points-analysis may not handle getelementptr

[joseph-isaacs]

I am running cclyzer over this (clang-5 compiled) c extract. [-g -Og -S -emit-llvm]

#include <stdlib.h>

#define N 100

struct X {
  int a[40];
  int **p;
};

struct X fX(struct X s) {
1  s.a[2] = 2;
2  int *af = malloc(sizeof (int));
3  *af = 4;
4  *(s.p) = af;
5  return s;
}

void fread(int);
void fU(int**);

void fU(int **ip) {
1  fread(**ip);
}

int main() {
1  struct X structX;
2  structX.a[1] = 2;
3  structX = fX(structX);
4  fU(structX.p);
}

I will attach the results and facts file, but the analysis fails to find that before line 1 in fU that ip -> heap_alloc:fX[...] (points_to), tracing this back I find that getelementptr instructions don't propagate any (ptr/var)_points_to information.