X-Git-Url: https://notaz.gp2x.de/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=deps%2Flightrec%2Foptimizer.c;h=10067a7d082d72d42ece4487a41445c6e87903c6;hb=13b02197fcb7575646408094d5583ed7391b1153;hp=cf431f2e264e14a28447facdd523b6c495f4c32c;hpb=67b91c4b9c44f0d973d2d6a85481e3f437ccc583;p=pcsx_rearmed.git

diff --git a/deps/lightrec/optimizer.c b/deps/lightrec/optimizer.c
index cf431f2e..10067a7d 100644
--- a/deps/lightrec/optimizer.c
+++ b/deps/lightrec/optimizer.c
@@ -1,17 +1,9 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
 /*
- * Copyright (C) 2014-2020 Paul Cercueil <paul@crapouillou.net>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
+ * Copyright (C) 2014-2021 Paul Cercueil <paul@crapouillou.net>
  */
 
+#include "lightrec-config.h"
 #include "disassembler.h"
 #include "lightrec.h"
 #include "memmanager.h"
@@ -21,61 +13,98 @@
 #include <errno.h>
 #include <stdbool.h>
 #include <stdlib.h>
+#include <string.h>
+
+#define IF_OPT(opt, ptr) ((opt) ? (ptr) : NULL)
 
 struct optimizer_list {
 	void (**optimizers)(struct opcode *);
 	unsigned int nb_optimizers;
 };
 
-bool opcode_reads_register(union code op, u8 reg)
+static bool is_nop(union code op);
+
+bool is_unconditional_jump(union code c)
+{
+	switch (c.i.op) {
+	case OP_SPECIAL:
+		return c.r.op == OP_SPECIAL_JR || c.r.op == OP_SPECIAL_JALR;
+	case OP_J:
+	case OP_JAL:
+		return true;
+	case OP_BEQ:
+	case OP_BLEZ:
+		return c.i.rs == c.i.rt;
+	case OP_REGIMM:
+		return (c.r.rt == OP_REGIMM_BGEZ ||
+			c.r.rt == OP_REGIMM_BGEZAL) && c.i.rs == 0;
+	default:
+		return false;
+	}
+}
+
+bool is_syscall(union code c)
+{
+	return (c.i.op == OP_SPECIAL && c.r.op == OP_SPECIAL_SYSCALL) ||
+		(c.i.op == OP_CP0 && (c.r.rs == OP_CP0_MTC0 ||
+					c.r.rs == OP_CP0_CTC0) &&
+		 (c.r.rd == 12 || c.r.rd == 13));
+}
+
+static u64 opcode_read_mask(union code op)
 {
 	switch (op.i.op) {
 	case OP_SPECIAL:
 		switch (op.r.op) {
 		case OP_SPECIAL_SYSCALL:
 		case OP_SPECIAL_BREAK:
-			return false;
+			return 0;
 		case OP_SPECIAL_JR:
 		case OP_SPECIAL_JALR:
 		case OP_SPECIAL_MTHI:
 		case OP_SPECIAL_MTLO:
-			return op.r.rs == reg;
+			return BIT(op.r.rs);
 		case OP_SPECIAL_MFHI:
-			return reg == REG_HI;
+			return BIT(REG_HI);
 		case OP_SPECIAL_MFLO:
-			return reg == REG_LO;
+			return BIT(REG_LO);
 		case OP_SPECIAL_SLL:
+			if (!op.r.imm)
+				return 0;
+			fallthrough;
 		case OP_SPECIAL_SRL:
 		case OP_SPECIAL_SRA:
-			return op.r.rt == reg;
+			return BIT(op.r.rt);
 		default:
-			return op.r.rs == reg || op.r.rt == reg;
+			return BIT(op.r.rs) | BIT(op.r.rt);
 		}
 	case OP_CP0:
 		switch (op.r.rs) {
 		case OP_CP0_MTC0:
 		case OP_CP0_CTC0:
-			return op.r.rt == reg;
+			return BIT(op.r.rt);
 		default:
-			return false;
+			return 0;
 		}
 	case OP_CP2:
 		if (op.r.op == OP_CP2_BASIC) {
 			switch (op.r.rs) {
 			case OP_CP2_BASIC_MTC2:
 			case OP_CP2_BASIC_CTC2:
-				return op.r.rt == reg;
+				return BIT(op.r.rt);
 			default:
-				return false;
+				break;
 			}
-		} else {
-			return false;
 		}
+		return 0;
 	case OP_J:
 	case OP_JAL:
 	case OP_LUI:
-		return false;
+		return 0;
 	case OP_BEQ:
+		if (op.i.rs == op.i.rt)
+			return 0;
+		fallthrough;
 	case OP_BNE:
 	case OP_LWL:
 	case OP_LWR:
@@ -84,33 +113,58 @@ bool opcode_reads_register(union code op, u8 reg)
 	case OP_SWL:
 	case OP_SW:
 	case OP_SWR:
-		return op.i.rs == reg || op.i.rt == reg;
+		return BIT(op.i.rs) | BIT(op.i.rt);
 	default:
-		return op.i.rs == reg;
+		return BIT(op.i.rs);
 	}
 }
 
