Commit Graph

10011 Commits

Author SHA1 Message Date
Ana Peško
611d84ee13 [regexp] Naive tier-up testing
This CL adds initial tests for the tier-up logic.

Change-Id: I6e6ff69604b14387e81b08d178f98d2227b4f496
Bug: v8:9566
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1776080
Commit-Queue: Ana Pesko <anapesko@google.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63503}
2019-09-02 12:55:54 +00:00
Leszek Swirski
981aafaf97 Reland "[ic] In-place Double -> Tagged transitions"
This is a reland of 0736599a69.
This is a reland of 7e1fbe8f34.

Original change description:
> [ic] In-place Double -> Tagged transitions
>
> With no more MutableHeapNumber, we can make Double -> Tagged transitions
> in-place, at the cost of an extra map check when accessing double fields
> to make sure they are still doubles.
>
> Bug: v8:9606
> Change-Id: I74ff39ed6fba62ee223cd37dfe761f7d73020e1c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1743973
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63374}

TBR=verwaest@chromium.org, tebbi@chromium.org

Bug: v8:9606
Change-Id: I2d1b7416064d743582f4983fb868316b7e8a4cf2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1777661
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63499}
2019-09-02 10:18:34 +00:00
Dan Elphick
3e545f38cb [coverage] Collect source positions when toggling mode
When changing the code coverage or type profiler modes, first ensure
there are source positions for all BytecodeArrays as regenerating the
source positions after toggling the mode will result in a bytecode
mismatch.

Bug: v8:9656, v8:8510
Change-Id: Ic6cf3afec1588f11e5ce5fcbea2fd13e4452e15f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1774721
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63484}
2019-08-30 17:58:30 +00:00
Joyee Cheung
df12eb194e [class] implement private accessors
This patch implements the access of private accessors by loading the
referenced component from the AccessorPair associated with private
name variables. It also makes the error messages for invalid kind
of private accessor access more specific.

Bug: v8:8330
Design doc: https://docs.google.com/document/d/10W4begYfs7lmldSqBoQBBt_BKamgT8igqxF9u50RGrI/edit

Change-Id: I6d441cffb85f8d9cd0417ec9b6ae20f3e34ef418
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1695205
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Joyee Cheung <joyee@igalia.com>
Cr-Commit-Position: refs/heads/master@{#63474}
2019-08-30 10:16:29 +00:00
Ulan Degenbaev
9da3483136 Revert "Reland x5 [arraybuffer] Rearchitect backing store ownership"
This reverts commit 62e168308c.

Reason for revert: it will be relanded after branch

Original change's description:
> Reland x5 [arraybuffer] Rearchitect backing store ownership
> 
> This reverts commit 8fdb23873b.
> 
> Original change's description:
> > "Reland x4 [arraybuffer] Rearchitect backing store ownership"
> >
> > This is a reland of bc33f5aeba
> >
> > Contributed by titzer@chromium.org
> >
> > Original change's description:
> > > [arraybuffer] Rearchitect backing store ownership
> > >
> > > This CL completely rearchitects the ownership of array buffer backing stores,
> > > consolidating ownership into a {BackingStore} C++ object that is tracked
> > > throughout V8 using unique_ptr and shared_ptr where appropriate.
> > >
> > > Overall, lifetime management is simpler and more explicit. The numerous
> > > ways that array buffers were initialized have been streamlined to one
> > > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > > and the construction and destruction of the BackingStore object itself
> > > handles the underlying page or embedder-allocated memory.
> > >
> > > The embedder API remains unchanged for now. We use the
> > > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > > keep the backing store alive properly, even in the case of aliases
> > > from live heap objects. Thus the embedder has a lower chance of making
> > > a mistake. Long-term, we should move the embedder to a model where they
> > > manage backing stores using shared_ptr to an opaque backing store object.
> >
> > TBR=yangguo@chromium.org
> >
> > BUG=v8:9380,v8:9221,chromium:986318
> >
> > Change-Id: If671a4a9ca0476e8f084efae46e0d2bf99ed99ef
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1731005
> > Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> > Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> > Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#63041}
> 
> TBR=yangguo@chromium.org,clemensh@chromium.org,mstarzinger@chromium.org
> 
> Change-Id: Iba55c7ab71e5642b5cb6aeb699d6fc9cf9061486
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771795
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63461}

TBR=ulan@chromium.org,mlippautz@chromium.org

Change-Id: Id8f67a68ab398032eb2975b1b24ee125394d9c4b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1776095
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63471}
2019-08-30 08:23:40 +00:00
Ulan Degenbaev
62e168308c Reland x5 [arraybuffer] Rearchitect backing store ownership
This reverts commit 8fdb23873b.

