Move generation of Function objects for native trampolines to the Precompiler, so they can be generated during AOT and tree-shaken if possible.
Issue dartbug.com/35765
Change-Id: I0e69b7e0b22db73e3a40f2fe445660e57ddb6fa9
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-bare-linux-release-simarm64-try, vm-kernel-precomp-bare-linux-release-x64-try, vm-kernel-precomp-linux-debug-x64-try, vm-dartkb-linux-debug-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107407
Commit-Queue: Samir Jindel <sjindel@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
- Hook up allocation tracing.
- Fix off-by-one when mapping bcpcs to token positions.
- Fix missing class loading for predefined classes in Dart_Invoke type checks.
Change-Id: Id9177001d493725a0545c5948b7f7c6b4693027c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107564
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Régis Crelier <regis@google.com>
Previously, core snapshot was generated from AST
(because --enable-interpreter/--use-bytecode-compiler was not specified
when building core snapshot).
As the result, CL
https://dart.googlesource.com/sdk/+/da8cb470cc94830a98d49532e8d5d1a5b3d80f8b
which declared libraries in bytecode also removed bytecode entirely from
core snapshot in Dart SDK.
This CL enables bytecode by default if --bytecode argument is
specified for gn.py. This enables JIT compiler from bytecode
(interpreter is still disabled by default but can be enabled
using --enable-interpreter). Core snapshot and other
snapshots now have bytecode.
This change revealed a bunch of bugs which are fixed in this CL:
* _Closure fields were treated as unboxing candidates which triggered
assertion in LoadFieldTOS in interpreter.
* Several places should load class declarations if they are not loaded yet.
* Canonicalization of TypeRef objects which are not fully initialized
may cause duplicate entries in the hash table of canonical
TypeArguments. This triggers assertions when hash table is rehashed.
The solution is to avoid canonicalization of non-root recursive types
and recursive type arguments. Also, TypeRef::Canonicalize and
TypeRef::Hash are reverted to assert and work only if type was set.
* Native wrapper classes are eagerly stamped as type-finalized
which caused assertion failures when reading their class declarations
from bytecode.
* When building flow graph for FFI trampolines kernel offset of library
(which is now declared in bytecode) was queried. Added special case
to Function::KernelDataProgramOffset().
* In interpreter-only mode with simulator (e.g. SIMARM64) if simulator
is not called before code is interrupted with stack overflow check,
simulator returns get_sp() = 0, which was treated as stack overflow.
* test standalone_2/io/platform_resolved_executable_test.dart
spawns sub-process but it didn't pass VM options.
Change-Id: I81bc4f1a4c6725cfa246a435ebe5d8abe43abc67
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107199
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Régis Crelier <regis@google.com>
This was triggered by 85360 which introduced external code observers
called during dart init.
The bug is however susceptible to racing as tests often shutdown the VM
before the code is fully deserialised.
Code::function() is deceptive as it does in fact not guarantee that its
return value is a Function. This in turn caused observer code to try access
non-exists members on not-actually-Functions.
Tested:
tools/test.py -n dartk-asan-linux-debug-x64 vm/cc/DartAPI_DartInitializeCallsCodeObserver
Change-Id: I12e367be06a3630d2d401a37b9097273c13f31e1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107289
Commit-Queue: Clement Skau <cskau@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Instead, we set a bit on force-optimized code so that deoptimization knows to skip it and exception
handling will execute catch-entry moves.
In addition we don't throw away deoptimization info for these codes, so that exception handling
works.
Bug: dartbug.com/37311
Change-Id: If5bcff41a98c0053c581648a9ee22b3302ceea04
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/106740
Commit-Queue: Samir Jindel <sjindel@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Rationale:
Previously all constants were read from the constants table,
whether they were needed (at that point or at all) or not. This
CL replaces that eager reading with a lazy reading that makes
the raw bytes of the constants table available through
KernelProgramInfo and attaches a hashmap to KernelProgramInfo,
which maps offsets into the constant table to evaluated constants.
