mips without optimize

midend/llvm/instr/AllocateInstr.java

@@ -1,21 +1,49 @@
-package midend.llvm.instr;
-
-import midend.llvm.type.IrPointerType;
-import midend.llvm.type.IrType;
-
-public class AllocateInstr extends IrInstr {
-    private IrType pointeeType;
-
-    public AllocateInstr(IrType pointeeType, String name) { // name即为局部变量的name，因为要声明一个局部变量
-        super(new IrPointerType(pointeeType), name, IrInstrType.ALLOCA);
-        this.pointeeType = pointeeType;
-    }
-
-    public IrType getPointeeType() {
-        return pointeeType;
-    }
-
-    public String toString() {
-        return getName() + " = alloca " + this.pointeeType;
-    }
-}
+package midend.llvm.instr;
+
+import backend.mips.MipsBuilder;
+import midend.llvm.type.IrArrayType;
+import midend.llvm.type.IrPointerType;
+import midend.llvm.type.IrType;
+import backend.mips.Register;
+import backend.mips.instr.MipsAlu;
+import backend.mips.instr.MipsLs;
+import backend.mips.instr.type.MipsAluType;
+import backend.mips.instr.type.MipsLsType;
+
+public class AllocateInstr extends IrInstr {
+    private IrType pointeeType;
+
+    public AllocateInstr(IrType pointeeType, String name) { // name即为局部变量的name，因为要声明一个局部变量
+        super(new IrPointerType(pointeeType), name, IrInstrType.ALLOCA);
+        this.pointeeType = pointeeType;
+    }
+
+    public IrType getPointeeType() {
+        return pointeeType;
+    }
+
+    public String toString() {
+        return getName() + " = alloca " + this.pointeeType;
+    }
+
+    public void toMips() {
+        // 想法：在栈上分配数据所需要的空间，再分配四字节的指针，这就是个指针，将其当作指针就好理解了
+        if (pointeeType instanceof IrArrayType) {
+            MipsBuilder.allocaOffset(4 * ((IrArrayType) pointeeType).getSize());
+        } else {
+            MipsBuilder.allocaOffset(4);
+        }
+
+        Register reg = MipsBuilder.getRegister(this);
+        if (reg == null) { // 未分配寄存器情况
+            int offset = MipsBuilder.getOffset();
+            new MipsAlu(MipsAluType.ADDI, Register.K0, Register.SP, offset);
+            MipsBuilder.allocaOffset(this);  // 将该变量的偏移量设置为其指针的偏移量，后续取值先取指针，再根据指针取值
+            offset = MipsBuilder.getOffset();
+            new MipsLs(MipsLsType.SW, Register.K0, Register.SP, offset);
+        } else {
+            int offset = MipsBuilder.getOffset();
+            new MipsAlu(MipsAluType.ADDI, reg, Register.SP, offset);
+        }
+    }
+}