97 points! I was afraid a huge change may lower the score hhhh..

Reports/3-ir-gen/report.md

@@ -81,13 +81,27 @@ PB20111654 李晓奇
       
       这个在访问`ASTVar`时解决掉：加入全局变量`LV`表式当前处理的是左值，所以要返回对应的地址，否则返回load出来的右值。
       
-      ```cpp
-      struct ASTCall : ASTFactor {
-          virtual void accept(ASTVisitor &) override final;
-          std::string id;
-          std::vector<std::shared_ptr<ASTExpression>> args;
-      };
-      ```
+      LV为`true`时，对应的是赋值语句的左式、函数的指针引用。
+      
+      另外嵌套递归调用可能导致LV发生变化，要注意。
+      
+      > 关于函数传参的探讨
+      > 
+      > - 值传递：由于LV是false，所以访问ASTVar的时候会load出来。可能需要类型转换。
+      > 
+      > - 指针传递：设置LV是true，这时ASTVar会返回一个指针，**指向基本元素类型**(int|float)。
+      >   
+      >   所以保证ASTVar返回的Value*变量符合要求，应该可以拿来直接使用，否则抛出异常。
+   
+    - 针对ASTVar的探讨
+      
+        - LV：如果标记为true，则做左值，返回数据地址，否则返回提取出来的数据。
+      
+        - node.expression：如果非空，则有数组下标
+      
+        - Var的类型：这里断言是指针类型，所有push操作都应该维护这个性质。其指向的类型应该有三种：基本类型(int\*, float\*)，数组类型([i32 x n]\*, [float x n]\*)，二级指针类型(int\*\*, float\*\*)。
+          
+          每种类型都有不同的对待逻辑，如何区分不同的Var类型呢？
    
     - 全局变量要特殊对待
    

src/cminusfc/cminusf_builder.cpp

@@ -16,8 +16,9 @@
 // definitions if you need to.
 
 // the latest return value
-bool LV = false;
 Value *cur_value = nullptr;
+// if var is assignment's left part, LV is true
+bool LV = false;
 // function that is being built
 Function *cur_fun = nullptr;
 
@@ -265,10 +266,16 @@ void CminusfBuilder::visit(ASTParam &node) {
     auto param_value = cur_value;
     switch (node.type) {
         case TYPE_INT: {
+            if (node.isarray)
+                cur_value = builder->create_alloca(INT32PTR_T);
+            else
                 cur_value = builder->create_alloca(INT32_T);
             break;
         }
         case TYPE_FLOAT: {
+            if (node.isarray)
+                cur_value = builder->create_alloca(FLOATPTR_T);
+            else
                 cur_value = builder->create_alloca(FLOAT_T);
             break;
         }
@@ -403,20 +410,26 @@ void CminusfBuilder::visit(ASTVar &node) {
     //!TODO: This function is empty now.
     // Add some code here.
     //
-    // Goal: calculate address
-    // 1. get base
-    // 2. get bias if there is, and cast it if needed.
-
-    bool old_LV = LV;
+    // First it's pointer type, the pointed elements have 3 cases:
+    // 1. int or float
+    // 2. [i32 x n] or [float x n]
+    // 3. int*
     auto memory = scope.find(node.id);
     Value *addr;
     if (memory == nullptr)
         error_exit("variable " + node.id + " not declared");
     LOG_DEBUG << "find entry: " << node.id << " " << memory;
-    if (node.expression) { // e.g. int a[10]; // mem is [i32 x 10]*
+
     assert(memory->get_type()->is_pointer_type());
+    auto element_type = memory->get_type()->get_pointer_element_type();
+
+    if (node.expression) { // e.g. int a[10]; // mem is [i32 x 10]*
+        bool old_LV = LV;
         LV = false;
         node.expression->accept(*this);
+        LV = old_LV;
+
+        // subscription type cast
         if (not Type::is_eq_type(cur_value->get_type(), INT32_T)) {
             if (Type::is_eq_type(cur_value->get_type(), FLOAT_T))
                 cur_value = builder->create_fptosi(cur_value, INT32_T);
@@ -436,15 +449,61 @@ void CminusfBuilder::visit(ASTVar &node) {
 
         builder->set_insert_point(passBB);
 
