[Mesa-dev] [PATCH 4/9] i965/fs: Get rid of all remaining algebraic optimizations for floats

[Jason Ekstrand]

Forgot to mention it in the commit message, but no shader-db changes on
Broadwell.

On Thu, Mar 17, 2016 at 10:21 AM, Jason Ekstrand <jason at jlekstrand.net>
wrote:

> ---
>  src/mesa/drivers/dri/i965/brw_fs.cpp | 74
> +++++++++---------------------------
>  1 file changed, 18 insertions(+), 56 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
> b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index 365231e..9f303d5 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -2097,28 +2097,27 @@ fs_visitor::opt_algebraic()
>     bool progress = false;
>
>     foreach_block_and_inst(block, fs_inst, inst, cfg) {
> -      switch (inst->opcode) {
> -      case BRW_OPCODE_MOV:
> -         if (inst->src[0].file != IMM)
> -            break;
> -
> -         if (inst->saturate) {
> -            if (inst->dst.type != inst->src[0].type)
> -               assert(!"unimplemented: saturate mixed types");
> +      /* We don't want to do any float algebraic optimizations in the
> backend
> +       * because they aren't bit-for-bit safe and the backend doesn't know
> +       * when a value is declared precise or invariant.
> +       */
> +      if (inst->dst.type == BRW_REGISTER_TYPE_F)
> +         continue;
>
> -            if (brw_saturate_immediate(inst->dst.type,
> -                                       &inst->src[0].as_brw_reg())) {
> -               inst->saturate = false;
> -               progress = true;
> -            }
> -         }
> -         break;
> +      bool has_float_src = false;
> +      for (unsigned i = 0; i < inst->sources; i++) {
> +         if (inst->src[i].type == BRW_REGISTER_TYPE_F)
> +            has_float_src = true;
> +      }
> +      if (has_float_src)
> +         continue;
>
> +      switch (inst->opcode) {
>        case BRW_OPCODE_MUL:
>          if (inst->src[1].file != IMM)
>             continue;
>
> -        /* a * 1.0 = a */
> +        /* a * 1 = a */
>          if (inst->src[1].is_one()) {
>             inst->opcode = BRW_OPCODE_MOV;
>             inst->src[1] = reg_undef;
> @@ -2126,7 +2125,7 @@ fs_visitor::opt_algebraic()
>             break;
>          }
>
> -         /* a * -1.0 = -a */
> +         /* a * -1 = -a */
>           if (inst->src[1].is_negative_one()) {
>              inst->opcode = BRW_OPCODE_MOV;
>              inst->src[0].negate = !inst->src[0].negate;
> @@ -2135,7 +2134,7 @@ fs_visitor::opt_algebraic()
>              break;
>           }
>
> -         /* a * 0.0 = 0.0 */
> +         /* a * 0 = 0 */
>           if (inst->src[1].is_zero()) {
>              inst->opcode = BRW_OPCODE_MOV;
>              inst->src[0] = inst->src[1];
> @@ -2157,7 +2156,7 @@ fs_visitor::opt_algebraic()
>           if (inst->src[1].file != IMM)
>              continue;
>
> -         /* a + 0.0 = a */
> +         /* a + 0 = a */
>           if (inst->src[1].is_zero()) {
>              inst->opcode = BRW_OPCODE_MOV;
>              inst->src[1] = reg_undef;
> @@ -2182,16 +2181,6 @@ fs_visitor::opt_algebraic()
>              break;
>           }
>           break;
> -      case BRW_OPCODE_LRP:
> -         if (inst->src[1].equals(inst->src[2])) {
> -            inst->opcode = BRW_OPCODE_MOV;
> -            inst->src[0] = inst->src[1];
> -            inst->src[1] = reg_undef;
> -            inst->src[2] = reg_undef;
> -            progress = true;
> -            break;
> -         }
> -         break;
>        case BRW_OPCODE_CMP:
>           if (inst->conditional_mod == BRW_CONDITIONAL_GE &&
>               inst->src[0].abs &&
> @@ -2213,33 +2202,6 @@ fs_visitor::opt_algebraic()
>              progress = true;
>           }
>           break;
> -      case BRW_OPCODE_MAD:
> -         if (inst->src[1].is_zero() || inst->src[2].is_zero()) {
> -            inst->opcode = BRW_OPCODE_MOV;
> -            inst->src[1] = reg_undef;
> -            inst->src[2] = reg_undef;
> -            progress = true;
> -         } else if (inst->src[0].is_zero()) {
> -            inst->opcode = BRW_OPCODE_MUL;
> -            inst->src[0] = inst->src[2];
> -            inst->src[2] = reg_undef;
> -            progress = true;
> -         } else if (inst->src[1].is_one()) {
> -            inst->opcode = BRW_OPCODE_ADD;
> -            inst->src[1] = inst->src[2];
> -            inst->src[2] = reg_undef;
> -            progress = true;
> -         } else if (inst->src[2].is_one()) {
> -            inst->opcode = BRW_OPCODE_ADD;
> -            inst->src[2] = reg_undef;
> -            progress = true;
> -         } else if (inst->src[1].file == IMM && inst->src[2].file == IMM)
> {
> -            inst->opcode = BRW_OPCODE_ADD;
> -            inst->src[1].f *= inst->src[2].f;
> -            inst->src[2] = reg_undef;
> -            progress = true;
> -         }
> -         break;
>        case SHADER_OPCODE_BROADCAST:
>           if (is_uniform(inst->src[0])) {
>              inst->opcode = BRW_OPCODE_MOV;
> --
> 2.5.0.400.gff86faf
>
>
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