1271972 - wasm: Implement i64.{clz,ctz,popcnt,eqz}

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, defect)

Comment 1

[Lars T Hansen [:lth]]

I have some basic masm-level code pending here, will upload soonish.

Comment 2

[Benjamin Bouvier [:bbouvier] (inactive)]

Attachment: 1.eqz.patch

Comment 3

[Benjamin Bouvier [:bbouvier] (inactive)]

Attachment: 2.i64.infra.patch

For the ability to have int64 temporaries. I've tried making a templated class from which Int64Allocation/Int64Definition would inherit from, but doing so means having to redefine the ctors in the children classes, taking away all the interest of doing the inheritance at all.

Comment 4

[Benjamin Bouvier [:bbouvier] (inactive)]

Attachment: 3.unary.i64.patch

This makes us pass i64.wast from the spec repo.

Comment 5

[Benjamin Bouvier [:bbouvier] (inactive)]

Attachment: 4. Hoist popcnt to the MacroAssembler

Based on your ctz/clz patches, this hoists popcnt64 to the macro assembler. (if you want to comment on the code sequence when we don't have the popcnt instruction, i would ask kindly to do so in a review of the previous patch, please :))

Comment 6

[Benjamin Bouvier [:bbouvier] (inactive)]

Attachment: 1.eqz.patch

Sorry for the spam, rebasing and histediting issues.

Comment 7

[Benjamin Bouvier [:bbouvier] (inactive)]

Attachment: 3.unary.i64.patch

Sorry for the spam, rebasing and histediting issues.

Comment 8

[Lars T Hansen [:lth]]

Comment on attachment 8751367 [details] [diff] [review]
4. Hoist popcnt to the MacroAssembler

Review of attachment 8751367 [details] [diff] [review]:
-----------------------------------------------------------------

I landed the clz64/ctz64 patches, and I removed knownNotZero in the process.

Would it be useful to have an InvalidReg64?

Comment 9

[Jan de Mooij [:jandem]]

Comment on attachment 8751364 [details] [diff] [review]
2.i64.infra.patch

Review of attachment 8751364 [details] [diff] [review]:
-----------------------------------------------------------------

Makes sense.

::: js/src/jit/LIR.h
@@ +635,5 @@
>  
>      void dump() const;
>  };
>  
> +class LInt64Definition

Maybe templatize LInt64Allocation (LInt64Value<T> or something), then we can add:

using LInt64Allocation = LInt64Value<LAllocation>;
using LInt64Definition = LInt64Value<LDefinition>;

Comment 10

[Dan Gohman [:sunfish]]

Comment on attachment 8751372 [details] [diff] [review]
1.eqz.patch

Review of attachment 8751372 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/asmjs/Wasm.cpp
@@ +277,5 @@
>        case Expr::Else:
>          return f.iter().readElse(nullptr, nullptr);
>        case Expr::End:
>          return f.iter().readEnd(nullptr, nullptr, nullptr);
> +      case Expr::I32Eqz:

The i64 form of eqz uses readConversion rather than readUnary because it needs a different type for the operand and result. It'd make sense to me to make the i32 form be a Conversion too, just to preserve what symmetry there is between i32 and i64, but we can go either way.

Comment 11

[Dan Gohman [:sunfish]]

Comment on attachment 8751373 [details] [diff] [review]
3.unary.i64.patch

Review of attachment 8751373 [details] [diff] [review]:
-----------------------------------------------------------------

Cool!

Yay for the optimized path when the popcnt instruction is present. lzcnt and tzcnt are less critical, so we can do them in the future. :-).

Comment 12

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/6b6de61e1364
https://hg.mozilla.org/integration/mozilla-inbound/rev/906763ccdf9a
https://hg.mozilla.org/integration/mozilla-inbound/rev/4daee0696926
https://hg.mozilla.org/integration/mozilla-inbound/rev/8178f7c2581b

Comment 13

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/e126886f6df8

Comment 14

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/6b6de61e1364
https://hg.mozilla.org/mozilla-central/rev/906763ccdf9a
https://hg.mozilla.org/mozilla-central/rev/4daee0696926
https://hg.mozilla.org/mozilla-central/rev/8178f7c2581b
https://hg.mozilla.org/mozilla-central/rev/e126886f6df8