Is this correct behaviour?

[Bingfeng Mei]

Hi, 
I compile the following code with arm gcc 4.6 (x86 is the similar with one of 
4.7 snapshot).
I noticed "a" is written to memory three times instead of being added by 3 and 
written at the
end. Doesn't restrict guarantee "a" won't be aliased to "p" so 3 "a++" can be 
optimized?

Thanks,
Bingfeng Mei

int a;
int P[100];
void foo (int * restrict p)
{
  P[0] = *p;
  a++;
  P[1] = *p;
  a++;
  P[2] = *p;
  a++;
}

~/work/install-arm/bin/arm-elf-gcc tst.c -O2 -S -std=c99

foo:
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        ldr     r3, .L2
        ldr     r1, [r3, #0]
        ldr     ip, [r0, #0]
        ldr     r2, .L2+4
        str     r4, [sp, #-4]!
        add     r4, r1, #1
        str     r4, [r3, #0]
        str     ip, [r2, #0]
        ldr     ip, [r0, #0]
        add     r4, r1, #2
        str     r4, [r3, #0]
        str     ip, [r2, #4]
        ldr     r0, [r0, #0]
        add     r1, r1, #3
        str     r0, [r2, #8]
        str     r1, [r3, #0]
        ldmfd   sp!, {r4}
        bx      lr