Thumb uses a special register allocation order to increase the use of low registers.

Thumb uses a special register allocation order to increase the use of low registers.

Thumb uses a special register allocation order to increase the use of low
registers.  Oddly enough, LR appears before R12, which means that LR must
be saved and restored even if R12 is available.  Swapping R12 and LR means
this simple example now uses R12 as a temporary (just like ARM):

int f(long long a, long long b)
{
  if (a < b) return 1;
  return a + b;
}

    gcc/
	* config/arm/arm.c (thumb_core_reg_alloc_order): Swap R12 and R14.

From-SVN: r243744