https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93051
--- Comment #3 from Alexander Cherepanov <ch3root at openwall dot com> ---
For completeness, an example with a guessed pointer, based on the testcase from
bug 65752, comment 0, gcc-only (dom2):
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#include <stdint.h>
#include <stdio.h>
__attribute__((noipa)) // imagine it in a separate TU
static uintptr_t opaque_to_int(void *p) { return (uintptr_t)p; }
int main()
{
int x;
int *p = &x;
uintptr_t ip = (uintptr_t)p;
uintptr_t iq = 0;
while (iq < ip)
iq++;
uintptr_t ir = opaque_to_int(p); // hide provenance of p
if (ir == iq) {
*p = 1;
*(int *)ir = 2;
printf("result: %d\n", *p);
}
}
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$ gcc -std=c11 -pedantic -Wall -Wextra -O3 test.c && ./a.out
result: 1
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gcc x86-64 version: gcc (GCC) 10.0.0 20191224 (experimental)
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