-void
-glsl_to_tgsi_visitor::emit_swz(ir_expression *ir)
-{
- /* Assume that the vector operator is in a form compatible with OPCODE_SWZ.
- * This means that each of the operands is either an immediate value of -1,
- * 0, or 1, or is a component from one source register (possibly with
- * negation).
- */
- uint8_t components[4] = { 0 };
- bool negate[4] = { false };
- ir_variable *var = NULL;
-
- for (unsigned i = 0; i < ir->type->vector_elements; i++) {
- ir_rvalue *op = ir->operands[i];
-
- assert(op->type->is_scalar());
-
- while (op != NULL) {
- switch (op->ir_type) {
- case ir_type_constant: {
-
- assert(op->type->is_scalar());
-
- const ir_constant *const c = op->as_constant();
- if (c->is_one()) {
- components[i] = SWIZZLE_ONE;
- } else if (c->is_zero()) {
- components[i] = SWIZZLE_ZERO;
- } else if (c->is_negative_one()) {
- components[i] = SWIZZLE_ONE;
- negate[i] = true;
- } else {
- assert(!"SWZ constant must be 0.0 or 1.0.");
- }
-
- op = NULL;
- break;
- }
-
- case ir_type_dereference_variable: {
- ir_dereference_variable *const deref =
- (ir_dereference_variable *) op;
-
- assert((var == NULL) || (deref->var == var));
- components[i] = SWIZZLE_X;
- var = deref->var;
- op = NULL;
- break;
- }
-
- case ir_type_expression: {
- ir_expression *const expr = (ir_expression *) op;
-
- assert(expr->operation == ir_unop_neg);
- negate[i] = true;
-
- op = expr->operands[0];
- break;
- }
-
- case ir_type_swizzle: {
- ir_swizzle *const swiz = (ir_swizzle *) op;
-
- components[i] = swiz->mask.x;
- op = swiz->val;
- break;
- }
-
- default:
- assert(!"Should not get here.");
- return;
- }
- }
- }
-
- assert(var != NULL);
-
- ir_dereference_variable *const deref =
- new(mem_ctx) ir_dereference_variable(var);
-
- this->result.file = PROGRAM_UNDEFINED;
- deref->accept(this);
- if (this->result.file == PROGRAM_UNDEFINED) {
- ir_print_visitor v;
- printf("Failed to get tree for expression operand:\n");
- deref->accept(&v);
- exit(1);
- }
-
- st_src_reg src;
-
- src = this->result;
- src.swizzle = MAKE_SWIZZLE4(components[0],
- components[1],
- components[2],
- components[3]);
- src.negate = ((unsigned(negate[0]) << 0)
- | (unsigned(negate[1]) << 1)
- | (unsigned(negate[2]) << 2)
- | (unsigned(negate[3]) << 3));
-
- /* Storage for our result. Ideally for an assignment we'd be using the
- * actual storage for the result here, instead.
- */
- const st_src_reg result_src = get_temp(ir->type);
- st_dst_reg result_dst = st_dst_reg(result_src);
-
- /* Limit writes to the channels that will be used by result_src later.
- * This does limit this temp's use as a temporary for multi-instruction
- * sequences.
- */
- result_dst.writemask = (1 << ir->type->vector_elements) - 1;
-
- emit(ir, OPCODE_SWZ, result_dst, src);
- this->result = result_src;
-}
-