Fix incorrect deref behavior

Previously, using subscription operator (literally "[]") with arrow
operator (literally "->") or dot operator (literally ".") would cause
incorrect dereference result due to inappropriate delayed dereference
strategy. In this patch, by adding dereference instructin when encount-
ered subscription operator and under correct circumstances fixes the
issue.

Author: ChAoSUnItY

src/globals.c

@@ -250,9 +250,7 @@ void hashmap_free(hashmap_t *map)
             next = cur->next;
             free(cur->key);
             free(cur->val);
-            /* FIXME: Remove this if-clause will cause double free error */
-            if (cur != map->buckets[0])
-                free(cur);
+            free(cur);
             cur = next;
         }
     }

src/parser.c

@@ -750,7 +750,7 @@ void read_lvalue(lvalue_t *lvalue,
                  var_t *var,
                  block_t *parent,
                  basic_block_t **bb,
-                 int eval,
+                 bool eval,
                  opcode_t op);
 
 /* Maintain a stack of expression values and operators, depending on next
@@ -805,7 +805,7 @@ void read_expr_operand(block_t *parent, basic_block_t **bb)
 
         lex_peek(T_identifier, token);
         var_t *var = find_var(token, parent);
-        read_lvalue(&lvalue, var, parent, bb, 0, OP_generic);
+        read_lvalue(&lvalue, var, parent, bb, false, OP_generic);
 
         if (!lvalue.is_reference) {
             ph1_ir = add_ph1_ir(OP_address_of);
@@ -825,7 +825,7 @@ void read_expr_operand(block_t *parent, basic_block_t **bb)
         int open_bracket = lex_accept(T_open_bracket);
         lex_peek(T_identifier, token);
         var_t *var = find_var(token, parent);
-        read_lvalue(&lvalue, var, parent, bb, 1, OP_generic);
+        read_lvalue(&lvalue, var, parent, bb, true, OP_generic);
         if (open_bracket)
             lex_expect(T_close_bracket);
 
@@ -962,7 +962,7 @@ void read_expr_operand(block_t *parent, basic_block_t **bb)
         } else if (var) {
             /* evalue lvalue expression */
             lvalue_t lvalue;
-            read_lvalue(&lvalue, var, parent, bb, 1, prefix_op);
+            read_lvalue(&lvalue, var, parent, bb, true, prefix_op);
 
             /* is it an indirect call with function pointer? */
             if (lex_peek(T_open_bracket, NULL)) {
@@ -1234,13 +1234,13 @@ void read_lvalue(lvalue_t *lvalue,
                  var_t *var,
                  block_t *parent,
                  basic_block_t **bb,
-                 int eval,
+                 bool eval,
                  opcode_t prefix_op)
 {
     ph1_ir_t *ph1_ir;
     var_t *vd;
-    int is_address_got = 0;
-    int is_member = 0;
+    bool is_address_got = false;
+    bool is_member = false;
 
     /* already peeked and have the variable */
     lex_expect(T_identifier);
@@ -1260,6 +1260,21 @@ void read_lvalue(lvalue_t *lvalue,
     while (lex_peek(T_open_square, NULL) || lex_peek(T_arrow, NULL) ||
            lex_peek(T_dot, NULL)) {
         if (lex_accept(T_open_square)) {
+            /* if subscripted member's is not yet resolved, deference to resolve base address
+             * e.g. dereference of "->" in "data->raw[0]" would be performed here
+             */
+            if (lvalue->is_reference && lvalue->is_ptr && is_member) {
+                ph1_ir = add_ph1_ir(OP_read);
+                ph1_ir->src0 = opstack_pop();
+                vd = require_var(parent);
+                strcpy(vd->var_name, gen_name());
+                ph1_ir->dest = vd;
+                opstack_push(vd);
+                ph1_ir->size = 4;
+                add_insn(parent, *bb, OP_read, ph1_ir->dest, ph1_ir->src0, NULL,
+                         ph1_ir->size, NULL);
+            }
+
             /* var must be either a pointer or an array of some type */
             if (var->is_ptr == 0 && var->array_size == 0)
                 error("Cannot apply square operator to non-pointer");
@@ -1303,8 +1318,8 @@ void read_lvalue(lvalue_t *lvalue,
                      ph1_ir->src1, 0, NULL);
 
