Re: [PATCH v10 04/26] target/loongarch: Add fixed point arithmetic instruction translation

[Richard Henderson]

On 11/12/21 7:53 AM, Song Gao wrote:
> +#
> +# Fields
> +#
> +%rd      0:5
> +%rj      5:5
> +%rk      10:5
> +%sa2     15:2
> +%si12    10:s12
> +%ui12    10:12
> +%si16    10:s16
> +%si20    5:s20

You should only create separate field definitions like this when they are complex: e.g. 
the logical field is disjoint or there's a need for !function.

> +
> +#
> +# Argument sets
> +#
> +&fmt_rdrjrk         rd rj rk
> +&fmt_rdrjsi12       rd rj si12
> +&fmt_rdrjrksa2      rd rj rk sa2
> +&fmt_rdrjsi16       rd rj si16
> +&fmt_rdrjui12       rd rj ui12
> +&fmt_rdsi20         rd si20

Some of these should be combined.  The width of the immediate is a detail of the format, 
not the decoded argument set.  Thus you should have

&fmt_rdimm     rd imm
&fmt_rdrjimm   rd rj imm
&fmt_rdrjrk    rd rj rk
&fmt_rdrjrksa  rd rj rk sa

> +alsl_w           0000 00000000 010 .. ..... ..... .....   @fmt_rdrjrksa2
> +alsl_wu          0000 00000000 011 .. ..... ..... .....   @fmt_rdrjrksa2
> +alsl_d           0000 00000010 110 .. ..... ..... .....   @fmt_rdrjrksa2

The encoding of these insns is that the shift is sa+1.

While you compensate for this in gen_alsl_*, we print the "wrong" number in the 
disassembly.  I think it would be better to do

%sa2p1     15:2 !function=plus_1
@fmt_rdrjrksa2p1  .... ........ ... .. rk:5 rj:5 rd:5 \
                  &fmt_rdrjrksa sa=%sa2p1


r~