gcc/testsuite/gcc.target/arc/builtin_arc_aligned-3.c

   1 /* { dg-do run } */
   2 /* { dg-options "-O" } */
   3
   4 extern void abort (void);
   5
   6 typedef struct {
   7   int b, c;
   8 }
   9 __attribute__((aligned(32))) inner_t; // data type is 32 byte aligned
  10
  11 typedef struct {
  12   inner_t *inner;
  13   int a;
  14 } outer_t;
  15
  16 void __attribute__  ((noinline,weak))
  17 somefunc (int a, int b, int c)
  18 {
  19   if (!a || !b || c)
  20     abort ();
  21 };
  22
  23 __attribute__  ((noinline,weak))
  24 outer_t *
  25 some_alloc_1 ()
  26 {
  27   static outer_t x;
  28   return &x;
  29 }
  30
  31 __attribute__  ((noinline,weak))
  32 inner_t *
  33 some_alloc_2 ()
  34 {
  35   static inner_t x;
  36   return &x;
  37 }
  38
  39 int main (void)
  40 {
  41   int y, y2, y3;
  42   // @p_out is pointing to instance of outer_t, naturally aligned to 4+4 = 8
  43   // and not gauranteed be 32 byte aligned.
  44   outer_t *p_out = some_alloc_1( ); // returns 8 byte aligned ptr
  45
  46   // @ptr is pointing to instance of inner_t which is naturally aligned to 32.
  47   // It is assigned to p_out->inner which is of type inner_t thus 32 byte
  48   // aligned as well
  49   // Note that gcc can deduce p_out->inner is 32b aligned, not at runtime,
  50   // because it was assigned @ptr, but even at compile time, because it's data
  51   // type is naturally 32 byte aligned.
  52   inner_t *ptr = some_alloc_2(); // returns 32 byte aligned ptr
  53   p_out->inner = ptr; // this ptr will also be 32 byte aligned
  54
  55   y = __builtin_arc_aligned(ptr, 32); // this shd return 1
  56   y2 = __builtin_arc_aligned(p_out->inner, 32); // this also shd return 1
  57   // Although p_out->inner ptr is 32 byte aligned,
  58   // it's container &(p_out->inner) need not be.
  59   // That is because the hoister has no relation to contents.
  60   // p_out is not gauranteed to be 32 byte
  61   // aligned, so it's member @inner in p_out need not be.
  62   y3 = __builtin_arc_aligned(&(p_out->inner), 32);
  63   // compiler not sure, so must return 0
  64
  65   somefunc(y, y2, y3);
  66   return 0;
  67 }