[Mesa-dev] [PATCH 1/2] glsl: Add constant evaluation of ir_binop_bfm.

[Matt Turner]

---
 src/glsl/ir_constant_expression.cpp | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp
index f811fd1..7fa5a09 100644
--- a/src/glsl/ir_constant_expression.cpp
+++ b/src/glsl/ir_constant_expression.cpp
@@ -1397,6 +1397,23 @@ ir_expression::constant_expression_value(struct hash_table *variable_context)
       break;
    }
 
+   case ir_binop_bfm: {
+      int bits = op[0]->value.i[0];
+      int offset = op[1]->value.i[0];
+
+      for (unsigned c = 0; c < components; c++) {
+         if (bits == 0)
+            data.u[c] = op[0]->value.u[c];
+         else if (offset < 0 || bits < 0)
+            data.u[c] = 0; /* Undefined for bitfieldInsert, per spec. */
+         else if (offset + bits > 32)
+            data.u[c] = 0; /* Undefined for bitfieldInsert, per spec. */
+         else
+            data.u[c] = ((1 << bits) - 1) << offset;
+      }
+      break;
+   }
+
    case ir_binop_ldexp:
       for (unsigned c = 0; c < components; c++) {
          data.f[c] = ldexp(op[0]->value.f[c], op[1]->value.i[c]);
-- 
1.8.3.2