https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86204
Bug ID: 86204 Summary: [9 Regression] wrong strlen result after prior strnlen Product: gcc Version: 8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: msebor at gcc dot gnu.org Target Milestone: --- A bug in the strnlen() implementation committed in r261705 lets a strnlen() result be substituted for the result of subsequent calls to strlen() with the same argument: $ cat c.c && gcc -O2 -Wall -Wextra -fdump-tree-optimized=/dev/stdout c.c && ./a.out char a[4] = "123"; int main (void) { unsigned n0 = __builtin_strnlen (a, 1); unsigned n1 = __builtin_strlen (a); if (n0 != 1 || n1 != 3) __builtin_abort (); } ;; Function main (main, funcdef_no=0, decl_uid=1899, cgraph_uid=1, symbol_order=1) (executed once) main () { <bb 2> [count: 0]: __builtin_abort (); } Aborted (core dumped)