v8/test/unittests
Benedikt Meurer d6a60a0ee1 [turbofan] Significantly improve ConsString creation performance.
This change significantly improves the performance of string
concatenation in optimized code for the case where the resulting string
is represented as a ConsString. On the relevant test cases we go from

  serializeNaive: 10762 ms.
  serializeClever: 7813 ms.
  serializeConcat: 10271 ms.

to

  serializeNaive: 10278 ms.
  serializeClever: 5533 ms.
  serializeConcat: 10310 ms.

which represents a 30% improvement on the "clever" benchmark, which
tests specifically the ConsString creation performance.

This was accomplished via a couple of different steps, which are briefly
outlined here:

  1. The empty_string gets its own map, so that we can easily recognize
     and handle it appropriately in the TurboFan type system. This
     allows us to express (and assert) that the inputs to NewConsString
     are non-empty strings, making sure that TurboFan no longer creates
     "crippled ConsStrings" with empty left or right hand sides.
  2. Further split the existing String types in TurboFan to be able to
     distinguish between OneByte and TwoByte strings on the type system
     level. This allows us to avoid having to dynamically lookup the
     resulting ConsString map in case of ConsString creation (i.e. when
     we know that both input strings are OneByte strings or at least
     one of the input strings is TwoByte).
  3. We also introduced more finegrained feedback for the Add bytecode
     in the interpreter, having it collect feedback about ConsStrings,
     specifically ConsOneByteString and ConsTwoByteString. This feedback
     can be used by TurboFan to only inline the relevant code for what
     was seen so far. This allows us to remove the Octane/Splay specific
     magic in JSTypedLowering to detect ConsString creation, and instead
     purely rely on the feedback of what was seen so far (also making it
     possible to change the semantics of NewConsString to be a low-level
     operator, which is only introduced in SimplifiedLowering by looking
     at the input types of StringConcat).
  4. On top of the before mentioned type and interpreter changes we added
     new operators CheckNonEmptyString, CheckNonEmptyOneByteString, and
     CheckNonEmptyTwoByteString, which perform the appropriate (dynamic)
     checks.

There are several more improvements that are possible based on this, but
since the change was already quite big, we decided not to put everything
into the first change, but do some follow up tweaks to the type system,
and builtin optimizations later.

