glsl: Add conditional-select IR.

It's a ?: that operates per-component on vectors. Will be used in
upcoming lowering pass for ldexp and the implementation of frexp.

 csel(selector, a, b):
   per-component result = selector ? a : b

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp
index ec338a8..a67470b 100644
--- a/src/glsl/ir_constant_expression.cpp
+++ b/src/glsl/ir_constant_expression.cpp
@@ -395,6 +395,7 @@ ir_expression::constant_expression_value(struct hash_table *variable_context)
       case ir_binop_lshift:
       case ir_binop_rshift:
       case ir_binop_vector_extract:
+      case ir_triop_csel:
       case ir_triop_bitfield_extract:
          break;
 
@@ -1399,6 +1400,13 @@ ir_expression::constant_expression_value(struct hash_table *variable_context)
       break;
    }
 
+   case ir_triop_csel:
+      for (unsigned c = 0; c < components; c++) {
+         data.u[c] = op[0]->value.b[c] ? op[1]->value.u[c]
+                                       : op[2]->value.u[c];
+      }
+      break;
+
    case ir_triop_vector_insert: {
       const unsigned idx = op[2]->value.u[0];