Stream: git-wasmtime

Topic: wasmtime / PR #5999 x64: Add `shuffle` specialization for...

Wasmtime GitHub notifications bot (Mar 12 2023 at 19:05):

alexcrichton requested abrown for a review on PR #5999.

Wasmtime GitHub notifications bot (Mar 12 2023 at 19:05):

alexcrichton opened PR #5999 from palignr to main:

This commit adds specializations for the palignr instruction to the x64 backend to specialize some more patterns of byte shuffles.

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Wasmtime GitHub notifications bot (Mar 13 2023 at 17:01):

fitzgen submitted PR review.

Wasmtime GitHub notifications bot (Mar 13 2023 at 17:01):

fitzgen submitted PR review.

Wasmtime GitHub notifications bot (Mar 13 2023 at 17:01):

fitzgen created PR review comment:

Why this change? Why always 32?

Wasmtime GitHub notifications bot (Mar 13 2023 at 17:01):

fitzgen created PR review comment:

I guess it was always passed 32, but I'm still a little confused why it was like that.

Wasmtime GitHub notifications bot (Mar 13 2023 at 18:56):

alexcrichton submitted PR review.

Wasmtime GitHub notifications bot (Mar 13 2023 at 18:56):

alexcrichton created PR review comment:

@abrown do you perhaps remember why palignr was always generated with OperandSize.Size32? I'll admit I don't fully understand how OperandSize maps to instructions all the time but I naively figured that it could be "constant folded" into the palignr constructor, but a double-check would be good.

Wasmtime GitHub notifications bot (Mar 13 2023 at 19:37):

alexcrichton submitted PR review.

Wasmtime GitHub notifications bot (Mar 13 2023 at 19:37):

alexcrichton created PR review comment:

Ah I remember now actually, this has to do with the rex flags when encoding where a 64-bit size forces the W bit to be set and otherwise W is unset. I believe the encoding of the palignr instruction forces this to "unset" so for palignr it should always be a non-64-bit size.

Wasmtime GitHub notifications bot (Mar 13 2023 at 20:30):

alexcrichton updated PR #5999 from palignr to main.

Wasmtime GitHub notifications bot (Mar 13 2023 at 20:35):

alexcrichton has enabled auto merge for PR #5999.

Wasmtime GitHub notifications bot (Mar 13 2023 at 20:54):

abrown submitted PR review.

Wasmtime GitHub notifications bot (Mar 13 2023 at 20:54):

abrown created PR review comment:

Yeah, I think that sounds right. The OperandSize isn't my invention and I recall having to work around it--I think things would be more clear if we hid OperandSize completely or alternately surfaced it as REX.W, which is more direct.

Wasmtime GitHub notifications bot (Mar 13 2023 at 21:45):

alexcrichton merged PR #5999.

Last updated: Dec 23 2024 at 12:05 UTC