nrv5.c

用于进行gcc测试

/* Verify that NRV optimizations are prohibited when the LHS is
   something that may be call-clobbered. */
/* { dg-do compile } */
/* { dg-options "-O -fdump-tree-optimized" } */

typedef struct { int x[20]; void *y; } S;
typedef struct { int a; S b; } T;
S nrv_candidate (void);
void use_result (S);
void make_escape (S *);
void foo (void)
{
  S result;
  T result_arr[10][5];

  make_escape (&result);
  make_escape (&(result_arr[3][4].b));

  /* Neither call should be allowed to use NRV optimization.  */
  result = nrv_candidate ();
  result_arr[3][4].b = nrv_candidate ();

  use_result (result);
  use_result (result_arr[3][4].b);
}

/* { dg-final { scan-tree-dump-times "return slot optimization" 0 "optimized" } } */
/* { dg-final { cleanup-tree-dump "optimized" } } */