The maps starts empty and on a miss, the constant is evaluated,
but no sooner than when it it needed.
https://github.com/dart-lang/sdk/issues/36220
Change-Id: Ief4df3d70c950c4beb61d896632ce06cfd12d525
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/99088
Commit-Queue: Aart Bik <ajcbik@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Size of a large application:
Before: 26628600
After: 21480120 (-19.3%)
Size of snapshots:
isolate_snapshot_framework.bin
Before: 9322496
After: 6782976 (-27.2%)
isolate_snapshot_product_framework.bin
Before: 9166848
After: 6602752 (-27.9%)
Regressions in tests:
1) Test language_2/type_alias_equality_test/04 fails similarly to default mode, as VM
does not implement comparison of function types according to the specification.
Previously this test was passing as function types were canonicalized in bytecode,
which was not always correct. This CL fixes the problem with canonicalization of
function types in bytecode and the test starts failing again.
2) Tests standalone_2/entrypoints_verification_test, standalone_2/io/test_extension_test,
standalone_2/io/test_extension_fail_test fail as native extensions are not supported
in bytecode yet. These tests start passing after df5e7aac17,
which switched bytecode tests to kernel service (on x64), because kernel service doesn't
drop ASTs. This CL switches from reading AST library declarations to bytecode even if
AST is not removed, so tests fail again.
Change-Id: I8b7ba44bfa49d0b1599b2509553ff7c831a4e244
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/104700
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Régis Crelier <regis@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
dart-bytecode, arm64: +4.742% geomean
dart-bytecode-jit-unopt, arm64: +12.73% geomean
dart2js-compile, x64: +3.635% geomean
In the polymorphic and unlinked cases, call to a stub the does a linear scan against an ICData.
In the monomorphic case, call to a prologue of the expected target function that checks the expected receiver class. There is additional indirection in the JIT version compared to the AOT version to also tick a usage counter so the inliner can make good decisions.
In the megamorphic case, call to a stub that does a hash table lookup against a MegamorphicCache.
Megamorphic call sites face a loss of precision in usage counts. The call site count is not recorded and the usage counter of the target function is used as an approximation.
Monomorphic and megamorphic calls sites are reset to the polymorphic/unlinked state on hot reload.
Monomorphic and megamorphic calls sites do not check the stepping state, so they are reset to the polymorphic/unlinked state when stepping begins and disabled.
Back-edges now increment the usage counter in addition to checking it. This ensures function with loops containing monomorphic calls will eventually cross the optimization threshold.
Fixed backwards use of kMonomorphicEntryOffset and kPolymorphicEntryOffset.
Fixed C stack overflow when bouncing between the KBC interpreter and a simulator.
Bug: https://github.com/dart-lang/sdk/issues/26780
Bug: https://github.com/dart-lang/sdk/issues/36409
Bug: https://github.com/dart-lang/sdk/issues/36731
Change-Id: I78a49cccd962703a459288e71ce246ed845df474
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/102820
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Calculation of Class::NumTypeArguments() is reimplemented so that it does
no require separate calculation of Class::NumOwnTypeArguments().
Number of own type arguments is no longer stored in Class, and has_pragma
bit is moved into state_bits.
This simplifies overall calculation and does not require to keep both
num_type_arguments and num_own_type_arguments. This also allows us to add
up to 15 more flag bits to Class.
Change-Id: Iac7a751145fea7adb673ab9369eeb8eea5c5794d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/105544
Reviewed-by: Régis Crelier <regis@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
TransferableTypedData instances are one-use kind of thing: once receiver materializes it, it can't be used
again, once sender sends it out to an isolate, sender can't send it to different isolate.
Example of use:
sender isolate:
```
Future<TransferableTypedData> consolidateHttpClientResponseBytes(HttpClientResponse response) {
final completer = Completer<TransferableTypedData>();
final chunks = <Uint8List>[];
response.listen((List<int> chunk) {
chunks.add(chunk);
}, onDone: () {
completer.complete(TransferableTypedData.fromList(chunks));
});
return completer.future;
}
...
sendPort.send(await consolidateHttpClientResponseBytes(response));
```
receiver isolate:
```
RawReceivePort port = RawReceivePort((TransferableTypedData transferable) {
Uint8List content = transferable.materialize().asUint8List();
...
});
```
31959[tr] and 31960[tr] tests were inspired by dartbug.com/31959, dartbug.com/31960 that this CL attempts to address:
```
╰─➤ out/ReleaseX64/dart 31960.dart
sending...
163ms for round-trip
sending...
81ms for round-trip
sending...
20ms for round-trip
sending...
14ms for round-trip
sending...
