Stream: git-wasmtime

Topic: wasmtime / PR #8360 fuzzgen: Use the correct ISA when run...


view this post on Zulip Wasmtime GitHub notifications bot (Apr 13 2024 at 12:33):

afonso360 requested elliottt for a review on PR #8360.

view this post on Zulip Wasmtime GitHub notifications bot (Apr 13 2024 at 12:33):

afonso360 requested wasmtime-compiler-reviewers for a review on PR #8360.

view this post on Zulip Wasmtime GitHub notifications bot (Apr 13 2024 at 12:33):

afonso360 opened PR #8360 from afonso360:fuzzgen-use-correct-target-isa to bytecodealliance:main:

:wave: Hey,

cranelift-fuzzgen unconditionally runs the NaN Canonicalization pass on all functions that it generates. This is so that we can ensure that when running in the interpreter vs natively we get the same bitpattern for all NaN's.

Until now we just picked a random ISA (the host ISA), disabled the verifier and ran the pass with that. This was because the ISA didn't really matter for the passes that we wanted to run.

In #8313 the ISA now drives some codegen decisions for the NaN Canonicalization pass. Namely, if the ISA supports Vectors, it tries to use that.

In #8359 a fuzz bug was reported where fuzzgen generated vector code for RISC-V without the has_v flag, something that should never happen, because we simply cannot compile that code.

It turns out that fuzzgen did not generate vector code itself. But since we were passing the host ISA to the NaN canonicalization pass, it assumed that it could use vectors and did so. But the actual target ISA did not support vectors.

To fix this, we now correctly pass the target ISA that we are building a function for.

Fixes #8359

view this post on Zulip Wasmtime GitHub notifications bot (Apr 13 2024 at 17:29):

elliottt submitted PR review:

Looks good to me!

view this post on Zulip Wasmtime GitHub notifications bot (Apr 13 2024 at 18:58):

alexcrichton merged PR #8360.


Last updated: Dec 23 2024 at 12:05 UTC