Re: [Tinycc-devel] Pointers to variable-length arrays are broken

[Ivan Kozlov]

The issue appears to be that TCC creates a temporary object to store the computed address of the variable-length array. The _expression_ &a is then wrongly interpreted as taking the address of the temporary object, and not the array.

 

Attached is a workaround for x86-64 targets. I don’t understand the code, so I wouldn’t know how to fix this properly.

 

03.09.2021, 13:09, "Ivan Kozlov" <kanichos@yandex.ru>:

The following program miscompiles as of TCC 0.9.27:

#include <stdio.h>

int
main (void)
{
  size_t n = 10;
  int a[n];
  printf ("%p\n%p\n", (void *)a, (void *)*&a);
}

The second address is off. GCC 10.2.0, among others, handles this correctly.

Pointers to constant-length arrays work as intended (and indeed have the same representation as the address of the first element of the target array).

vla-address-of.patch
Description: Text Data