[Mesa-dev] [PATCH 3/3] glsl: Optimize clamp(x, b, 1.0), where b > 0.0 as saturate(max(x, b))

[Abdiel Janulgue]

Signed-off-by: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
---
 src/glsl/opt_algebraic.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 0d694b6..ee52de7 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -593,6 +593,12 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
             /* Found a min (max(x, 0.0) b), where b < 1.0 */
             if ((outer_const->get_float_component(0) < 1.0f) && inner_val_b->is_zero())
                return saturate(expr(ir_binop_min, inner_val_a, outer_const));
+
+            /* Found a min (max(x, b, 1.0), where b > 0.0 */
+            ir_constant *inner_const = inner_val_b->as_constant();
+            if (outer_const->is_one() &&
+                (inner_const && inner_const->get_float_component(0) > 0.0f))
+               return saturate(expr(ir_binop_max, inner_val_a, inner_val_b));
          }
       }
 
-- 
1.9.1