Stream: git-wasmtime

Topic: wasmtime / Issue #1043 Use callee-saved registers across ...

Wasmtime GitHub notifications bot (Feb 03 2021 at 17:00):

bjorn3 commented on Issue #1043:

This is fixed with the new backends, right?

Wasmtime GitHub notifications bot (Feb 03 2021 at 17:27):

cfallin commented on Issue #1043:

Indeed; I think we can go ahead and close this since we've addressed the issue (no longer need to track it); even if the new backend is not yet the default for the codegen crate or in wasmtime, it will be soon enough.

Wasmtime GitHub notifications bot (Feb 03 2021 at 17:27):

cfallin closed Issue #1043:

Currently, cranelift spills all registers across calls, without regard to whether they're callee-saved.

However the nice thing about callee-saved registers is that they're saved across calls ;-), and Cranelift indeed supports the callee side of this.

At a high level, the steps here are:

• Generalize x86's callee_saved_gprs into callee_saved_regs and make it not specific to GPRs (this appears needed for saving XMM registers on windows_fastcall too).
• Refactor this callee_saved_regs from being a private function to being a function in the TargetIsa trait, so that we can access the callee_saved_gprs from other places in the code.
• Make the code mentioned above in spilling.rs consult the TargetIsa's callee_saved_regs set and skip spilling registers in the callee-saved set.

Last updated: Oct 23 2024 at 20:03 UTC