use -fno-unroll-loops
~d
On Wednesday 27 August 2003 03:01, Takahashi, Chris wrote:
> The following code creates some interesting asm with the following flags:
> -g -c -Os -fno-force-mem -mmcu=msp430x437
>
> It looks like it unrolled the loop in 64 byte chunks and is instead
> iterating over that. While this is faster this would hardly ever get run
> so I would rather have it small.
>
> attached are list files with the -fno-force-mem on and off and the C file.
>
> If I change the span it iterates over to a nonmultiple of 64 I get the
> expected asm.
>
> My question is what does no-force-mem have to do with this and why isn't
> auto increment addressing being used? In this case it would save quite a
> bit here.
>
> -Chris
>
> ---
>
> #include <msp430x44x.h>
>
> int test()
> {
> unsigned int sum = 0;
> unsigned int *addr;
>
> for (addr = (int *)0x8000; addr != 0x0000; addr++) {
> sum += *addr;
> }
>
> return sum;
> }
>
> -------
>
> for (addr = (int *)0x8000; addr != 0x0000; addr++) {^M
> 2: 3e 40 00 80 mov #-32768,r14 ;#0x8000
> sum += *addr;^M
> 6: 2f 5e add @r14, r15 ;
> 8: 1f 5e 02 00 add 2(r14), r15 ;
> c: 1f 5e 04 00 add 4(r14), r15 ;
> 10: 1f 5e 06 00 add 6(r14), r15 ;
> 14: 1f 5e 08 00 add 8(r14), r15 ;
> 18: 1f 5e 0a 00 add 10(r14),r15 ;
> 1c: 1f 5e 0c 00 add 12(r14),r15 ;
> 20: 1f 5e 0e 00 add 14(r14),r15 ;
> 24: 1f 5e 10 00 add 16(r14),r15 ;
> 28: 1f 5e 12 00 add 18(r14),r15 ;
> 2c: 1f 5e 14 00 add 20(r14),r15 ;
> 30: 1f 5e 16 00 add 22(r14),r15 ;
> 34: 1f 5e 18 00 add 24(r14),r15 ;
> 38: 1f 5e 1a 00 add 26(r14),r15 ;
> 3c: 1f 5e 1c 00 add 28(r14),r15 ;
> 40: 1f 5e 1e 00 add 30(r14),r15 ;
> 44: 1f 5e 20 00 add 32(r14),r15 ;
> 48: 1f 5e 22 00 add 34(r14),r15 ;
> 4c: 1f 5e 24 00 add 36(r14),r15 ;
> 50: 1f 5e 26 00 add 38(r14),r15 ;
> 54: 1f 5e 28 00 add 40(r14),r15 ;
> 58: 1f 5e 2a 00 add 42(r14),r15 ;
> 5c: 1f 5e 2c 00 add 44(r14),r15 ;
> 60: 1f 5e 2e 00 add 46(r14),r15 ;
> 64: 1f 5e 30 00 add 48(r14),r15 ;
> 68: 1f 5e 32 00 add 50(r14),r15 ;
> 6c: 1f 5e 34 00 add 52(r14),r15 ;
> 70: 1f 5e 36 00 add 54(r14),r15 ;
> 74: 1f 5e 38 00 add 56(r14),r15 ;
> 78: 1f 5e 3a 00 add 58(r14),r15 ;
> 7c: 1f 5e 3c 00 add 60(r14),r15 ;
> 80: 1f 5e 3e 00 add 62(r14),r15 ;
> 84: 3e 50 40 00 add #64, r14 ;#0x0040
> 88: be 23 jnz $-130 ;abs 0x6
> }
--
/*****************************************************************
("`-''-/").___..--''"`-._ (\ Dimmy the Wild UA1ACZ
`6_ 6 ) `-. ( ).`-.__.`) State Polytechnical Univ.
(_Y_.)' ._ ) `._ `. ``-..-' Radio-Physics Departament
_..`--'_..-_/ /--'_.' ,' Saint Petersburg, Russia
(il),-'' (li),' ((!.-' +7 (812) 5403923, 5585314
*****************************************************************/
