Stream: git-wasmtime

Topic: wasmtime / PR #5948 Stop supporting vectors with `bmask`

Wasmtime GitHub notifications bot (Mar 07 2023 at 01:36):

elliottt opened PR #5948 from trevor/bmask-simd to main:

The bmask instruction does not have a lowering in any backend that will produce a vector result, but the opcode constraints indicate that it is possible to produce a vector. Any attempt to produce a vector with bmask currently yields a panic, so this PR avoids that by rejecting these cases in the verifier instead.

Additionally, it's possible to produce a vector of comparison results whose lanes will be all 1 or 0 using either icmp or fcmp, rendering this possible behavior of bmask redundant.

Co-authored-by: Jamey Sharp <jsharp@fastly.com>

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Wasmtime GitHub notifications bot (Mar 07 2023 at 01:36):

elliottt updated PR #5948 from trevor/bmask-simd to main.

Wasmtime GitHub notifications bot (Mar 07 2023 at 01:38):

elliottt edited PR #5948 from trevor/bmask-simd to main:

The bmask instruction does not have a lowering in any backend that will produce a vector result, but the opcode constraints indicate that it is possible to produce a vector. Any attempt to produce a vector with bmask currently yields a panic, so this PR avoids that by rejecting these cases in the verifier instead.

Additionally, it's possible to produce a vector of comparison results whose lanes will be all 1 or 0 using either icmp or fcmp, rendering this possible behavior of bmask redundant. @jameysharp also points out that we can use a combination of bmask and splat to get similar behavior as well, so there are many ways to work around bmask not supporting vector results.

Co-authored-by: Jamey Sharp <jsharp@fastly.com>

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Wasmtime GitHub notifications bot (Mar 07 2023 at 12:02):

afonso360 submitted PR review.

Wasmtime GitHub notifications bot (Mar 07 2023 at 18:14):

elliottt merged PR #5948.

Last updated: Dec 06 2025 at 06:05 UTC