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//! Frame layout item changes.
use crate::ir::entities::Inst;
use crate::isa::RegUnit;
use std::boxed::Box;
use crate::HashMap;
/// Change in the frame layout information.
#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
pub enum FrameLayoutChange {
/// Base CallFrameAddress (CFA) pointer moved to different register/offset.
CallFrameAddressAt {
/// CFA register.
reg: RegUnit,
/// CFA offset.
offset: isize,
},
/// Register saved at.
RegAt {
/// Saved register.
reg: RegUnit,
/// Offset in the frame (offset from CFA).
cfa_offset: isize,
},
/// Return address saved at.
ReturnAddressAt {
/// Offset in the frame (offset from CFA).
cfa_offset: isize,
},
/// The entire frame layout must be preserved somewhere to be restored at a corresponding
/// `Restore` change.
///
/// This likely maps to the DWARF call frame instruction `.cfa_remember_state`.
Preserve,
/// Restore the entire frame layout from a corresponding prior `Preserve` frame change.
///
/// This likely maps to the DWARF call frame instruction `.cfa_restore_state`.
Restore,
}
/// Set of frame layout changes.
pub type FrameLayoutChanges = Box<[FrameLayoutChange]>;
/// Frame items layout for (prologue/epilogue) instructions.
#[derive(Debug, Clone)]
pub struct FrameLayout {
/// Initial frame layout.
pub initial: FrameLayoutChanges,
/// Instruction frame layout (changes). Because the map will not be dense,
/// a HashMap is used instead of a SecondaryMap.
pub instructions: HashMap<Inst, FrameLayoutChanges>,
}
impl FrameLayout {
/// Create instance of FrameLayout.
pub fn new() -> Self {
Self {
initial: vec![].into_boxed_slice(),
instructions: HashMap::new(),
}
}
/// Clear the structure.
pub fn clear(&mut self) {
self.initial = vec![].into_boxed_slice();
self.instructions.clear();
}
}