The CloneObject bytecode was only able to handle objects, null and
undefined, and explicit bytecode had to be generated to perform the
ToObject outside the bytecode (unlike the other IC bytecodes that
just perform the ToObject implicitly). That means the simplest possible
object cloning would also generate a sequence of 5 bytecodes (at least):
```
Mov <register>, a0
JumpIfNull @1
JumpIfUndefined @1
ToObject <register>
1: CloneObject <register>
```
That is quite wasteful and unnecessary, since the core logic in the
runtime already does the ToObject properly anyways. This change
refactors the CloneObjectIC slightly to behave more like the other ICs
and do the ToObject implicitly when necessary.
Bug: v8:7611, v8:9114, v8:9183, v8:9343
Change-Id: I11973e90bf875f154a5a7739287bee17041e4a7a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1649554
Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62064}
This adds a new %_CopyDataProperties intrinsic, that reuses most of the
existing machinery that we already have in place for Object.assign() and
computed property names in object literals. This speeds up the general
case for object spread (where the spread is not the first item in an
object literal) and brings it on par with Object.assign() at least - in
most cases it's significantly faster than Object.assign().
In the test case [1] referenced from the bug, the performance goes from
objectSpreadLast: 3624 ms.
objectAssignLast: 1938 ms.
to
objectSpreadLast: 646 ms.
objectAssignLast: 1944 ms.
which corresponds to a **5-6x performance boost**, making object spread
faster than Object.assign() in general.
Drive-by-fix: This refactors the Object.assign() fast-path in a way that
it can be reused appropriately for object spread, and adds another new
builtin SetDataProperties, which does the core of the Object.assign()
work. We can teach TurboFan to inline Object.assign() based on the new
SetDataProperties builtin at some later point to further optimize
Object.assign().
[1]: https://gist.github.com/bmeurer/0dae4a6b0e23f43d5a22d7c91476b6c0
Bug: v8:9167
Change-Id: I57bea7a8781c4a1e8ff3d394873c3cd4c5d73834
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1587376
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61100}
This flag has been on by default since Chrome 61.
Bug: v8:5549
Cq-Include-Trybots: master.tryserver.v8:v8_linux_noi18n_rel_ng
Change-Id: I81c34d1d3a7dbd219acce2cdf0cf4917eb484002
Reviewed-on: https://chromium-review.googlesource.com/738312
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48945}
