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Implement ExactSizeIterator for RegSetIter.

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The set of available registers in a register class is known ahead of
time. It can be computed with pop-count.
This commit is contained in:
Jakob Stoklund Olesen
2017-05-16 10:46:19 -07:00
parent 66d2c0a95a
commit 06afd3b77b
1 changed files with 10 additions and 1 deletions
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11
lib/cretonne/src/regalloc/allocatable_set.rs
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@@ -5,8 +5,9 @@
//! "register unit" abstraction. Every register contains one or more register units. Registers that //! "register unit" abstraction. Every register contains one or more register units. Registers that
//! share a register unit can't be in use at the same time. //! share a register unit can't be in use at the same time.
use std::mem::size_of_val;
use isa::registers::{RegUnit, RegUnitMask, RegClass}; use isa::registers::{RegUnit, RegUnitMask, RegClass};
use std::iter::ExactSizeIterator;
use std::mem::size_of_val;
/// Set of registers available for allocation. /// Set of registers available for allocation.
#[derive(Clone)] #[derive(Clone)]
@@ -128,8 +129,15 @@ impl Iterator for RegSetIter {
// All of `self.regs` is 0. // All of `self.regs` is 0.
None None
} }
fn size_hint(&self) -> (usize, Option<usize>) {
let bits = self.regs.iter().map(|&w| w.count_ones() as usize).sum();
(bits, Some(bits))
}
} }
impl ExactSizeIterator for RegSetIter {}
#[cfg(test)] #[cfg(test)]
mod tests { mod tests {
use super::*; use super::*;
@@ -162,6 +170,7 @@ mod tests {
let mut regs = AllocatableSet::new(); let mut regs = AllocatableSet::new();
// `GPR` has units 28-36. // `GPR` has units 28-36.
assert_eq!(regs.iter(GPR).len(), 8);
assert_eq!(regs.iter(GPR).count(), 8); assert_eq!(regs.iter(GPR).count(), 8);
assert_eq!(regs.iter(DPR).collect::<Vec<_>>(), [28, 30, 33, 35]); assert_eq!(regs.iter(DPR).collect::<Vec<_>>(), [28, 30, 33, 35]);