On Wed, Jun 3, 2015 at 6:42 AM, Siarhei Siamashka
<siarhei.siamas...@gmail.com> wrote:
>> + AVV (endian_xor.c[1]),0);
>> + perm = vec_xor (perm,(vector unsigned char) AVV (
>> + 0x00, 0x00, 0x00, 0x00, 0x04, 0x04, 0x04, 0x04,
>> + 0x08, 0x08, 0x08, 0x08, 0x0C, 0x0C, 0x0C, 0x0C));
>> + return vec_perm (pix, pix, perm);
>> }
>
> For this part, both the original and the patched code resulted in
> identical instruction sequences:
>
> 0000000000000000 <.vmx_splat_alpha>:
> 0: 3d 22 00 00 addis r9,r2,0
> 4: 39 29 00 00 addi r9,r9,0
> 8: 7c 00 48 ce lvx v0,0,r9
> c: 10 42 10 2b vperm v2,v2,v2,v0
> 10: 4e 80 00 20 blr
>
> This is actually good. I was afraid that the compiler might screw up
> it a bit and do something stupid like adding an extra VXOR instruction
> here (for the 'vec_xor' intrinsic).
>
Actually, I get a different disassembly:
0000000000007b10 <vmx_splat_alpha>:
7b10: 00 00 4c 3c addis r2,r12,0
7b14: 00 00 42 38 addi r2,r2,0
7b18: 00 00 22 3d addis r9,r2,0
7b1c: 0c 03 23 10 vspltisb v1,3
7b20: 00 00 29 39 addi r9,r9,0
7b24: 99 4e 00 7c lxvd2x vs32,0,r9
7b28: 57 02 00 f0 xxswapd vs32,vs32
7b2c: d7 04 01 f0 xxlxor vs32,vs33,vs32
7b30: 17 05 00 f0 xxlnor vs32,vs32,vs32
7b34: 2b 10 42 10 vperm v2,v2,v2,v0
7b38: 20 00 80 4e blr
And without the patch, I get this:
0000000000007930 <vmx_splat_alpha>:
7930: 00 00 4c 3c addis r2,r12,0
7934: 00 00 42 38 addi r2,r2,0
7938: 00 00 22 3d addis r9,r2,0
793c: 00 00 29 39 addi r9,r9,0
7940: 98 4e 00 7c lxvd2x vs0,0,r9
7944: 50 02 00 f0 xxswapd vs0,vs0
7948: 11 05 00 f0 xxlnor vs32,vs0,vs0
794c: 2b 10 42 10 vperm v2,v2,v2,v0
7950: 20 00 80 4e blr
So there is an added vspltisb + xxlxor command.
I used the default configure+make.
Maybe I need to define some special flag to the compiler ?
This is my gcc version:
gcc (GCC) 4.8.3 20140911 (Red Hat 4.8.3-9)
I'm running RHEL 7.1 ppc64le on POWER8 machine.
Oded
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