glsl/opt_algebraic: Drop x + -x -> 0 optimization.

No change on freedreno shader-db.

Acked-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21475>

src/compiler/glsl/opt_algebraic.cpp

@@ -322,18 +322,6 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
 #undef HANDLE_PACK_UNPACK_INVERSE
 
    case ir_binop_add:
-      /* Replace (x + (-x)) with constant 0 */
-      for (int i = 0; i < 2; i++) {
-         if (op_expr[i]) {
-            if (op_expr[i]->operation == ir_unop_neg) {
-               ir_rvalue *other = ir->operands[(i + 1) % 2];
-               if (other && op_expr[i]->operands[0]->equals(other)) {
-                  return ir_constant::zero(ir, ir->type);
-               }
-            }
-         }
-      }
-
       /* Reassociate addition of constants so that we can do constant
        * folding.
        */