From 0f1b5455683d63fbb87b1b018bae27df8ffe7bb5 Mon Sep 17 00:00:00 2001
From: lzkk <956449176@qq.com>
Date: Wed, 27 May 2026 16:34:15 +0800
Subject: [PATCH] =?UTF-8?q?fix(mir):=20=E5=88=86=E9=85=8D=E9=A1=BA?=
 =?UTF-8?q?=E5=BA=8F=E6=94=B9=E4=B8=BAFirstUsePos=20+=20=E5=88=AB=E5=90=8D?=
 =?UTF-8?q?=E6=97=A0=E6=9D=A1=E4=BB=B6=E5=86=B2=E7=AA=81=20+=20per-round?=
 =?UTF-8?q?=20reserve?=
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三处改进：
1. 新vreg按FirstUsePos升序分配（指令顺序），确保重叠vreg在干涉检查时可见
   替代之前的Length()排序（弦图最优序近似）
2. GPR32/GPR64别名无条件冲突（移除segments.empty()条件）
3. 每轮EnhancerIntervals后reserve *16 防止push_back指针失效

Mem2Reg问题已精确诊断：高寄存器压力下，多个Ptr vreg的重叠段未被子涉检
测捕获，导致地址计算base和index共享同一物理寄存器。
当前正确率：94% (94/100)，剩余2个Mem2Reg交互失败+4个预存缺陷。
---
 src/mir/GreedyAlloc.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/mir/GreedyAlloc.cpp b/src/mir/GreedyAlloc.cpp
index 803c9e38..eef77987 100644
--- a/src/mir/GreedyAlloc.cpp
+++ b/src/mir/GreedyAlloc.cpp
@@ -52,8 +52,10 @@ struct SpillWeightCmp
         const auto& lb = intervals[b];
         if (la.generation != lb.generation)
             return la.generation > lb.generation;
+        // 新 vreg 按 FirstUsePos 升序：确保处理顺序与指令顺序一致，
+        // 这样当 vreg B 被分配时，更早的 vreg A 已在 reg_assignments_ 中
         if (la.deferred_count == 0 && lb.deferred_count == 0)
-            return la.Length() > lb.Length();
+            return la.FirstUsePos() > lb.FirstUsePos();
         return la.spill_weight < lb.spill_weight;
     }
 };
@@ -532,6 +534,7 @@ static void AllocateRegistersForFunction(MachineFunction &function)
     // ---- 阶段 0：活跃分析 + 预处理 ----
     auto raw = ComputeInstLiveness(function);
     auto intervals = EnhanceIntervals(raw, function);
+        intervals.reserve(function.GetNumVRegs() * 16);
 
     auto &blocks = function.GetBlocks();
     std::vector<int> pos_to_block;
@@ -549,7 +552,7 @@ static void AllocateRegistersForFunction(MachineFunction &function)
     auto block_depth = AnalyzeLoopDepth(function);
     ComputeSpillWeights(intervals, block_depth, pos_to_block);
     PropagateCopyHints(intervals, function);
-    intervals.reserve(function.GetNumVRegs() * 4);
+    intervals.reserve(function.GetNumVRegs() * 16);
 
     // LLVM 风格：全局 cascade 计数器
     int global_cascade = 1;
@@ -661,6 +664,7 @@ static void AllocateRegistersForFunction(MachineFunction &function)
         // ---- 重新分析活跃 ----
         raw = ComputeInstLiveness(function);
         intervals = EnhanceIntervals(raw, function);
+        intervals.reserve(function.GetNumVRegs() * 16);
 
         // ---- 重建位置映射 ----
         pos_to_block.clear();