| Ralf S. Engelschall | d02b48c | 1998-12-21 10:52:47 +0000 | [diff] [blame] | 1 | /* NOCW */ |
| 2 | /* dggccbug.c */ |
| 3 | /* bug found by Eric Young (eay@cryptsoft.com) - May 1995 */ |
| 4 | |
| 5 | #include <stdio.h> |
| 6 | |
| 7 | /* There is a bug in |
| 8 | * gcc version 2.5.8 (88open OCS/BCS, DG-2.5.8.3, Oct 14 1994) |
| 9 | * as shipped with DGUX 5.4R3.10 that can be bypassed by defining |
| 10 | * DG_GCC_BUG in my code. |
| 11 | * The bug manifests itself by the vaule of a pointer that is |
| 12 | * used only by reference, not having it's value change when it is used |
| 13 | * to check for exiting the loop. Probably caused by there being 2 |
| 14 | * copies of the valiable, one in a register and one being an address |
| 15 | * that is passed. */ |
| 16 | |
| 17 | /* compare the out put from |
| 18 | * gcc dggccbug.c; ./a.out |
| 19 | * and |
| 20 | * gcc -O dggccbug.c; ./a.out |
| 21 | * compile with -DFIXBUG to remove the bug when optimising. |
| 22 | */ |
| 23 | |
| 24 | void inc(a) |
| 25 | int *a; |
| 26 | { |
| 27 | (*a)++; |
| 28 | } |
| 29 | |
| 30 | main() |
| 31 | { |
| 32 | int p=0; |
| 33 | #ifdef FIXBUG |
| 34 | int dummy; |
| 35 | #endif |
| 36 | |
| 37 | while (p<3) |
| 38 | { |
| 39 | fprintf(stderr,"%08X\n",p); |
| 40 | inc(&p); |
| 41 | #ifdef FIXBUG |
| 42 | dummy+=p; |
| 43 | #endif |
| 44 | } |
| 45 | } |
