glsl: Add ir_unop_i2u and ir_unop_u2i operations.

These are necessary to handle int/uint constructor conversions.  For
example, the following code currently results in a type mismatch:

int x = 7;
uint y = uint(x);

In particular, uint(x) still has type int.

This commit simply adds the new operations; it does not generate them,
nor does it add backend support for them.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/glsl/ir.cpp

@@ -272,6 +272,7 @@ ir_expression::ir_expression(int op, ir_rvalue *op0)
 
    case ir_unop_f2i:
    case ir_unop_b2i:
+   case ir_unop_u2i:
       this->type = glsl_type::get_instance(GLSL_TYPE_INT,
 					   op0->type->vector_elements, 1);
       break;
@@ -289,6 +290,11 @@ ir_expression::ir_expression(int op, ir_rvalue *op0)
 					   op0->type->vector_elements, 1);
       break;
 
+   case ir_unop_i2u:
+      this->type = glsl_type::get_instance(GLSL_TYPE_UINT,
+					   op0->type->vector_elements, 1);
+      break;
+
    case ir_unop_noise:
       this->type = glsl_type::float_type;
       break;
@@ -419,6 +425,8 @@ static const char *const operator_strs[] = {
    "i2b",
    "b2i",
    "u2f",
+   "i2u",
+   "u2i",
    "any",
    "trunc",
    "ceil",