Addressed more review comments.

src/ion/data_structures.rs

@@ -13,9 +13,9 @@
 
 //! Data structures for backtracking allocator.
 
-use crate::bitvec::BitVec;
 use crate::cfg::CFGInfo;
 use crate::index::ContainerComparator;
+use crate::indexset::IndexSet;
 use crate::{
     define_index, Allocation, Block, Edit, Function, Inst, MachineEnv, Operand, PReg, ProgPoint,
     RegClass, SpillSlot, VReg,
@@ -267,8 +267,8 @@ pub struct Env<'a, F: Function> {
     pub func: &'a F,
     pub env: &'a MachineEnv,
     pub cfginfo: CFGInfo,
-    pub liveins: Vec<BitVec>,
-    pub liveouts: Vec<BitVec>,
+    pub liveins: Vec<IndexSet>,
+    pub liveouts: Vec<IndexSet>,
     /// Blockparam outputs: from-vreg, (end of) from-block, (start of)
     /// to-block, to-vreg. The field order is significant: these are sorted so
     /// that a scan over vregs, then blocks in each range, can scan in

src/ion/liveranges.rs

@@ -18,7 +18,7 @@ use super::{
     LiveRangeIndex, LiveRangeKey, LiveRangeListEntry, LiveRangeSet, PRegData, PRegIndex, RegClass,
     SpillSetIndex, Use, VRegData, VRegIndex, SLOT_NONE,
 };
-use crate::bitvec::BitVec;
+use crate::indexset::IndexSet;
 use crate::{
     Allocation, Block, Function, Inst, InstPosition, Operand, OperandConstraint, OperandKind,
     OperandPos, PReg, ProgPoint, RegAllocError, VReg,
@@ -248,8 +248,8 @@ impl<'a, F: Function> Env<'a, F> {
     pub fn compute_liveness(&mut self) -> Result<(), RegAllocError> {
         // Create initial LiveIn and LiveOut bitsets.
         for _ in 0..self.func.num_blocks() {
-            self.liveins.push(BitVec::new());
-            self.liveouts.push(BitVec::new());
+            self.liveins.push(IndexSet::new());
+            self.liveouts.push(IndexSet::new());
         }
 
         // Run a worklist algorithm to precisely compute liveins and
@@ -301,7 +301,7 @@ impl<'a, F: Function> Env<'a, F> {
             }
 
             for &pred in self.func.block_preds(block) {
-                if self.liveouts[pred.index()].or(&live) {
+                if self.liveouts[pred.index()].union_with(&live) {
                     if !workqueue_set.contains(&pred) {
                         workqueue_set.insert(pred);
                         workqueue.push_back(pred);