+
+ v[ldop->i.rt].known = 0;
+ v[ldop->i.rt].sign = 0xffffff80 << 24 - curr->r.imm;
+ }
+ }
+
+ if (!ldop) {
+ pr_debug("Convert SLL/SRA #%u to EXT%c\n",
+ curr->r.imm, curr->r.imm == 24 ? 'C' : 'S');
+
+ if (to_change == curr) {
+ to_change->i.rs = curr->r.rt;
+ to_change->i.rt = next->r.rd;
+ } else {
+ to_change->i.rt = next->r.rd;
+ to_change->i.rs = curr->r.rt;
+ }
+
+ if (to_nop->r.imm == 24)
+ to_change->i.op = OP_META_EXTC;
+ else
+ to_change->i.op = OP_META_EXTS;
+ }
+
+ to_nop->opcode = 0;
+}
+
+static void
+lightrec_remove_useless_lui(struct block *block, unsigned int offset,
+ const struct constprop_data *v)
+{
+ struct opcode *list = block->opcode_list,
+ *op = &block->opcode_list[offset];
+ int reader;
+
+ if (!op_flag_sync(op->flags) && is_known(v, op->i.rt) &&
+ v[op->i.rt].value == op->i.imm << 16) {
+ pr_debug("Converting duplicated LUI to NOP\n");
+ op->opcode = 0x0;
+ return;
+ }
+
+ if (op->i.imm != 0 || op->i.rt == 0 || offset == block->nb_ops - 1)
+ return;
+
+ reader = find_next_reader(list, offset + 1, op->i.rt);
+ if (reader <= 0)
+ return;
+
+ if (opcode_writes_register(list[reader].c, op->i.rt) ||
+ reg_is_dead(list, reader, op->i.rt)) {
+ pr_debug("Removing useless LUI 0x0\n");
+
+ if (list[reader].i.rs == op->i.rt)
+ list[reader].i.rs = 0;
+ if (list[reader].i.op == OP_SPECIAL &&
+ list[reader].i.rt == op->i.rt)
+ list[reader].i.rt = 0;
+ op->opcode = 0x0;
+ }
+}
+
+static void lightrec_modify_lui(struct block *block, unsigned int offset)
+{
+ union code c, *lui = &block->opcode_list[offset].c;
+ bool stop = false, stop_next = false;
+ unsigned int i;
+
+ for (i = offset + 1; !stop && i < block->nb_ops; i++) {
+ c = block->opcode_list[i].c;
+ stop = stop_next;
+
+ if ((opcode_is_store(c) && c.i.rt == lui->i.rt)
+ || (!opcode_is_load(c) && opcode_reads_register(c, lui->i.rt)))
+ break;
+
+ if (opcode_writes_register(c, lui->i.rt)) {
+ pr_debug("Convert LUI at offset 0x%x to kuseg\n",
+ i - 1 << 2);
+ lui->i.imm = kunseg(lui->i.imm << 16) >> 16;
+ break;
+ }
+
+ if (has_delay_slot(c))
+ stop_next = true;
+ }
+}
+
+static int lightrec_transform_branches(struct lightrec_state *state,
+ struct block *block)
+{
+ struct opcode *op;
+ unsigned int i;
+ s32 offset;
+
+ for (i = 0; i < block->nb_ops; i++) {
+ op = &block->opcode_list[i];
+
+ switch (op->i.op) {
+ case OP_J:
+ /* Transform J opcode into BEQ $zero, $zero if possible. */
+ offset = (s32)((block->pc & 0xf0000000) >> 2 | op->j.imm)
+ - (s32)(block->pc >> 2) - (s32)i - 1;
+
+ if (offset == (s16)offset) {
+ pr_debug("Transform J into BEQ $zero, $zero\n");
+ op->i.op = OP_BEQ;
+ op->i.rs = 0;
+ op->i.rt = 0;
+ op->i.imm = offset;
+
+ }
+ fallthrough;
+ default:
+ break;
+ }
+ }
+
+ return 0;
+}
+
+static inline bool is_power_of_two(u32 value)
+{
+ return popcount32(value) == 1;
+}
+
+static void lightrec_patch_known_zero(struct opcode *op,
+ const struct constprop_data *v)
+{
+ switch (op->i.op) {
+ case OP_SPECIAL:
+ switch (op->r.op) {
+ case OP_SPECIAL_JR:
+ case OP_SPECIAL_JALR:
+ case OP_SPECIAL_MTHI:
+ case OP_SPECIAL_MTLO:
+ if (is_known_zero(v, op->r.rs))
+ op->r.rs = 0;
+ break;
+ default:
+ if (is_known_zero(v, op->r.rs))
+ op->r.rs = 0;
+ fallthrough;
+ case OP_SPECIAL_SLL:
+ case OP_SPECIAL_SRL:
+ case OP_SPECIAL_SRA:
+ if (is_known_zero(v, op->r.rt))
+ op->r.rt = 0;
+ break;
+ case OP_SPECIAL_SYSCALL:
+ case OP_SPECIAL_BREAK:
+ case OP_SPECIAL_MFHI:
+ case OP_SPECIAL_MFLO:
+ break;
+ }
+ break;
+ case OP_CP0:
+ switch (op->r.rs) {
+ case OP_CP0_MTC0:
+ case OP_CP0_CTC0:
+ if (is_known_zero(v, op->r.rt))
+ op->r.rt = 0;
+ break;
+ default:
+ break;
+ }
+ break;
+ case OP_CP2:
+ if (op->r.op == OP_CP2_BASIC) {
+ switch (op->r.rs) {
+ case OP_CP2_BASIC_MTC2:
+ case OP_CP2_BASIC_CTC2:
+ if (is_known_zero(v, op->r.rt))
+ op->r.rt = 0;
+ break;
+ default:
+ break;
+ }