+ /* If it's a vector type, we can do per-channel elimination of
+ * use of the RHS.
+ */
+ if (deref_var && (deref_var->var->type->is_scalar() ||
+ deref_var->var->type->is_vector())) {
+
+ if (debug)
+ printf("looking for %s.0x%01x to remove\n", var->name,
+ ir->write_mask);
+
+ foreach_iter(exec_list_iterator, iter, *assignments) {
+ assignment_entry *entry = (assignment_entry *)iter.get();
+
+ if (entry->lhs != var)
+ continue;
+
+ int remove = entry->available & ir->write_mask;
+ if (debug) {
+ printf("%s 0x%01x - 0x%01x = 0x%01x\n",
+ var->name,
+ entry->ir->write_mask,
+ remove, entry->ir->write_mask & ~remove);
+ }
+ if (remove) {
+ progress = true;
+
+ if (debug) {
+ printf("rewriting:\n ");
+ entry->ir->print();
+ printf("\n");
+ }
+
+ entry->ir->write_mask &= ~remove;
+ entry->available &= ~remove;
+ if (entry->ir->write_mask == 0) {
+ /* Delete the dead assignment. */
+ entry->ir->remove();
+ entry->remove();
+ } else {
+ void *mem_ctx = ralloc_parent(entry->ir);
+ /* Reswizzle the RHS arguments according to the new
+ * write_mask.
+ */
+ unsigned components[4];
+ unsigned channels = 0;
+ unsigned next = 0;
+
+ for (int i = 0; i < 4; i++) {
+ if ((entry->ir->write_mask | remove) & (1 << i)) {
+ if (!(remove & (1 << i)))
+ components[channels++] = next;
+ next++;
+ }
+ }
+
+ entry->ir->rhs = new(mem_ctx) ir_swizzle(entry->ir->rhs,
+ components,
+ channels);
+ if (debug) {
+ printf("to:\n ");
+ entry->ir->print();
+ printf("\n");
+ }
+ }
+ }
+ }
+ } else if (ir->whole_variable_written() != NULL) {
+ /* We did a whole-variable assignment. So, any instruction in
+ * the assignment list with the same LHS is dead.
+ */
+ if (debug)
+ printf("looking for %s to remove\n", var->name);
+ foreach_iter(exec_list_iterator, iter, *assignments) {
+ assignment_entry *entry = (assignment_entry *)iter.get();
+
+ if (entry->lhs == var) {
+ if (debug)
+ printf("removing %s\n", var->name);
+ entry->ir->remove();
+ entry->remove();
+ progress = true;
+ }