-bool opcode_writes_register(union code op, u8 reg)
+static u64 mult_div_write_mask(union code op)
+{
+	u64 flags;
+
+	if (!OPT_FLAG_MULT_DIV)
+		return BIT(REG_LO) | BIT(REG_HI);
+
+	if (op.r.rd)
+		flags = BIT(op.r.rd);
+	else
+		flags = BIT(REG_LO);
+	if (op.r.imm)
+		flags |= BIT(op.r.imm);
+	else
+		flags |= BIT(REG_HI);
+
+	return flags;
+}
+
+static u64 opcode_write_mask(union code op)
 {
 	switch (op.i.op) {
+	case OP_META_MULT2:
+	case OP_META_MULTU2:
+		return mult_div_write_mask(op);
 	case OP_SPECIAL:
 		switch (op.r.op) {
 		case OP_SPECIAL_JR:
-		case OP_SPECIAL_JALR:
 		case OP_SPECIAL_SYSCALL:
 		case OP_SPECIAL_BREAK:
-			return false;
+			return 0;
 		case OP_SPECIAL_MULT:
 		case OP_SPECIAL_MULTU:
 		case OP_SPECIAL_DIV:
 		case OP_SPECIAL_DIVU:
-			return reg == REG_LO || reg == REG_HI;
+			return mult_div_write_mask(op);
 		case OP_SPECIAL_MTHI:
-			return reg == REG_HI;
+			return BIT(REG_HI);
 		case OP_SPECIAL_MTLO:
-			return reg == REG_LO;
+			return BIT(REG_LO);
+		case OP_SPECIAL_SLL:
+			if (!op.r.imm)
+				return 0;
+			fallthrough;
 		default:
-			return op.r.rd == reg;
+			return BIT(op.r.rd);
 		}
 	case OP_ADDI:
 	case OP_ADDIU:
@@ -127,34 +181,218 @@ bool opcode_writes_register(union code op, u8 reg)
 	case OP_LBU:
 	case OP_LHU:
 	case OP_LWR:
-		return op.i.rt == reg;
+	case OP_META_EXTC:
+	case OP_META_EXTS:
+		return BIT(op.i.rt);
+	case OP_JAL:
+		return BIT(31);
 	case OP_CP0:
 		switch (op.r.rs) {
 		case OP_CP0_MFC0:
 		case OP_CP0_CFC0:
-			return op.i.rt == reg;
+			return BIT(op.i.rt);
 		default:
-			return false;
+			return 0;
 		}
 	case OP_CP2:
 		if (op.r.op == OP_CP2_BASIC) {
 			switch (op.r.rs) {
 			case OP_CP2_BASIC_MFC2:
 			case OP_CP2_BASIC_CFC2:
-				return op.i.rt == reg;
+				return BIT(op.i.rt);
 			default:
-				return false;
+				break;
 			}
-		} else {
-			return false;
+		}
+		return 0;
+	case OP_REGIMM:
+		switch (op.r.rt) {
+		case OP_REGIMM_BLTZAL:
+		case OP_REGIMM_BGEZAL:
+			return BIT(31);
+		default:
+			return 0;
 		}
 	case OP_META_MOV:
-		return op.r.rd == reg;
+		return BIT(op.r.rd);
+	default:
+		return 0;
+	}
+}
+
+bool opcode_reads_register(union code op, u8 reg)
+{
+	return opcode_read_mask(op) & BIT(reg);
+}
+
+bool opcode_writes_register(union code op, u8 reg)
+{
+	return opcode_write_mask(op) & BIT(reg);
+}
+
+static int find_prev_writer(const struct opcode *list, unsigned int offset, u8 reg)
+{
+	union code c;
+	unsigned int i;
+
+	if (op_flag_sync(list[offset].flags))
+		return -1;
+
+	for (i = offset; i > 0; i--) {
+		c = list[i - 1].c;
+
+		if (opcode_writes_register(c, reg)) {
+			if (i > 1 && has_delay_slot(list[i - 2].c))
+				break;
+
+			return i - 1;
+		}
+
+		if (op_flag_sync(list[i - 1].flags) ||
+		    has_delay_slot(c) ||
+		    opcode_reads_register(c, reg))
+			break;
+	}
+
+	return -1;
+}
+
+static int find_next_reader(const struct opcode *list, unsigned int offset, u8 reg)
+{
+	unsigned int i;
+	union code c;
+
+	if (op_flag_sync(list[offset].flags))
+		return -1;
+
+	for (i = offset; ; i++) {
+		c = list[i].c;
+
+		if (opcode_reads_register(c, reg)) {
+			if (i > 0 && has_delay_slot(list[i - 1].c))
+				break;
+
+			return i;
+		}
+
+		if (op_flag_sync(list[i].flags) ||
+		    has_delay_slot(c) || opcode_writes_register(c, reg))
+			break;
+	}
+
+	return -1;
+}
+
+static bool reg_is_dead(const struct opcode *list, unsigned int offset, u8 reg)
+{
+	unsigned int i;
+
+	if (op_flag_sync(list[offset].flags))
+		return false;
+
+	for (i = offset + 1; ; i++) {
+		if (opcode_reads_register(list[i].c, reg))
+			return false;
+
+		if (opcode_writes_register(list[i].c, reg))
+			return true;
+
+		if (has_delay_slot(list[i].c)) {
+			if (op_flag_no_ds(list[i].flags) ||
+			    opcode_reads_register(list[i + 1].c, reg))
+				return false;
+
+			return opcode_writes_register(list[i + 1].c, reg);
+		}
+	}
+}
+
+static bool reg_is_read(const struct opcode *list,
+			unsigned int a, unsigned int b, u8 reg)
+{
+	/* Return true if reg is read in one of the opcodes of the interval
+	 * [a, b[ */
+	for (; a < b; a++) {
+		if (!is_nop(list[a].c) && opcode_reads_register(list[a].c, reg))
+			return true;
+	}
+
+	return false;
+}
+
+static bool reg_is_written(const struct opcode *list,
+			   unsigned int a, unsigned int b, u8 reg)
+{
+	/* Return true if reg is written in one of the opcodes of the interval
+	 * [a, b[ */
+
+	for (; a < b; a++) {
+		if (!is_nop(list[a].c) && opcode_writes_register(list[a].c, reg))
+			return true;
+	}
+
+	return false;
+}
+
+static bool reg_is_read_or_written(const struct opcode *list,
+				   unsigned int a, unsigned int b, u8 reg)
+{
+	return reg_is_read(list, a, b, reg) || reg_is_written(list, a, b, reg);
+}
+
+static bool opcode_is_load(union code op)
+{
+	switch (op.i.op) {
+	case OP_LB:
+	case OP_LH:
+	case OP_LWL:
+	case OP_LW:
+	case OP_LBU:
+	case OP_LHU:
+	case OP_LWR:
+	case OP_LWC2:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool opcode_is_store(union code op)
+{
+	switch (op.i.op) {
+	case OP_SB:
+	case OP_SH:
+	case OP_SW:
+	case OP_SWL:
+	case OP_SWR:
+	case OP_SWC2:
+		return true;
 	default:
 		return false;
 	}
 }
 
+static u8 opcode_get_io_size(union code op)
+{
+	switch (op.i.op) {
+	case OP_LB:
+	case OP_LBU:
+	case OP_SB:
+		return 8;
+	case OP_LH:
+	case OP_LHU:
+	case OP_SH:
+		return 16;
+	default:
+		return 32;
+	}
+}
+
+bool opcode_is_io(union code op)
+{
+	return opcode_is_load(op) || opcode_is_store(op);
+}
+
 /* TODO: Complete */
 static bool is_nop(union code op)
 {
@@ -196,6 +434,9 @@ static bool is_nop(union code op)
 		case OP_SPECIAL_SRA:
 		case OP_SPECIAL_SRL:
 			return op.r.rd == op.r.rt && op.r.imm == 0;
+		case OP_SPECIAL_MFHI:
+		case OP_SPECIAL_MFLO:
+			return op.r.rd == 0;
 		default:
 			return false;
 		}
@@ -256,8 +497,19 @@ bool load_in_delay_slot(union code op)
 	return false;
 }
 
