[Mesa-dev] [PATCH] r600g: Use hardware sqrt instruction

[Alex Deucher]

On Fri, Jul 18, 2014 at 3:54 AM, Glenn Kennard <glenn.kennard at gmail.com> wrote:
> Piglit quick tests including sqrt pass, no other regressions,
> tested on radeon 6670.
> ---
> Should be slightly more precise than the invsqrt/recip/mul combination
> used previously, I reckon up to about 2 bits of mantissa, and saves
> two instructions per sqrt emitted.
>
> It would be good if someone could test this on Cayman since it uses
> a slightly different codepath.

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

>
>  src/gallium/drivers/r600/r600_pipe.c   | 2 +-
>  src/gallium/drivers/r600/r600_shader.c | 9 +++------
>  2 files changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/src/gallium/drivers/r600/r600_pipe.c b/src/gallium/drivers/r600/r600_pipe.c
> index 5bf9c00..ee6a416 100644
> --- a/src/gallium/drivers/r600/r600_pipe.c
> +++ b/src/gallium/drivers/r600/r600_pipe.c
> @@ -428,7 +428,7 @@ static int r600_get_shader_param(struct pipe_screen* pscreen, unsigned shader, e
>         case PIPE_SHADER_CAP_TGSI_CONT_SUPPORTED:
>                 return 1;
>         case PIPE_SHADER_CAP_TGSI_SQRT_SUPPORTED:
> -               return 0;
> +               return 1;
>         case PIPE_SHADER_CAP_INDIRECT_INPUT_ADDR:
>         case PIPE_SHADER_CAP_INDIRECT_OUTPUT_ADDR:
>         case PIPE_SHADER_CAP_INDIRECT_TEMP_ADDR:
> diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
> index db928f3..907547d 100644
> --- a/src/gallium/drivers/r600/r600_shader.c
> +++ b/src/gallium/drivers/r600/r600_shader.c
> @@ -6498,8 +6498,7 @@ static struct r600_shader_tgsi_instruction r600_shader_tgsi_instruction[] = {
>         {TGSI_OPCODE_SUB,       0, ALU_OP2_ADD, tgsi_op2},
>         {TGSI_OPCODE_LRP,       0, ALU_OP0_NOP, tgsi_lrp},
>         {TGSI_OPCODE_CND,       0, ALU_OP0_NOP, tgsi_unsupported},
> -       /* gap */
> -       {20,                    0, ALU_OP0_NOP, tgsi_unsupported},
> +       {TGSI_OPCODE_SQRT,      0, ALU_OP1_SQRT_IEEE, tgsi_trans_srcx_replicate},
>         {TGSI_OPCODE_DP2A,      0, ALU_OP0_NOP, tgsi_unsupported},
>         /* gap */
>         {22,                    0, ALU_OP0_NOP, tgsi_unsupported},
> @@ -6693,8 +6692,7 @@ static struct r600_shader_tgsi_instruction eg_shader_tgsi_instruction[] = {
>         {TGSI_OPCODE_SUB,       0, ALU_OP2_ADD, tgsi_op2},
>         {TGSI_OPCODE_LRP,       0, ALU_OP0_NOP, tgsi_lrp},
>         {TGSI_OPCODE_CND,       0, ALU_OP0_NOP, tgsi_unsupported},
> -       /* gap */
> -       {20,                    0, ALU_OP0_NOP, tgsi_unsupported},
> +       {TGSI_OPCODE_SQRT,      0, ALU_OP1_SQRT_IEEE, tgsi_trans_srcx_replicate},
>         {TGSI_OPCODE_DP2A,      0, ALU_OP0_NOP, tgsi_unsupported},
>         /* gap */
>         {22,                    0, ALU_OP0_NOP, tgsi_unsupported},
> @@ -6888,8 +6886,7 @@ static struct r600_shader_tgsi_instruction cm_shader_tgsi_instruction[] = {
>         {TGSI_OPCODE_SUB,       0, ALU_OP2_ADD, tgsi_op2},
>         {TGSI_OPCODE_LRP,       0, ALU_OP0_NOP, tgsi_lrp},
>         {TGSI_OPCODE_CND,       0, ALU_OP0_NOP, tgsi_unsupported},
> -       /* gap */
> -       {20,                    0, ALU_OP0_NOP, tgsi_unsupported},
> +       {TGSI_OPCODE_SQRT,      0, ALU_OP1_SQRT_IEEE, cayman_emit_float_instr},
>         {TGSI_OPCODE_DP2A,      0, ALU_OP0_NOP, tgsi_unsupported},
>         /* gap */
>         {22,                    0, ALU_OP0_NOP, tgsi_unsupported},
> --
> 1.8.3.2
>
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