Enum ControlStackFrame

pub enum ControlStackFrame {
    If {
        destination: Block,
        else_data: ElseData,
        num_param_values: usize,
        num_return_values: usize,
        original_stack_size: usize,
        exit_is_branched_to: bool,
        blocktype: BlockType,
        head_is_reachable: bool,
        consequent_ends_reachable: Option<bool>,
    },
    Block {
        destination: Block,
        num_param_values: usize,
        num_return_values: usize,
        original_stack_size: usize,
        exit_is_branched_to: bool,
        try_table_info: Option<(HandlerStateCheckpoint, Vec<Block>)>,
    },
    Loop {
        destination: Block,
        header: Block,
        num_param_values: usize,
        num_return_values: usize,
        original_stack_size: usize,
    },
}

A control stack frame can be an if, a block or a loop, each one having the following fields:

• destination: reference to the Block that will hold the code after the control block;
• num_return_values: number of values returned by the control block;
• original_stack_size: size of the value stack at the beginning of the control block.

Moreover, the if frame has the branch_inst field that points to the brz instruction separating the true and false branch. The loop frame has a header field that references the Block that contains the beginning of the body of the loop.

Variants

If

Fields

destination: Block

else_data: ElseData

num_param_values: usize

num_return_values: usize

original_stack_size: usize

exit_is_branched_to: bool

blocktype: BlockType

head_is_reachable: bool

Was the head of the if reachable?

consequent_ends_reachable: Option<bool>

What was the reachability at the end of the consequent?

This is None until we’re finished translating the consequent, and is set to Some either by hitting an else when we will begin translating the alternative, or by hitting an end in which case there is no alternative.

Block

Fields

destination: Block

num_param_values: usize

num_return_values: usize

original_stack_size: usize

exit_is_branched_to: bool

try_table_info: Option<(HandlerStateCheckpoint, Vec<Block>)>

When this block corresponds to a try-table, keep the handler state checkpoint and the list of catch blocks to seal once the scope ends.

Loop

Fields

destination: Block

header: Block

num_param_values: usize

num_return_values: usize

original_stack_size: usize

Implementations

impl ControlStackFrame

Helper methods for the control stack objects.

pub fn num_return_values(&self) -> usize

pub fn num_param_values(&self) -> usize

pub fn following_code(&self) -> Block

pub fn br_destination(&self) -> Block

fn original_stack_size(&self) -> usize

Private helper. Use truncate_value_stack_to_else_params() or truncate_value_stack_to_original_size() to restore value-stack state.

pub fn is_loop(&self) -> bool

pub fn exit_is_branched_to(&self) -> bool

pub fn set_branched_to_exit(&mut self)

pub fn truncate_value_stack_to_else_params(&self, stack: &mut Vec<Value>)

Pop values from the value stack so that it is left at the input-parameters to an else-block.

pub fn truncate_value_stack_to_original_size(&self, stack: &mut Vec<Value>)

Pop values from the value stack so that it is left at the state it was before this control-flow frame.

pub fn restore_catch_handlers( &self, handlers: &mut HandlerState, builder: &mut FunctionBuilder<'_>, )

Restore exception handler state and seal catch blocks when exiting a try-table scope.

Trait Implementations

impl Debug for ControlStackFrame

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.