glsl: Convert mix() to use a new ir_triop_lrp opcode.

Many GPUs have an instruction to do linear interpolation which is more
efficient than simply performing the algebra necessary (two multiplies,
an add, and a subtract).

Pattern matching or peepholing this is more desirable, but can be
tricky.  By using an opcode, we can at least make shaders which use the
mix() built-in get the more efficient behavior.

Currently, all consumers lower ir_triop_lrp.  Subsequent patches will
actually generate different code.

v2 [mattst88]:
   - Add LRP_TO_ARITH flag to ir_to_mesa.cpp. Will be removed in a
     subsequent patch and ir_triop_lrp translated directly.
v3 [mattst88]:
   - Move changes from the next patch to opt_algebraic.cpp to accept
     3-src operations.

Reviewed-by: Matt Turner <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>
Signed-off-by: Kenneth Graunke <[email protected]>

1 files changed, 7 insertions, 7 deletions

diff --git a/src/glsl/builtins/ir/mix.ir b/src/glsl/builtins/ir/mix.ir
index 70ae13c9f3f..e6665321143 100644
--- a/src/glsl/builtins/ir/mix.ir
+++ b/src/glsl/builtins/ir/mix.ir
@@ -4,49 +4,49 @@
        (declare (in) float arg0)
        (declare (in) float arg1)
        (declare (in) float arg2))
-     ((return (expression float + (expression float * (var_ref arg0) (expression float - (constant float (1.000000)) (var_ref arg2))) (expression float * (var_ref arg1) (var_ref arg2))))))
+     ((return (expression float lrp (var_ref arg0) (var_ref arg1) (var_ref arg2)))))
 
    (signature vec2
      (parameters
        (declare (in) vec2 arg0)
        (declare (in) vec2 arg1)
        (declare (in) vec2 arg2))
-     ((return (expression vec2 + (expression vec2 * (var_ref arg0) (expression vec2 - (constant float (1.000000)) (var_ref arg2))) (expression vec2 * (var_ref arg1) (var_ref arg2))))))
+     ((return (expression vec2 lrp (var_ref arg0) (var_ref arg1) (var_ref arg2)))))
 
    (signature vec3
      (parameters
        (declare (in) vec3 arg0)
        (declare (in) vec3 arg1)
        (declare (in) vec3 arg2))
-     ((return (expression vec3 + (expression vec3 * (var_ref arg0) (expression vec3 - (constant float (1.000000)) (var_ref arg2))) (expression vec3 * (var_ref arg1) (var_ref arg2))))))
+     ((return (expression vec3 lrp (var_ref arg0) (var_ref arg1) (var_ref arg2)))))
 
    (signature vec4
      (parameters
        (declare (in) vec4 arg0)
        (declare (in) vec4 arg1)
        (declare (in) vec4 arg2))
-     ((return (expression vec4 + (expression vec4 * (var_ref arg0) (expression vec4 - (constant float (1.000000)) (var_ref arg2))) (expression vec4 * (var_ref arg1) (var_ref arg2))))))
+     ((return (expression vec4 lrp (var_ref arg0) (var_ref arg1) (var_ref arg2)))))
 
    (signature vec2
      (parameters
        (declare (in) vec2 arg0)
        (declare (in) vec2 arg1)
        (declare (in) float arg2))
-     ((return (expression vec2 + (expression vec2 * (var_ref arg0) (expression float - (constant float (1.000000)) (var_ref arg2))) (expression vec2 * (var_ref arg1) (var_ref arg2))))))
+     ((return (expression vec2 lrp (var_ref arg0) (var_ref arg1) (var_ref arg2)))))
 
    (signature vec3
      (parameters
        (declare (in) vec3 arg0)
        (declare (in) vec3 arg1)
        (declare (in) float arg2))
-     ((return (expression vec3 + (expression vec3 * (var_ref arg0) (expression float - (constant float (1.000000)) (var_ref arg2))) (expression vec3 * (var_ref arg1) (var_ref arg2))))))
+     ((return (expression vec3 lrp (var_ref arg0) (var_ref arg1) (var_ref arg2)))))
 
    (signature vec4
      (parameters
        (declare (in) vec4 arg0)
        (declare (in) vec4 arg1)
        (declare (in) float arg2))
-     ((return (expression vec4 + (expression vec4 * (var_ref arg0) (expression float - (constant float (1.000000)) (var_ref arg2))) (expression vec4 * (var_ref arg1) (var_ref arg2))))))
+     ((return (expression vec4 lrp (var_ref arg0) (var_ref arg1) (var_ref arg2)))))
 
    (signature float
      (parameters