[Bug tree-optimization/101401] New: strlen of a constant char vector not folded

[msebor at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101401

            Bug ID: 101401
           Summary: strlen of a constant char vector not folded
           Product: gcc
           Version: 11.1.0
            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: ---

The strlen pass only folds the result in f() but not the equivalent in g().  It
should be able to handle both.

$ cat a.c && gcc -O2 -S -fdump-tree-optimized=/dev/stdout a.c
void f (void)
{
  char c8[8] = { 1, 2, 3 };
  if (__builtin_strlen (&c8[0]) != 3)
    __builtin_abort ();
}

void g (void)
{
  __attribute__ ((vector_size (8))) char c8 = { 1, 2, 3 };
  if (__builtin_strlen (&c8[0]) != 3)
    __builtin_abort ();
}

;; Function f (f, funcdef_no=0, decl_uid=1943, cgraph_uid=1, symbol_order=0)

void f ()
{
  <bb 2> [local count: 1073741824]:
  return;

}



;; Function g (g, funcdef_no=1, decl_uid=1947, cgraph_uid=2, symbol_order=1)

void g ()
{
  vector(8) char c8;
  long unsigned int _1;

  <bb 2> [local count: 1073741824]:
  c8 = { 1, 2, 3, 0, 0, 0, 0, 0 };
  _1 = __builtin_strlen (&VIEW_CONVERT_EXPR<char[8]>(c8)[0]);
  if (_1 != 3)
    goto <bb 3>; [0.00%]
  else
    goto <bb 4>; [100.00%]

  <bb 3> [count: 0]:
  __builtin_abort ();

  <bb 4> [local count: 1073741824]:
  c8 ={v} {CLOBBER};
  return;

}