Original change's description:
> "Reland x4 [arraybuffer] Rearchitect backing store ownership"
>
> This is a reland of bc33f5aeba
>
> Contributed by titzer@chromium.org
>
> Original change's description:
> > [arraybuffer] Rearchitect backing store ownership
> >
> > This CL completely rearchitects the ownership of array buffer backing stores,
> > consolidating ownership into a {BackingStore} C++ object that is tracked
> > throughout V8 using unique_ptr and shared_ptr where appropriate.
> >
> > Overall, lifetime management is simpler and more explicit. The numerous
> > ways that array buffers were initialized have been streamlined to one
> > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > and the construction and destruction of the BackingStore object itself
> > handles the underlying page or embedder-allocated memory.
> >
> > The embedder API remains unchanged for now. We use the
> > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > keep the backing store alive properly, even in the case of aliases
> > from live heap objects. Thus the embedder has a lower chance of making
> > a mistake. Long-term, we should move the embedder to a model where they
> > manage backing stores using shared_ptr to an opaque backing store object.
>
> TBR=yangguo@chromium.org
>
> BUG=v8:9380,v8:9221,chromium:986318
>
> Change-Id: If671a4a9ca0476e8f084efae46e0d2bf99ed99ef
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1731005
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63041}

TBR=yangguo@chromium.org,clemensh@chromium.org,mstarzinger@chromium.org

Change-Id: Iba55c7ab71e5642b5cb6aeb699d6fc9cf9061486
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771795
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63461}
2019-08-29 16:40:18 +00:00
Leszek Swirski
f6057ff1e3 [scopes] Push sloppy eval check through eval scopes
Sloppy eval extends the outer declaration scope's context. This is also
true for sloppy eval inside of other sloppy evals -- the outer declaration
scope's context is extended rather than the outer sloppy eval's
declaration scope. However, we consider eval scopes to also be declaration
scopes, for the purposes of strict eval and caching lookup variables. So,
we need to make sure that we skip through sloppy eval scopes when marking
a scope as calls_sloppy_eval.

In fact, we implement this rather as never marking sloppy eval scopes as
calls_sloppy_eval, under the assumption that the parent scope will already
have been marked calls_sloppy_eval by the outer eval.

As a drive-by, fix a TODO to move this logic from calls_sloppy_eval() to
RecordEvalCall(), rename the variable to something more meaningful, and
make Snapshotting to use a new calls_eval bit on Scope.

Bug: chromium:996751
Change-Id: I27ccc7ef429a7ce60b3bb02bf64a3820ae4a2c36
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1773247
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63455}
2019-08-29 14:49:28 +00:00
Leszek Swirski
e39c701963 Revert "[ic] In-place Double -> Tagged transitions"
This reverts commit 0736599a69.
This reverts commit 7e1fbe8f34.

Reason for revert: Still some crashes, reverting to unblock dev.

TBR=ishell@chromium.org,tebbi@chromium.org

Bug: v8:9606
Bug: chromium:997485
Bug: chromium:997989
Change-Id: I9a0cb5440bf4fce06c9e6134dacf5c03d512f049
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1773271
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63441}
2019-08-29 09:50:08 +00:00
Jun Lim
6bead6bd00 [compiler]Use Phi in Branch if control flow is known
This CL try to use a phi as a branch condition if the control flow from the
branch is known from previous conditions. This change will open up more branch
folding opportunities for later pass.

Change-Id: I26316ab3a68c2d58d0df53691981288a996d4ba1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1674484
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63434}
2019-08-28 19:12:03 +00:00
Z Nguyen-Huu
1f4bec2775 Add new nonextensible element kinds
Currently the backing store and elements kind might not aligned aka
backing store can be dictionary where elements kind is frozen/sealed
element kinds or the other way around. The reason is that
Object.preventExtensions change elements kind to DICTIONARY while
Object.seal/freeze change elements kind to SEALED/FROZEN element kind.
Apply both these operations can lead to that problem as in
chromium:992914

To solve this issue, we avoid Object.preventExtensions to change backing
store to dictionary by introducing new nonextensible elements kind.
These new nonextensible elements kind are handled similar to frozen,
sealed element kinds. This change not only fixes the problem but also
optimize the performance of nonextensible objects.