-static u32 lightrec_propagate_consts(union code c, u32 known, u32 *v)
+static u32 lightrec_propagate_consts(const struct opcode *op,
+				     const struct opcode *prev,
+				     u32 known, u32 *v)
 {
+	union code c = prev->c;
+
+	/* Register $zero is always, well, zero */
+	known |= BIT(0);
+	v[0] = 0;
+
+	if (op_flag_sync(op->flags))
+		return BIT(0);
+
 	switch (c.i.op) {
 	case OP_SPECIAL:
 		switch (c.r.op) {
@@ -376,10 +628,52 @@ static u32 lightrec_propagate_consts(union code c, u32 known, u32 *v)
 				known &= ~BIT(c.r.rd);
 			}
 			break;
+		case OP_SPECIAL_MULT:
+		case OP_SPECIAL_MULTU:
+		case OP_SPECIAL_DIV:
+		case OP_SPECIAL_DIVU:
+			if (OPT_FLAG_MULT_DIV && c.r.rd)
+				known &= ~BIT(c.r.rd);
+			if (OPT_FLAG_MULT_DIV && c.r.imm)
+				known &= ~BIT(c.r.imm);
+			break;
+		case OP_SPECIAL_MFLO:
+		case OP_SPECIAL_MFHI:
+			known &= ~BIT(c.r.rd);
+			break;
 		default:
 			break;
 		}
 		break;
+	case OP_META_MULT2:
+	case OP_META_MULTU2:
+		if (OPT_FLAG_MULT_DIV && (known & BIT(c.r.rs))) {
+			if (c.r.rd) {
+				known |= BIT(c.r.rd);
+
+				if (c.r.op < 32)
+					v[c.r.rd] = v[c.r.rs] << c.r.op;
+				else
+					v[c.r.rd] = 0;
+			}
+
+			if (c.r.imm) {
+				known |= BIT(c.r.imm);
+
+				if (c.r.op >= 32)
+					v[c.r.imm] = v[c.r.rs] << (c.r.op - 32);
+				else if (c.i.op == OP_META_MULT2)
+					v[c.r.imm] = (s32) v[c.r.rs] >> (32 - c.r.op);
+				else
+					v[c.r.imm] = v[c.r.rs] >> (32 - c.r.op);
+			}
+		} else {
+			if (OPT_FLAG_MULT_DIV && c.r.rd)
+				known &= ~BIT(c.r.rd);
+			if (OPT_FLAG_MULT_DIV && c.r.imm)
+				known &= ~BIT(c.r.imm);
+		}
+		break;
 	case OP_REGIMM:
 		break;
 	case OP_ADDI:
@@ -471,6 +765,22 @@ static u32 lightrec_propagate_consts(union code c, u32 known, u32 *v)
 			known &= ~BIT(c.r.rd);
 		}
 		break;
+	case OP_META_EXTC:
+		if (known & BIT(c.i.rs)) {
+			known |= BIT(c.i.rt);
+			v[c.i.rt] = (s32)(s8)v[c.i.rs];
+		} else {
+			known &= ~BIT(c.i.rt);
+		}
+		break;
+	case OP_META_EXTS:
+		if (known & BIT(c.i.rs)) {
+			known |= BIT(c.i.rt);
+			v[c.i.rt] = (s32)(s16)v[c.i.rs];
+		} else {
+			known &= ~BIT(c.i.rt);
+		}
+		break;
 	default:
 		break;
 	}
@@ -478,120 +788,353 @@ static u32 lightrec_propagate_consts(union code c, u32 known, u32 *v)
 	return known;
 }
 
-static int lightrec_add_meta(struct block *block,
-			     struct opcode *op, union code code)
+static void lightrec_optimize_sll_sra(struct opcode *list, unsigned int offset)
 {
-	struct opcode *meta;
+	struct opcode *prev, *prev2 = NULL, *curr = &list[offset];
+	struct opcode *to_change, *to_nop;
+	int idx, idx2;
 
-	meta = lightrec_malloc(block->state, MEM_FOR_IR, sizeof(*meta));
-	if (!meta)
-		return -ENOMEM;
+	if (curr->r.imm != 24 && curr->r.imm != 16)
+		return;
+
+	idx = find_prev_writer(list, offset, curr->r.rt);
+	if (idx < 0)
+		return;
+
+	prev = &list[idx];
+
+	if (prev->i.op != OP_SPECIAL || prev->r.op != OP_SPECIAL_SLL ||
+	    prev->r.imm != curr->r.imm || prev->r.rd != curr->r.rt)
+		return;
+
+	if (prev->r.rd != prev->r.rt && curr->r.rd != curr->r.rt) {
+		/* sll rY, rX, 16
+		 * ...
+		 * srl rZ, rY, 16 */
 
-	meta->c = code;
-	meta->flags = 0;
+		if (!reg_is_dead(list, offset, curr->r.rt) ||
+		    reg_is_read_or_written(list, idx, offset, curr->r.rd))
+			return;
 
-	if (op) {
-		meta->offset = op->offset;
-		meta->next = op->next;
-		op->next = meta;
+		/* If rY is dead after the SRL, and rZ is not used after the SLL,
+		 * we can change rY to rZ */
+
+		pr_debug("Detected SLL/SRA with middle temp register\n");
+		prev->r.rd = curr->r.rd;
+		curr->r.rt = prev->r.rd;
+	}
+
+	/* We got a SLL/SRA combo. If imm #16, that's a cast to u16.
+	 * If imm #24 that's a cast to u8.
+	 *
+	 * First of all, make sure that the target register of the SLL is not
+	 * read before the SRA. */
+
+	if (prev->r.rd == prev->r.rt) {
+		/* sll rX, rX, 16
+		 * ...
+		 * srl rY, rX, 16 */
+		to_change = curr;
+		to_nop = prev;
+
+		/* rX is used after the SRA - we cannot convert it. */
+		if (prev->r.rd != curr->r.rd && !reg_is_dead(list, offset, prev->r.rd))
+			return;
 	} else {
-		meta->offset = 0;
-		meta->next = block->opcode_list;
-		block->opcode_list = meta;
+		/* sll rY, rX, 16
+		 * ...
+		 * srl rY, rY, 16 */
+		to_change = prev;
+		to_nop = curr;
+	}
+
+	idx2 = find_prev_writer(list, idx, prev->r.rt);
+	if (idx2 >= 0) {
+		/* Note that PSX games sometimes do casts after
+		 * a LHU or LBU; in this case we can change the
+		 * load opcode to a LH or LB, and the cast can
+		 * be changed to a MOV or a simple NOP. */
+
+		prev2 = &list[idx2];
+
+		if (curr->r.rd != prev2->i.rt &&
+		    !reg_is_dead(list, offset, prev2->i.rt))
+			prev2 = NULL;
+		else if (curr->r.imm == 16 && prev2->i.op == OP_LHU)
+			prev2->i.op = OP_LH;
+		else if (curr->r.imm == 24 && prev2->i.op == OP_LBU)
+			prev2->i.op = OP_LB;
+		else
+			prev2 = NULL;
+
+		if (prev2) {
+			if (curr->r.rd == prev2->i.rt) {
+				to_change->opcode = 0;
+			} else if (reg_is_dead(list, offset, prev2->i.rt) &&
+				   !reg_is_read_or_written(list, idx2 + 1, offset, curr->r.rd)) {
+				/* The target register of the SRA is dead after the
+				 * LBU/LHU; we can change the target register of the
+				 * LBU/LHU to the one of the SRA. */
+				prev2->i.rt = curr->r.rd;
+				to_change->opcode = 0;
+			} else {
+				to_change->i.op = OP_META_MOV;
+				to_change->r.rd = curr->r.rd;
+				to_change->r.rs = prev2->i.rt;
+			}
+
+			if (to_nop->r.imm == 24)
+				pr_debug("Convert LBU+SLL+SRA to LB\n");
+			else
+				pr_debug("Convert LHU+SLL+SRA to LH\n");
+		}
+	}
+
+	if (!prev2) {
+		pr_debug("Convert SLL/SRA #%u to EXT%c\n",
+			 prev->r.imm,
+			 prev->r.imm == 24 ? 'C' : 'S');
+
+		if (to_change == prev) {
+			to_change->i.rs = prev->r.rt;
+			to_change->i.rt = curr->r.rd;
+		} else {
+			to_change->i.rt = curr->r.rd;
+			to_change->i.rs = prev->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,
+					u32 known, u32 *values)
+{
+	struct opcode *list = block->opcode_list,
+		      *op = &block->opcode_list[offset];
+	int reader;
+
+	if (!op_flag_sync(op->flags) && (known & BIT(op->i.rt)) &&
+	    values[op->i.rt] == 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)
+		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 int lightrec_add_sync(struct block *block, struct opcode *prev)
+static inline bool is_power_of_two(u32 value)
 {
-	return lightrec_add_meta(block, prev, (union code){
-				 .j.op = OP_META_SYNC,
-				 });
+	return popcount32(value) == 1;
 }
 
