Re: [PATCH v3 4/4] target/hexagon: idef-parser simplify predicate init

[Brian Cain]

On 5/21/2024 3:16 PM, Anton Johansson via wrote:
> Only predicate instruction arguments need to be initialized by
> idef-parser. This commit removes registers from the init_list and
> simplifies gen_inst_init_args() slightly.
>
> Signed-off-by: Anton Johansson <anjo@rev.ng>
> Reviewed-by: Taylor Simpson <ltaylorsimpson@gmail.com>
> ---

Reviewed-by: Brian Cain <bcain@quicinc.com>

>   target/hexagon/idef-parser/idef-parser.y    |  2 --
>   target/hexagon/idef-parser/parser-helpers.c | 26 +++++++++++----------
>   2 files changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/target/hexagon/idef-parser/idef-parser.y 
> b/target/hexagon/idef-parser/idef-parser.y
> index cd2612eb8c..9ffb9f9699 100644
> --- a/target/hexagon/idef-parser/idef-parser.y
> +++ b/target/hexagon/idef-parser/idef-parser.y
> @@ -233,8 +233,6 @@ code : '{' statements '}'
>   argument_decl : REG
>                   {
>                       emit_arg(c, &@1, &$1);
> -                    /* Enqueue register into initialization list */
> -                    g_array_append_val(c->inst.init_list, $1);
>                   }
>                 | PRED
>                   {
> diff --git a/target/hexagon/idef-parser/parser-helpers.c 
> b/target/hexagon/idef-parser/parser-helpers.c
> index c150c308be..a7dcd85fe4 100644
> --- a/target/hexagon/idef-parser/parser-helpers.c
> +++ b/target/hexagon/idef-parser/parser-helpers.c
> @@ -1652,26 +1652,28 @@ void gen_inst(Context *c, GString *iname)
>   
>   
>   /*
> - * Initialize declared but uninitialized registers, but only for
> - * non-conditional instructions
> + * Initialize declared but uninitialized instruction arguments. Only needed for
> + * predicate arguments, initialization of registers is handled by the Hexagon
> + * frontend.
>    */
>   void gen_inst_init_args(Context *c, YYLTYPE *locp)
>   {
> +    HexValue *val = NULL;
> +    char suffix;
> +
> +    /* If init_list is NULL arguments have already been initialized */
>       if (!c->inst.init_list) {
>           return;
>       }
>   
>       for (unsigned i = 0; i < c->inst.init_list->len; i++) {
> -        HexValue *val = &g_array_index(c->inst.init_list, HexValue, i);
> -        if (val->type == REGISTER_ARG) {
> -            /* Nothing to do here */
> -        } else if (val->type == PREDICATE) {
> -            char suffix = val->is_dotnew ? 'N' : 'V';
> -            EMIT_HEAD(c, "tcg_gen_movi_i%u(P%c%c, 0);\n", val->bit_width,
> -                      val->pred.id, suffix);
> -        } else {
> -            yyassert(c, locp, false, "Invalid arg type!");
> -        }
> +        val = &g_array_index(c->inst.init_list, HexValue, i);
> +        suffix = val->is_dotnew ? 'N' : 'V';
> +        yyassert(c, locp, val->type == PREDICATE,
> +                 "Only predicates need to be initialized!");
> +        yyassert(c, locp, val->bit_width == 32,
> +                 "Predicates should always be 32 bits");
> +        EMIT_HEAD(c, "tcg_gen_movi_i32(P%c%c, 0);\n", val->pred.id, suffix);
>       }
>   
>       /* Free argument init list once we have initialized everything */