+/**
+ * Peephole optimization for Test instructions.
+ * - Remove the Test, if an appropriate flag was produced which is still live
+ * - Change a Test(x, c) to 8Bit, if 0 <= c < 256 (3 byte shorter opcode)
+ */
+static void peephole_ia32_Test(ir_node *node)
+{
+ ir_node *left = get_irn_n(node, n_ia32_Test_left);
+ ir_node *right = get_irn_n(node, n_ia32_Test_right);
+
+ assert((int)n_ia32_Test_left == (int)n_ia32_Test8Bit_left
+ && (int)n_ia32_Test_right == (int)n_ia32_Test8Bit_right);
+
+ if (left == right) { /* we need a test for 0 */
+ ir_node *block = get_nodes_block(node);
+ int pn = pn_ia32_res;
+ ir_node *op = left;
+ ir_node *flags_proj;
+ ir_mode *flags_mode;
+ ir_mode *op_mode;
+ ir_node *schedpoint;
+ const ir_edge_t *edge;
+ produces_flag_t produced;
+
+ if (get_nodes_block(left) != block)
+ return;
+
+ if (is_Proj(op)) {
+ pn = get_Proj_proj(op);
+ op = get_Proj_pred(op);
+ }
+
+ /* walk schedule up and abort when we find left or some other node
+ * destroys the flags */
+ schedpoint = node;
+ for (;;) {
+ schedpoint = sched_prev(schedpoint);
+ if (schedpoint == op)
+ break;
+ if (arch_irn_is(schedpoint, modify_flags))
+ return;
+ if (schedpoint == block)
+ panic("couldn't find left");
+ }
+
+ produced = check_produces_zero_sign(op, pn);
+ if (produced == produces_no_flag)
+ return;
+
+ /* make sure users only look at the sign/zero flag */
+ foreach_out_edge(node, edge) {
+ ir_node *user = get_edge_src_irn(edge);
+ ia32_condition_code_t cc = get_ia32_condcode(user);
+
+ if (cc == ia32_cc_equal || cc == ia32_cc_not_equal)
+ continue;
+ if (produced == produces_zero_sign
+ && (cc == ia32_cc_sign || cc == ia32_cc_not_sign)) {
+ continue;
+ }
+ return;
+ }
+
+ op_mode = get_ia32_ls_mode(op);
+ if (op_mode == NULL)
+ op_mode = get_irn_mode(op);
+
+ /* Make sure we operate on the same bit size */
+ if (get_mode_size_bits(op_mode) != get_mode_size_bits(get_ia32_ls_mode(node)))
+ return;
+
+ if (produced == produces_zero_in_carry) {
+ /* patch users to look at the carry instead of the zero flag */
+ foreach_out_edge(node, edge) {
+ ir_node *user = get_edge_src_irn(edge);
+ ia32_condition_code_t cc = get_ia32_condcode(user);
+
+ switch (cc) {
+ case ia32_cc_equal: cc = ia32_cc_above_equal; break;
+ case ia32_cc_not_equal: cc = ia32_cc_below; break;
+ default: panic("unexpected pn");
+ }
+ set_ia32_condcode(user, cc);
+ }
+ }
+
+ if (get_irn_mode(op) != mode_T) {
+ set_irn_mode(op, mode_T);
+
+ /* If there are other users, reroute them to result proj */
+ if (get_irn_n_edges(op) != 2) {
+ ir_node *res = new_r_Proj(op, mode_Iu, pn_ia32_res);
+
+ edges_reroute(op, res);
+ /* Reattach the result proj to left */
+ set_Proj_pred(res, op);
+ }
+ } else {
+ if (get_irn_n_edges(left) == 2)
+ kill_node(left);
+ }
+
+ flags_mode = ia32_reg_classes[CLASS_ia32_flags].mode;
+ flags_proj = new_r_Proj(op, flags_mode, pn_ia32_flags);
+ arch_set_irn_register(flags_proj, &ia32_registers[REG_EFLAGS]);
+
+ assert(get_irn_mode(node) != mode_T);
+
+ be_peephole_exchange(node, flags_proj);
+ } else if (is_ia32_Immediate(right)) {
+ ia32_immediate_attr_t const *const imm = get_ia32_immediate_attr_const(right);
+ unsigned offset;
+
+ /* A test with a symconst is rather strange, but better safe than sorry */
+ if (imm->symconst != NULL)
+ return;
+
+ offset = imm->offset;
+ if (get_ia32_op_type(node) == ia32_AddrModeS) {
+ ia32_attr_t *const attr = get_ia32_attr(node);
+
+ if ((offset & 0xFFFFFF00) == 0) {
+ /* attr->am_offs += 0; */
+ } else if ((offset & 0xFFFF00FF) == 0) {
+ ir_node *imm_node = ia32_create_Immediate(NULL, 0, offset>>8);
+ set_irn_n(node, n_ia32_Test_right, imm_node);
+ attr->am_offs += 1;
+ } else if ((offset & 0xFF00FFFF) == 0) {
+ ir_node *imm_node = ia32_create_Immediate(NULL, 0, offset>>16);
+ set_irn_n(node, n_ia32_Test_right, imm_node);
+ attr->am_offs += 2;
+ } else if ((offset & 0x00FFFFFF) == 0) {
+ ir_node *imm_node = ia32_create_Immediate(NULL, 0, offset>>24);
+ set_irn_n(node, n_ia32_Test_right, imm_node);
+ attr->am_offs += 3;
+ } else {
+ return;
+ }
+ } else if (offset < 256) {
+ arch_register_t const* const reg = arch_get_irn_register(left);
+
+ if (reg != &ia32_registers[REG_EAX] &&
+ reg != &ia32_registers[REG_EBX] &&
+ reg != &ia32_registers[REG_ECX] &&
+ reg != &ia32_registers[REG_EDX]) {
+ return;
+ }
+ } else {
+ return;
+ }
+
+ /* Technically we should build a Test8Bit because of the register
+ * constraints, but nobody changes registers at this point anymore. */
+ set_ia32_ls_mode(node, mode_Bu);
+ }
+}