Symptom of the problem:
Set your Linux workstation (or Mac or MIPS board) to the Europe/London timezone
and the corelib/date_time test will fail, claiming that 1/1/1970 was a Wednesday
(it was actually a Thursday, trust me, I was already born).
Problem:
The implementation of DateTime in the VM relies on Unix time_t, the number of
seconds since the Epoch (1/1/1970 UTC). When asked for the weekday of a given
time, our implementation limits itself to a 32-bit positive range of time_t.
If the time falls outside of this range, the implementation picks an equivalent
time in the valid range with the same weekday, also in leap year or not, etc...
The issue is that DateTime is using the underlying OS in an inconsistent manner.
Let's take the example above: 1/1/1970 in the Europe/London timezone.
First, the number of seconds since the Epoch in UTC is calculated, here 0.
Then, the timezone offset at the given time is calculated using the underlying
OS. In this case, an historical deviation is taken into account. Indeed, London
stayed on British Summer Time between 27 October 1968 and 31 October 1971. See
https://en.wikipedia.org/wiki/British_Summer_Time#Periods_of_deviation for
details.
Our resulting time is therefore negative (one hour difference with UTC).
When asked about the weekday of this time, the implementation notices that the
time is not in the positive range and picks an "equivalent" time in the future.
It then asks the underlying OS about the timezone offset for this time, which
is 0 (usually no daylight saving time in January in London). Unfortunately,
this time is not really equivalent, because it ignores the original historical
deviation. The result is wrongly equivalent to 12/31/1969 23:00 in London, i.e.
a Wednesday, and not a Thursday as expected.
Solution:
We should use the underlying OS in a consistent way, by simply allowing the
value of time_t passed to the underlying OS to be negative, which is legal.
R=floitsch@google.com, rmacnak@google.com
Review URL: https://codereview.chromium.org/1845483002 .
Problems this addresses:
1. dart2js has hashCode functions like
get hashCode = this.x.hashCode + 17 * this.y.hashCode
When x and y are ints or bools VM optimizing compiler inlined the call
to Object.hashCode and generated MegamorphicLookups for
Object._identityHashCode.
2. HashMaps with _Smi keys had a double MegamorphicLookup: The hash
table reasonably calls MegamorphicLookup(get:hashCode) which returns
Object.hashCode; the compiled Object.hashCode is essentially
MegamorphicLookup(get:_identityHashCode), which returns
_Smi._identityHashCode which finally returns 'this'.
3. _interpolateSingle's call to o.toString() is megamorphic. We can
avoid it for the common case of String arguments, this is often
comming from StringBuffer.write() with a literal or interpolated
argument.
R=srdjan@google.com
Review URL: https://codereview.chromium.org/1820653002 .
This removes the additional indirection to the VM's implementation
for all the factory constructors.
Additionally, it removes one class per typed data list type, thus reducing
snapshot and generated code size.
BUG=
R=asiva@google.com
Review URL: https://codereview.chromium.org/1790593002 .
API changes:
- Remove isolate specific Timeline APIs.
- Remove Dart_EmbedderTimelineGetTimeline callback.
- Add Dart_TimelineEvent so that arbitrary trace events can be added.
Internal changes:
- Remove isolate specific streams which were never used or controllable from outside the VM.
R=rmacnak@google.com
Review URL: https://codereview.chromium.org/1811613002 .
For now, change compilation-related flags to be regular
command line options. They won't affect the size of the
precompiled runtime anyway since the compiler is not included
there.
Also introduce a separate switch for precompiled runtime. This can be
used instead of the macro since it is a compile-time constant in the
precompiled runtime.
BUG=
Review URL: https://codereview.chromium.org/1759913002 .
Move optimizations for precompilation into separate file.
Remove precompilation-specific code from flow_graph_optimizer.cc.
Add precompilation-flags: They are const in the precompiled runtime. Started moving flags to use the new flag-definition macros.
Add libdart_lib_precompiled target.
Define PRECOMPILED_RUNTIME_MACRO in more places (dart_precompiled_runtime)
BUG=
R=rmacnak@google.com
Review URL: https://codereview.chromium.org/1714743002 .
Async generators should only react to a cancellation when they
yield a value. Otherwise, the cancellation is ignored.
The example in dartbug.com/23436 should therefore never terminate,
because the generator function contains no yield statement.
This CL fixes bug 23436 by implementing the expected behavior, i.e.
not terminating the generator. If a yield statement is added to the
generator, the finally clause is executed once only, as expected.
BUG=23436
R=floitsch@google.com
Review URL: https://codereview.chromium.org/1683763002 .
- Use TokenDescriptor instead of intptr_t for all token positions.
- Use TokenDescriptor in raw_object instead of int32_t.
- TokenDescriptor is a POD with an int32_t (this shrinks the size of AST and IR nodes by 32-bits on 64-bit architectures).
There are some cleanups I plan on doing as a follow up CL:
- Replace TokenDescriptor::value() with TokenDescriptor::TokenPos()
R=iposva@google.com, rmacnak@google.com
Review URL: https://codereview.chromium.org/1644793002 .
- uses thread execution status transition to track when a thread is in a safepoint or needs to block for a safepoint
- introduces a monitor per Thread object
- uses a per thread safepoint handshake between the thread requesting a safepoint and the requested thread.
The ThreadRegistry class now contains only the thread list for an isolate and the functionality of scheduling a thread onto an Isolate and unscheduling it from teh isolate. We could fold this functionality into the Isolate class in a different CL.
R=rmacnak@google.com, zra@google.com
Review URL: https://codereview.chromium.org/1541073002 .
- Cleanups to the embedder's Dart sources for the service isolate. This lets us stop keeping a local copy in the mojo and flutter trees.
- Let the VM know Observatory's server address.
R=zra@google.com
Review URL: https://codereview.chromium.org/1640773005 .
They were used as the class of closure instances and as the type class of
function types.
All closure instances now have class _Closure and function types are represented
by a new class FunctionType extending AbstractType.
Fix issue 24567 and add regression test.
R=asiva@google.com, rmacnak@google.com
Review URL: https://codereview.chromium.org/1584223006 .
- Rework token position address space.
- Use ClassifyingTokenPositions::kMethodExtractor for the token position of a method extractor.
- Plumb token positions through all of Ast Transformer.
- Plumb token positions for temporary expressions, etc in Flow Graph Builder.
- Add token positions for parts of the await machinery.
- Move ClassifyingTokenPositions into token.h.
- Remove default token position of Scanner::kNoSourcePos for many IR instructions.
- A couple of unit tests.
- Use synthetic token positions for synthetic AstNodes.
- Fix SLEB128 encoding / decoding + test
- s/Scanner::kNoSourcePos/Token::kNoSourcePos.
- Remove >= 0 and < 0 checks against token positions and use helpers instead.
R=rmacnak@google.com
Review URL: https://codereview.chromium.org/1589643002 .
Super initializer calls get implicitly moved to the end of the initializer list, so we don't need the two-phase constructor protocol anymore.
Ryan, can you please look at the mirror changes and check wether I've missed something?
BUG=
R=asiva@google.com, rmacnak@google.com
Review URL: https://codereview.chromium.org/1569213003 .
Regis Crelier