[Bug tree-optimization/80769] New: Invalid delayed string length computation in tree-ssa-strlen.c

["rsandifo at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80769

            Bug ID: 80769
           Summary: Invalid delayed string length computation in
                    tree-ssa-strlen.c
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rsandifo at gcc dot gnu.org
  Target Milestone: ---

This testcase below (which uses strlenopt.h in gcc/testsuite/gcc.dg) fails at
-O2 but passes with -O0.  tree-ssa-strlen.c isn't invalidating delayed string
lengths when "x" is added to the end.


#define USE_GNU
#include "strlenopt.h"

__attribute__((noinline, noclone)) int
bar (char *p1, const char *q)
{
  strcpy (p1, "abcde");
  char *p2 = strchr (p1, '\0');
  strcpy (p2, q);
  char *p3 = strchr (p2, '\0');
  memcpy (p3, "x", 2);
  return strlen (p1);
}

int
main (void)
{
  char buffer[10];
  int res = bar (buffer, "foo");
  if (strcmp (buffer, "abcdefoox") != 0 || res != 9)
    abort ();
  return 0;
}