Struct JitVmGuard 

pub struct JitVmGuard { /* private fields */ }

RAII guard pinning the active Vm (and optional closure) pointer for JIT-emitted Rust helper calls.

Real RAII rebind

enter_jit captures the prior (JIT_VM, JIT_CL) values into the guard, and Drop restores them. A drop that skipped the restore would save 2 TLS writes per dispatch, but under feature = "send" a Vm can park on thread A, move to thread B, and dispatch there: the per-thread JIT_VM slot on thread B is null/stale at entry, and a no-op drop would leave stale Vm pointers behind for any nested JIT entry (Lua-from-Rust-from-JIT call chains, e.g. metamethod dispatch under a JIT’d op). With nested entries, restoring the outer Vm pointer is load-bearing. In the single-thread-no-nesting case the values restored on exit are the same null/stale ones the next enter_jit would overwrite anyway.

NullJitBackend::enter keeps the no-op shape via noop_jit_guard — its guard has restore = None.

Debug-mode assertions still catch misuse via current_jit_vm’s is_null check IF a helper runs outside enter_jit (would happen only if some bug calls a helper symbol from interp code, which never happens by design).

Trait Implementations

impl Drop for JitVmGuard

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.