Change-Id: Iffc7f14eb48223c11abf3c577f305d2d072eb65b
Bug: chromium:992914, v8:6831
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1760976
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63432}
2019-08-28 17:24:49 +00:00
Sigurd Schneider
4477097489 [runtime] Throw range error on too many properties
This change allows the KeyAccumulator to throw a range error if there
are too many properties to be enumerated.

This CL introduces extensive checks during key enumeration in the run-time,
and might introduce regressions. If so, feel free to revert.

Bug: chromium:918301
Change-Id: I6166c0b15f1a05eac7116a979f12ba4833d1d1b1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1545902
Auto-Submit: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63430}
2019-08-28 15:58:04 +00:00
Jakob Gruber
1990b1e14e [regexp] Dont attempt to match '^' before the start of the string
This fixes an invalid assumption when emitting code for matching '^'
(start of line) in multiline regexps and '\b', '\B' in general.

What we used to do: if the current trace's cp_offset (the offset from
the current position) was non-zero, we assumed that we were looking at
subject string index 1 or greater (i.e.: not at the start of the string
or before).

This is no longer valid since cp_offsets can now be negative.

This CL changes the logic to omit start- and bounds-checks only for
strictly positive cp_offsets, where the above assumption still holds.

Bug: chromium:996391
Change-Id: I79be4fc295c6f0b63e41c13d1e91fdd00f2f2b42
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771794
Commit-Queue: Erik Corry <erikcorry@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Erik Corry <erikcorry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63424}
2019-08-28 14:23:39 +00:00
Michael Starzinger
cdf2e7539b [wasm] Extend type reflection to 'exnref' types.
R=ahaas@chromium.org
TEST=mjsunit/wasm/type-reflection-with-exnref
BUG=v8:7742,v8:8091

Change-Id: Ib8bd7b7cfafa3509db743e4404c2f1b573253881
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771790
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63415}
2019-08-27 14:31:37 +00:00
Michael Starzinger
7f00bb5ad6 [wasm] Add support to construct 'exnref' type globals.
R=ahaas@chromium.org
TEST=mjsunit/wasm/exceptions-global
BUG=v8:8091

Change-Id: I9eb4c92cca087719afda2da5d11c206aaed28c95
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771788
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63414}
2019-08-27 14:29:16 +00:00
Toon Verwaest
864cacd65a [json] Don't consume sibling feedback from objects with detached maps
By marking maps detached from the transition tree as prototypes, we'll
automatically stop tracking transitions from those detached fast maps. That
allows us to quickly check whether a map is detached (or the initial map
anyway); and saves memory. We can use this information to ignore sibling type
feedback when parsing a JSON array with many distinctly shaped json objects.

Bug: chromium:993980
Change-Id: I86d493ac2cabec2c31c6e322ad5c5a7ace059dfc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771778
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63403}
2019-08-26 15:57:52 +00:00
Leszek Swirski
7e1fbe8f34 [ic] Check Double representation on store
For stores with Double feedback, StoreIC needs to check that the
representation is still Double before doing the store, in case it
accidentally tries to write to an object or worse, mutate a non-mutable
HeapNumber.

Bug: v8:9606
Bug: chromium:997485
Change-Id: I51e0953b40f752648c5e86b8644c23baf636367e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1768373
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63402}
2019-08-26 15:40:12 +00:00
Joshua Litt
1fcbe01a04 Revert "[regexp] Implement the match indices proposal"
This reverts commit 9460101cdb.

Reason for revert: Causes confusion on Blink side, as it introduces
an object with >=2 internal fields that is not a wrapper (see bug).

Bug: chromium:996681
Change-Id: I275b5a064a4ee8c73c05f97be322924a3bc5370e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1769148
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Joshua Litt <joshualitt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63386}
2019-08-23 17:39:38 +00:00
Georg Schmid
7fd1922823 [turbofan] Relax double const store invariant in load elim. for literals
Even when a field is marked const, we may emit multiple consecutive in-literal stores to that field. That is, in 'JSNativeContextSpecialization::BuildPropertyStore', when the access mode is 'kStoreInLiteral' and we are accessing a const field, we may produce a StoreField node, even though another StoreField (that stores something other than 'Uninitialized') to the same const field dominates it. This appears to be sound, since earlier stores to literals cannot be observed anyways.