-static int lightrec_transform_ops(struct block *block)
+static int lightrec_transform_ops(struct lightrec_state *state, struct block *block)
 {
 	struct opcode *list = block->opcode_list;
+	struct opcode *prev, *op = NULL;
+	u32 known = BIT(0);
+	u32 values[32] = { 0 };
+	unsigned int i;
+	u8 tmp;
+
+	for (i = 0; i < block->nb_ops; i++) {
+		prev = op;
+		op = &list[i];
 
-	for (; list; list = list->next) {
+		if (prev)
+			known = lightrec_propagate_consts(op, prev, known, values);
 
 		/* Transform all opcodes detected as useless to real NOPs
 		 * (0x0: SLL r0, r0, #0) */
-		if (list->opcode != 0 && is_nop(list->c)) {
+		if (op->opcode != 0 && is_nop(op->c)) {
 			pr_debug("Converting useless opcode 0x%08x to NOP\n",
-					list->opcode);
-			list->opcode = 0x0;
+					op->opcode);
+			op->opcode = 0x0;
 		}
 
-		if (!list->opcode)
+		if (!op->opcode)
 			continue;
 
-		switch (list->i.op) {
-		/* Transform BEQ / BNE to BEQZ / BNEZ meta-opcodes if one of the
-		 * two registers is zero. */
+		switch (op->i.op) {
 		case OP_BEQ:
-			if ((list->i.rs == 0) ^ (list->i.rt == 0)) {
-				list->i.op = OP_META_BEQZ;
-				if (list->i.rs == 0) {
-					list->i.rs = list->i.rt;
-					list->i.rt = 0;
-				}
-			} else if (list->i.rs == list->i.rt) {
-				list->i.rs = 0;
-				list->i.rt = 0;
+			if (op->i.rs == op->i.rt) {
+				op->i.rs = 0;
+				op->i.rt = 0;
+			} else if (op->i.rs == 0) {
+				op->i.rs = op->i.rt;
+				op->i.rt = 0;
 			}
 			break;
+
 		case OP_BNE:
-			if (list->i.rs == 0) {
-				list->i.op = OP_META_BNEZ;
-				list->i.rs = list->i.rt;
-				list->i.rt = 0;
-			} else if (list->i.rt == 0) {
-				list->i.op = OP_META_BNEZ;
+			if (op->i.rs == 0) {
+				op->i.rs = op->i.rt;
+				op->i.rt = 0;
 			}
 			break;
 
+		case OP_LUI:
+			if (!prev || !has_delay_slot(prev->c))
+				lightrec_modify_lui(block, i);
+			lightrec_remove_useless_lui(block, i, known, values);
+			break;
+
 		/* Transform ORI/ADDI/ADDIU with imm #0 or ORR/ADD/ADDU/SUB/SUBU
 		 * with register $zero to the MOV meta-opcode */
 		case OP_ORI:
 		case OP_ADDI:
 		case OP_ADDIU:
-			if (list->i.imm == 0) {
+			if (op->i.imm == 0) {
 				pr_debug("Convert ORI/ADDI/ADDIU #0 to MOV\n");
-				list->i.op = OP_META_MOV;
-				list->r.rd = list->i.rt;
+				op->i.op = OP_META_MOV;
+				op->r.rd = op->i.rt;
 			}
 			break;
 		case OP_SPECIAL:
-			switch (list->r.op) {
-			case OP_SPECIAL_SLL:
+			switch (op->r.op) {
 			case OP_SPECIAL_SRA:
+				if (op->r.imm == 0) {
+					pr_debug("Convert SRA #0 to MOV\n");
+					op->i.op = OP_META_MOV;
+					op->r.rs = op->r.rt;
+					break;
+				}
+
+				lightrec_optimize_sll_sra(block->opcode_list, i);
+				break;
+			case OP_SPECIAL_SLL:
 			case OP_SPECIAL_SRL:
-				if (list->r.imm == 0) {
-					pr_debug("Convert SLL/SRL/SRA #0 to MOV\n");
-					list->i.op = OP_META_MOV;
-					list->r.rs = list->r.rt;
+				if (op->r.imm == 0) {
+					pr_debug("Convert SLL/SRL #0 to MOV\n");
+					op->i.op = OP_META_MOV;
+					op->r.rs = op->r.rt;
+				}
+				break;
+			case OP_SPECIAL_MULT:
+			case OP_SPECIAL_MULTU:
+				if ((known & BIT(op->r.rs)) &&
+				    is_power_of_two(values[op->r.rs])) {
+					tmp = op->c.i.rs;
+					op->c.i.rs = op->c.i.rt;
+					op->c.i.rt = tmp;
+				} else if (!(known & BIT(op->r.rt)) ||
+					   !is_power_of_two(values[op->r.rt])) {
+					break;
 				}
+
+				pr_debug("Multiply by power-of-two: %u\n",
+					 values[op->r.rt]);
+
+				if (op->r.op == OP_SPECIAL_MULT)
+					op->i.op = OP_META_MULT2;
+				else
+					op->i.op = OP_META_MULTU2;
+
+				op->r.op = ctz32(values[op->r.rt]);
 				break;
 			case OP_SPECIAL_OR:
 			case OP_SPECIAL_ADD:
 			case OP_SPECIAL_ADDU:
-				if (list->r.rs == 0) {
+				if (op->r.rs == 0) {
 					pr_debug("Convert OR/ADD $zero to MOV\n");
-					list->i.op = OP_META_MOV;
-					list->r.rs = list->r.rt;
+					op->i.op = OP_META_MOV;
+					op->r.rs = op->r.rt;
 				}
-			case OP_SPECIAL_SUB: /* fall-through */
+				fallthrough;
+			case OP_SPECIAL_SUB:
 			case OP_SPECIAL_SUBU:
-				if (list->r.rt == 0) {
+				if (op->r.rt == 0) {
 					pr_debug("Convert OR/ADD/SUB $zero to MOV\n");
-					list->i.op = OP_META_MOV;
+					op->i.op = OP_META_MOV;
 				}
-			default: /* fall-through */
+				fallthrough;
+			default:
 				break;
 			}
-		default: /* fall-through */
+			fallthrough;
+		default:
 			break;
 		}
 	}
@@ -599,96 +1142,149 @@ static int lightrec_transform_ops(struct block *block)
 	return 0;
 }
 
