https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118012
--- Comment #19 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
Mow it seems we need even more hacks in the avr BE to work around that insanits
in match.pd: For the following test case
__uint24 mul24 (__uint24 a, __uint24 b)
{
return a * b;
}
$ avr-gcc -Os -mmcu=atmega103
generates that:
mul24:
push r28 ; 34 [c=4 l=1] pushqi1/0
push r29 ; 35 [c=4 l=1] pushqi1/0
in r28,__SP_L__ ; 47 [c=4 l=2] *movhi/7
in r29,__SP_H__
sbiw r28,8 ; 48 [c=8 l=1] *addhi3/2
in __tmp_reg__,__SREG__ ; 38 [c=8 l=5] movhi_sp_r/2
cli
out __SP_H__,r29
out __SREG__,__tmp_reg__
out __SP_L__,r28
/* prologue: function */
/* frame size = 8 */
/* stack size = 10 */
std Y+1,r22 ; 49 [c=4 l=1] movqi_insn/2
std Y+2,r23 ; 50 [c=4 l=1] movqi_insn/2
std Y+3,r24 ; 51 [c=4 l=1] movqi_insn/2
std Y+5,r18 ; 52 [c=4 l=1] movqi_insn/2
std Y+6,r19 ; 53 [c=4 l=1] movqi_insn/2
std Y+7,r20 ; 54 [c=4 l=1] movqi_insn/2
ldd r18,Y+1 ; 55 [c=4 l=1] movqi_insn/3
ldd r19,Y+2 ; 56 [c=4 l=1] movqi_insn/3
ldd r20,Y+3 ; 57 [c=4 l=1] movqi_insn/3
ldd r21,Y+4 ; 58 [c=4 l=1] movqi_insn/3
ldd r22,Y+5 ; 59 [c=4 l=1] movqi_insn/3
ldd r23,Y+6 ; 60 [c=4 l=1] movqi_insn/3
ldd r24,Y+7 ; 61 [c=4 l=1] movqi_insn/3
ldd r25,Y+8 ; 62 [c=4 l=1] movqi_insn/3
call __mulsi3 ; 33 [c=20 l=2] *mulsi3_call_pr118012
/* epilogue start */
adiw r28,8 ; 63 [c=8 l=1] *addhi3/2
in __tmp_reg__,__SREG__ ; 42 [c=8 l=5] movhi_sp_r/2
cli
out __SP_H__,r29
out __SREG__,__tmp_reg__
out __SP_L__,r28
pop r29 ; 43 [c=4 l=1] popqi
pop r28 ; 44 [c=4 l=1] popqi
ret ;
The expected code is just a __mulpsi3 libcall:
mul24:
call __mulpsi3 ; 9 [c=20 l=2] call_value_insn/1
/* epilogue start */
ret ; 24 [c=0 l=1] return
