[Bug tree-optimization/39804] [4.5 Regression] internal compiler error: in propagate_necessity, at tree-ssa-dce.c:754

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

------- Comment #4 from rguenth at gcc dot gnu dot org  2009-04-18 10:22 -------
typedef unsigned char u8;
struct __large_struct { unsigned long buf[100]; };
static inline __attribute__((always_inline)) unsigned long
__copy_from_user_inatomic(void *to, const void *from, unsigned long n)
{
  unsigned long ret = 0;
  asm volatile("1:      mov""b"" %2,%""b""1\n" "2:\n"
               ".section .fixup,\"ax\"\n"
               "3:      mov %3,%0\n"
               "        xor""b"" %""b""1,%""b""1\n"
               "        jmp 2b\n"
               ".previous\n"
               " .section __ex_table,\"a\"\n"
               " " ".balign 4" " " "\n"
               " " ".long" " " "1b" "," "3b" "\n"
               " .previous\n"
               : "=r" (ret), "=q"(*(u8 *)to)
               : "m" ((*(struct __large_struct *)(from))), "i" (1), "0" (ret));
  return ret;
}
int romchecksum(const unsigned char *rom, unsigned char c) 
{   
  unsigned char sum;
  for (sum = 0;
       !__copy_from_user_inatomic(&(c), ( typeof(c) *)(rom++), sizeof(c));)
    sum += c;
}

Likely some missed corner-case in walking address-taken operations in asms.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39804