-static int lightrec_switch_delay_slots(struct block *block)
+static bool lightrec_can_switch_delay_slot(union code op, union code next_op)
 {
-	struct opcode *list, *prev;
-	u8 flags;
-
-	for (list = block->opcode_list, prev = NULL; list->next;
-	     prev = list, list = list->next) {
-		union code op = list->c;
-		union code next_op = list->next->c;
-
-		if (!has_delay_slot(op) ||
-		    list->flags & (LIGHTREC_NO_DS | LIGHTREC_EMULATE_BRANCH) ||
-		    op.opcode == 0)
-			continue;
-
-		if (prev && has_delay_slot(prev->c))
-			continue;
-
-		switch (list->i.op) {
-		case OP_SPECIAL:
-			switch (op.r.op) {
-			case OP_SPECIAL_JALR:
-				if (opcode_reads_register(next_op, op.r.rd) ||
-				    opcode_writes_register(next_op, op.r.rd))
-					continue;
-			case OP_SPECIAL_JR: /* fall-through */
-				if (opcode_writes_register(next_op, op.r.rs))
-					continue;
-			default: /* fall-through */
-				break;
-			}
-		case OP_J: /* fall-through */
+	switch (op.i.op) {
+	case OP_SPECIAL:
+		switch (op.r.op) {
+		case OP_SPECIAL_JALR:
+			if (opcode_reads_register(next_op, op.r.rd) ||
+			    opcode_writes_register(next_op, op.r.rd))
+				return false;
+			fallthrough;
+		case OP_SPECIAL_JR:
+			if (opcode_writes_register(next_op, op.r.rs))
+				return false;
+			fallthrough;
+		default:
 			break;
-		case OP_JAL:
+		}
+		fallthrough;
+	case OP_J:
+		break;
+	case OP_JAL:
+		if (opcode_reads_register(next_op, 31) ||
+		    opcode_writes_register(next_op, 31))
+			return false;;
+
+		break;
+	case OP_BEQ:
+	case OP_BNE:
+		if (op.i.rt && opcode_writes_register(next_op, op.i.rt))
+			return false;
+		fallthrough;
+	case OP_BLEZ:
+	case OP_BGTZ:
+		if (op.i.rs && opcode_writes_register(next_op, op.i.rs))
+			return false;
+		break;
+	case OP_REGIMM:
+		switch (op.r.rt) {
+		case OP_REGIMM_BLTZAL:
+		case OP_REGIMM_BGEZAL:
 			if (opcode_reads_register(next_op, 31) ||
 			    opcode_writes_register(next_op, 31))
-				continue;
-			else
-				break;
-		case OP_BEQ:
-		case OP_BNE:
-			if (op.i.rt && opcode_writes_register(next_op, op.i.rt))
-				continue;
-		case OP_BLEZ: /* fall-through */
-		case OP_BGTZ:
-		case OP_META_BEQZ:
-		case OP_META_BNEZ:
+				return false;
+			fallthrough;
+		case OP_REGIMM_BLTZ:
+		case OP_REGIMM_BGEZ:
 			if (op.i.rs && opcode_writes_register(next_op, op.i.rs))
-				continue;
-			break;
-		case OP_REGIMM:
-			switch (op.r.rt) {
-			case OP_REGIMM_BLTZAL:
-			case OP_REGIMM_BGEZAL:
-				if (opcode_reads_register(next_op, 31) ||
-				    opcode_writes_register(next_op, 31))
-					continue;
-			case OP_REGIMM_BLTZ: /* fall-through */
-			case OP_REGIMM_BGEZ:
-				if (op.i.rs &&
-				    opcode_writes_register(next_op, op.i.rs))
-					continue;
-				break;
-			}
-		default: /* fall-through */
+				return false;
 			break;
 		}
+		fallthrough;
+	default:
+		break;
+	}
+
+	return true;
+}
+
+static int lightrec_switch_delay_slots(struct lightrec_state *state, struct block *block)
+{
+	struct opcode *list, *next = &block->opcode_list[0];
+	unsigned int i;
+	union code op, next_op;
+	u32 flags;
+
+	for (i = 0; i < block->nb_ops - 1; i++) {
+		list = next;
+		next = &block->opcode_list[i + 1];
+		next_op = next->c;
+		op = list->c;
+
+		if (!has_delay_slot(op) || op_flag_no_ds(list->flags) ||
+		    op_flag_emulate_branch(list->flags) ||
+		    op.opcode == 0 || next_op.opcode == 0)
+			continue;
+
+		if (i && has_delay_slot(block->opcode_list[i - 1].c) &&
+		    !op_flag_no_ds(block->opcode_list[i - 1].flags))
+			continue;
+
+		if (op_flag_sync(next->flags))
+			continue;
+
+		if (!lightrec_can_switch_delay_slot(list->c, next_op))
+			continue;
 
 		pr_debug("Swap branch and delay slot opcodes "
-			 "at offsets 0x%x / 0x%x\n", list->offset << 2,
-			 list->next->offset << 2);
+			 "at offsets 0x%x / 0x%x\n",
+			 i << 2, (i + 1) << 2);
 
-		flags = list->next->flags;
+		flags = next->flags | (list->flags & LIGHTREC_SYNC);
 		list->c = next_op;
-		list->next->c = op;
-		list->next->flags = list->flags | LIGHTREC_NO_DS;
+		next->c = op;
+		next->flags = (list->flags | LIGHTREC_NO_DS) & ~LIGHTREC_SYNC;
 		list->flags = flags | LIGHTREC_NO_DS;
-		list->offset++;
-		list->next->offset--;
 	}
 
 	return 0;
 }
 
-static int lightrec_detect_impossible_branches(struct block *block)
+static int shrink_opcode_list(struct lightrec_state *state, struct block *block, u16 new_size)
+{
+	struct opcode_list *list, *old_list;
+
+	if (new_size >= block->nb_ops) {
+		pr_err("Invalid shrink size (%u vs %u)\n",
+		       new_size, block->nb_ops);
+		return -EINVAL;
+	}
+
+	list = lightrec_malloc(state, MEM_FOR_IR,
+			       sizeof(*list) + sizeof(struct opcode) * new_size);
+	if (!list) {
+		pr_err("Unable to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	old_list = container_of(block->opcode_list, struct opcode_list, ops);
+	memcpy(list->ops, old_list->ops, sizeof(struct opcode) * new_size);
+
+	lightrec_free_opcode_list(state, block->opcode_list);
+	list->nb_ops = new_size;
+	block->nb_ops = new_size;
+	block->opcode_list = list->ops;
+
+	pr_debug("Shrunk opcode list of block PC 0x%08x to %u opcodes\n",
+		 block->pc, new_size);
+
+	return 0;
+}
+
+static int lightrec_detect_impossible_branches(struct lightrec_state *state,
+					       struct block *block)
 {
-	struct opcode *op, *next;
+	struct opcode *op, *list = block->opcode_list, *next = &list[0];
+	unsigned int i;
+	int ret = 0;
+	s16 offset;
+
+	for (i = 0; i < block->nb_ops - 1; i++) {
+		op = next;
+		next = &list[i + 1];
 
-	for (op = block->opcode_list, next = op->next; next;
-	     op = next, next = op->next) {
 		if (!has_delay_slot(op->c) ||
 		    (!load_in_delay_slot(next->c) &&
 		     !has_delay_slot(next->c) &&
@@ -702,29 +1298,48 @@ static int lightrec_detect_impossible_branches(struct block *block)
 			continue;
 		}
 