Unfortunately this behavior conflicts with the double const store invariant in load elimination: Roughly speaking, we assume that load elimination may never observe two consecutive const stores to the same field on the same object.

The apparent solution would be to treat 'kStoreInLiteral' accesses like regular 'kStore' accesses: For consecutive stores to const properties we don't emit StoreField, but instead emit code that checks whether the value about to be written is equivalent to the previously written one, and otherwise deopt ('DeoptimizeReason::kWrongValue'). Unfortunately this turns out impractical, since for 'kStoreInLiteral' accesses we can't easily decide whether we're dealing with the first such store or one of the consecutive ones. Also see this abandoned CL: https://chromium-review.googlesource.com/c/v8/v8/+/1762020.

This CL instead adds an exception to the invariant in load elimination. We track whether a store arose from a 'kStoreInLiteral' access, and use this information when visiting StoreField nodes in load elimination.

R=neis@chromium.org, tebbi@chromium.org

Bug: chromium:987205
Change-Id: I8829752aa0637e9599677d20aad2d706d40d7fe6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1763535
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Georg Schmid <gsps@google.com>
Cr-Commit-Position: refs/heads/master@{#63385}
2019-08-23 17:10:48 +00:00
Andreas Haas
585943d4e2 Reland "[regexp] Only append to JSRegExpResult's initial map if we add descriptor"
This reverts commit 5db04cc0dd.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Revert "[regexp] Only append to JSRegExpResult's initial map if we add descriptor"
> 
> This reverts commit dc1cc2232b.
> 
> Revert "[regexp] Implement the match indices proposal"
> 
> This reverts commit 9460101cdb.
> 
> Reason for revert: Causes confusion on Blink side, as it introduces
> an object with >=2 internal fields that is not a wrapper (see bug).
> 
> Bug: chromium:996681
> Change-Id: I5c167e9e15bfbec2aa6b843e3063ead5d52fb26c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1768897
> Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63376}

TBR=yangguo@chromium.org,sigurds@chromium.org,joshualitt@chromium.org

Change-Id: Ic58fc3fc83faaf86bd895da29eacb7d51c443beb
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:996681
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1768584
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63379}
2019-08-23 16:14:52 +00:00
Sigurd Schneider
bad6116e85 [mjsunit] Harden %GetOptimizationStatus against races
With this Cl, a function that has been marked for deoptimization will
not be reported as optimized. This protects against potential races
where an mjsunit tests assertUnoptimized, and the optimized code for
the function has been marked for deoptimization, but not been disposed
of yet.

The potential for this race has been discovered in the context of bug
v8:9563, but this CL is not a fix for that bug.

Change-Id: I89d8aa85f19033e6b823324b3307b95d61367147
Bug: v8:9563
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1763543
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63377}
2019-08-23 15:57:21 +00:00
Joshua Litt
5db04cc0dd Revert "[regexp] Only append to JSRegExpResult's initial map if we add descriptor"
This reverts commit dc1cc2232b.

Revert "[regexp] Implement the match indices proposal"

This reverts commit 9460101cdb.

Reason for revert: Causes confusion on Blink side, as it introduces
an object with >=2 internal fields that is not a wrapper (see bug).

Bug: chromium:996681
Change-Id: I5c167e9e15bfbec2aa6b843e3063ead5d52fb26c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1768897
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63376}
2019-08-23 15:28:21 +00:00
Joshua Litt
48c9ca4462 [names] Fix some test262 name tests to conform with spec changes
In order to reflect web reality, TC39 has made some slight changes to
name descriptors, see https://github.com/tc39/ecma262/pull/1490 for
details. V8 was mostly already in compliance with these changes, but
ThrowTypeError and anonymous classes needed some slight changes.

