Example: provenance_union_punning_3_global.c

up: index
prev: provenance_union_punning_2_auto_yx.c
next: provenance_via_io_percentp_global.c

1
2
3
4
5
6
7
8
9
10
11
12
13
14

    #include <stdio.h>
    #include <string.h> 
    #include <inttypes.h>
    int x=1;
    typedef union { uintptr_t ui; int *up; } un;
    int main() {
      un u; 
      int *p = &x;
      u.up = p;
      uintptr_t i = u.ui;
      int *q = (int*)i;
      *q = 11;  // does this have UB?
      printf("x=%d *p=%d *q=%d\n",x,*p,*q);
    }
[link to run test in Cerberus]

Experimental data (what does this mean?) 



cerberus-concrete-PVI-plain x=11 *p=11 *q=11


cerberus-concrete-PVI-ae x=11 *p=11 *q=11


cerberus-concrete-PVI-ae-udi x=11 *p=11 *q=11


gcc-8.3-O0 x=11 *p=11 *q=11


gcc-8.3-O2 x=11 *p=11 *q=11


gcc-8.3-O3 x=11 *p=11 *q=11


gcc-8.3-O2-no-strict-aliasing x=11 *p=11 *q=11


gcc-8.3-O3-no-strict-aliasing x=11 *p=11 *q=11


clang-7.0.1-O0 x=11 *p=11 *q=11


clang-7.0.1-O2 x=11 *p=11 *q=11


clang-7.0.1-O3 x=11 *p=11 *q=11


clang-7.0.1-O2-no-strict-aliasing x=11 *p=11 *q=11


clang-7.0.1-O3-no-strict-aliasing x=11 *p=11 *q=11


icc-19-O0 x=11 *p=11 *q=11


icc-19-O2 x=11 *p=11 *q=11


icc-19-O3 x=11 *p=11 *q=11


icc-19-O2-no-strict-aliasing x=11 *p=11 *q=11


icc-19-O3-no-strict-aliasing x=11 *p=11 *q=11