-		if (op == block->opcode_list) {
+		offset = i + 1 + (s16)op->i.imm;
+		if (load_in_delay_slot(next->c) &&
+		    (offset >= 0 && offset < block->nb_ops) &&
+		    !opcode_reads_register(list[offset].c, next->c.i.rt)) {
+			/* The 'impossible' branch is a local branch - we can
+			 * verify here that the first opcode of the target does
+			 * not use the target register of the delay slot */
+
+			pr_debug("Branch at offset 0x%x has load delay slot, "
+				 "but is local and dest opcode does not read "
+				 "dest register\n", i << 2);
+			continue;
+		}
+
+		op->flags |= LIGHTREC_EMULATE_BRANCH;
+
+		if (op == list) {
+			pr_debug("First opcode of block PC 0x%08x is an impossible branch\n",
+				 block->pc);
+
 			/* If the first opcode is an 'impossible' branch, we
 			 * only keep the first two opcodes of the block (the
 			 * branch itself + its delay slot) */
-			lightrec_free_opcode_list(block->state, next->next);
-			next->next = NULL;
-			block->nb_ops = 2;
+			if (block->nb_ops > 2)
+				ret = shrink_opcode_list(state, block, 2);
+			break;
 		}
-
-		op->flags |= LIGHTREC_EMULATE_BRANCH;
 	}
 
-	return 0;
+	return ret;
 }
 
-static int lightrec_local_branches(struct block *block)
+static int lightrec_local_branches(struct lightrec_state *state, struct block *block)
 {
-	struct opcode *list, *target, *prev;
+	struct opcode *list;
+	unsigned int i;
 	s32 offset;
-	int ret;
 
-	for (list = block->opcode_list; list; list = list->next) {
-		if (list->flags & LIGHTREC_EMULATE_BRANCH)
+	for (i = 0; i < block->nb_ops; i++) {
+		list = &block->opcode_list[i];
+
+		if (should_emulate(list))
 			continue;
 
 		switch (list->i.op) {
@@ -733,48 +1348,30 @@ static int lightrec_local_branches(struct block *block)
 		case OP_BLEZ:
 		case OP_BGTZ:
 		case OP_REGIMM:
-		case OP_META_BEQZ:
-		case OP_META_BNEZ:
-			offset = list->offset + 1 + (s16)list->i.imm;
+			offset = i + 1 + (s16)list->i.imm;
 			if (offset >= 0 && offset < block->nb_ops)
 				break;
-		default: /* fall-through */
+			fallthrough;
+		default:
 			continue;
 		}
 
 		pr_debug("Found local branch to offset 0x%x\n", offset << 2);
 
-		for (target = block->opcode_list, prev = NULL;
-		     target; prev = target, target = target->next) {
-			if (target->offset != offset ||
-			    target->j.op == OP_META_SYNC)
-				continue;
-
-			if (target->flags & LIGHTREC_EMULATE_BRANCH) {
-				pr_debug("Branch target must be emulated"
-					 " - skip\n");
-				break;
-			}
-
-			if (prev && has_delay_slot(prev->c)) {
-				pr_debug("Branch target is a delay slot"
-					 " - skip\n");
-				break;
-			}
+		if (should_emulate(&block->opcode_list[offset])) {
+			pr_debug("Branch target must be emulated - skip\n");
+			continue;
+		}
 
-			if (prev && prev->j.op != OP_META_SYNC) {
-				pr_debug("Adding sync before offset "
-					 "0x%x\n", offset << 2);
-				ret = lightrec_add_sync(block, prev);
-				if (ret)
-					return ret;
+		if (offset && has_delay_slot(block->opcode_list[offset - 1].c)) {
+			pr_debug("Branch target is a delay slot - skip\n");
+			continue;
+		}
 
-				prev->next->offset = target->offset;
-			}
+		pr_debug("Adding sync at offset 0x%x\n", offset << 2);
 
-			list->flags |= LIGHTREC_LOCAL_BRANCH;
-			break;
-		}
+		block->opcode_list[offset].flags |= LIGHTREC_SYNC;
+		list->flags |= LIGHTREC_LOCAL_BRANCH;
 	}
 
 	return 0;
@@ -798,224 +1395,728 @@ bool has_delay_slot(union code op)
 	case OP_BLEZ:
 	case OP_BGTZ:
 	case OP_REGIMM:
-	case OP_META_BEQZ:
-	case OP_META_BNEZ:
 		return true;
 	default:
 		return false;
 	}
 }
 
-static int lightrec_add_unload(struct block *block, struct opcode *op, u8 reg)
+bool should_emulate(const struct opcode *list)
 {
-	return lightrec_add_meta(block, op, (union code){
-				 .i.op = OP_META_REG_UNLOAD,
-				 .i.rs = reg,
-				 });
+	return op_flag_emulate_branch(list->flags) && has_delay_slot(list->c);
 }
 
-static int lightrec_early_unload(struct block *block)
+static bool op_writes_rd(union code c)
 {
-	struct opcode *list = block->opcode_list;
-	u8 i;
+	switch (c.i.op) {
+	case OP_SPECIAL:
+	case OP_META_MOV:
+		return true;
+	default:
+		return false;
+	}
+}
 
-	for (i = 1; i < 34; i++) {
-		struct opcode *op, *last_r = NULL, *last_w = NULL;
-		unsigned int last_r_id = 0, last_w_id = 0, id = 0;
-		int ret;
+static void lightrec_add_reg_op(struct opcode *op, u8 reg, u32 reg_op)
+{
+	if (op_writes_rd(op->c) && reg == op->r.rd)
+		op->flags |= LIGHTREC_REG_RD(reg_op);
+	else if (op->i.rs == reg)
+		op->flags |= LIGHTREC_REG_RS(reg_op);
+	else if (op->i.rt == reg)
+		op->flags |= LIGHTREC_REG_RT(reg_op);
+	else
+		pr_debug("Cannot add unload/clean/discard flag: "
+			 "opcode does not touch register %s!\n",
+			 lightrec_reg_name(reg));
+}
 
-		for (op = list; op->next; op = op->next, id++) {
-			if (opcode_reads_register(op->c, i)) {
-				last_r = op;
-				last_r_id = id;
-			}
+static void lightrec_add_unload(struct opcode *op, u8 reg)
+{
+	lightrec_add_reg_op(op, reg, LIGHTREC_REG_UNLOAD);
+}
 
-			if (opcode_writes_register(op->c, i)) {
-				last_w = op;
-				last_w_id = id;
-			}
+static void lightrec_add_discard(struct opcode *op, u8 reg)
+{
+	lightrec_add_reg_op(op, reg, LIGHTREC_REG_DISCARD);
+}
+
+static void lightrec_add_clean(struct opcode *op, u8 reg)
+{
+	lightrec_add_reg_op(op, reg, LIGHTREC_REG_CLEAN);
+}
+
+static void
+lightrec_early_unload_sync(struct opcode *list, s16 *last_r, s16 *last_w)
+{
+	unsigned int reg;
+	s16 offset;
+
+	for (reg = 0; reg < 34; reg++) {
+		offset = s16_max(last_w[reg], last_r[reg]);
+
+		if (offset >= 0)
+			lightrec_add_unload(&list[offset], reg);
+	}
+
+	memset(last_r, 0xff, sizeof(*last_r) * 34);
+	memset(last_w, 0xff, sizeof(*last_w) * 34);
+}
+
+static int lightrec_early_unload(struct lightrec_state *state, struct block *block)
+{
+	u16 i, offset;
+	struct opcode *op;
+	s16 last_r[34], last_w[34], last_sync = 0, next_sync = 0;
+	u64 mask_r, mask_w, dirty = 0, loaded = 0;
+	u8 reg;
+
+	memset(last_r, 0xff, sizeof(last_r));
+	memset(last_w, 0xff, sizeof(last_w));
+
+	/*
+	 * Clean if:
+	 * - the register is dirty, and is read again after a branch opcode
+	 *
+	 * Unload if:
+	 * - the register is dirty or loaded, and is not read again
+	 * - the register is dirty or loaded, and is written again after a branch opcode
+	 * - the next opcode has the SYNC flag set
+	 *
+	 * Discard if:
+	 * - the register is dirty or loaded, and is written again
+	 */
+
+	for (i = 0; i < block->nb_ops; i++) {
+		op = &block->opcode_list[i];
+
+		if (op_flag_sync(op->flags) || should_emulate(op)) {
+			/* The next opcode has the SYNC flag set, or is a branch
+			 * that should be emulated: unload all registers. */
+			lightrec_early_unload_sync(block->opcode_list, last_r, last_w);
+			dirty = 0;
+			loaded = 0;
+		}
+
+		if (next_sync == i) {
+			last_sync = i;
+			pr_debug("Last sync: 0x%x\n", last_sync << 2);
+		}
+
+		if (has_delay_slot(op->c)) {
+			next_sync = i + 1 + !op_flag_no_ds(op->flags);
+			pr_debug("Next sync: 0x%x\n", next_sync << 2);
 		}
 