20ms for round-trip
sending...
14ms for round-trip
```
(notice no "since last checking" pauses") vs
```
╰─➤ out/ReleaseX64/dart 31960.dart
sending...
154ms since last checkin
174ms for round-trip
sending...
68ms since last checkin
9ms since last checkin
171ms for round-trip
sending...
13ms since last checkin
108ms for round-trip
sending...
14ms since last checkin
108ms for round-trip
sending...
14ms since last checkin
107ms for round-trip
```
Change-Id: I0fcb5ce285394f498c3f1db4414204531f98199d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/99623
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
This change renames Class::is_cycle_free to Class::is_declaration_loaded
and under the hood replaces cycle_free and type_finalized bits with
class loading state enum.
Also, added new assertions to check is_declaration_loaded().
Change-Id: Ib43e12731d0dc782e273be8e55912494e102cd79
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/104920
Reviewed-by: Régis Crelier <regis@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
This reverts commit ab6aeaa106.
Revert "[vm/compiler] Speed up the compiler part which deals with kernel reading up in DEBUG mode"
This reverts commit b316210d94.
Reason for revert: regression of snapshot sizes (DNO-599).
Original change's description:
> [vm/kernel] Use GC-tracked ExternalTypedData/TypedDataView for kernel buffers
>
> Until now we often leaked kernel buffers (e.g. hot reload buffers) because various
> objects were referencing ExternalTypedData objects pointing into the middle of
> c-allocated memory. This made it impossible for the GC to determine when the last
> reference is gone.
>
> This CL ensures that the actual buffers are *always* made available via
> ExternalTypedData and any inner pointers into it are created via TypedDataViews.
>
> The embedder guarantees to the free kernel buffers it has provided to:
> - Dart_CreateIsolateFromKernel
> - Dart_LoadScriptFromKernel
> - Dart_LoadLibraryFromKernel
> - Dart_SetDartLibrarySourcesKernel
> on isolate shutdown.
>
> All other kernel buffers will get a finalizer attached, which ensures the
> kernel buffers get freed by the GC once they are no longer referenced:
> - Kernel blobs for expression evaluation
> - Kernel blobs for Hot-Reload
> - Kernel blobs for cc tests
>
> Fixes https://github.com/dart-lang/sdk/issues/33973
> Fixes https://github.com/dart-lang/sdk/issues/36857
> Issue https://github.com/dart-lang/sdk/issues/37030
>
> Change-Id: I1cc410c94c0f4b229413e793728a261afcb10aaf
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103130
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
> Commit-Queue: Martin Kustermann <kustermann@google.com>
TBR=kustermann@google.com,rmacnak@google.com
# Not skipping CQ checks because original CL landed > 1 day ago.
Change-Id: I49715d2400f4a5c8806b7d6a2912b7258f671a0a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/104343
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
Auto-Submit: Alexander Markov <alexmarkov@google.com>
This reverts commit fde6a5917e.
Reason for revert: This commit looks to be causing new test failures on dart2js. While there are some odd results on some builders that look like infra failures, some builders (for example, dart2js-minified-strong-linux-x64-d8) show the new failing tests clearly.
Original change's description:
> [vm, compiler] Unoptimized megamorphic calls.
>
> When an instance call in unoptimized code creates more than FLAG_max_polymorphic_checks cases, switch the call to use a MegamorphicCache instead of ICData. The prevents unbounded collection of type feedback, and gives improvements on microbenchmarks in the 3-8% range for unoptimized code.
>
> It also leads to a loss of target frequency information for the optimizer, leading to different ordering for range checks in polymorphic inlining. This leads to changes on megamorphic microbenchmarks from -31% to +60%, weighted toward the negative end.
>
> In practice the frequency information seems unimportant, as dart2js has 4.01% geomean improvement.
>
> This is a step toward direct monomorphic calls in unoptimized code, which will also make use of the patching and type feedback extraction added here.
