[Bug target/69833] Warning during bootstrap of --with-build-config=bootstrap-asan

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69833

--- Comment #6 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #5)
> Something like:
> #!/bin/sh
> .../cc1plus -quiet ...opts... -fsanitize=address -Werror=maybe-uninitialized
> pr69833.ii 2>&1 | awk '/may be used uninitialized in this
> function/{seen=seen+1;next}/error:/{exit 1}END{if (seen != 1)exit 1}'
> if ! test $? == 0; then
>   exit 1
> fi
> .../cc1plus -quiet ...opts... -fno-sanitize=address
> -Werror=maybe-uninitialized pr69833.ii 2>&1 | awk '/error:/{exit 1}'
> if ! test $? == 0; then
>   exit 1
> fi
> ?  For creduce, for delta replace pr69833.ii with $1 .

I use very similar script, btw. your's produces:

typedef struct tree_node *tree;
struct A {
  tree type;
};
struct tree_node {
  A typed;
};
tree a;
void fn1(tree);
void fn2() {
  tree b;
  if (a)
    fn1((b->typed.type));
}

There's the difference in tree optimized dump:

w/o asan:
void fn2() ()
{
  struct tree_node * b;
  struct tree_node * a.0_3;
  struct tree_node * _5;

  <bb 2>:
  a.0_3 = a;
  if (a.0_3 != 0B)
    goto <bb 3>;
  else
    goto <bb 4>;

  <bb 3>:
  _5 = b_4(D)->typed.type;
  fn1 (_5); [tail call]

  <bb 4>:
  return;

}

w/ asan:
void fn2() ()
{
  struct tree_node * b;
  struct tree_node * a.0_3;
  struct tree_node * _5;
  struct tree_node * * _7;
  unsigned long _9;
  unsigned long _10;
  unsigned long _11;
  signed char * _12;
  signed char _13;

  <bb 2>:
  a.0_3 = a;
  if (a.0_3 != 0B)
    goto <bb 3>;
  else
    goto <bb 6>;

  <bb 3>:
  _7 = &b_4(D)->typed.type;
  _9 = (unsigned long) _7;
  _10 = _9 >> 3;
  _11 = _10 + 2147450880;
  _12 = (signed char *) _11;
  _13 = *_12;
  if (_13 != 0)
    goto <bb 4>;
  else
    goto <bb 5>;

  <bb 4>:
  __builtin___asan_report_load8 (_9);

  <bb 5>:
  _5 = b_4(D)->typed.type;
  fn1 (_5); [tail call]

  <bb 6>:
  return;
}

Which is not a false positive as there's really missing an assignment to 'b'. I
will add dbg_cnt to asan emission..

M.