Example: provenance_equality_global_xy.c

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    #include <stdio.h>
    #include <string.h> 
    int x=1, y=2;
    int main() {
      int *p = &x + 1;
      int *q = &y;
      printf("Addresses: p=%p q=%p\n",(void*)p,(void*)q);
      _Bool b = (p==q);
      // can this be false even with identical addresses?
      printf("(p==q) = %s\n", b?"true":"false");
      return 0;
    }

Experimental data (what does this mean?)

cerberus-concrete-PVI
 
EXECUTION 0 (exit = Specified(0)):
Addresses: p=(@7, 0x4c) q=(@8, 0x4c)
(p==q) = true

EXECUTION 1 (exit = Specified(0)):
Addresses: p=(@7, 0x4c) q=(@8, 0x4c)
(p==q) = false

cerberus-concrete-PNVI
 
EXECUTION 0 (exit = Specified(0)):
Addresses: p=(@7, 0x4c) q=(@8, 0x4c)
(p==q) = true

EXECUTION 1 (exit = Specified(0)):
Addresses: p=(@7, 0x4c) q=(@8, 0x4c)
(p==q) = false

gcc-8.1-O0
 
Addresses: p=0x6009b4 q=0x6009b4
(p==q) = true

gcc-8.1-O2
 
Addresses: p=0x600990 q=0x600988
(p==q) = false

gcc-8.1-O3
 
Addresses: p=0x600990 q=0x600988
(p==q) = false

gcc-8.1-O2-no-strict-aliasing
 
Addresses: p=0x600990 q=0x600988
(p==q) = false

gcc-8.1-O3-no-strict-aliasing
 
Addresses: p=0x600990 q=0x600988
(p==q) = false

clang-6.0-O0
 
Addresses: p=0x60103c q=0x60103c
(p==q) = true

clang-6.0-O2
 
Addresses: p=0x60103c q=0x60103c
(p==q) = true

clang-6.0-O3
 
Addresses: p=0x60103c q=0x60103c
(p==q) = true

clang-6.0-O2-no-strict-aliasing
 
Addresses: p=0x60103c q=0x60103c
(p==q) = true

clang-6.0-O3-no-strict-aliasing
 
Addresses: p=0x60103c q=0x60103c
(p==q) = true

clang-6.0-UBSAN
 
Addresses: p=0x631b54 q=0x631b54
(p==q) = true

clang-6.0-ASAN
 
Addresses: p=0x716b64 q=0x716ba0
(p==q) = false

clang-6.0-MSAN
 
Addresses: p=0x6b7af4 q=0x6b7af4
(p==q) = true

icc-19-O0
 
Addresses: p=0x600ae4 q=0x600ae4
(p==q) = true

icc-19-O2
 
Addresses: p=0x6046c4 q=0x6046c4
(p==q) = true

icc-19-O3
 
Addresses: p=0x6046c4 q=0x6046c4
(p==q) = true

icc-19-O2-no-strict-aliasing
 
Addresses: p=0x6046c4 q=0x6046c4
(p==q) = true

icc-19-O3-no-strict-aliasing
 
Addresses: p=0x6046c4 q=0x6046c4
(p==q) = true

compcert-3.4
 
Addresses: p=0x60103c q=0x60103c
(p==q) = true

compcert-3.4-O
 
Addresses: p=0x60103c q=0x60103c
(p==q) = true

kcc-1.0
 
Addresses: p=(nil) q=(nil)
(p==q) = true
Comparison of unspecified value:
      > in main at provenance_equality_global_xy.c:10:3

    Unspecified value or behavior (USP-CERL7):
        see C11 section 6.5.9 http://rvdoc.org/C11/6.5.9
        see MISRA-C section 8.1:3 http://rvdoc.org/MISRA-C/8.1