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  1. 27 Jan, 2020 4 commits
    • Andreas Haas's avatar
      [x64] Introduce negb and negw instructions · 911f38c4
      Andreas Haas authored 
      This CL introduces the negb and negw instructions (8-bit and 16-bit
versions of neg) in the x64 assembler. These instructions are needed to
implement I32AtomicSub8U and similar WebAssembly instructions
efficiently.

The existing implementation was embedded in a generic macro, and it was
difficult to change it without introducing also the 8-bit and 16-bit
versions of many other instructions. This would have introduced a lot
of dead code. Instead this CL extracted the neg instructions from the
macro and implements them directly. This should be fine because the
assembler does not change much, and approachability of the code is
improved.

R=clemensb@chromium.org

Bug: v8:10108
Change-Id: I46099bbebd47f864311a67da3ba8ddc4fe4cd35d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2019165
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: 's avatarClemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65989}
      911f38c4
    • Clemens Backes's avatar
      [wasm] Pass breakpoints to Liftoff compiler · 261a22e2
      Clemens Backes authored 
      This extends the API to pass breakpoint information to Liftoff. The
Liftoff compiler identifies the places where breakpoints should be set,
but does not emit breakpoints yet.
This allows us to see the performance overhead of just checking where to
emit breakpoints (which should be negligible).

R=thibaudm@chromium.org

Bug: v8:10147
Change-Id: I3fd40ab9009e9c317a26f70b4f06db512f96a763
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2019169Reviewed-by: 's avatarThibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65988}
      261a22e2
    • Justin Ridgewell's avatar
      Fix two overflow cases in SourceMap VLQ decoding · 615ecdf8
      Justin Ridgewell authored 
      These both have to do with extremely large numbers, so it's unlikely to cause a problem in practice. Still, correctness.

First, encoding `-2147483648` in VLQ returns the value `"B"`. When decoding, we get the value `1` after reading the base64. We then check if the first bit is set (it is) to see if we should negate it, then we shift all bits right once. Now, `value` will be `0` and `negate` will be `true`. So, we'd return `-0`. Which is a bug! `-0` isn't `-2147483648`, and we've broken a round trip.

Second, encoding any number with the 31st bit set, we'd return the opposite sign. Let's use `1073741824`. Encoding, we get `"ggggggC"`. When decoding, we get the value `-2147483648` after reading the base64. Notice, it's already negative (the 32nd bit is set, because the 31st was set and we shifted everything left once). We'd then check the first bit (it's not) and shift right. But we used `>>`, which does not shift the sign bit. We actually wanted `>>>`, which will. Because of that bug, we get back `-1073741824` instead of the positive `1073741824`. It's even worse if the 32nd and 31st bits are set, `-1610612736` becomes `536870912` after a round trip.

I recently fixed the same two bugs in Closure Compiler: https://github.com/google/closure-compiler/commit/584418eb

Change-Id: Ib6592ad50ae3764479c1a766bbb19042ee83b99d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2018882
Auto-Submit: Justin Ridgewell <jridgewell@google.com>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Reviewed-by: 's avatarMathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65987}
      615ecdf8
    • Jakob Gruber's avatar
      [regexp] Correctly escape a backslash-newline sequence · 7d1f95d6
      Jakob Gruber authored 
      When printing the source string, a backslash-newline sequence ('\\\n',
'\\\r', '\\\u2028', '\\\u2029') should be formatted as '\n', '\r',
'\u2028', '\u2029', respectively. Prior to this CL it was formatted as
a backslash followed by the literal newline character.

Bug: v8:8615
Change-Id: Iac90195c56ea1707ea8469066b0cc967ea87fc73
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2016583
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: 's avatarGeorg Neis <neis@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65986}
      7d1f95d6
  3. 24 Jan, 2020 23 commits
  5. 23 Jan, 2020 13 commits