Bug: v8:9646
Change-Id: I163238954938f0c005e3adbc61b90498e01436da
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1764622
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Commit-Queue: Joshua Litt <joshualitt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63373}
2019-08-23 15:04:31 +00:00
Maya Lekova
f16a3a7436 [turbofan] Fix memory corruption
Bug: chromium:997057
Change-Id: I821b91ff51f82e6325dae5719e1669142c82b05e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1768579
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Auto-Submit: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63369}
2019-08-23 14:03:01 +00:00
Georg Neis
450128c79e [turbofan] Fix stability checks in InferHasInPrototypeChain
While we only need to check stability of the receiver map if its
inference was "unreliable", we must check stability of each prototype's
map unconditionally.

Bug: chromium:997100
Change-Id: I20071ac9eb74c810ad2ab1d78abfb54a1a006c29
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1768576
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Auto-Submit: Georg Neis <neis@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63364}
2019-08-23 11:29:30 +00:00
Ana Peško
c317f606bd [regexp] Print correct kind of regexp code (native/bytecode) when tier-up
is enabled.

Change-Id: Iab87b9c7a0d0600782b02537844338ff065622ab
Bug: chromium:996234
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1765531
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Ana Pesko <anapesko@google.com>
Cr-Commit-Position: refs/heads/master@{#63360}
2019-08-23 09:24:22 +00:00
Michael Starzinger
e16775163a [wasm] Preserve identity on {WasmJSFunction} re-export.
This preserves the object identity of a {WebAssembly.Function} instance
that is being re-exported by a module. Such functions are considered to
have an internal [[FunctionAddress]] slot and hence require their object
identity to be preserved (similar to {WasmExportedFunction} already).

R=jkummerow@chromium.org
TEST=mjsunit/wasm/type-reflection
BUG=v8:7742

Change-Id: I88ba75fcd91ce04440008467f3b218a1ac3047db
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1763545
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63346}
2019-08-22 15:00:22 +00:00
Andreas Haas
73010d22dd [wasm][bigint] Fix calls to imports with I64 in their signature
For import wrappers, we add a special "callable" parameter as the last
parameter. This parameter is not set in the TurboFan graph but in the
code generator. Therefore this parameter has to be allocated in a
special register and cannot be lowered generically. With this CL we
detect in the CallDescriptor lowering if the last parameter is this
special "callable" parameter. If so, we preserve it in the lowered
CallDescriptor in the same register.

R=jkummerow@chromium.org

Bug: v8:7741
Change-Id: I884baa41813011c811612ec84f4e3cfe86a0e83a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762014
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63344}
2019-08-22 14:22:06 +00:00
Sigurd Schneider
6d9b7988f7 [testing] Prevent heuristics from triggering optimization in tests
This CL adds a mechanism that prevents the RuntimeProfiler from
triggering optimization of a function after
%PrepareFunctionForOptimization has been called. This is useful to
prevent flakiness in tests, as sometimes a function that already
got deoptimized would receive a new code object from a concurrent
compile that was triggered by a heuristic just in the right moment
for the assertUnoptimized test to fail. For example, the following
was happening:

PrepareFunctionForOptimization
[marking `testAdd` for optimized recompilation, reason: small function]
[concurrently compiling method `testAdd` using TurboFan]
[manually marking `testAdd` for non-concurrent optimization]
[synchonously compiling method `testAdd` using TurboFan]
[synchonously optimizing `testAdd` produced code object 0xAAAA - took 1.638 ms]
Runtime_GetOptimizationStatus OPTIMIZED `testAdd` (code object 0xAAAA)
DeoptimizeFunction `testAdd` with Code Object 0xAAAA
[concurrently optimizing `testAdd` produced code object 0xBBBB - took 3.377 ms]
Runtime_GetOptimizationStatus OPTIMIZED `testAdd` (code object 0xBBBB)

Bug: v8:9563
Change-Id: Ia4c846aba95281589317d43b82383e70fe0a35f5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1763546
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63343}
2019-08-22 13:51:36 +00:00
Andreas Haas
12c009dee7 [wasm] 32-bit support WebAssembly's i64<>JavaScript's BigInt conversions
This CL was reviewed originally in https://crrev.com/c/1518181.

Bug: v8:7741
Change-Id: Iddb139a24c4b9aee6694e20cb5d04e9f9887160c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1752859
Auto-Submit: Sven Sauleau <sven@cloudflare.com>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63321}
2019-08-21 17:03:51 +00:00
Joshua Litt
3ec1036526 [nullish] Add support for nullish operator
This CL implements the nullish operator in bytecode as defined by:
https://github.com/tc39/proposal-nullish-coalescing. It can be
enabled by passing '--harmony-nullish'.

