gcc/testsuite/gcc.dg/pr56997-4.c

   1 /* Test volatile access to unaligned field.  */
   2 /* { dg-do compile } */
   3 /* { dg-options "-fno-strict-volatile-bitfields -fdump-rtl-final" } */
   4
   5 #define test_type unsigned short
   6
   7 typedef struct s{
   8  unsigned char Prefix[1];
   9  volatile test_type Type;
  10 }__attribute((__packed__,__aligned__(4))) ss;
  11
  12 extern volatile ss v;
  13
  14 void
  15 foo (test_type u)
  16 {
  17   v.Type = u;
  18 }
  19
  20 /* The C++ memory model forbids data store race conditions outside the
  21    unaligned data member, therefore only QI or HI access is allowed, no SI.  */
  22 /* { dg-final { scan-rtl-dump-not "mem/v(/.)*:SI" "final" } } */
  23 /* { dg-final { cleanup-rtl-dump "final" } } */