Inline instance object hash code into object header on 64 bit.
64 bit objects have 32 bits of free space in the header word.
This is used for the hash code in string objects. We take it
for the default hash code on all objects that don't override
the hashCode getter.
This is both faster and a memory reduction. Eg it makes the
MegaHashCode part of the Megamorphic benchmark 6 times faster.
This is a reland of https://codereview.chromium.org/2912863006/
It fixes issues with the 32 bit compare-swap instruction on
ARM64 and fixes a fragile tree shaking test that is sensitive
to which private methods are in the core libraries.
R=kustermann@google.com, vegorov@google.com
BUG=
Review-Url: https://codereview.chromium.org/2954453002 .
I collected statistics for the sizes and capacities of growable arrays which are promoted to old-space or survive an old-space gc when running dart2js and Fasta. For these applications, the vast majority of arrays stay empty. More than half of the total object size of promoted backing arrays is backing for empty growable arrays.
Furthermore, since the overhead for an array is 3 words (header, type parameters and length), and object sizes are rounded up to an even number of words, we waste one word for all even-sized arrays.
This CL changes the growth strategy so that empty growable arrays are created with a shared, zero-sized array as backing, avoiding the allocation of a backing array if no elements are added. When the array needs to grow, it starts out at 3 and grows to double size plus one each time: 7, 15, 31, ...
A few places in the VM code need to handle these shared, zero-sized arrays specially. In particular, the Array::MakeArray function needs to allocate a new, empty array if its result is to be returned to Dart code.
Benchmarks suggest that the change improves memory usage by a few percent overall and does not significantly affect run time.
BUG=
R=erikcorry@google.com
Review-Url: https://codereview.chromium.org/2949803002 .
64 bit objects have 32 bits of free space in the header word.
This is used for the hash code in string objects. We take it
for the default hash code on all objects that don't override
the hashCode getter.
This is both faster and a memory reduction. Eg it shaves about
70% off the running time of this microbenchmark:
List list = [];
class Thing {
get hashCode => 42;
}
class Thing2 {
get hashCode => 42;
}
class Thing3 { }
class Thing4 { }
main() {
int sum = 103;
for (int i = 0; i < 10000000; i++) {
list = [];
list.add("foo");
list.add(123);
list.add(1.23);
list.add(new Object());
list.add(new Thing());
list.add(new Thing2());
list.add(new Thing3());
list.add(new Thing4());
for (int j = 0; j < 2; j++) {
sum ^= biz(list);
}
}
print(sum);
}
int biz(List list) {
int sum = 103;
for (var x in list) {
sum ^= x.hashCode;
}
return sum;
}
R=rmacnak@google.com, vegorov@google.com
BUG=
Review-Url: https://codereview.chromium.org/2912863006 .
Also, fix a minor bug in variable declaration inference that was
preventing a local variable without an initializer from having its
type properly "inferred" as `dynamic`.
R=sigmund@google.com
Review-Url: https://codereview.chromium.org/2949093002 .
It can compile and run tests on Chrome. There are a lot of failing tests
that I (or the team) will need to triage, but I think at least basic
tests are working as expected.
There is code that could be cleaned up to more neatly factor how dart2js
and dartdevc are handled now that there are two separate compilers to
JS. There's also some redundant code between the path for testing
compile errors (enqueueStandardTest()) and the path for running a test
in the browser.
R=whesse@google.com
Review-Url: https://codereview.chromium.org/2947473002 .
Do this in unoptimized code only, when --reify-generic-functions is specified.
This is still work in progress, and support in optimizer, in inliner, in DBC,
in kernel to ir, and other areas, will follow.
Many small fixes and added todos.
R=rmacnak@google.com, vegorov@google.com
Review-Url: https://codereview.chromium.org/2941643002 .
Mostly stream kernel_reader, i.e. the code that sets up the libraries,
classes, methods etc.
Mostly because it still takes a "Program" ast node, and looks at the
"Library" ast nodes to get their kernel offset in the binary.
Currently the scripts (containing breakable points etc) are also created
from the ast nodes.
The rest is now streamed.
This also means that more ast visitors could be deleted.
R=kmillikin@google.com
Review-Url: https://codereview.chromium.org/2931813002 .
This file was auto-formatted 2 months ago.
This - among other things - removed a linebreak which shifted linenumbers
by one, but didn't update the expected linenumbers from a throw accordingly.
Somehow the testserver has claimed that this has passed until now.
I have no idea how that happened.
This CL re-introduces the linebreak by inserting a comment,
which (currently) forces dartfmt to have the wanted linebreak.
BUG=
R=dmitryas@google.com
Review-Url: https://codereview.chromium.org/2945273002 .
Previously these functions would only contain a single CheckStackOverflowInstr
in a backtracking block and that CheckStackOverflowInstr would have a zero
loop_depth - which means it would not be considered eligable for OSR.
This change:
* adds CheckStackOverflowInstr with non-zero loop_depth in two other places
(Boyer-Moore lookahead skip loop and greedy loop) where loops arise in the
generated IL;
* sets non-zero loop depth on the CheckStackOverflowInstr in the backtracking
block;
* adds a flag on CheckStackOverflowInstr that allows optimizing compiler to
optimize away those checks that were inserted solely to serve as OSR entries.
We allow the optimizing compiler to remove preemption checks from
non-backtracking loops in the regexp code because those loops
unlike backtracking have guaranteed O(input_length) time
complexity.
Performance Implications
------------------------
This change improves performance of regexps in cases where regexp spends a lot
of time in the first invocation (either due to backtracking or due to long non
matching prefix) by allowing VM to optimize the :matcher while :matcher is
running.
For example on regex-redux[1] benchmark it improves Dart performance by 3x
(from ~18s to ~6s on my Mac Book Pro).
[1] https://benchmarksgame.alioth.debian.org/u64q/program.php?test=regexredux&lang=dart&id=2
BUG=
R=erikcorry@google.com
Review-Url: https://codereview.chromium.org/2950783003 .
