sdcc/support/regression/tests/bug-3003.c

   1 /*
   2    bug-3003.c
   3
   4    The wrong location is used for a local variable; observable effects vary by backend.
   5    For stm8, this results in overwriting other local variables.
   6    For z80, it results in use of location below the stack.
   7 */
   8
   9 #include <testfwk.h>
  10
  11 #include <stdint.h>
  12 #include <string.h>
  13
  14 #pragma disable_warning 88
  15
  16 void g(void)
  17 {
  18 }
  19
  20 static volatile uint8_t* f(const uint8_t id)
  21 {
  22     volatile uint8_t* result = 0; // Bug: For stm8, this variable is accessed at stack at sp+255, overwriting part of buffer.
  23     switch (id)
  24     {
  25         case 0:
  26             result = (volatile uint8_t *)0x5000;
  27             break;
  28         case 1:
  29             result = (volatile uint8_t *)0x5005;
  30             break;
  31         case 2:
  32             result = (volatile uint8_t *)0x500a;
  33             break;
  34     }
  35     g(); // This call overwrites result by the return address for z80.
  36     return result;
  37 }
  38
  39 #if defined (__SDCC_pdk14) || defined (__SDCC_pdk15) || defined (__SDCC_mcs51) || defined (__SDCC_STACK_AUTO) // Lack of memory
  40 #define BUFFERSIZE 20
  41 #else
  42 #define BUFFERSIZE 300
  43 #endif
  44
  45 void testBug(void)
  46 {
  47         unsigned char buffer[BUFFERSIZE]; // Bug: Overwritten in f() on stm8.
  48
  49         memset(buffer, 0xa5, BUFFERSIZE);
  50
  51         ASSERT(f(0) == (volatile uint8_t *)0x5000);
  52         ASSERT(f(1) == (volatile uint8_t *)0x5005);
  53         ASSERT(f(2) == (volatile uint8_t *)0x500a);
  54
  55         for(size_t i = 0; i < BUFFERSIZE; i++)
  56                 ASSERT (buffer[i] == 0xa5);
  57 }
  58