[Mesa-dev] [PATCH 03/13] i965: Print subreg in units of type-size on ternary instructions

[Scott D Phillips]

Matt Turner <mattst88 at gmail.com> writes:

> The instruction word contains SubRegNum[4:2] so it's in units of dwords
> (hence the * 4 to get it in terms of bytes). Before this patch, the
> subreg would have been wrong for DF arguments.

Trying to grok the subregnum stuff here, in brw_eu_emit.c I see:

static int
get_3src_subreg_nr(struct brw_reg reg)
{

   /* Normally, SubRegNum is in bytes (0..31).  However, 3-src
    * instructions use 32-bit units (components 0..7).  Since they
    * only support F/D/UD types, this doesn't lose any
    * flexibility, but uses fewer bits.
    */

   return reg.subnr / 4;
}

Does the code above need updated for DF registers too? Or is that
already accounted for somehow?

I'm probably just missing something. With an explanation Patches 1-3 are:

Reviewed-by: Scott D Phillips <scott.d.phillips at intel.com>

> ---
>  src/intel/compiler/brw_disasm.c | 31 ++++++++++++++++++++++++++-----
>  1 file changed, 26 insertions(+), 5 deletions(-)
>
> diff --git a/src/intel/compiler/brw_disasm.c b/src/intel/compiler/brw_disasm.c
> index e2675b5f4c..188c7c53d0 100644
> --- a/src/intel/compiler/brw_disasm.c
> +++ b/src/intel/compiler/brw_disasm.c
> @@ -764,6 +764,12 @@ dest_3src(FILE *file, const struct gen_device_info *devinfo, const brw_inst *ins
>  {
>     int err = 0;
>     uint32_t reg_file;
> +   enum brw_reg_type type =
> +      brw_hw_3src_type_to_reg_type(devinfo,
> +                                   brw_inst_3src_dst_type(devinfo, inst));
> +   unsigned dst_subreg_nr =
> +      brw_inst_3src_dst_subreg_nr(devinfo, inst) * 4 /
> +      brw_reg_type_to_size(type);
>  
>     if (devinfo->gen == 6 && brw_inst_3src_dst_reg_file(devinfo, inst))
>        reg_file = BRW_MESSAGE_REGISTER_FILE;
> @@ -773,8 +779,8 @@ dest_3src(FILE *file, const struct gen_device_info *devinfo, const brw_inst *ins
>     err |= reg(file, reg_file, brw_inst_3src_dst_reg_nr(devinfo, inst));
>     if (err == -1)
>        return 0;
> -   if (brw_inst_3src_dst_subreg_nr(devinfo, inst))
> -      format(file, ".%"PRIu64, brw_inst_3src_dst_subreg_nr(devinfo, inst));
> +   if (dst_subreg_nr)
> +      format(file, ".%u", dst_subreg_nr);
>     string(file, "<1>");
>     err |= control(file, "writemask", writemask,
>                    brw_inst_3src_dst_writemask(devinfo, inst), NULL);
> @@ -928,7 +934,12 @@ static int
>  src0_3src(FILE *file, const struct gen_device_info *devinfo, const brw_inst *inst)
>  {
>     int err = 0;
> -   unsigned src0_subreg_nr = brw_inst_3src_src0_subreg_nr(devinfo, inst);
> +   enum brw_reg_type type =
> +      brw_hw_3src_type_to_reg_type(devinfo,
> +                                   brw_inst_3src_src_type(devinfo, inst));
> +   unsigned src0_subreg_nr =
> +      brw_inst_3src_src0_subreg_nr(devinfo, inst) * 4 /
> +      brw_reg_type_to_size(type);
>  
>     err |= control(file, "negate", m_negate,
>                    brw_inst_3src_src0_negate(devinfo, inst), NULL);
> @@ -955,7 +966,12 @@ static int
>  src1_3src(FILE *file, const struct gen_device_info *devinfo, const brw_inst *inst)
>  {
>     int err = 0;
> -   unsigned src1_subreg_nr = brw_inst_3src_src1_subreg_nr(devinfo, inst);
> +   enum brw_reg_type type =
> +      brw_hw_3src_type_to_reg_type(devinfo,
> +                                   brw_inst_3src_src_type(devinfo, inst));
> +   unsigned src1_subreg_nr =
> +      brw_inst_3src_src1_subreg_nr(devinfo, inst) * 4 /
> +      brw_reg_type_to_size(type);
>  
>     err |= control(file, "negate", m_negate,
>                    brw_inst_3src_src1_negate(devinfo, inst), NULL);
> @@ -983,7 +999,12 @@ static int
>  src2_3src(FILE *file, const struct gen_device_info *devinfo, const brw_inst *inst)
>  {
>     int err = 0;
> -   unsigned src2_subreg_nr = brw_inst_3src_src2_subreg_nr(devinfo, inst);
> +   enum brw_reg_type type =
> +      brw_hw_3src_type_to_reg_type(devinfo,
> +                                   brw_inst_3src_src_type(devinfo, inst));
> +   unsigned src2_subreg_nr =
> +      brw_inst_3src_src2_subreg_nr(devinfo, inst) * 4 /
> +      brw_reg_type_to_size(type);
>  
>     err |= control(file, "negate", m_negate,
>                    brw_inst_3src_src2_negate(devinfo, inst), NULL);
> -- 
> 2.13.5
>
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