https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126109
Bug ID: 126109
Summary: cselim could better handle maybe non-trapping
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
```
struct f
{
int t[16];
int m;
};
struct f arr;
int bitset2 (int n, int b)
{
if (n >= 16) __builtin_unreachable ();
int bit = 0x4;
//arr.t[n] = b;
if ((arr.t[n] & bit) == 0)
arr.t[n] |= bit;
return arr.t[n];
}
```
With `-O2 -fallow-store-data-races`.
Currently cselim uses tree_could_trap_p; tree_could_trap_p calls
in_array_bounds_p but that only handles INTEGER_CSTs and does not look at the
range of n here.
With https://gcc.gnu.org/pipermail/gcc-patches/2026-July/722737.html, we can
improve the call to tree_could_trap_p to take into account that the range of
the index here at the statements we are checking even.
Note I am not sure we want to always have tree_could_trap_p look into the range
either.