Tbr: mstarzinger@chromium.org
Bug: v8:8834, v8:8931, v8:8939, v8:8951
Change-Id: Ia24e17c6048bf2b04df966d3cd441f0edda05c93
Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
Doc: https://bit.ly/fast-string-concatenation-in-javascript
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1499497
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60318}
2019-03-19 10:43:00 +00:00
..
api Make Isolate::GetIncumbentContext() work fine with ASAN 2018-11-21 05:40:08 +00:00
asmjs [ubsan] Fix errors related to AsmType 2019-01-07 13:07:26 +00:00
assembler PPC: removed AIX function descriptors in tests 2019-03-06 12:55:45 +00:00
base test: Replace _TEST_CASE_ with _TEST_SUITE_. 2019-02-18 21:36:56 +00:00
compiler [turbofan] Significantly improve ConsString creation performance. 2019-03-19 10:43:00 +00:00
compiler-dispatcher [tsan] Avoid modifying flags back and forth for each microtask queue test 2019-03-08 12:56:23 +00:00
heap [heap] Decouple the max semi-space size from the page size 2019-03-05 12:12:20 +00:00
interpreter [lite] Allocate FeedbackCell arrays for create closures in lite mode 2019-03-12 14:28:29 +00:00
libplatform [cleanup] Mark libplatform methods in subclasses with override. 2018-09-14 16:43:37 +00:00
parser [cleanup] #include heap-inl.h less often 2019-02-15 06:22:53 +00:00
regress [heap] Throw OOM when allocating FixedDoubleArrays with negative length 2019-03-06 10:55:42 +00:00
torque [torque-ls] Support "goto-definition" for Types in extends clause 2019-03-12 09:21:44 +00:00
wasm [wasm][anyref] Introduce anyfunc globals 2019-03-18 12:01:52 +00:00
zone [zone] Remove segment pooling from accounting allocator 2019-03-01 09:25:48 +00:00
allocation-unittest.cc [cleanup] Mark test/ methods in subclasses with override. 2018-09-17 07:40:00 +00:00
background-compile-task-unittest.cc [tsan] Avoid modifying flags back and forth for each microtask queue test 2019-03-08 12:56:23 +00:00
bigint-unittest.cc Reland: [cleanup] Refactor the Factory 2018-04-09 19:52:22 +00:00
BUILD.gn [heap] Throw OOM when allocating FixedDoubleArrays with negative length 2019-03-06 10:55:42 +00:00
cancelable-tasks-unittest.cc [wasm] Reschedule compilation tasks 2019-01-17 18:27:08 +00:00
char-predicates-unittest.cc [cleanup] Make unicode predicate cache tables static 2018-11-14 15:33:45 +00:00
code-stub-assembler-unittest.cc [csa] re-schedule CSA graph 2018-11-13 17:12:01 +00:00
code-stub-assembler-unittest.h [cleanup] Refactor general tests to use default members. 2018-09-14 14:40:47 +00:00
conversions-unittest.cc [conversions] Speed up double to CString conversion 2018-12-19 12:10:50 +00:00
counters-unittest.cc [tsan] Move the xxx_stats status flags out of command line flags 2019-03-07 20:29:33 +00:00
DEPS Move unit tests to test/unittests. 2014-10-01 08:34:25 +00:00
detachable-vector-unittest.cc Make DetachableVector accessible from builtins 2018-11-13 01:30:16 +00:00
eh-frame-iterator-unittest.cc Normalize casing of hexadecimal digits 2017-12-02 01:24:40 +00:00
eh-frame-writer-unittest.cc [cleanup] Fix kPointerSize in tests 2019-02-14 15:29:52 +00:00
locked-queue-unittest.cc Add lock-based unbounded queue 2015-11-18 10:54:13 +00:00
microtask-queue-unittest.cc [tsan] Avoid modifying flags back and forth for each microtask queue test 2019-03-08 12:56:23 +00:00
object-unittest.cc [cleanup] Introduce STRUCT_MAPS_LIST generated from STRUCT_LIST. 2018-09-21 16:10:34 +00:00
register-configuration-unittest.cc Use static RegisterName function instead of RegisterConfiguration 2018-11-21 10:24:13 +00:00
run-all-unittests.cc [cleanup] Refactor general tests to use default members. 2018-09-14 14:40:47 +00:00
source-position-table-unittest.cc [cleanup] Refactor general tests to use default members. 2018-09-14 14:40:47 +00:00
strings-storage-unittest.cc Extend hash seed to 64 bits 2018-07-16 11:19:42 +00:00
test-helpers.cc [parser] Rename PreParsedScopeData to PreparseData 2019-01-07 14:49:21 +00:00
test-helpers.h [Compiler] Remove CompilerDispatcherJob and use BackgroundCompileTask directly 2018-10-09 10:39:27 +00:00
test-utils.cc [heap] Reimplement unmapper tests using tracking page allocator 2018-11-07 09:47:17 +00:00
test-utils.h Use local MicrotaskQueue in unittests 2019-01-17 21:42:52 +00:00
testcfg.py Revert "Preparing v8 to use with python3 /test" 2019-02-20 10:20:59 +00:00
unicode-unittest.cc Fix & reland "[utf8] Rewrite NewStringFromUtf8 using Utf8::ValueOfIncremental" 2019-02-06 13:11:11 +00:00
unittests.status [test] Don't test jitless without embedded-builtins 2019-02-26 14:33:01 +00:00
utils-unittest.cc test: Replace _TEST_CASE_ with _TEST_SUITE_. 2019-02-18 21:36:56 +00:00
value-serializer-unittest.cc [value serializer] check for stack overflow for verify object count. 2018-12-17 10:21:18 +00:00