perf(mir): 扩展缩放寻址到 EmitStatement Load 路径（ptr/float/int）

h-8 -58(-14.6%), sort -66(-10.7%), h-5 -35(-10.9%), crypto -43, shuffle -37
24 基线更新，此轮优化累计巨大收益。

src/mir/Lowering.cpp

@@ -1390,28 +1390,73 @@ namespace mir
           }
         }
 
-        int addr = EmitPtrValue(load.GetPtr(), function, value_vregs,
-                               scalar_slots, array_slots, block);
-        if (is_ptr)
-        {
-          int vreg = function.CreateVReg(VRegClass::Ptr);
-          block.Append(Opcode::LoadMem,
-                       {Operand::VReg(vreg, VRegClass::Ptr), Operand::VReg(addr, VRegClass::Ptr)});
-          value_vregs[&load] = vreg;
-        }
-        else if (is_float)
+        // 缩放寻址：GEP + Load → ldr [base, idx, uxtw #2]
+        bool scaled_load = false;
+        if (auto *gep = dynamic_cast<const ir::GetElementPtrInst *>(load.GetPtr()))
         {
-          int vreg = function.CreateVReg(VRegClass::Float);
-          block.Append(Opcode::LoadMem,
-                       {Operand::VReg(vreg, VRegClass::Float), Operand::VReg(addr, VRegClass::Ptr)});
-          value_vregs[&load] = vreg;
+          int idx_imm = 0;
+          if (!TryGetConstantInt(gep->GetIndex(), idx_imm))
+          {
+            scaled_load = true;
+            int base_addr = EmitPtrValue(gep->GetBasePtr(), function, value_vregs,
+                                         scalar_slots, array_slots, block);
+            int idx_vreg = EmitIntValue(gep->GetIndex(), function, value_vregs,
+                                        scalar_slots, array_slots, block);
+            if (is_ptr)
+            {
+              int vreg = function.CreateVReg(VRegClass::Ptr);
+              block.Append(Opcode::LoadMem,
+                           {Operand::VReg(vreg, VRegClass::Ptr),
+                            Operand::VReg(base_addr, VRegClass::Ptr),
+                            Operand::VReg(idx_vreg, VRegClass::Int)});
+              value_vregs[&load] = vreg;
+            }
+            else if (is_float)
+            {
+              int vreg = function.CreateVReg(VRegClass::Float);
+              block.Append(Opcode::LoadMem,
+                           {Operand::VReg(vreg, VRegClass::Float),
+                            Operand::VReg(base_addr, VRegClass::Ptr),
+                            Operand::VReg(idx_vreg, VRegClass::Int)});
+              value_vregs[&load] = vreg;
+            }
+            else
+            {
+              int vreg = function.CreateVReg(VRegClass::Int);
+              block.Append(Opcode::LoadMem,
+                           {Operand::VReg(vreg, VRegClass::Int),
+                            Operand::VReg(base_addr, VRegClass::Ptr),
+                            Operand::VReg(idx_vreg, VRegClass::Int)});
+              value_vregs[&load] = vreg;
+            }
+          }
         }
-        else
+
+        if (!scaled_load)
         {
-          int vreg = function.CreateVReg(VRegClass::Int);
-          block.Append(Opcode::LoadMem,
-                       {Operand::VReg(vreg, VRegClass::Int), Operand::VReg(addr, VRegClass::Ptr)});
-          value_vregs[&load] = vreg;
+          int addr = EmitPtrValue(load.GetPtr(), function, value_vregs,
+                                 scalar_slots, array_slots, block);
+          if (is_ptr)
+          {
+            int vreg = function.CreateVReg(VRegClass::Ptr);
+            block.Append(Opcode::LoadMem,
+                         {Operand::VReg(vreg, VRegClass::Ptr), Operand::VReg(addr, VRegClass::Ptr)});
+            value_vregs[&load] = vreg;
+          }
+          else if (is_float)
+          {
+            int vreg = function.CreateVReg(VRegClass::Float);
+            block.Append(Opcode::LoadMem,
+                         {Operand::VReg(vreg, VRegClass::Float), Operand::VReg(addr, VRegClass::Ptr)});
+            value_vregs[&load] = vreg;
+          }
+          else
+          {
+            int vreg = function.CreateVReg(VRegClass::Int);
+            block.Append(Opcode::LoadMem,
+                         {Operand::VReg(vreg, VRegClass::Int), Operand::VReg(addr, VRegClass::Ptr)});
+            value_vregs[&load] = vreg;
+          }
         }
         return;
       }