Nullish is similar to logical operators, but instead of truthy/falsey
values, it short circuits when it evaluates a null or undefined value.


Bug: v8:9547
Change-Id: Ia0f55877fc2714482b5547942baef9733537d1b9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1738568
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Joshua Litt <joshualitt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63317}
2019-08-21 15:48:34 +00:00
Michael Starzinger
fd8fe87387 [wasm] Add WebAssembly.Module type reflection of memories.
This adds type reflection support to the {WebAssembly.Module.exports} as
well as {WebAssembly.Module.imports} method. It also refactors existing
reflective code to use the internal instead of the public embedder API,
which is slightly more efficient anyways.

R=ahaas@chromium.org
TEST=mjsunit/wasm/type-reflection
BUG=v8:7742

Change-Id: I88a6c7e9236a549808707c72e40a63302b7747a9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1763527
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63312}
2019-08-21 14:45:14 +00:00
Michael Starzinger
df76f1e55a [wasm] Add test case for {WebAssembly.Function} re-export.
This just adds a test case checking against the current behavior, but
expectations might change once the proposal is clarified. For details
see: https://github.com/WebAssembly/js-types/issues/11

R=ahaas@chromium.org
TEST=mjsunit/wasm/type-reflection
BUG=v8:7742

Change-Id: I2fc502460c0a8094a414d138703b75497b2d1c6f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762517
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63311}
2019-08-21 14:43:03 +00:00
Michael Starzinger
431cfbc4e8 [wasm] Add WebAssembly.Module type reflection of tables.
This adds type reflection support to the {WebAssembly.Module.exports} as
well as {WebAssembly.Module.imports} method. It also refactors existing
reflective code to use the internal instead of the public embedder API,
which is slightly more efficient anyways.

R=ahaas@chromium.org
TEST=mjsunit/wasm/type-reflection
BUG=v8:7742

Change-Id: Ic51b7b4744f7b3ad056a778aecfc4614ca8d6e75
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762019
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63299}
2019-08-21 08:40:56 +00:00
Leszek Swirski
489e7deb7e [object] Remove MutableHeapNumber
Since the mutability of HeapNumbers is determined by their owning
object's descriptor array, we can remove the MutableHeapNumber type
entirely, at the cost of a few fewer DCHECKs and a couple of TODOs
to use the descriptor array information.

This is a necessary step towards a follow-up which allows in-place
Double -> Tagged transitions

Design doc: https://docs.google.com/document/d/1VeKIskAakxQFnUBNkhBmVswgR7Vk6T1kAyKRLhqerb4/

Bug: v8:9606
Change-Id: I13209f9c86f1f204088f6fd80089e17d956b4a50
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1743972
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63294}
2019-08-20 19:04:04 +00:00
Joyee Cheung
77d50cd8e7 [class] implement private accessor declarations
This patch implements the declaration of private accessors.
When iterating over the class properties, we track private
accessors associated with the same name in a ZoneHashMap.
Once we get to all the necessary components for a private name
(we know statically whether we should expect only a setter,
only a getter, or both), we emit a call to a runtime function
`CreatePrivateAccessors` that creates an AccessorPair, and
store the components in it. The AccessorPair is then associated
with the private name variable and stored in the context
for later retrieval when the private accessors are accessed.

Design doc: https://docs.google.com/document/d/10W4begYfs7lmldSqBoQBBt_BKamgT8igqxF9u50RGrI/edit

Bug: v8:8330
Change-Id: Ie6d3882507d143b1f645d7ae82b21b7358656e89
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1725670
Commit-Queue: Joyee Cheung <joyee@igalia.com>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63284}
2019-08-20 15:32:34 +00:00
Dan Elphick
dd54736795 [parser] Fix bytecode mismatch for this
Fixes bytecode mismatch between lazy and non-lazy where "this" was
marked as maybe assigned in constructors that called the super
constructor. Since this will return the hole in cases where it was not
yet initialized by super (and the hole is explicitly handled by
JSContextSpecialization::ReduceJSLoadContext), it's safe to treat it as
a constant in all cases. In the case of lazy compilation case, "this"
is never added to the ScopeInfo so is never seen as mutable.

