[Bug tree-optimization/110176] wrong code at -Os and above on x86_64-linux-gnu

2023-06-08 Thread pinskia at gcc dot gnu.org via Gcc-bugs 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110176

Andrew Pinski  changed:

   What|Removed |Added

 Status|UNCONFIRMED |NEW
 Ever confirmed|0   |1
   Last reconfirmed||2023-06-08

--- Comment #2 from Andrew Pinski  ---
Here is a testcase which will abort rather than do an infinite loop:
```


int f(_Bool t)
{
int tt = t;
unsigned x = -1;
int xx = x;
return xx <= tt;
}

int a, b;
void c() {}
[[gnu::noipa]]
void h() {__builtin_abort();}
int d() {
  unsigned f[1];
  int i;
  if (a)
goto h;
  f[0] = -1;
  while (1) {
c();
for (; a < 1; a++) {
  if (0) {
  j:
continue;
  }
  i = f[0];
  if (a)
break;
  b = i >= (b == 0);
}
if (!b) {
  if (0) {
  h:
goto j;
  }
  return 0;
}
h();
  }
}
int main() {
  d();
  return 0;
}
```

[Bug tree-optimization/110176] wrong code at -Os and above on x86_64-linux-gnu

2023-06-08 Thread pinskia at gcc dot gnu.org via Gcc-bugs 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110176

--- Comment #1 from Andrew Pinski  ---
Fre turns:
  b.2_4 = b;
  _5 = b.2_4 == 0;
  _6 = (int) _5;
  _7 = _6 <= i_19;
  _8 = (int) _7;
  b = _8;

Into:
  b.2_4 = b;
  _5 = b.2_4 == 0;
  _6 = (int) _5;
  b = 1;

Which is wrong as _6 <= -1 is always 0.

(simplify
(cmp (convert@0 @00) (convert?@1 @10))

...

tree min = lower_bound_in_type (TREE_TYPE (@10), TREE_TYPE (@00));
tree max = upper_bound_in_type (TREE_TYPE (@10), TREE_TYPE (@00));
bool above = integer_nonzerop (const_binop (LT_EXPR, type, max, @10));
bool below = integer_nonzerop (const_binop (LT_EXPR, type, @10, min));
...
(if (above || below)
...
{ constant_boolean_node (above ? true : false, type); }