Optimization miss with __builtin_expect

The following code

int foo(int a, int b)
{

   do
   {
      a *= 77;
   } while (b-- > 0);

   return a * 77;
}

gets perfectly optimised into 

foo(int, int):
..B1.2:                         # Preds ..B1.2 ..B1.1
        imul      edi, edi, 77                                  #4.6
        dec       esi                                           #5.12
        jns       ..B1.2        # Prob 82%                      #5.18
        imul      eax, edi, 77                                  #6.14
        ret

Adding a __builtin_expect in the loop condition 

#define likely(x) __builtin_expect((x), 1)
#define unlikely(x) __builtin_expect((x), 0)

int foo(int a, int b)
{

   do {
     a *= 77;
  } while (unlikely(b-- > 0));

   return a * 77;
}

produces terrible code no matter the likelihood advised.  

foo(int, int):
        mov       eax, 1
..B1.2:
        xor       edx, edx
        test      esi, esi
        cmovg     edx, eax
        dec       esi
        imul      edi, edi, 77
        test      edx, edx
        jne       ..B1.2
        imul      eax, edi, 77
        ret      

By simply introducing a redundant local variable

#define likely(x) __builtin_expect((x), 1)
#define unlikely(x) __builtin_expect((x), 0)

int foo(int a, int b)
{
	int c;

	do
	{
		a *= 77;
		c = b--;
	}
	while (unlikely(c > 0));

   return a * 77;
}

the code generated improves

foo(int, int):
..B1.2:
        mov       eax, esi
        dec       esi
        imul      edi, edi, 77
        test      eax, eax
        jg        ..B1.2
        imul      eax, edi, 77
        ret 

It seems that ICC get confused by the use of __builtin_expect, is this a bug of ICC or this GCC built-in is not fully functional yet?