Method declare_value_needs_stack_map

cranelift/frontend/src/frontend.rs:556–565

Declare that the given value is a GC reference that requires inclusion in a stack map when it is live across GC safepoints. All values that are uses of this variable will be spilled to the stack before each safepoint and reloaded afterwards. Stack maps allow the garbage collector to identify the on-stack GC roots. Between spilling the stack and it being reloading again, the stack can be updated t

(&mut self, val: Value)

    ///
    /// Panics if `val` is larger than 16 bytes.
    pub fn declare_value_needs_stack_map(&mut self, val: Value) {
        log::trace!("declare_value_needs_stack_map({val:?})");

        // We rely on these properties in `insert_safepoint_spills`.
        let size = self.func.dfg.value_type(val).bytes();
        assert!(size <= 16);
        assert!(size.is_power_of_two());

        self.func_ctx.ssa.stack_map_values_mut().insert(val);
    }

    /// Creates a jump table in the function, to be used by [`br_table`](InstBuilder::br_table) instructions.
    pub fn create_jump_table(&mut self, data: JumpTableData) -> JumpTable {