Method push_stack

crates/environ/src/compile/frame_table.rs:104–134

Push a stack entry. Returns the stack-shape descriptor and the offset at which to write the pushed value.

(
        &mut self,
        parent: Option<FrameStackShape>,
        ty: FrameValType,
    )

    /// Push a stack entry. Returns the stack-shape descriptor and the
    /// offset at which to write the pushed value.
    pub fn push_stack(
        &mut self,
        parent: Option<FrameStackShape>,
        ty: FrameValType,
    ) -> (FrameStackShape, FrameStateSlotOffset) {
        let offset = parent
            .map(|parent| {
                let (_, ty, offset) = self.stacks[parent.index()];
                offset.add(ty.storage_size(self.pointer_size))
            })
            // N.B.: the stack starts at vmctx_size + locals_size,
            // because the layout puts vmctx first, then locals, then
            // stack.
            .unwrap_or(FrameStateSlotOffset(self.vmctx_size + self.locals_size));

        self.slot_size = core::cmp::max(
            self.slot_size,
            offset.0 + ty.storage_size(self.pointer_size),
        );

        let shape = match self.stacks_dedup.entry((parent, ty, offset)) {
            Entry::Occupied(o) => *o.get(),
            Entry::Vacant(v) => {
                let shape = FrameStackShape(u32::try_from(self.stacks.len()).unwrap());
                self.stacks.push((parent, ty, offset));
                *v.insert(shape)
            }
        };

        (shape, offset)
    }

    /// Get the offset for the top slot in a given stack shape.
    pub fn stack_last_offset(&self, shape: FrameStackShape) -> FrameStateSlotOffset {