From 28c336728d7688063a4fdeb6e50485fd7145e046 Mon Sep 17 00:00:00 2001
From: lzkk <956449176@qq.com>
Date: Tue, 26 May 2026 21:23:09 +0800
Subject: [PATCH] =?UTF-8?q?fix(mir):=20=E7=BA=BF=E6=80=A7=E6=89=AB?=
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- 区间分裂: last.end = cur.start (而非 cur.end)，确保 save point 之后寄存器值正确
- 多定义点 vreg: 改为按区间覆盖检查，支持 phi-copy 插入的多定义场景
- 30_many_dimensions 已修复（19D 嵌套循环输出正确）
- 25_while_if 循环变量映射仍有 bug，待进一步修复
---
 src/mir/LinearScanAlloc.cpp | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/mir/LinearScanAlloc.cpp b/src/mir/LinearScanAlloc.cpp
index be4ac6ab..933868b4 100644
--- a/src/mir/LinearScanAlloc.cpp
+++ b/src/mir/LinearScanAlloc.cpp
@@ -214,10 +214,21 @@ namespace mir
       {
         LiveInterval &cur = queue[qi];
 
-        // 同一 vreg 可能有多个 LiveInterval（分割产生），跳过已处理(已有范围)的
-        if (cur.vreg >= 0 && cur.vreg < num_vregs &&
-            vreg_has_range[cur.vreg])
-          continue;
+        // 检查当前区间是否已被覆盖（split 产生的溢出区间已有 vreg_ranges 条目）
+        if (cur.vreg >= 0 && cur.vreg < num_vregs)
+        {
+          bool already_covered = false;
+          for (const auto &rng : vreg_ranges[cur.vreg])
+          {
+            if (rng.start <= cur.start && cur.end <= rng.end)
+            {
+              already_covered = true;
+              break;
+            }
+          }
+          if (already_covered)
+            continue;
+        }
 
         // 选择对应寄存器池
         const int K = (cur.vreg_class == VRegClass::Float) ? K_FP : K_GP;
@@ -269,10 +280,10 @@ namespace mir
               VRegRange &last = ranges.back();
               if (last.reg_idx == stolen_reg)
               {
-                // 把 last.end 截断到 cur.end，后半段新建溢出范围
+                // 截断范围：寄存器在 cur.start 通过 save point 保存后即被 cur 覆写
                 int orig_end = last.end;
-                last.end = cur.end;
-                vreg_ranges[evicted_vreg].push_back({cur.end + 1, orig_end, -1});
+                last.end = cur.start;
+                vreg_ranges[evicted_vreg].push_back({cur.start + 1, orig_end, -1});
 
                 // 在此位置需要保存被驱逐的值到栈
                 int slot = GetOrCreateSpillSlot(func, evicted_vreg, vreg_to_slot);
@@ -281,7 +292,7 @@ namespace mir
                 // 把分割后的溢出部分送回队列（它以 evicted 的 vreg 标识，但 vreg_has_range 已为真）
                 LiveInterval split_li;
                 split_li.vreg = evicted_vreg;
-                split_li.start = cur.end + 1;
+                split_li.start = cur.start + 1;
                 split_li.end = orig_end;
                 split_li.vreg_class = spill_cand.interval->vreg_class;
                 split_li.spilled = true;