Bug: chromium:994719
Change-Id: I43478fbc626b19eb1533aa9dec61b7f276ae140b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762025
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63283}
2019-08-20 15:21:24 +00:00
Michael Starzinger
f2bb20f6c5 [wasm] Add WebAssembly.Module type reflection of functions.
This adds type reflection support to the {WebAssembly.Module.exports} as
well as {WebAssembly.Module.imports} method. It also refactors existing
reflective code to use the internal instead of the public embedder API,
which is slightly more efficient anyways.

R=ahaas@chromium.org
TEST=mjsunit/wasm/type-reflection
BUG=v8:7742

Change-Id: I168741d382373ec47ebe0517ce7803732cbb3b24
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762011
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63276}
2019-08-20 13:49:05 +00:00
Michael Starzinger
017a68c0ee [wasm] Add WebAssembly.Module type reflection of globals.
This adds type reflection support to the {WebAssembly.Module.exports} as
well as {WebAssembly.Module.imports} method. It also refactors existing
reflective code to use the internal instead of the public embedder API,
which is slightly more efficient anyways.

R=ahaas@chromium.org
TEST=mjsunit/wasm/type-reflection
BUG=v8:7742

Change-Id: I5f20ea57261f6433b8d86f55054216bf96b41382
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1760826
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63273}
2019-08-20 12:48:43 +00:00
Joshua Litt
9460101cdb [regexp] Implement the match indices proposal
Implements match indices for regexp, as specified by
https://github.com/tc39/proposal-regexp-match-indices,
a stage 3 TC39 proposal. This implementation is hidden
behind the '--harmony-regexp-match-indices' flag.

Regexp match indices extends the JSRegExpResult object
with an array of indices of matches, as well as a
dictionary of capture names to match indices.

Bug: v8:9548
Change-Id: I9866a2d1f5af6a507de710357cb5e74c694e7558
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1734937
Commit-Queue: Joshua Litt <joshualitt@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63272}
2019-08-20 12:32:43 +00:00
Georg Neis
7a253510c8 [turbofan] Try to insert soft deopt for exponentiation
This brings the graph builder in sync with the serializer (and
exponentiation in sync with the other binary operators).

Bug: chromium:995430, v8:7790
Change-Id: I809b6f3756f75392cdc6747f8bcee8cdf0ee0f74
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762013
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63269}
2019-08-20 11:55:46 +00:00
Georg Neis
4ec75d8409 [turbofan] Fix JSStoreDataPropertyInLiteral reduction
... by making the operator have a control output, since we could deopt
after my last change.

Bug: chromium:995562, v8:7790
Change-Id: Ibc8c44708b4d43c4b2c3dfab2fd8fdf79c7ea671
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762010
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63268}
2019-08-20 11:37:16 +00:00
Santiago Aboy Solanes
761addecef [arm64][ptr-compr] Mark some Arm64 sim pointer compression tests as slow
They were timeouting, e.g
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20-%20arm64%20-%20sim%20-%20pointer%20compression/2193

Change-Id: Icf3fcde15510cbdefcd2da8e66530c589f4423f1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762008
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Auto-Submit: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63267}
2019-08-20 10:46:57 +00:00
Z Nguyen-Huu
bc1c36ee56 Reland "[builtins] Port RegExpTest to Torque"
This is a reland of f54f92dda1.

Fix IsFastRegExpPermissive to call BranchIfFastRegExp_Permissive.

Original change's description:
> [builtins] Port RegExpTest to Torque
>
> Bug: v8:8976
> Change-Id: Ia4dc120a31eb363599b47b22b749a3146a9c7c73
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1746083
> Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63211}

Bug: v8:8976, chromium:994041
Change-Id: I86c9c66b060f47164515e29f914b95456c233d30
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1756390
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63255}
2019-08-19 16:44:55 +00:00
Gus Caplan
5d4ca7ba86 fix delete + optional chain jump condition
The optional chaining bytecode in delete expressions was
unconditionally jumping if the receiver was nullish, instead
of just when the property was an actual optional chain link.
This change adds the missing check around the jump.

Change-Id: Ic7bed58be4ae62d157e63e4f77666b1abd1f802d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1755264
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63251}
2019-08-19 15:21:20 +00:00
Patrick Thier
098f85a464 Skip jitless tests on builds without embedded builtins
Test mjsunit/regress/regress-992389 explicitly sets the jitless flag
when run.
Skip this test when run on builds without embedded-builtins.

