From c277aa2226bc43b5338fbf3e29c8ba502a03e1af Mon Sep 17 00:00:00 2001
From: lzkk <956449176@qq.com>
Date: Thu, 28 May 2026 01:59:27 +0800
Subject: [PATCH] =?UTF-8?q?perf(mir):=20=E5=B8=A7=E6=A7=BD=E6=8C=89?=
 =?UTF-8?q?=E5=A4=A7=E5=B0=8F=E9=87=8D=E6=8E=92=E5=BA=8F=E2=80=94=E2=80=94?=
 =?UTF-8?q?=E5=B0=8F=E6=A7=BD=E4=BC=98=E5=85=88=E8=8E=B7=E5=BE=97=20ldur?=
 =?UTF-8?q?=20=E8=8C=83=E5=9B=B4=E5=86=85=E5=81=8F=E7=A7=BB?=
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4字节标量优先分配，大数组靠后，使热访问在 [-256,0] 的 ldur 范围。
crypto -176(-10.3%)，消除大量 mov x13,x29 + sub 地址计算链。
---
 src/mir/FrameLowering.cpp | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/mir/FrameLowering.cpp b/src/mir/FrameLowering.cpp
index 34422b00..291d55dd 100644
--- a/src/mir/FrameLowering.cpp
+++ b/src/mir/FrameLowering.cpp
@@ -39,15 +39,35 @@ namespace mir
       }
       callee_saved_bytes = AlignTo(callee_saved_bytes, 16);
 
+      // 将小槽位（频繁访问的标量）排在前面，使偏移在 ldur 范围 [-256,0] 内
+      std::vector<size_t> slot_order(slots.size());
+      for (size_t i = 0; i < slots.size(); ++i)
+        slot_order[i] = i;
+      std::stable_sort(slot_order.begin(), slot_order.end(),
+                       [&](size_t a, size_t b) {
+                         const auto &sa = slots[a];
+                         const auto &sb = slots[b];
+                         if (sa.is_stack_arg != sb.is_stack_arg)
+                           return !sa.is_stack_arg;
+                         if (sa.is_callee_stack_arg != sb.is_callee_stack_arg)
+                           return !sa.is_callee_stack_arg;
+                         return sa.size < sb.size;
+                       });
+
+      std::vector<int> new_offsets(slots.size(), 0);
       int offset = 0;
-      for (auto &slot : slots)
+      for (size_t si : slot_order)
       {
+        auto &slot = slots[si];
         if (slot.is_stack_arg || slot.is_callee_stack_arg)
           continue;
         offset -= slot.size;
         offset = AlignTo(offset, slot.size >= 8 ? 8 : 4);
-        slot.offset = offset;
+        new_offsets[si] = offset;
       }
+      for (size_t i = 0; i < slots.size(); ++i)
+        if (!slots[i].is_stack_arg && !slots[i].is_callee_stack_arg)
+          slots[i].offset = new_offsets[i];
 
       offset -= callee_saved_bytes;
       offset -= 16;