feat: impl pointer calc

50cc.h

@@ -50,6 +50,12 @@ bool startswith(char *p, char *q);
 Token *new_token(TokenKind kind, Token *cur, char *str, int len);
 Token *tokenize();
 
+typedef struct Type Type;
+struct Type {
+  enum { INT, PTR } ty;
+  struct Type *ptr_to;
+};
+
 typedef enum {
   ND_ADD,
   ND_SUB,
@@ -88,12 +94,7 @@ struct Node {
   int len;
   int val;
   int offset;
-};
-
-typedef struct Type Type;
-struct Type {
-  enum { INT, PTR } ty;
-  struct Type *ptr_to;
+  Type *type;
 };
 
 extern Node *code[];

func/func.c

@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <stdlib.h>
 
 int foo() { printf("%d\n", 10); }
 
@@ -7,4 +8,12 @@ int fooo(int x, int y) { printf("%d\n", x + y); }
 int foooo(int x, int y, int z) {
   printf("%d\n", z + y + z);
   return x + y + z;
+}
+
+void alloc(int **p, int a, int b, int c, int d) {
+  *p = malloc(sizeof(int) * 4);
+  (*p)[0] = a;
+  (*p)[1] = b;
+  (*p)[2] = c;
+  (*p)[3] = d;
 }

parser.c

@@ -269,9 +269,19 @@ Node *add() {
   Node *node = mul();
   for (;;) {
     if (consume("+")) {
-      node = new_node(ND_ADD, node, mul());
+      Node *r = mul();
+      if (node->type && node->type->ty == PTR) {
+        int c = node->type->ptr_to->ty == INT ? 4 : 8;
+        r = new_node(ND_MUL, r, new_node_num(c));
+      }
+      node = new_node(ND_ADD, node, r);
     } else if (consume("-")) {
-      node = new_node(ND_SUB, node, mul());
+      Node *r = mul();
+      if (node->type && node->type->ty == PTR) {
+        int c = node->type->ptr_to->ty == INT ? 4 : 8;
+        r = new_node(ND_MUL, r, new_node_num(c));
+      }
+      node = new_node(ND_SUB, node, r);
     } else {
       return node;
     }
@@ -365,6 +375,7 @@ Node *define_variable() {
   }
   lvar->type = type;
   node->offset = lvar->offset;
+  node->type = type;
   locals[cur_func] = lvar;
 
   return node;
@@ -380,5 +391,6 @@ Node *variable(Token *tok) {
     error("undefined variable: %s\n", name);
   }
   node->offset = lvar->offset;
+  node->type = lvar->type;
   return node;
 }

test.sh

@@ -31,6 +31,14 @@ int main(){
 }
 "
 
+assert 4 "int main() {
+  int *p;
+  alloc(&p, 1, 2, 4, 8);
+  int *q;
+  q = p + 2;
+  return *q;
+}"
+
 
 # define variables with type "int"
 # assert 5 "int main() {