Am 17.11.24 um 15:42 schrieb Georg-Johann Lay:
Here are some examples:
Here are the examples again, but unTABified for legibility:
Without optimization | With optimization
==================== | =================
long long fn_zero (void)
{
return 0;
}
ldi r18, 0 ; movqi_insn | ldi r18, 0 ; movqi_insn
ldi r19, 0 ; movqi_insn | ldi r19, 0 ; movqi_insn
ldi r20, 0 ; movqi_insn | movw r20, r18 ; *movhi
ldi r21, 0 ; movqi_insn |
ldi r22, 0 ; movqi_insn | movw r22, r18 ; *movhi
ldi r23, 0 ; movqi_insn |
ldi r24, 0 ; movqi_insn | movw r24, r18 ; *movhi
ldi r25, 0 ; movqi_insn |
ret | ret
int fn_eq0 (char c)
{
return c == 0;
}
mov r18, r24 ; movqi_insn | mov r18, r24 ; movqi_insn
ldi r24, 1 ; *movhi | ldi r24, 1 ; *movhi
ldi r25, 0 | ldi r25, 0
cp r18, ZERO ; cmpqi3 | cpse r18, ZERO ; peephole
breq .+4 ; branch |
ldi r24, 0 ; *movhi | ldi r24, 0 ; movqi_insn
ldi r25, 0 |
ret | ret
unsigned fn_crc (unsigned x, unsigned y)
{
for (char i = 8; i--; x <<= 1)
y ^= (x ^ y) & 0x80 ? 79u : 0u;
return y;
}
movw r18, r24 ; *movhi | movw r18, r24 ; *movhi
movw r24, r22 ; *movhi | movw r24, r22 ; *movhi
ldi r22, 8 ; movqi_insn | ldi r22, 8 ; movqi_insn
.L13: | .L13:
movw r30, r18 ; *movhi | movw r30, r18 ; *movhi
eor r30, r24 ; *xorqi3 | eor r30, r24 ; *xorqi3
eor r31, r25 ; *xorqi3 | eor r31, r25 ; *xorqi3
mov r20, r30 ; *andhi3 | mov r20, r30 ; *andqi3
andi r20, 1<<7 | andi r20, 1<<7
clr r21 |
sbrs r30, 7 ; *sbrx_branchhi | sbrc r30, 7 ; *sbrx_branchhi
rjmp .+4 |
ldi r20, 79 ; movqi_insn | ldi r20, 79 ; movqi_insn
ldi r21, 0 ; movqi_insn |
eor r24, r20 ; *xorqi3 | eor r24, r20 ; *xorqi3
eor r25, r21 ; *xorqi3 |
lsl r18 ; *ashlhi3_const | lsl r18 ; *ashlhi3_const
rol r19 | rol r19
subi r22, 1 ; *op8.for.cczn.p| subi r22, 1 ;
*op8.for.cczn.plus
brne .L13 ; branch_ZN | brne .L13 ; branch_ZN
ret | ret
#define SPDR (*(uint8_t volatile*) 0x2c)
void fn_PR49807 (long big)
{
SPDR = big >> 24;
SPDR = big >> 16;
SPDR = big >> 8;
SPDR = big;
}
movw r20, r22 ; *movhi | movw r20, r22 ; *movhi
movw r22, r24 ; *movhi | movw r22, r24 ; *movhi
mov r24, r23 ; *ashrsi3_const |
clr r27 |
sbrc r24,7 |
com r27 |
mov r25, r27 |
mov r26, r27 |
out 0xc, r24 ; movqi_insn | out 0xc, r23 ; movqi_insn
movw r24, r22 ; *ashrsi3_const |
clr r27 |
sbrc r25, 7 |
com r27 |
mov r26, r27 |
out 0xc, r24 ; movqi_insn | out 0xc, r24 ; movqi_insn
clr r27 ; *ashrsi3_const |
sbrc r23, 7 |
dec r27 |
mov r26, r23 |
mov r25, r22 |
mov r24, r21 |
out 0xc, r24 ; movqi_insn | out 0xc, r21 ; movqi_insn
out 0xc, r20 ; movqi_insn | out 0xc, r20 ; movqi_insn
ret | ret
Johann