>
> Bug: https://github.com/dart-lang/sdk/issues/26780
> Bug: https://github.com/dart-lang/sdk/issues/36409
> Bug: https://github.com/dart-lang/sdk/issues/36731
> Change-Id: I29f53f23b6794c5f5f0db8b8184788cee16fd9c5
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/99270
> Reviewed-by: Alexander Markov <alexmarkov@google.com>
TBR=rmacnak@google.com,alexmarkov@google.com,ajcbik@google.com
Change-Id: Icad46b93cdf8541a00563f49da6b4ac0a4df1ba1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: https://github.com/dart-lang/sdk/issues/26780, https://github.com/dart-lang/sdk/issues/36409, https://github.com/dart-lang/sdk/issues/36731
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103440
Reviewed-by: Teagan Strickland <sstrickl@google.com>
Commit-Queue: Teagan Strickland <sstrickl@google.com>
Until now we often leaked kernel buffers (e.g. hot reload buffers) because various
objects were referencing ExternalTypedData objects pointing into the middle of
c-allocated memory. This made it impossible for the GC to determine when the last
reference is gone.
This CL ensures that the actual buffers are *always* made available via
ExternalTypedData and any inner pointers into it are created via TypedDataViews.
The embedder guarantees to the free kernel buffers it has provided to:
- Dart_CreateIsolateFromKernel
- Dart_LoadScriptFromKernel
- Dart_LoadLibraryFromKernel
- Dart_SetDartLibrarySourcesKernel
on isolate shutdown.
All other kernel buffers will get a finalizer attached, which ensures the
kernel buffers get freed by the GC once they are no longer referenced:
- Kernel blobs for expression evaluation
- Kernel blobs for Hot-Reload
- Kernel blobs for cc tests
Fixes https://github.com/dart-lang/sdk/issues/33973
Fixes https://github.com/dart-lang/sdk/issues/36857
Issue https://github.com/dart-lang/sdk/issues/37030
Change-Id: I1cc410c94c0f4b229413e793728a261afcb10aaf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103130
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
When an instance call in unoptimized code creates more than FLAG_max_polymorphic_checks cases, switch the call to use a MegamorphicCache instead of ICData. The prevents unbounded collection of type feedback, and gives improvements on microbenchmarks in the 3-8% range for unoptimized code.
It also leads to a loss of target frequency information for the optimizer, leading to different ordering for range checks in polymorphic inlining. This leads to changes on megamorphic microbenchmarks from -31% to +60%, weighted toward the negative end.
In practice the frequency information seems unimportant, as dart2js has 4.01% geomean improvement.
This is a step toward direct monomorphic calls in unoptimized code, which will also make use of the patching and type feedback extraction added here.
Bug: https://github.com/dart-lang/sdk/issues/26780
Bug: https://github.com/dart-lang/sdk/issues/36409
Bug: https://github.com/dart-lang/sdk/issues/36731
Change-Id: I29f53f23b6794c5f5f0db8b8184788cee16fd9c5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/99270
Reviewed-by: Alexander Markov <alexmarkov@google.com>
When a mixin class is created, there might be anonymous closures copied over to the other script.
Previously the script of closure function is the script of its parent function, which is not true in that case.
The solution is to create a patch class as the owner if parent function has a different script object. Return script of owner when query for script of closure function.
Bug: https://github.com/dart-lang/sdk/issues/34841
Change-Id: I53065cbf13f2d0dc8da320993fd3cd425e5c9714
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/102226
Commit-Queue: Zichang Guo <zichangguo@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
There were rare crashes
../../runtime/vm/compiler/call_specializer.cc: 1393: error: expected: call->MatchesCoreName(Symbols::_simpleInstanceOf())
version=2.3.0-edge.796ebc6069bde3a59475a9b45075f49e50b0cc34 (Thu May 9 09:38:28 2019 -0700) on "linux_x64"
thread=82540, isolate=vm-service(0x558748c5d200)
pc 0x000055874635dd6c fp 0x00007fa94dd3bf30 dart::Profiler::DumpStackTrace(void*)
pc 0x0000558745f90332 fp 0x00007fa94dd3c010 dart::Assert::Fail(char const*, ...)
pc 0x000055874653909b fp 0x00007fa94dd3c0a0 dart::CallSpecializer::ReplaceWithInstanceOf(dart::InstanceCallInstr*)
pc 0x0000558746496ed6 fp 0x00007fa94dd3c0f0 dart::FlowGraphVisitor::VisitBlocks()
when running
tools/test.py --repeat 5000 -n dartkb-mixed-linux-debug-x64 language_2/null_test
at the rate ~1-3 crashes per 30,000 test cases.
