Wasmtime GitHub notifications bot (Apr 14 2025 at 23:37): Wasmtime GitHub notifications bot (Apr 14 2025 at 23:37):abrown opened PR #10580 from abrown:asm-flags to bytecodealliance:main:
This change replaces ISLE lowerings for the
ProducesFlagsandConsumesFlagswrappers with instructions from the new assembler. This is a necessary step towards fully using the new assembler for ALU instructions (AluRmiRis only used for zeroing registers now).A couple items of note:
- there are a few places where
lower.islewants to abstract over some subset of ALU operations to avoid repetition; this change retains that via somex64_*_flagshelpers that take a new type (ChainFlagsOp, e.g.) that restricts which operations the helper can use. This is not a major refactor but it does show that we use these flag-producing instructions in quite limited ways.- we previously decided to keep rules that used wider versions of registers for i8/i16 operations to avoid CPU dependencies; this is problematic for instructions that rely on overflow, though, so this change extracts those "wider register" rules into
x64_*_break_depshelpers.<!--
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Wasmtime GitHub notifications bot (Apr 15 2025 at 20:56):abrown updated PR #10580.
Wasmtime GitHub notifications bot (Apr 15 2025 at 20:56):abrown has marked PR #10580 as ready for review.
Wasmtime GitHub notifications bot (Apr 15 2025 at 20:56):abrown requested wasmtime-compiler-reviewers for a review on PR #10580.
Wasmtime GitHub notifications bot (Apr 15 2025 at 20:56):abrown requested cfallin for a review on PR #10580.
Wasmtime GitHub notifications bot (Apr 15 2025 at 23:03):cfallin submitted PR review:
Nice! I like the factoring here -- once the low-level helpers are out of the way, the application of this to each instruction is pretty straightforward.
Wasmtime GitHub notifications bot (Apr 15 2025 at 23:03):cfallin created PR review comment:
Can we add a comment here that this should only be provided an instruction that actually produces flags, and is meant to be used by helpers that bind it with explicit instructions? In other words, it's semantically "unsafe" in the Rust sense and has to be used in the right way to uphold invariants.
Wasmtime GitHub notifications bot (Apr 16 2025 at 17:44):abrown updated PR #10580.
Wasmtime GitHub notifications bot (Apr 16 2025 at 17:44):abrown has enabled auto merge for PR #10580.
Wasmtime GitHub notifications bot (Apr 16 2025 at 18:24):abrown merged PR #10580.
Last updated: Dec 06 2025 at 07:03 UTC