Hi there,
I just came past the following code. I'm optimizing with -Os.
static INLINE void setBeef(HEAPNODE * node){
*((u_long *) ((uptr_t) node + node->hn_size - sizeof(0xDEADBEEF))) =
0xDEADBEEF;
3c8: 8f ee ldi r24, 0xEF ; 239
3ca: 9e eb ldi r25, 0xBE ; 190
3cc: ad ea ldi r26, 0xAD ; 173
3ce: be ed ldi r27, 0xDE ; 222
3d0: b2 93 st -Z, r27
3d2: a2 93 st -Z, r26
3d4: 92 93 st -Z, r25
3d6: 82 93 st -Z, r24
The T register is already filled, so that's fine. But why are 4
additional registers needed? Doesn't the following code do the same?
Especially as registers are quite valuable?
ldi r24, 0xDE ; 222
st -Z, r24
ldi r24, 0xAD ; 173
st -Z, r24
ldi r24, 0xBE ; 190
st -Z, r24
ldi r24, 0xEF ; 239
st -Z, r24
I'm neither too familiar with assembler nor compiler. Therefore an
answer like: "Yes, your're right, but adding such an optimization is
difficult / nobody was motivated to implement it." will satisfy me. ;-)
Cheers
Morty
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