Bug: v8:9632, chromium:992389
Change-Id: Ieb52a33006b1104080d8f5adb8c4f2c36e4413af
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1758317
Commit-Queue: Patrick Thier <pthier@google.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63240}
2019-08-19 12:02:19 +00:00
Georg Schmid
f85826eaf2 [turbofan] Track field owner maps during load elimination
This CL adds additional information in PropertyAccessInfos and FieldAccesses about the map that introduced the accessed field. We use this information to prevent load elimination from incorrectly optimizing certain accesses marked const.

Prior to this CL, load elimination simply stored information about eliminatable field accesses based on objects (identified by nodes in the graph) and offsets (i.e., statically known ones). In the presence of const stores and loads this is insufficient, since a single object (in the above sense) may contain distinct *const* properties at the same offset throughout its lifetime. As an example, consider the following piece of code:

    let obj = {};
    obj.a = 0;
    obj[1024] = 1;  // An offset of >=1024 forces an elements-kind transition
    delete obj.a;
    obj.b = 2;
    assertEquals(obj.b, 2);

In this scenario, *both* the first ('obj.a = 0') and the second ('obj.b = 2') store to a field will be marked const by the runtime. The reason that storing to 'a' above ends up being marked const, is that 'a' before and after the elements-kind transition is encoded in separate transition trees. Removing 'a' ('delete obj.a') only invalidates const-ness in the dictionary-elements transition tree; not the holey-elements one used at the time of 'obj.a = 0'.

The above situation on its own violates an invariant in load elimination. Namely, we assume that for the same object and offset, we will never encounter two const stores. One can extend the above snippet to coax load-elimination into producing incorrect results. For instance, by "hiding" 'obj.b = 2' in an unoptimized function call, the consecutive load from 'b' will incorrectly produce 0, violating the assert.

R=neis@chromium.org, tebbi@chromium.org

Bug: chromium:980183, chromium:983764
Change-Id: I576a9c7efd416fa9db6daff1f42d483e4bd369b4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1751346
Commit-Queue: Georg Schmid <gsps@google.com>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63226}
2019-08-16 16:08:45 +00:00
Dan Elphick
cfe6ceae3f Fix crash Code::DropStackFrameCacheCommon
Fixes DCHECK failure in DropStackFrameCacheCommon by returning early if
the source_position_table is Exception.

Bug: chromium:990582, v8:8510
Change-Id: I671f3e0cdc9f880dedf8ecd2fffb1083229dc6dc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1752856
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Auto-Submit: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63209}
2019-08-14 15:03:27 +00:00
Ross McIlroy
8c4609fdee [Parser] Don't mark receiver as MaybeAssigned since it can't be assigned.
Otherwise there is a mismatch between eager parsing (where the reciever
is marked as MaybeAssigned) and lazy parsing (where the receiver is
deserialized and not marked MaybeAssigned) for arrow functions that
have an inner scope that calls eval.

BUG=chromium:989914

Change-Id: I8b8b78140858985a75a971b0e0a95bd61463457b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1752851
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63206}
2019-08-14 11:15:11 +00:00
Patrick Thier
52c7565de8 [regexp] Fix dirty read in regexp interpreter.
When GC triggered while an exception is pending, a read to
memory that was no longer valid could happen while backtracking in the
regexp interpreter (introduced with commit fb0df2c).
This CL prevents this dirty read, that could have been a security issue.

Bug: chromium:992389, v8:9575
Change-Id: Ie1acd6faa16665e211666c6a8dcf2a9d74e0c886
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1751342
Commit-Queue: Patrick Thier <pthier@google.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63195}
2019-08-13 16:08:18 +00:00
Ross McIlroy
69b1f07229 [Parsing] Fix a bug in UpdateBufferPointers where it incorrectly updated the buffer range.
When a RelocatingCharacterStream is Seeked, it's buffer_pos_ could be set a non-zero value.
However, UpdateBufferPointers was assuming the position was zero to relocate the buffer_start_
and buffer_end_, which would lead to the stream becoming misaligned. Fix this and add a
unittest and the clusterfuzz script which highlighted the issue.

BUG=chromium:991133

Change-Id: I20dd510b3dcc5df6df058b7e06d2c8a838aef855
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1751782
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63190}
2019-08-13 14:20:17 +00:00