GCC C816 sometimes generates inefficient code. 

When there is such C code:

static struct { uint8_t a, b, c, d, e, f; } dat __attribute__ ((page_0));

dat.a = 0; dat.b = 1; dat.c = 2; dat.d = 3; dat.e = 4; datf = 5;

then, the compiler may generate following ASM code:

MOVE i0h,#0x0
MOVE i0l,#0xXX ; address of `dat` < 0x100
MOVE a,#0x0
MOVE (i0,0),a
MOVE a,#0x1
MOVE (i0,1),a
MOVE a,#0x2
MOVE (i0,2),a
MOVE a,#0x3
MOVE (i0,3),a
MOVE a,#0x4
MOVE (i0,4),a
MOVE a,#0x5
MOVE (i0,4),a

The compiler will generate ASM code that seems to ignore that all fields of the structure exist in the Page0 region.
Originally, this code should have been written in half the lines.