Example: pointer_from_int_disambiguation_2.c

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    #include <stdio.h>
    #include <string.h> 
    #include <stdint.h>
    #include <inttypes.h>
    int y=2, x=1;
    int main() {
      int *p = &x+1;
      int *q = &y;
      uintptr_t i = (uintptr_t)p;
      uintptr_t j = (uintptr_t)q;
      if (memcmp(&p, &q, sizeof(p)) == 0) {
        int *r = (int *)i;
        r=r-1;  // is this free of UB?
        *r=11;  // and this?    
        printf("x=%d y=%d *q=%d *r=%d\n",x,y,*q,*r); 
      }
    }
[link to run test in Cerberus]

Experimental data (what does this mean?) 



cerberus-concrete-concrete-permissive_pointer_arith-PVI-plain Undefined behaviour: out of bounds pointer at memory store at 14:5-10


cerberus-concrete-concrete-permissive_pointer_arith-PVI-ae Undefined behaviour: out of bounds pointer at memory store at 14:5-10


cerberus-concrete-permissive_pointer_arith-PVI-ae-udi x=11 y=2 *q=2 *r=11


gcc-8.3-O0 

gcc-8.3-O2 x=11 y=2 *q=2 *r=11


gcc-8.3-O3 x=11 y=2 *q=2 *r=11


gcc-8.3-O2-no-strict-aliasing x=11 y=2 *q=2 *r=11


gcc-8.3-O3-no-strict-aliasing x=11 y=2 *q=2 *r=11


clang-7.0.1-O0 

clang-7.0.1-O2 

clang-7.0.1-O3 

clang-7.0.1-O2-no-strict-aliasing 

clang-7.0.1-O3-no-strict-aliasing 

icc-19-O0 

icc-19-O2 

icc-19-O3 

icc-19-O2-no-strict-aliasing 

icc-19-O3-no-strict-aliasing