1507493 - Update table and reftypes instructions to spec encodings

Status: RESOLVED FIXED

(Core :: JavaScript: WebAssembly, enhancement, P3)

Description

[Lars T Hansen [:lth]]

For the initial work on tables and reftypes we used some instruction encodings that are not canonical, the spec being in flux.  Once the spec settles down we need to make sure we use canonical encodings.

Comment 1

[Lars T Hansen [:lth]]

Also make sure we use the right value for MaxTables, at the moment we have a placeholder.

Comment 2

[Lars T Hansen [:lth]]

Blocks (in part) the bulk memory proposal because that proposal requires an opcode for ref.func to implement passive element segments, and that opcode is probably going to be 0xD2, and we have taken 0xD2 for ref.eq in our prototype implementation.

Comment 3

[Lars T Hansen [:lth]]

Current opcode proposals here: https://github.com/WebAssembly/reference-types/blob/master/interpreter/binary/decode.ml#L446

0xd0 == ref_null
0xd1 == ref_is_null
0xd2 == ref_func

and here: https://github.com/WebAssembly/reference-types/blob/master/interpreter/binary/decode.ml#L268

0x25 == table_get
0x26 == table_set

There are no proposed opcodes yet for table.grow, table.fill, table.size, ref.eq

Comment 4

[Lars T Hansen [:lth]]

Concrete proposal for encodings filed here: https://github.com/WebAssembly/reference-types/issues/29

Comment 5

[Lars T Hansen [:lth]]

Attachment: Bug 1507493 - Use canonical encodings for table instructions. r?jseward

Our initial prototype of the generalized table operations used a flag
byte optionally followed by a table index, and we used opcodes that
were at hand.

The agreed encoding does not use a flag byte, and some opcodes have
changed. So let's update SpiderMonkey.

Comment 6

[Lars T Hansen [:lth]]

Attachment: Bug 1507493 - Update the gc feature version number to 3. r?jseward

Since the encoding of in-flight operations for the reftypes and GC
proposals have changed, we must update the gc-feature opt-in version
number (that's why it's there); this requires a small validator change.

Alas this means a large number of test cases must also be updated.

Depends on D19794

Comment 7

[Lars T Hansen [:lth]]

I'll spin off updating MaxTable as its own bug.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/c7065bf19f4a
Use canonical encodings for table instructions. r=jseward
https://hg.mozilla.org/integration/mozilla-inbound/rev/03c225b8ccfc
Update the gc feature version number to 3. r=jseward

Comment 9

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/c7065bf19f4a
https://hg.mozilla.org/mozilla-central/rev/03c225b8ccfc