Re: [Qemu-devel] [PATCH 0/7] tcg: conditional set and move opcodes

[Richard Henderson <rth@twiddle.net>]

On 12/17/2009 09:07 AM, Richard Henderson wrote:
>> + case TCG_COND_NE:
>> + if (const_arg2) {
>> + if ((uint16_t) arg2 == arg2) {
>> + tcg_out32 (s, XORI | RS (arg1) | RA (0) | arg2);
>> + }
>> + else {
>> + tcg_out_movi (s, TCG_TYPE_I32, 0, arg2);
>> + tcg_out32 (s, XOR | SAB (arg1, 0, 0));
>> + }
>> + }
>> + else {
>> + tcg_out32 (s, XOR | SAB (arg1, 0, arg2));
>> + }
>> +
>> + tcg_out32 (s, ADDIC | RT (arg0) | RA (0) | 0xffff);
>> + tcg_out32 (s, SUBFE | TAB (arg0, arg0, 0));
>> + return;
>
> Heh, you know a trick that gcc doesn't for powerpc. It just adds an xor
> at the end of the EQ sequence.

Ah, gcc does know the trick, it just thinks it's only a win on old Power 
systems.


r~