[...]
>
> In "New Stuff", r20 gets clobbered and values copied from
> r26 are lost. That's not the case in the original code.
> "depw" only replaces 12 bits of "ret0" in the original code.
>
Good catch, in fact I would just have to save the read+write constraint on pa;
i.e this seems to make the drill:
__asm__ __volatile__ (
"lci %%r0(%%sr1, %2), %0\n"
"\textru %0,19,12,%0\n"
"\tdepw %0,15,12,%1\n"
: "=r" (ci), "+r" (pa)
: "r" (vba)
);
comparing produced objdump:
00000000 <ccio_io_pdir_entry>: 00000000 <ccio_io_pdir_entry>:
0: 00 19 58 20 mtsp r25,sr1 0: 00 19 58 20 mtsp r25,sr1
4: 23 80 0e 01 ldil L%-10000000,ret0 4: 23 80 0e 01 ldil L%-10000000,ret0
8: 0b 98 0a 1c add,l r24,ret0,ret0 8: 0b 98 0a 1c add,l r24,ret0,ret0
c: d7 97 0c 14 depw r23,31,12,ret0 c: d7 97 0c 14 depw r23,31,12,ret0
10: 0f 5c 12 88 stw ret0,4(r26) | 10: 34 13 00 00 ldi 0,r19
14: 07 00 53 18 lci r0(sr1,r24),r24 | 14: 0f 5c 12 88 stw ret0,4(r26)
18: d3 18 1a 74 extrw,u r24,19,12,r24 | 18: 07 00 53 1c lci r0(sr1,r24),ret0
1c: 34 1c 00 00 ldi 0,ret0 | 1c: d3 9c 1a 74 extrw,u ret0,19,12,ret0
20: d7 98 0e 14 depw r24,15,12,ret0 | 20: d6 7c 0e 14 depw ret0,15,12,r19
24: 0f 5c 12 80 stw ret0,0(r26) | 24: 0f 53 12 80 stw r19,0(r26)
28: 07 40 12 80 fdc r0(r26) 28: 07 40 12 80 fdc r0(r26)
2c: 00 00 04 00 sync 2c: 00 00 04 00 sync
30: e8 40 c0 02 bv,n r0(rp) 30: e8 40 c0 02 bv,n r0(rp)
Disassembly of section .text.ccio_free_consistent:Disassembly of section ...
This time r19 is well 'initialized' with 0 (as per C code pa = 0);
the coherent index in r28 (ret0) and after extrw, depw replaces 12 bits of r19.
Many thanks for re-reading ;-)
J.
> thanks,
> grant
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