sdcc/support/regression/tests/bug-3788.c

   1 /** bug-3788.c: The value of a write to a bit-field in a union member was used as read value for another union member.
   2 */
   3
   4 #include <testfwk.h>
   5
   6 enum g_bits_defs {
   7     BITS_RESERVED_0 = 0x1, BITS_RESERVED_1 = 0x2,
   8     BITS_RESERVED_2 = 0x4, BITS_RESERVED_3 = 0x8,
   9     MYBIT4 = 0x10, MYBIT5 = 0x20,
  10     BITS_RESERVED_6 = 0x40, BITS_RESERVED_7 = 0x80 };
  11
  12 union {
  13     struct {
  14         unsigned char BITS_RESERVED_0 : 1;
  15         unsigned char BITS_RESERVED_1 : 1;
  16         unsigned char BITS_RESERVED_2 : 1;
  17         unsigned char BITS_RESERVED_3 : 1;
  18         unsigned char MYBIT4 : 1;
  19         unsigned char MYBIT5 : 1;
  20         unsigned char BITS_RESERVED_6 : 1;
  21         unsigned char BITS_RESERVED_7 : 1;
  22     } a;
  23     unsigned char is;
  24 } g_bits;
  25
  26 void print_special( unsigned char c );
  27
  28 void send_loop_try( unsigned char c )
  29 {
  30     (g_bits).a.MYBIT5 = 1;;
  31     if ( ((MYBIT4) & (g_bits).is) ) // The read of (g_bits).is was incorrectly optimized into a constant 1.
  32         print_special( c );
  33 }
  34
  35 unsigned char d = 0x5a;
  36
  37 void testBug( void )
  38 {
  39     (g_bits).a.MYBIT4 = 1;;
  40     send_loop_try( 0xa5 );
  41 // The order of allocation of bit-fields within a unit
  42 // (high-order to low-order or low-order to high-order) is
  43 // implementation-defined. This test assumes the SDCC order,
  44 // It fails e.g. for powerpc64-linux-gnu.
  45 #ifdef __SDCC
  46     ASSERT (d == 0xa5);
  47 #endif
  48 }
  49
  50 void print_special( unsigned char c )
  51 {
  52     d = c;
  53 }
  54