Struct FrameTableBuilder 

pub struct FrameTableBuilder { /* private fields */ }

Builder for the Frame Table.

Format:

• num_slot_descriptors: u32
• num_progpoints: u32
• num_breakpoints: u32
• num_funcs: u32
• frame_descriptor_pool_length: u32
• progpoint_descriptor_pool_length: u32
• breakpoint_patch_pool_length: u32
• num_slot_descriptors times:
  • frame descriptor offset: u32
  • length: u32
• num_slot_descriptors times:
  • offset from frame up to FP: u32
• num_progpoints times:
  • PC, from start of text section, position (post/pre): u32
    • encoded as (pc << 1) | post_pre_bit
• num_progpoints times:
  • progpoint descriptor offset: u32
• num_breakpoints times:
  • Wasm PC: u32 (sorted order; may repeat)
• num_breakpoints times:
  • patch offset in text: u32
• num_breakpoints times:
  • end of breakpoint patch data in pool: u32 (find the start by end of previous; patches are in the pool in order and this saves storing redundant start/end values)
• num_funcs times:
  • function start offset in text: u32 (sorted order)
• frame descriptors (format described above; frame_descriptor_pool_length bytes)
• progpoint descriptors (progpoint_descriptor_pool_length bytes)
  • each descriptor: sequence of frames
    • Wasm PC: u32 (high bit set to indicate a parent frame)
    • slot descriptor index: u32
    • stack shape index: u32 (or u32::MAX for none)
• breakpoint patch pool (breakpoint_patch_pool_length bytes)
  • freeform slices of machine-code bytes to patch in

Implementations

impl FrameTableBuilder

pub fn add_frame_descriptor( &mut self, slot_to_fp_offset: u32, data: &[u8], ) -> FrameTableDescriptorIndex

Add one frame descriptor.

Returns the frame descriptor index.

pub fn add_func_start(&mut self, native_pc: u32)

Record the start of a function in the text section.

This must be called for every function in the text section (whether or not it has any program points), in ascending order of offset, so that program-point lookups do not fall through into a preceding function’s metadata.

pub fn add_program_point( &mut self, native_pc: u32, pos: FrameInstPos, frames: &[(ModulePC, FrameTableDescriptorIndex, FrameStackShape)], )

Add one program point.

pub fn add_breakpoint_patch( &mut self, wasm_pc: ModulePC, patch_start_native_pc: u32, patch: &[u8], )

Add one breakpoint patch.

pub fn serialize<F: FnMut(&[u8])>(&mut self, f: F)

Serialize the frame-table data section, taking a closure to consume slices.

Trait Implementations

impl Default for FrameTableBuilder

fn default() -> Self

Returns the “default value” for a type.