diff --git a/crates/oxide_regalloc/src/color.rs b/crates/oxide_regalloc/src/color.rs
index 668205e..79e4f9d 100644
--- a/crates/oxide_regalloc/src/color.rs
+++ b/crates/oxide_regalloc/src/color.rs
@@ -15,7 +15,7 @@ use crate::alloc_map::{Alloc, AllocMap, FreshKind, FreshVreg, SpillPlan};
 use crate::graph::{self, InterferenceGraph};
 
 /// 主染色循环：产出 AllocMap。
-pub(super) fn run(f: &IRFunction, live: &LiveInfo, _graph: &InterferenceGraph) -> Result<AllocMap, String> {
+pub(super) fn run(f: &IRFunction, live: &LiveInfo) -> Result<AllocMap, String> {
     let max_real = graph::collect_real_vregs(f).into_iter().max().unwrap_or(0);
     let mut next_fresh_id = max_real + 1;
     let mut next_slot: u16 = 0;
@@ -44,7 +44,7 @@ pub(super) fn run(f: &IRFunction, live: &LiveInfo, _graph: &InterferenceGraph) -
                 fresh.push(FreshVreg { id: next_fresh_id, at: d, kind: FreshKind::Def, owner: v });
                 next_fresh_id += 1;
             }
-            for u in use_points(live, v) {
+            for u in use_points(f, v) {
                 fresh.push(FreshVreg { id: next_fresh_id, at: u, kind: FreshKind::Use, owner: v });
                 next_fresh_id += 1;
             }
@@ -69,12 +69,15 @@ fn def_points(f: &IRFunction, v: u32) -> Vec<usize> {
         .collect()
 }
 
-/// use 点：`live_before[i][v]`（v 的活点）。RMW 指令同时是 def 与 use，各建一个 fresh。
-fn use_points(live: &LiveInfo, v: u32) -> Vec<usize> {
-    live.inst_live_before
+/// use 点：`inst.use_regs()` 含 v 的指令下标（精确 use，非 live_before 活集——
+/// 活集包含"仅经过不读取"的指令，会产生多余 UNSPILL）。RMW 指令（如 COMPOUND_ADD
+/// rd 读旧值写新值）同时是 def 与 use，此处与 def_points 各建一个 fresh，由 rewrite 判
+/// rmw_v 决定用 def-fresh（rewrite.rs RMW 分支）。
+fn use_points(f: &IRFunction, v: u32) -> Vec<usize> {
+    f.insts
         .iter()
         .enumerate()
-        .filter(|(_, set)| set.get(v as usize).copied().unwrap_or(false))
+        .filter(|(_, i)| i.use_regs().contains(&v))
         .map(|(i, _)| i)
         .collect()
 }
diff --git a/crates/oxide_regalloc/src/graph.rs b/crates/oxide_regalloc/src/graph.rs
index 4742b46..1f7e5a8 100644
--- a/crates/oxide_regalloc/src/graph.rs
+++ b/crates/oxide_regalloc/src/graph.rs
@@ -80,7 +80,8 @@ pub(super) fn build(
     f: &IRFunction, live: &LiveInfo, spill_set: &BTreeSet<u32>, fresh: &[FreshVreg],
 ) -> InterferenceGraph {
     let real = collect_real_vregs(f);
-    let reg_count = live.inst_live_before.len();
+    // inst_live_before 长度 = 指令数（逐指令活集索引）
+    let inst_count = live.inst_live_before.len();
 
     // ── 预着色 ──
     let mut pre_colors: BTreeMap<u32, u32> = BTreeMap::new();
@@ -143,7 +144,7 @@ pub(super) fn build(
     for &v in &node_ids {
         adj_sets.entry(v).or_default();
     }
-    for i in 0..reg_count {
+    for i in 0..inst_count {
         let mut at_i: Vec<u32> = Vec::new();
         for &v in &node_ids {
             if live.inst_live_before[i].get(v as usize).copied().unwrap_or(false) {
diff --git a/crates/oxide_regalloc/src/lib.rs b/crates/oxide_regalloc/src/lib.rs
index f60e3e2..0397c8c 100644
--- a/crates/oxide_regalloc/src/lib.rs
+++ b/crates/oxide_regalloc/src/lib.rs
@@ -24,8 +24,7 @@ pub fn color(f: &IRFunction, live: &LiveInfo) -> Result<AllocMap, String> {
     if f.insts.is_empty() {
         return Ok(AllocMap::new());
     }
-    let graph = graph::build(f, live, &std::collections::BTreeSet::new(), &[]);
-    color::run(f, live, &graph)
+    color::run(f, live)
 }
 
 /// 寄存器分配改写：`&mut IRFunction + &LiveInfo → Result<(), String>`（D-16）。