-		if (last_w_id > last_r_id) {
-			if (has_delay_slot(last_w->c) &&
-			    !(last_w->flags & LIGHTREC_NO_DS))
-				last_w = last_w->next;
+		mask_r = opcode_read_mask(op->c);
+		mask_w = opcode_write_mask(op->c);
+
+		for (reg = 0; reg < 34; reg++) {
+			if (mask_r & BIT(reg)) {
+				if (dirty & BIT(reg) && last_w[reg] < last_sync) {
+					/* The register is dirty, and is read
+					 * again after a branch: clean it */
+
+					lightrec_add_clean(&block->opcode_list[last_w[reg]], reg);
+					dirty &= ~BIT(reg);
+					loaded |= BIT(reg);
+				}
 
-			if (last_w->next) {
-				ret = lightrec_add_unload(block, last_w, i);
-				if (ret)
-					return ret;
+				last_r[reg] = i;
 			}
-		} else if (last_r) {
-			if (has_delay_slot(last_r->c) &&
-			    !(last_r->flags & LIGHTREC_NO_DS))
-				last_r = last_r->next;
 
-			if (last_r->next) {
-				ret = lightrec_add_unload(block, last_r, i);
-				if (ret)
-					return ret;
+			if (mask_w & BIT(reg)) {
+				if ((dirty & BIT(reg) && last_w[reg] < last_sync) ||
+				    (loaded & BIT(reg) && last_r[reg] < last_sync)) {
+					/* The register is dirty or loaded, and
+					 * is written again after a branch:
+					 * unload it */
+
+					offset = s16_max(last_w[reg], last_r[reg]);
+					lightrec_add_unload(&block->opcode_list[offset], reg);
+					dirty &= ~BIT(reg);
+					loaded &= ~BIT(reg);
+				} else if (!(mask_r & BIT(reg)) &&
+					   ((dirty & BIT(reg) && last_w[reg] > last_sync) ||
+					   (loaded & BIT(reg) && last_r[reg] > last_sync))) {
+					/* The register is dirty or loaded, and
+					 * is written again: discard it */
+
+					offset = s16_max(last_w[reg], last_r[reg]);
+					lightrec_add_discard(&block->opcode_list[offset], reg);
+					dirty &= ~BIT(reg);
+					loaded &= ~BIT(reg);
+				}
+
+				last_w[reg] = i;
 			}
+
 		}
+
+		dirty |= mask_w;
+		loaded |= mask_r;
 	}
 
+	/* Unload all registers that are dirty or loaded at the end of block. */
+	lightrec_early_unload_sync(block->opcode_list, last_r, last_w);
+
 	return 0;
 }
 
-static int lightrec_flag_stores(struct block *block)
+static int lightrec_flag_io(struct lightrec_state *state, struct block *block)
 {
-	struct opcode *list;
+	struct opcode *prev = NULL, *list = NULL;
+	enum psx_map psx_map;
 	u32 known = BIT(0);
 	u32 values[32] = { 0 };
+	unsigned int i;
+	u32 val, kunseg_val;
+	bool no_mask;
 
-	for (list = block->opcode_list; list; list = list->next) {
-		/* Register $zero is always, well, zero */
-		known |= BIT(0);
-		values[0] = 0;
+	for (i = 0; i < block->nb_ops; i++) {
+		prev = list;
+		list = &block->opcode_list[i];
+
+		if (prev)
+			known = lightrec_propagate_consts(list, prev, known, values);
 
 		switch (list->i.op) {
 		case OP_SB:
 		case OP_SH:
 		case OP_SW:
-			/* Mark all store operations that target $sp or $gp
-			 * as not requiring code invalidation. This is based
-			 * on the heuristic that stores using one of these
-			 * registers as address will never hit a code page. */
-			if (list->i.rs >= 28 && list->i.rs <= 29 &&
-			    !block->state->maps[PSX_MAP_KERNEL_USER_RAM].ops) {
-				pr_debug("Flaging opcode 0x%08x as not requiring invalidation\n",
-					 list->opcode);
-				list->flags |= LIGHTREC_NO_INVALIDATE;
-			}
+			if (OPT_FLAG_STORES) {
+				/* Mark all store operations that target $sp or $gp
+				 * as not requiring code invalidation. This is based
+				 * on the heuristic that stores using one of these
+				 * registers as address will never hit a code page. */
+				if (list->i.rs >= 28 && list->i.rs <= 29 &&
+				    !state->maps[PSX_MAP_KERNEL_USER_RAM].ops) {
+					pr_debug("Flaging opcode 0x%08x as not "
+						 "requiring invalidation\n",
+						 list->opcode);
+					list->flags |= LIGHTREC_NO_INVALIDATE;
+					list->flags |= LIGHTREC_IO_MODE(LIGHTREC_IO_DIRECT);
+				}
 