             lex_expect(T_close_square);
-            is_address_got = 1;
-            is_member = 1;
+            is_address_got = true;
+            is_member = true;
             lvalue->is_reference = true;
         } else {
             char token[MAX_ID_LEN];
@@ -1313,7 +1328,7 @@ void read_lvalue(lvalue_t *lvalue,
                 /* resolve where the pointer points at from the calculated
                  * address in a structure.
                  */
-                if (is_member == 1) {
+                if (is_member) {
                     ph1_ir = add_ph1_ir(OP_read);
                     ph1_ir->src0 = opstack_pop();
                     vd = require_var(parent);
@@ -1327,7 +1342,7 @@ void read_lvalue(lvalue_t *lvalue,
             } else {
                 lex_expect(T_dot);
 
-                if (is_address_got == 0) {
+                if (!is_address_got) {
                     ph1_ir = add_ph1_ir(OP_address_of);
                     ph1_ir->src0 = opstack_pop();
                     vd = require_var(parent);
@@ -1337,7 +1352,7 @@ void read_lvalue(lvalue_t *lvalue,
                     add_insn(parent, *bb, OP_address_of, ph1_ir->dest,
                              ph1_ir->src0, NULL, 0, NULL);
 
-                    is_address_got = 1;
+                    is_address_got = true;
                 }
             }
 
@@ -1376,8 +1391,8 @@ void read_lvalue(lvalue_t *lvalue,
             add_insn(parent, *bb, OP_add, ph1_ir->dest, ph1_ir->src0,
                      ph1_ir->src1, 0, NULL);
 
-            is_address_got = 1;
-            is_member = 1;
+            is_address_got = true;
+            is_member = true;
         }
     }
 
@@ -1860,7 +1875,7 @@ bool read_body_assignment(char *token,
         int size = 0;
 
         /* has memory address that we want to set */
-        read_lvalue(&lvalue, var, parent, bb, 0, OP_generic);
+        read_lvalue(&lvalue, var, parent, bb, false, OP_generic);
         size = lvalue.size;
 
         if (lex_accept(T_increment)) {

tests/driver.sh

@@ -433,6 +433,49 @@ int main() {
 }
 EOF
 
+# Mixed subscript and arrow / dot operators,
+# excerpted and modified from issue #165
+try_output 0 "DDDDDDMMMEEE1" << EOF
+#include <stdlib.h>
+#include <string.h>
+
+char a[100];
+
+typedef struct {
+    char *raw;
+} data_t;
+
+int main() {
+    strcpy(a, "DATA");
+    data_t *data = malloc(sizeof(data_t));
+    data->raw = a;
+    data_t data2;
+    data2.raw = a;
+    char *raw = data->raw;
+    char *raw2 = data2.raw;
+    // mixed arrow / dot with subscript operators dereference
+    printf("%c", a[0]);
+    printf("%c", raw[0]);
+    printf("%c", data->raw[0]);
+    printf("%c", a[0]);
+    printf("%c", raw2[0]);
+    printf("%c", data2.raw[0]);
+    // mixed arrow / dot with subscript operators assignment
+    data2.raw[0] = 'M';
+    data->raw[1] = 'E';
+    printf("%c", a[0]);
+    printf("%c", raw[0]);
+    printf("%c", data->raw[0]);
+    printf("%c", a[1]);
+    printf("%c", raw2[1]);
+    printf("%c", data2.raw[1]);
+    // their addresses should be same
+    printf("%d", &data2.raw[0] == &data->raw[0]);
+    free(data);
+    return 0;
+}
+EOF
+
 # global initialization
 try_ 20 << EOF
 int a = 5 * 2;