1787794 - Clean-up some code for destructuring bytecode and paren-free arrow parsing

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P1)

Comment 1

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 1: Prefer BytecodeEmitter::emitUnpickN() over JSOp::Unpick. r=arai!

This shaves off one byte in byte code size:

dis(function(){ [...a] = [] })

Before:
00092: 27 True # [] []Symbol.iterator.next []Symbol.iterator [] true
00093: 27 Unpick 1 # [] []Symbol.iterator.next []Symbol.iterator true []
00095: 27 TryDestructuring # [] []Symbol.iterator.next []Symbol.iterator true []

After:
00092: 1 True # [] []Symbol.iterator.next []Symbol.iterator [] true
00093: 1 Swap # [] []Symbol.iterator.next []Symbol.iterator true []
00094: 1 TryDestructuring # [] []Symbol.iterator.next []Symbol.iterator true []

Comment 2

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 2: Directly pass 'lhs' to emitSetOrInitializeDestructuring. r=arai!

Directly pass lhs to emitSetOrInitializeDestructuring().

Part 6 will further align Object and Array destructuring code.

Depends on D155850

Comment 3

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 3: Reorder access in destructuring so most likely cases come first. r=arai!

The property is most likely a normal property key and not a number, so let's
handle the normal property key case first.

Depends on D155851

Comment 4

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 4: Remove unreachable code for BigInt property keys. r=arai!

BigInt property keys are parsed as synthetic computed properties, so these
cases no longer apply.

Depends on D155852

Comment 5

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 5: Reorder more property name operations to handle simple names first. r=arai!

Similar to part 3.

Depends on D155853

Comment 6

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 6: Align Array and Object destructuring code paths. r=arai!

emitDestructuringLHSRef() and emitSetOrInitializeDestructuring() no longer
need to inspect target to handle spread and assignment expressions when we
directly pass the unpacked parse nodes.

Depends on D155854

Comment 7

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 7: Simplify paren-free arrow function parsing. r=arai!

Instead of branching around parenFreeArrow in multiple places, handle the
paren-free arrow function case in a separate if-block. This also simplifies
the Token::Modifier handling, because we can always pass a constant.

Depends on D155855

Comment 8

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 8: Remove a stale comment. r=arai!

TokenStreamPosition no longer contains GC things.

Depends on D155856

Comment 9

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 9: Remove unused NumericLiteral setters. r=arai!

Depends on D155857

Comment 10

[André Bargull [:anba]]

Attachment: Bug 1787794 - Part 10: Inline literalIsZeroNoRadix into its single caller. r=arai!

There isn't a good reason to keep a simple while loop in a separate function.

Depends on D155858

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5e9c66da7409
Part 1: Prefer BytecodeEmitter::emitUnpickN() over JSOp::Unpick. r=arai
https://hg.mozilla.org/integration/autoland/rev/f5e5764cc4d3
Part 2: Directly pass 'lhs' to emitSetOrInitializeDestructuring. r=arai
https://hg.mozilla.org/integration/autoland/rev/b495ed555e0d
Part 3: Reorder access in destructuring so most likely cases come first. r=arai
https://hg.mozilla.org/integration/autoland/rev/39525ff15d29
Part 4: Remove unreachable code for BigInt property keys. r=arai
https://hg.mozilla.org/integration/autoland/rev/4abc0092802a
Part 5: Reorder more property name operations to handle simple names first. r=arai
https://hg.mozilla.org/integration/autoland/rev/71436fb16132
Part 6: Align Array and Object destructuring code paths. r=arai
https://hg.mozilla.org/integration/autoland/rev/cd0dd29a5c65
Part 7: Simplify paren-free arrow function parsing. r=arai
https://hg.mozilla.org/integration/autoland/rev/8fbfb862f801
Part 8: Remove a stale comment. r=arai
https://hg.mozilla.org/integration/autoland/rev/ee76c50ba4b7
Part 9: Remove unused NumericLiteral setters. r=arai
https://hg.mozilla.org/integration/autoland/rev/2a4095902192
Part 10: Inline literalIsZeroNoRadix into its single caller. r=arai

Comment 12

[Norisz Fay [:noriszfay]]

Backed out for causing build bustages on BytecodeEmitter.cpp

Backout link

Push with failures

Failure log

Failure line: /builds/worker/checkouts/gecko/js/src/frontend/BytecodeEmitter.cpp:2635:5: error: unannotated fall-through between switch labels [-Werror,-Wimplicit-fallthrough]

Comment 13

[André Bargull [:anba]]

Sigh. Why does linux64 (opt and debug) don't have --enable-warnings-as-errors?

Comment 14

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/eba6980e67ff
Part 1: Prefer BytecodeEmitter::emitUnpickN() over JSOp::Unpick. r=arai
https://hg.mozilla.org/integration/autoland/rev/89b1c584ae8e
Part 2: Directly pass 'lhs' to emitSetOrInitializeDestructuring. r=arai
https://hg.mozilla.org/integration/autoland/rev/a05af0c15ace
Part 3: Reorder access in destructuring so most likely cases come first. r=arai
https://hg.mozilla.org/integration/autoland/rev/4a19790129b7
Part 4: Remove unreachable code for BigInt property keys. r=arai
https://hg.mozilla.org/integration/autoland/rev/28622fa10a79
Part 5: Reorder more property name operations to handle simple names first. r=arai
https://hg.mozilla.org/integration/autoland/rev/5cbe09ca8c43
Part 6: Align Array and Object destructuring code paths. r=arai
https://hg.mozilla.org/integration/autoland/rev/782ce39e8d24
Part 7: Simplify paren-free arrow function parsing. r=arai
https://hg.mozilla.org/integration/autoland/rev/6a84be70015e
Part 8: Remove a stale comment. r=arai
https://hg.mozilla.org/integration/autoland/rev/412ef9eb0609
Part 9: Remove unused NumericLiteral setters. r=arai
https://hg.mozilla.org/integration/autoland/rev/b267528cb51a
Part 10: Inline literalIsZeroNoRadix into its single caller. r=arai

Comment 15

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/eba6980e67ff
https://hg.mozilla.org/mozilla-central/rev/89b1c584ae8e
https://hg.mozilla.org/mozilla-central/rev/a05af0c15ace
https://hg.mozilla.org/mozilla-central/rev/4a19790129b7
https://hg.mozilla.org/mozilla-central/rev/28622fa10a79
https://hg.mozilla.org/mozilla-central/rev/5cbe09ca8c43
https://hg.mozilla.org/mozilla-central/rev/782ce39e8d24
https://hg.mozilla.org/mozilla-central/rev/6a84be70015e
https://hg.mozilla.org/mozilla-central/rev/412ef9eb0609
https://hg.mozilla.org/mozilla-central/rev/b267528cb51a