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//! Heaps.
use ir::immediates::Imm64;
use ir::GlobalValue;
use std::fmt;
/// Information about a heap declaration.
#[derive(Clone)]
pub struct HeapData {
/// Method for determining the heap base address.
pub base: HeapBase,
/// Guaranteed minimum heap size in bytes. Heap accesses before `min_size` don't need bounds
/// checking.
pub min_size: Imm64,
/// Size in bytes of the guard pages following the heap.
pub guard_size: Imm64,
/// Heap style, with additional style-specific info.
pub style: HeapStyle,
}
/// Method for determining the base address of a heap.
#[derive(Clone)]
pub enum HeapBase {
/// The heap base lives in a reserved register.
///
/// This feature is not yet implemented.
ReservedReg,
/// The heap base is a global value.
GlobalValue(GlobalValue),
}
/// Style of heap including style-specific information.
#[derive(Clone)]
pub enum HeapStyle {
/// A dynamic heap can be relocated to a different base address when it is grown.
Dynamic {
/// Global value providing the current bound of the heap in bytes.
bound_gv: GlobalValue,
},
/// A static heap has a fixed base address and a number of not-yet-allocated pages before the
/// guard pages.
Static {
/// Heap bound in bytes. The guard pages are allocated after the bound.
bound: Imm64,
},
}
impl fmt::Display for HeapData {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(match self.style {
HeapStyle::Dynamic { .. } => "dynamic",
HeapStyle::Static { .. } => "static",
})?;
match self.base {
HeapBase::ReservedReg => write!(f, " reserved_reg")?,
HeapBase::GlobalValue(gv) => write!(f, " {}", gv)?,
}
write!(f, ", min {}", self.min_size)?;
match self.style {
HeapStyle::Dynamic { bound_gv } => write!(f, ", bound {}", bound_gv)?,
HeapStyle::Static { bound } => write!(f, ", bound {}", bound)?,
}
write!(f, ", guard {}", self.guard_size)
}
}