Re: [Qemu-devel] [PATCH 5/6] target-ppc: add lxvb16x and lxvh8x

[Nikunj A Dadhania]

Richard Henderson <address@hidden> writes:

> On 08/10/2016 02:51 PM, Nikunj A Dadhania wrote:
>> I can fix the BE case using following but not sure if that will be
>> correct !
>>
>>         tcg_gen_qemu_ld_i64(xth, EA, ctx->mem_idx, MO_Q);
>>         gen_helper_bswap32x2(xth, xth);
>>         tcg_gen_addi_tl(EA, EA, 8);
>>         tcg_gen_qemu_ld_i64(xtl, EA, ctx->mem_idx, MO_Q);
>>         gen_helper_bswap32x2(xtl, xtl);
>
> This cannot be correct, because it assumes a host-dependent byte ordering.  
> You 
> should be able to see different results depending on a BE or LE host.
>
>
>> __vector uint32_t vrt32;
>> uint32_t rb32[4] = {0x00010203, 0x20212223, 0x30313233, 0x40414243};
>> asm("lxvw4x %x0, 0, %1 \n\t" \
>>      : "=ws"(vrt32) : "r"(&rb32));
>> printf("VRT32 = "); vec_put_u32(vrt32);
>>
>> Result On LE:
>> VRT32 = 40414243 30313233 20212223 00010203
>>
>> Result On BE:
>> VRT32 = 03020100 23222120 33323130 43424140
>
> Did you really recompile the test program for BE and LE, or did you just use 
> a 
> different command-line switch to qemu with the same executable image?

I have two different images one LE and other BE and run it like this;

./ppc64le-linux-user/qemu-ppc64le  -cpu POWER9 test-tcg/LElxvx
./ppc64-linux-user/qemu-ppc64  -cpu POWER9 test-tcg/BElxvx

$ file LElxvx 
LElxvx: ELF 64-bit LSB executable, 64-bit PowerPC or cisco 7500, version 1 
(GNU/Linux), statically linked, for GNU/Linux 2.6.32, not stripped
$ file BElxvx 
BElxvx: ELF 64-bit MSB executable, 64-bit PowerPC or cisco 7500, version 1 
(GNU/Linux), statically linked, for GNU/Linux 4.4.3, not stripped

> I can't see how you could possibly get these results for BE.

I have been confused since yesterday, so thought of asking you.

Regards
Nikunj