[Mesa-dev] [PATCH v2 25/28] glsl/lower_instructions: add double lowering passes

[Ian Romanick]

On 02/06/2015 06:56 AM, Ilia Mirkin wrote:
> From: Dave Airlie <airlied at gmail.com>
> 
> This lowers double dot product and lrp to fma.
> 
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
>  src/glsl/lower_instructions.cpp | 83 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 83 insertions(+)
> 
> diff --git a/src/glsl/lower_instructions.cpp b/src/glsl/lower_instructions.cpp
> index 5c1d6aa..140b6d4 100644
> --- a/src/glsl/lower_instructions.cpp
> +++ b/src/glsl/lower_instructions.cpp
> @@ -115,6 +115,7 @@
>   */
>  
>  #include "main/core.h" /* for M_LOG2E */
> +#include "program/prog_instruction.h" /* for swizzle */
>  #include "glsl_types.h"
>  #include "ir.h"
>  #include "ir_builder.h"
> @@ -148,6 +149,8 @@ private:
>     void carry_to_arith(ir_expression *);
>     void borrow_to_arith(ir_expression *);
>     void sat_to_clamp(ir_expression *);
> +   void double_dot_to_fma(ir_expression *);
> +   void double_lrp(ir_expression *);
>  };
>  
>  } /* anonymous namespace */
> @@ -521,10 +524,90 @@ lower_instructions_visitor::sat_to_clamp(ir_expression *ir)
>     this->progress = true;
>  }
>  
> +void
> +lower_instructions_visitor::double_dot_to_fma(ir_expression *ir)
> +{
> +   ir_variable *temp = new(ir) ir_variable(ir->operands[0]->type->get_base_type(), "dot_res",
> +					   ir_var_temporary);
> +   this->base_ir->insert_before(temp);
> +
> +   int nc = ir->operands[0]->type->components();
> +   for (int i = nc - 1; i >= 1; i--) {
> +      ir_assignment *assig;
> +      if (i == (nc - 1)) {
> +         assig = assign(temp, mul(swizzle(ir->operands[0]->clone(ir, NULL), i, 1),
> +                                  swizzle(ir->operands[1]->clone(ir, NULL), i, 1)));
> +      } else {
> +         assig = assign(temp, fma(swizzle(ir->operands[0]->clone(ir, NULL), i, 1),
> +                                  swizzle(ir->operands[1]->clone(ir, NULL), i, 1),
> +                                  temp));
> +      }
> +      this->base_ir->insert_before(assig);
> +   }
> +
> +   ir->operation = ir_triop_fma;
> +   ir->operands[0] = swizzle(ir->operands[0], 0, 1);
> +   ir->operands[1] = swizzle(ir->operands[1], 0, 1);
> +   ir->operands[2] = new(ir) ir_dereference_variable(temp);
> +
> +   this->progress = true;
> +
> +}
> +
> +void
> +lower_instructions_visitor::double_lrp(ir_expression *ir)
> +{
> +   ir_assignment *assig;
> +   ir_constant *one = new(ir) ir_constant(1.0, ir->operands[2]->type->vector_elements);
> +   ir_variable *temp = new(ir) ir_variable(ir->operands[0]->type, "lrp_res",
> +					   ir_var_temporary);
> +   ir_variable *t2 = new(ir) ir_variable(ir->operands[0]->type, "aval",
> +					   ir_var_temporary);
> +   int swizval;
> +   this->base_ir->insert_before(temp);
> +   this->base_ir->insert_before(t2);
> +
> +   assig = assign(temp, mul(sub(one, ir->operands[2]), ir->operands[0]));
> +   this->base_ir->insert_before(assig);
> +
> +   switch (ir->operands[2]->type->vector_elements) {
> +   case 1:
> +      swizval = SWIZZLE_XXXX;
> +      break;
> +   case 2:
> +      swizval = MAKE_SWIZZLE4(SWIZZLE_X, SWIZZLE_Y, SWIZZLE_X, SWIZZLE_X);
> +      break;
> +   case 3:
> +      swizval = MAKE_SWIZZLE4(SWIZZLE_X, SWIZZLE_Y, SWIZZLE_Z, SWIZZLE_X);
> +      break;
> +   case 4:
> +   default:
> +      swizval = SWIZZLE_XYZW;
> +      break;
> +   }

Isn't this just swizzle_for_size(ir->operands[2], 4) from ir_builder?

> +   assig = assign(t2, swizzle(ir->operands[2], swizval, ir->operands[0]->type->vector_elements));
> +   this->base_ir->insert_before(assig);
> +
> +   ir->operation = ir_triop_fma;
> +   ir->operands[0] = new(ir) ir_dereference_variable(t2);
> +   ir->operands[1] = ir->operands[1];
> +   ir->operands[2] = new(ir) ir_dereference_variable(temp);
> +
> +   this->progress = true;
> +}
> +
>  ir_visitor_status
>  lower_instructions_visitor::visit_leave(ir_expression *ir)
>  {
>     switch (ir->operation) {
> +   case ir_binop_dot:
> +      if (ir->operands[0]->type->is_double())
> +         double_dot_to_fma(ir);
> +      break;
> +   case ir_triop_lrp:
> +      if (ir->operands[0]->type->is_double())
> +         double_lrp(ir);
> +      break;
>     case ir_binop_sub:
>        if (lowering(SUB_TO_ADD_NEG))
>  	 sub_to_add_neg(ir);
>