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  1. 09 Mar, 2020 1 commit
    • Dan Elphick's avatar
      [api] Create v8::String::NewFromLiteral that returns Local<String> · b097a8e5
      Dan Elphick authored 
      String::NewFromLiteral is a templated function that takes a char[N]
argument that can be used as an alternative to String::NewFromUtf8 and
returns a Local<String> rather than a MaybeLocal<String> reducing the
number of ToLocalChecked() or other checks.

Since the string length is known at compile time, it can statically
assert that the length is less than String::kMaxLength, which means that
it can never fail at runtime.

This also converts all found uses of NewFromUtf8 taking a string literal
or a variable initialized from a string literal to use the new API. In
some cases the types of stored string literals are changed from const
char* to const char[] to ensure the size is retained.

This API does introduce a small difference compared to NewFromUtf8. For
a case like "abc\0def", NewFromUtf8 (using length -1 to infer length)
would treat this as a 3 character string, whereas the new API will treat
it as a 7 character string.

As a drive-by fix, this also fixes all redundant uses of
v8::NewStringType::kNormal when passed to any of the String::New*
functions.

Change-Id: Id96a44bc068d9c4eaa634aea688e024675a0e5b3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2089935
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: 's avatarMathias Bynens <mathias@chromium.org>
Reviewed-by: 's avatarMythri Alle <mythria@chromium.org>
Reviewed-by: 's avatarClemens Backes <clemensb@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66622}
      b097a8e5
  3. 03 Mar, 2020 1 commit
  5. 17 Feb, 2020 1 commit
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  27. 10 May, 2019 1 commit
  29. 29 Apr, 2019 2 commits
    • Clemens Hammacher's avatar
      [cleanup] Remove {StrLength} function · 423b357b
      Clemens Hammacher authored 
      The {Vector} class does not use it any more. External uses should be
converted to {size_t} instead of {int}.
This CL removes the function from vector.h and updates all users to
either use {size_t}, or cast to {int} explicitly. In tests, no further
checks are needed if the string is a constant.

R=mstarzinger@chromium.org

Bug: v8:9183
Change-Id: I60f99302504c74d8a7c79b147ca01d8ba61b6879
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1587393Reviewed-by: 's avatarMichael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61092}
      423b357b
    • Clemens Hammacher's avatar
      [cleanup] Use Vector::begin instead of Vector::start · 4b0f9c85
      Clemens Hammacher authored 
      Our {Vector} template provides both {start} and {begin} methods. They
return exactly the same value. Since the {begin} method is needed for
iteration, and is also what standard containers provide, this CL
switches all uses of the {start} method to use {begin} instead.

Patchset 1 was auto-generated by using this clang AST matcher:
    callExpr(
        callee(
          cxxMethodDecl(
            hasName("start"),
            ofClass(hasName("v8::internal::Vector")))
        ),
        argumentCountIs(0))

Patchset 2 was created by running clang-format. Patchset 3 then
removes the now unused {Vector::start} method.

R=jkummerow@chromium.org
TBR=mstarzinger@chromium.org,yangguo@chromium.org,verwaest@chromium.org

Bug: v8:9183
Change-Id: Id9f01c92870872556e2bb3f6d5667463b0e3e5c6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1587381Reviewed-by: 's avatarJakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61081}
      4b0f9c85
  31. 24 Apr, 2019 1 commit
  33. 18 Apr, 2019 1 commit
  35. 19 Mar, 2019 1 commit
    • Benedikt Meurer's avatar
      [turbofan] Significantly improve ConsString creation performance. · d6a60a0e
      Benedikt Meurer authored 
      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: 's avatarYang Guo <yangguo@chromium.org>
Reviewed-by: 's avatarJaroslav Sevcik <jarin@chromium.org>
Reviewed-by: 's avatarMythri Alle <mythria@chromium.org>
Reviewed-by: 's avatarBenedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60318}
      d6a60a0e
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