------- Comment #2 from mattst88 at gmail dot com 2009-04-18 15:25 -------
(In reply to comment #0)
> unsigned parity(unsigned x) {
> x ^= x >> 16;
> x ^= x >> 8;
> x ^= x >> 4;
> x &= 0xf;
> return (0x6996 >> x) & 1;
> }
>
> gcc 4.2.0 20060506 produces:
> extwl a0,0x2,t2
> lda v0,27030
> xor t2,a0,t2
> zapnot t2,0xf,t1 # redundant zero-extension
> srl t1,0x8,t1
> xor t1,t2,t1
> zapnot t1,0xf,t0 # redundant zero-extension
> srl t0,0x4,t0
> xor t0,t1,t0
> and t0,0xf,t0
> sra v0,t0,v0
> and v0,0x1,v0
>
> -fsee doesn't change anything here.
>
Compaq C generates:
0000000000000000 <parity>:
0: 82 16 02 4a srl a0,0x10,t1
4: 96 69 bf 20 lda t4,27030
8: 02 08 02 46 xor a0,t1,t1
c: 83 16 41 48 srl t1,0x8,t2
10: 02 08 43 44 xor t1,t2,t1
14: 84 96 40 48 srl t1,0x4,t3
18: 02 08 44 44 xor t1,t3,t1
1c: 02 f0 41 44 and t1,0xf,t1
20: 82 07 a2 48 sra t4,t1,t1
24: 00 30 40 44 and t1,0x1,v0
28: 01 80 fa 6b ret
--
mattst88 at gmail dot com changed:
What |Removed |Added
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CC| |mattst88 at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27469
