Wasmtime GitHub notifications bot (Feb 15 2023 at 15:05): Wasmtime GitHub notifications bot (Feb 15 2023 at 15:05):afonso360 commented on issue #5786:
Hey, I'm trying to understand why fuzzgen didn't catch this when you ran it a few weeks ago. This encoding error only triggers when we try to add a 16bit value directly from memory to a 32 bit register right?
I think fuzzgen can already generate code like that, although we only ever load from the stack, does s390x select a different encoding in those cases?
Wasmtime GitHub notifications bot (Feb 15 2023 at 15:09):uweigand commented on issue #5786:
Hey, I'm trying to understand why fuzzgen didn't catch this when you ran it a few weeks ago. This encoding error only triggers when we try to add a 16bit value directly from memory to a 32 bit register right?
Yes, and in addition the memory access must use a displacement of 4096 or larger. For smaller displacements, the (correctly encoded) AH instruction is used instead of AHY. This is probably a rare case - not sure if the fuzzer tries to enforce large displacements.
Wasmtime GitHub notifications bot (Feb 15 2023 at 15:16):afonso360 commented on issue #5786:
Oh! That explains it, We constrain the stack size quite a lot. We should probably increase that. Thanks!
Wasmtime GitHub notifications bot (Feb 15 2023 at 15:18):afonso360 edited a comment on issue #5786:
Oh! That explains it, We constrain the stack size quite a lot. We should probably increase that. Thanks!
Edit: Just looked it up, our max stack size is 1024, which is really low.
Last updated: Dec 23 2024 at 13:07 UTC