glsl: Transform pow(x, 4) into (x*x)*(x*x).

Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 3d2f2ca0ba..fa5db70f2d 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -99,6 +99,12 @@ is_vec_two(ir_constant *ir)
 }
 
 static inline bool
+is_vec_four(ir_constant *ir)
+{
+   return (ir == NULL) ? false : ir->is_value(4.0, 4);
+}
+
+static inline bool
 is_vec_negative_one(ir_constant *ir)
 {
    return (ir == NULL) ? false : ir->is_negative_one();
@@ -774,6 +780,20 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
          return mul(x, x);
       }
 
+      if (is_vec_four(op_const[1])) {
+         ir_variable *x = new(ir) ir_variable(ir->operands[1]->type, "x",
+                                              ir_var_temporary);
+         base_ir->insert_before(x);
+         base_ir->insert_before(assign(x, ir->operands[0]));
+
+         ir_variable *squared = new(ir) ir_variable(ir->operands[1]->type,
+                                                    "squared",
+                                                    ir_var_temporary);
+         base_ir->insert_before(squared);
+         base_ir->insert_before(assign(squared, mul(x, x)));
+         return mul(squared, squared);
+      }
+
       break;
 
    case ir_binop_min: