Re: [PATCH 5/8] target/ppc: Move multiply fixed-point insns (64-bit operands) to decodetree.

[Richard Henderson <richard.henderson@linaro.org>]

On 4/19/24 02:25, Chinmay Rath wrote:
> Hi Richard,
> 
> On 4/17/24 00:06, Richard Henderson wrote:
>> On 4/15/24 23:39, Chinmay Rath wrote:
>>> +static bool trans_MADDHDU(DisasContext *ctx, arg_MADDHDU *a)
>> ...
>>> +    tcg_gen_movi_i64(t1, 0);
>>
>> Drop the movi.
>>
>>> +    tcg_gen_add2_i64(t1, cpu_gpr[a->vrt], lo, hi, cpu_gpr[a->rc], t1);
>>
>> Use tcg_constant_i64(0).
>>
> Looks like tcg_gen_add2_i64 internally modifies the passed arguments, hence constant is 
> not expected.
> However, I tried using tcg_constant_i64(0) as suggested but this leads to an assert failure :
> qemu-system-ppc64: ../tcg/tcg.c:5071: tcg_reg_alloc_op: Assertion `!temp_readonly(ts)' 
> failed.

You misunderstood my suggestion.

   TCGv_i64 t1 = tcg_temp_new_i64();
   tcg_gen_add2_i64(t1, cpu_gpr[vrt], lo, hi, cpu_gpr[a->rc], tcg_constantant_i64(0));


r~