:
Failing Blink tests on Win and Mac:
- plugins/netscape-plugin-property-access-exception.html
- http/tests/plugins/cross-frame-object-access.html
Original issue's description:
> Cleanup and unify Isolate::ReportPendingMessages.
>
> Note that this is a pure cleanup CL and shouldn't have an observable
> impact on the functional behavior of message reporting.
>
> R=yangguo@chromium.orgTBR=yangguo@chromium.org,machenbach@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review URL: https://codereview.chromium.org/1016323002
Cr-Commit-Position: refs/heads/master@{#27306}
This relands commit 96f79568a9.
This makes the Isolate::Throw logic not depend on a prediction of
whether an exception is caught or uncaught. Such a prediction is
inherently undecidable because a finally block can decide between
consuming or re-throwing an exception depending on arbitray control
flow.
There still is a conservative prediction mechanism in place that
components like the debugger or tracing can use for reporting.
With this change we can get rid of the StackHandler::kind field, a
pre-requisite to do table-based lookups of exception handlers.
R=yangguo@chromium.org
Review URL: https://codereview.chromium.org/997213003
Cr-Commit-Position: refs/heads/master@{#27263}
Reason for revert:
Layout test failure in inspector/sources/debugger/debugger-pause-on-promise-rejection.html
Original issue's description:
> Remove kind field from StackHandler.
>
> This makes the Isolate::Throw logic not depend on a prediction of
> whether an exception is caught or uncaught. Such a prediction is
> inherently undecidable because a finally block can decide between
> consuming or re-throwing an exception depending on arbitray control
> flow.
>
> There still is a conservative prediction mechanism in place that
> components like the debugger or tracing can use for reporting.
>
> With this change we can get rid of the StackHandler::kind field, a
> pre-requisite to do table-based lookups of exception handlers.
>
> R=yangguo@chromium.org
>
> Committed: https://crrev.com/96f79568a926966ebcf0685bf9adc947f4e1fbff
> Cr-Commit-Position: refs/heads/master@{#27210}
TBR=yangguo@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review URL: https://codereview.chromium.org/1009903002
Cr-Commit-Position: refs/heads/master@{#27215}
This makes the Isolate::Throw logic not depend on a prediction of
whether an exception is caught or uncaught. Such a prediction is
inherently undecidable because a finally block can decide between
consuming or re-throwing an exception depending on arbitray control
flow.
There still is a conservative prediction mechanism in place that
components like the debugger or tracing can use for reporting.
With this change we can get rid of the StackHandler::kind field, a
pre-requisite to do table-based lookups of exception handlers.
R=yangguo@chromium.org
Review URL: https://codereview.chromium.org/1002203002
Cr-Commit-Position: refs/heads/master@{#27210}