The problem is that in function
bool InstanceCallInstr::MatchesCoreName(const String& name) {
return function_name().raw() == Library::PrivateCoreLibName(name).raw();
}
'function_name().raw()' is evaluated before PrivateCoreLibName(name) is called
and saved in a temporary (register). PrivateCoreLibName may trigger GC and
relocate objects. In such case, 'PrivateCoreLibName(name).raw()' results in a
moved object, which is compared to a stale object address.
This CL fixes InstanceCallInstr::MatchesCoreName and other similar places
by introducing Library::IsPrivateCoreLibName, which is also a little bit more
efficient as it avoids extra symbol table lookup.
Change-Id: I4dc91c586b0c595a3e85d6da13b98fc2248fb8fd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/102120
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Aart Bik <ajcbik@google.com>
It already is a static method in implementation, so this way
we don't duplicate the work of looking up the library. In addition,
it checks has_pragma, so we don't need to check before calling it.
Change-Id: I88281cf22615e30157c842c570bd0f6b499a6a3d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/101821
Commit-Queue: Teagan Strickland <sstrickl@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
This work pulls in v8 support for these features with
appropriate changes for Dart and closes
https://github.com/dart-lang/sdk/issues/34935.
This adds support for the following features:
* Interpreting patterns as Unicode patterns instead of
BMP patterns
* the dotAll flag (`/s`) for changing the behavior
of '.' to also match line terminators
* Escapes for character classes described by Unicode
property groups (e.g., \p{Greek} to match all Greek
characters, or \P{Greek} for all non-Greek characters).
The following TC39 proposals describe some of the added features:
* https://github.com/tc39/proposal-regexp-dotall-flag
* https://github.com/tc39/proposal-regexp-unicode-property-escapes
These additional changes are included:
* Extends named capture group names to include the full
range of identifier characters supported by ECMAScript,
not just ASCII.
* Changing the RegExp interface to return RegExpMatch
objects, not Match objects, so that downcasting is
not necessary to use named capture groups from Dart
**Note**: The changes to the RegExp interface are a
breaking change for implementers of the RegExp interface.
Current users of the RegExp interface (i.e., code using Dart
RegExp objects) will not be affected.
Change-Id: Ie62e6082a0e2fedc1680ef2576ce0c6db80fc19a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/100641
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Stevie Strickland <sstrickl@google.com>
This reverts commit 5ebb640a67.
Reason for revert: <INSERT REASONING HERE>
Original change's description:
> [vm] Finish adding support for ECMAScript 2018 features.
>
> This work pulls in v8 support for these features with
> appropriate changes for Dart and closes
> https://github.com/dart-lang/sdk/issues/34935.
>
> This adds support for the following features:
>
> * Interpreting patterns as Unicode patterns instead of
> BMP patterns
> * the dotAll flag (`/s`) for changing the behavior
> of '.' to also match line terminators
> * Escapes for character classes described by Unicode
> property groups (e.g., \p{Greek} to match all Greek
> characters, or \P{Greek} for all non-Greek characters).
>
> The following TC39 proposals describe some of the added features:
>
> * https://github.com/tc39/proposal-regexp-dotall-flag
> * https://github.com/tc39/proposal-regexp-unicode-property-escapes
>
> These additional changes are included:
>
> * Extends named capture group names to include the full
> range of identifier characters supported by ECMAScript,
> not just ASCII.
> * Changing the RegExp interface to return RegExpMatch
> objects, not Match objects, so that downcasting is
> not necessary to use named capture groups from Dart
>
> **Note**: The changes to the RegExp interface are a
> breaking change for implementers of the RegExp interface.
> Current users of the RegExp interface (i.e., code using Dart
> RegExp objects) will not be affected.
>
> Change-Id: I0709ed0a8d5db36680e32bbad585594857b9ace4
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/95651
> Commit-Queue: Stevie Strickland <sstrickl@google.com>
> Reviewed-by: Johnni Winther <johnniwinther@google.com>
> Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
TBR=lrn@google.com,kustermann@google.com,jmesserly@google.com,johnniwinther@google.com,sstrickl@google.com
# Not skipping CQ checks because original CL landed > 1 day ago.
Change-Id: I1eda0fee4fd9e94df095944049833a67b07277e2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/100560
Reviewed-by: Keerti Parthasarathy <keertip@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Keerti Parthasarathy <keertip@google.com>