https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111519
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Reverting
@@ -5089,8 +5123,9 @@ strlen_pass::handle_store (bool *zero_write)
return false;
}
- if (storing_all_zeros_p
- || storing_nonzero_p
+ if (storing_nonzero_p
+ || storing_all_zeros_p
+ || (full_string_p && lenrange[1] == 0)
|| (offset != 0 && store_before_nul[1] > 0))
{
/* When STORING_NONZERO_P, we know that the string will start
fixes the issue. We somehow compute a lenrange of { 0, 0, 1 } for
d = _8 but also set storing_all_zeros_p to false.
It seems that strlen_pass::count_nonzero_bytes happily skips intermediate
stores when it handles SSA names here:
gimple *stmt = SSA_NAME_DEF_STMT (exp);
if (gimple_assign_single_p (stmt))
{
exp = gimple_assign_rhs1 (stmt);
if (!DECL_P (exp)
&& TREE_CODE (exp) != CONSTRUCTOR
&& TREE_CODE (exp) != MEM_REF)
return false;
/* Handle DECLs, CONSTRUCTOR and MEM_REF below. */
we have
_8 = *_7;
...
*_7 = prephitmp_89;
d = _8;
when we recursively process a memory reference we need to verify there
are no intermediate aliases, the simplest thing would be to pass down
a virtual use. Trying some prototype.