+        // Now the subscription is in cur_value, which is good value
+        // We should focus on the var type:
+        //
+        // assert it's pointer type
+        if (element_type->is_float_type() or element_type->is_integer_type()) {
+            // 1. int or float
+            error_exit("invalid types for array subscript");
+        } else if (element_type->is_array_type()) {
+            // 2. [i32 x n] or [float x n]
+            //
+            // addr is actually &memory[0][cur_value]
             addr = builder->create_gep(memory, {CONST_INT(0), cur_value});
+        } else if (element_type->is_pointer_type()) {
+            // 3. int*
+            // what to do:
+            // - int**->int*
+            // - seek addr
+            //
+            // addr is actually &(*memory)[cur_value]
+            addr = builder->create_load(memory);
+            addr = builder->create_gep(addr, {cur_value});
+        }
+
+        // The logic for this part is the same as `int|float` without subscription.
+        // Cause we have subscription to find the particular element(int or float),
+        // we make `addr` its memory address.
 
     } else { // e.g. int a; // a is i32*
+        if (element_type->is_float_type() or element_type->is_integer_type()) {
+            // 1. int or float
+            // addr is the element's addr
             addr = memory;
-    }
-    LV = old_LV;
+        } else {
             if (LV)
+                error_exit("error: pointer or array type is not assignable");
+            // For array* or pointer* type, the right-value behaviour is quite special,
+            // so treat them apart.
+            if (element_type->is_array_type()) {
+                // 2. [i32 x n] or [float x n]
+                // addr is the first element's address in the array
+                cur_value = builder->create_gep(memory, {CONST_INT(0), CONST_INT(0)});
+            } else if (element_type->is_pointer_type()) {
+                // 3. int*
+                // addr is the content in the memory, which is actually pointer type
+                cur_value = builder->create_load(memory);
+            }
+            return;
+        }
+    }
+
+    if (LV) {
+        LOG_INFO << "directly return addr" << node.id;
         cur_value = addr;
-    else {
+    } else {
+        LOG_INFO << "create load for var: " << node.id;
         cur_value = builder->create_load(addr);
     }
 }
@@ -624,11 +683,18 @@ void CminusfBuilder::visit(ASTCall &node) {
         // type cast
         if (not Type::is_eq_type(param_type, cur_value->get_type())) {
             if (param_type->is_pointer_type()) {
-                if (not Type::is_eq_type(param_type->get_pointer_element_type(),
-                                         cur_value->get_type()->get_array_element_type()))
-                    error_exit("expected right pointer type");
-                // int[] to int* or float[] to flot*
-                cur_value = builder->create_gep(cur_value, {CONST_INT(0), CONST_INT(0)});
+                // shouldn't need type cast for pointer, logically
+                if (param_type->get_pointer_element_type()->is_integer_type() or
+                    param_type->get_pointer_element_type()->is_float_type())
+                    error_exit("BUG HERE: ASTVar return value is not int* or float*");
+                else
+                    error_exit("BUG HERE: function param needs weird pointer type");
+
+                /* if (not Type::is_eq_type(param_type->get_pointer_element_type(),
+                 *                          cur_value->get_type()->get_pointer_element_type()->get_array_element_type()))
+                 *     error_exit("expected right pointer type");
+                 * // int[] to int* or float[] to flot*
+                 * cur_value = builder->create_gep(cur_value, {CONST_INT(0), CONST_INT(0)}); */
             } else if (param_type->is_integer_type() or param_type->is_float_type()) {
                 // need type cast between int and float
                 if (not cur_value->get_type()->is_integer_type() and not cur_value->get_type()->is_float_type())