1536699 - Enable TypedArray JIT optimizations for Big(U)Int64Array

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, enhancement, P2)

Description

[Robin Templeton [:terpri]]

ElementAccessIsTypedArray should return true for BigInt scalar types. Currently it returns false in order to bypass TypedArray-specific JIT optimizations that aren't yet implemented for BigInt.

Comment 1

[Robin Templeton [:terpri]]

v. review comments from bug 1456569 for optimization ideas from :wingo and :Waldo

Comment 2

[André Bargull [:anba]]

Required for bug 1631920.

Running with --no-threads --warp

var ta = new BigInt64Array(2);
var q = 0;
for (var i = 0; i < 10000; ++i) {
  if (ta[i&1]) q++;
}

asserts with Assertion failure: IsNumberType(ins->type()) || ins->type() == MIRType::Boolean, at /home/andre/hg/mozilla-inbound/js/src/jit/Lowering.cpp:3486.

Comment 3

[André Bargull [:anba]]

Attachment: Bug 1536699 - Part 1: Add missing helpers for Register64. r=jandem!

These functions are needed for the next parts.

Comment 4

[André Bargull [:anba]]

Attachment: Bug 1536699 - Part 2: Support BigInts in MLoadUnboxedScalar and MLoadTypedArrayElementHole. r=jandem!

There are too few registers available on x86, therefore LLoadTypedArrayElementHoleBigInt
is reusing the ValueOperand's type register, similar to CacheIRCompiler::emitLoadTypedElementResult.

LLoadUnboxedBigInt and LLoadTypedArrayElementHoleBigInt are both using an OOL vm-call
if the result BigInt can't be allocated inline, similar to CodeGenerator::visitInt64ToBigInt.

Depends on D72639

Comment 5

[André Bargull [:anba]]

Attachment: Bug 1536699 - Part 3: Add MToBigInt and ToBigIntPolicy. r=jandem!

The next part needs ToBigIntPolicy when storing BigInts into a typed array.

MToBigInt is currently only used as part of ToBigIntPolicy, therefore we
have to bailout for effectful operations, like ToBigInt(object). Only strings
and booleans can be handled without a bailout.

Depends on D72640

Comment 6

[André Bargull [:anba]]

Attachment: Bug 1536699 - Part 4: Support BigInts in MStoreUnboxedScalar and MStoreTypedArrayElementHole. r=jandem!

Also adds Register64::scratchReg() to make sure we don't run out of registers on x86.

Depends on D72641

Comment 7

[André Bargull [:anba]]

Attachment: Bug 1536699 - Part 5: Remove unnecessary safepoint for LLoadTypedArrayElementHole. r=jandem!

LLoadTypedArrayElementHole used to need to a safepoint for a vm-call (bug 737783),
but this vm-call was later removed in bug 829896.

Depends on D72642

Comment 8

[Tom Schuster [:evilpie]]

Thanks for catching and fixing this issue! Can you also land the testcase?

Comment 9

[André Bargull [:anba]]

Attachment: Bug 1536699 - Part 6: Add test case. r=jandem!

Depends on D72643

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/329a180ed9a0
Part 1: Add missing helpers for Register64. r=jandem
https://hg.mozilla.org/integration/autoland/rev/778475971875
Part 2: Support BigInts in MLoadUnboxedScalar and MLoadTypedArrayElementHole. r=jandem
https://hg.mozilla.org/integration/autoland/rev/984382fdbcd9
Part 3: Add MToBigInt and ToBigIntPolicy. r=jandem
https://hg.mozilla.org/integration/autoland/rev/a5f9b78cf7ba
Part 4: Support BigInts in MStoreUnboxedScalar and MStoreTypedArrayElementHole. r=jandem
https://hg.mozilla.org/integration/autoland/rev/031dee539212
Part 5: Remove unnecessary safepoint for LLoadTypedArrayElementHole. r=jandem
https://hg.mozilla.org/integration/autoland/rev/c43819fbce22
Part 6: Add test case. r=jandem

Comment 11

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/329a180ed9a0
https://hg.mozilla.org/mozilla-central/rev/778475971875
https://hg.mozilla.org/mozilla-central/rev/984382fdbcd9
https://hg.mozilla.org/mozilla-central/rev/a5f9b78cf7ba
https://hg.mozilla.org/mozilla-central/rev/031dee539212
https://hg.mozilla.org/mozilla-central/rev/c43819fbce22