glsl: Add ir_binop_carry and ir_binop_borrow.

Calculates the carry out of the addition of two values and the
borrow from subtraction respectively. Will be used in uaddCarry() and
usubBorrow() built-in implementations.

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

src/glsl/ir.cpp

@@ -398,6 +398,8 @@ ir_expression::ir_expression(int op, ir_rvalue *op0, ir_rvalue *op1)
       this->type = glsl_type::uint_type;
       break;
 
+   case ir_binop_carry:
+   case ir_binop_borrow:
    case ir_binop_lshift:
    case ir_binop_rshift:
    case ir_binop_bfm:
@@ -528,6 +530,8 @@ static const char *const operator_strs[] = {
    "-",
    "*",
    "/",
+   "carry",
+   "borrow",
    "%",
    "<",
    ">",

src/glsl/ir.h

@@ -1094,6 +1094,21 @@ enum ir_expression_operation {
    ir_binop_mul,
    ir_binop_div,
 
+   /**
+    * Returns the carry resulting from the addition of the two arguments.
+    */
+   /*@{*/
+   ir_binop_carry,
+   /*@}*/
+
+   /**
+    * Returns the borrow resulting from the subtraction of the second argument
+    * from the first argument.
+    */
+   /*@{*/
+   ir_binop_borrow,
+   /*@}*/
+
    /**
     * Takes one of two combinations of arguments:
     *

src/glsl/ir_builder.cpp

@@ -221,6 +221,16 @@ ir_expression *div(operand a, operand b)
    return expr(ir_binop_div, a, b);
 }
 
+ir_expression *carry(operand a, operand b)
+{
+   return expr(ir_binop_carry, a, b);
+}
+
+ir_expression *borrow(operand a, operand b)
+{
+   return expr(ir_binop_borrow, a, b);
+}
+
 ir_expression *round_even(operand a)
 {
    return expr(ir_unop_round_even, a);

src/glsl/ir_builder.h

@@ -134,6 +134,8 @@ ir_expression *add(operand a, operand b);
 ir_expression *sub(operand a, operand b);
 ir_expression *mul(operand a, operand b);
 ir_expression *div(operand a, operand b);
+ir_expression *carry(operand a, operand b);
+ir_expression *borrow(operand a, operand b);
 ir_expression *round_even(operand a);
 ir_expression *dot(operand a, operand b);
 ir_expression *dotlike(operand a, operand b);

src/glsl/ir_validate.cpp

@@ -429,6 +429,13 @@ ir_validate::visit_leave(ir_expression *ir)
       }
       break;
 
+   case ir_binop_carry:
+   case ir_binop_borrow:
+      assert(ir->type == ir->operands[0]->type);
+      assert(ir->type == ir->operands[1]->type);
+      assert(ir->type->base_type == GLSL_TYPE_UINT);
+      break;
+
    case ir_binop_less:
    case ir_binop_greater:
    case ir_binop_lequal:

src/mesa/program/ir_to_mesa.cpp

@@ -1497,6 +1497,8 @@ ir_to_mesa_visitor::visit(ir_expression *ir)
    case ir_quadop_bitfield_insert:
    case ir_binop_ldexp:
    case ir_triop_csel:
+   case ir_binop_carry:
+   case ir_binop_borrow:
       assert(!"not supported");
       break;
 

src/mesa/state_tracker/st_glsl_to_tgsi.cpp

@@ -1978,6 +1978,8 @@ glsl_to_tgsi_visitor::visit(ir_expression *ir)
    case ir_binop_vector_extract:
    case ir_triop_vector_insert:
    case ir_binop_ldexp:
+   case ir_binop_carry:
+   case ir_binop_borrow:
       /* This operation is not supported, or should have already been handled.
        */
       assert(!"Invalid ir opcode in glsl_to_tgsi_visitor::visit()");