-			/* Detect writes whose destination address is inside the
-			 * current block, using constant propagation. When these
-			 * occur, we mark the blocks as not compilable. */
-			if ((known & BIT(list->i.rs)) &&
-			    kunseg(values[list->i.rs]) >= kunseg(block->pc) &&
-			    kunseg(values[list->i.rs]) < (kunseg(block->pc) +
-							  block->nb_ops * 4)) {
-				pr_debug("Self-modifying block detected\n");
-				block->flags |= BLOCK_NEVER_COMPILE;
-				list->flags |= LIGHTREC_SMC;
+				/* Detect writes whose destination address is inside the
+				 * current block, using constant propagation. When these
+				 * occur, we mark the blocks as not compilable. */
+				if ((known & BIT(list->i.rs)) &&
+				    kunseg(values[list->i.rs]) >= kunseg(block->pc) &&
+				    kunseg(values[list->i.rs]) < (kunseg(block->pc) +
+								  block->nb_ops * 4)) {
+					pr_debug("Self-modifying block detected\n");
+					block_set_flags(block, BLOCK_NEVER_COMPILE);
+					list->flags |= LIGHTREC_SMC;
+				}
+			}
+			fallthrough;
+		case OP_SWL:
+		case OP_SWR:
+		case OP_SWC2:
+		case OP_LB:
+		case OP_LBU:
+		case OP_LH:
+		case OP_LHU:
+		case OP_LW:
+		case OP_LWL:
+		case OP_LWR:
+		case OP_LWC2:
+			if (OPT_FLAG_IO && (known & BIT(list->i.rs))) {
+				val = values[list->i.rs] + (s16) list->i.imm;
+				kunseg_val = kunseg(val);
+				psx_map = lightrec_get_map_idx(state, kunseg_val);
+
+				list->flags &= ~LIGHTREC_IO_MASK;
+				no_mask = val == kunseg_val;
+
+				switch (psx_map) {
+				case PSX_MAP_KERNEL_USER_RAM:
+					if (no_mask)
+						list->flags |= LIGHTREC_NO_MASK;
+					fallthrough;
+				case PSX_MAP_MIRROR1:
+				case PSX_MAP_MIRROR2:
+				case PSX_MAP_MIRROR3:
+					pr_debug("Flaging opcode %u as RAM access\n", i);
+					list->flags |= LIGHTREC_IO_MODE(LIGHTREC_IO_RAM);
+					if (no_mask && state->mirrors_mapped)
+						list->flags |= LIGHTREC_NO_MASK;
+					break;
+				case PSX_MAP_BIOS:
+					pr_debug("Flaging opcode %u as BIOS access\n", i);
+					list->flags |= LIGHTREC_IO_MODE(LIGHTREC_IO_BIOS);
+					if (no_mask)
+						list->flags |= LIGHTREC_NO_MASK;
+					break;
+				case PSX_MAP_SCRATCH_PAD:
+					pr_debug("Flaging opcode %u as scratchpad access\n", i);
+					list->flags |= LIGHTREC_IO_MODE(LIGHTREC_IO_SCRATCH);
+					if (no_mask)
+						list->flags |= LIGHTREC_NO_MASK;
+
+					/* Consider that we're never going to run code from
+					 * the scratchpad. */
+					list->flags |= LIGHTREC_NO_INVALIDATE;
+					break;
+				case PSX_MAP_HW_REGISTERS:
+					if (state->ops.hw_direct &&
+					    state->ops.hw_direct(kunseg_val,
+								 opcode_is_store(list->c),
+								 opcode_get_io_size(list->c))) {
+						pr_debug("Flagging opcode %u as direct I/O access\n",
+							 i);
+						list->flags |= LIGHTREC_IO_MODE(LIGHTREC_IO_DIRECT_HW);
+
+						if (no_mask)
+							list->flags |= LIGHTREC_NO_MASK;
+						break;
+					}
+					fallthrough;
+				default:
+					pr_debug("Flagging opcode %u as I/O access\n",
+						 i);
+					list->flags |= LIGHTREC_IO_MODE(LIGHTREC_IO_HW);
+					break;
+				}
 			}
-		default: /* fall-through */
+			fallthrough;
+		default:
 			break;
 		}
-
-		known = lightrec_propagate_consts(list->c, known, values);
 	}
 
 	return 0;
 }
 
-static bool is_mult32(const struct block *block, const struct opcode *op)
+static u8 get_mfhi_mflo_reg(const struct block *block, u16 offset,
+			    const struct opcode *last,
+			    u32 mask, bool sync, bool mflo, bool another)
 {
-	const struct opcode *next, *last = NULL;
-	u32 offset;
+	const struct opcode *op, *next = &block->opcode_list[offset];
+	u32 old_mask;
+	u8 reg2, reg = mflo ? REG_LO : REG_HI;
+	u16 branch_offset;
+	unsigned int i;
+
+	for (i = offset; i < block->nb_ops; i++) {
+		op = next;
+		next = &block->opcode_list[i + 1];
+		old_mask = mask;
+
+		/* If any other opcode writes or reads to the register
+		 * we'd use, then we cannot use it anymore. */
+		mask |= opcode_read_mask(op->c);
+		mask |= opcode_write_mask(op->c);
+
+		if (op_flag_sync(op->flags))
+			sync = true;
 
-	for (op = op->next; op != last; op = op->next) {
 		switch (op->i.op) {
 		case OP_BEQ:
 		case OP_BNE:
 		case OP_BLEZ:
 		case OP_BGTZ:
 		case OP_REGIMM:
-		case OP_META_BEQZ:
-		case OP_META_BNEZ:
 			/* TODO: handle backwards branches too */
-			if ((op->flags & LIGHTREC_LOCAL_BRANCH) &&
+			if (!last && op_flag_local_branch(op->flags) &&
 			    (s16)op->c.i.imm >= 0) {
-				offset = op->offset + 1 + (s16)op->c.i.imm;
-
-				for (next = op; next->offset != offset;
-				     next = next->next);
-
-				if (!is_mult32(block, next))
-					return false;
-
-				last = next;
-				continue;
-			} else {
-				return false;
+				branch_offset = i + 1 + (s16)op->c.i.imm
+					- !!op_flag_no_ds(op->flags);
+
+				reg = get_mfhi_mflo_reg(block, branch_offset, NULL,
+							mask, sync, mflo, false);
+				reg2 = get_mfhi_mflo_reg(block, offset + 1, next,
+							 mask, sync, mflo, false);
+				if (reg > 0 && reg == reg2)
+					return reg;
+				if (!reg && !reg2)
+					return 0;
 			}
+
+			return mflo ? REG_LO : REG_HI;
+		case OP_META_MULT2:
+		case OP_META_MULTU2:
+			return 0;
 		case OP_SPECIAL:
 			switch (op->r.op) {
 			case OP_SPECIAL_MULT:
 			case OP_SPECIAL_MULTU:
 			case OP_SPECIAL_DIV:
 			case OP_SPECIAL_DIVU:
+				return 0;
 			case OP_SPECIAL_MTHI:
-				return true;
+				if (!mflo)
+					return 0;
+				continue;
+			case OP_SPECIAL_MTLO:
+				if (mflo)
+					return 0;
+				continue;
 			case OP_SPECIAL_JR:
-				return op->r.rs == 31 &&
-					((op->flags & LIGHTREC_NO_DS) ||
-					 !(op->next->i.op == OP_SPECIAL &&
-					   op->next->r.op == OP_SPECIAL_MFHI));
+				if (op->r.rs != 31)
+					return reg;
+
+				if (!sync && !op_flag_no_ds(op->flags) &&
+				    (next->i.op == OP_SPECIAL) &&
+				    ((!mflo && next->r.op == OP_SPECIAL_MFHI) ||
+				    (mflo && next->r.op == OP_SPECIAL_MFLO)))
+					return next->r.rd;
+
+				return 0;
 			case OP_SPECIAL_JALR:
+				return reg;
 			case OP_SPECIAL_MFHI:
-				return false;
-			default:
+				if (!mflo) {
+					if (another)
+						return op->r.rd;
+					/* Must use REG_HI if there is another MFHI target*/
+					reg2 = get_mfhi_mflo_reg(block, i + 1, next,
+							 0, sync, mflo, true);
+					if (reg2 > 0 && reg2 != REG_HI)
+						return REG_HI;
+
+					if (!sync && !(old_mask & BIT(op->r.rd)))
+						return op->r.rd;
+					else
+						return REG_HI;
+				}
 				continue;
+			case OP_SPECIAL_MFLO:
+				if (mflo) {
+					if (another)
+						return op->r.rd;
+					/* Must use REG_LO if there is another MFLO target*/
+					reg2 = get_mfhi_mflo_reg(block, i + 1, next,
+							 0, sync, mflo, true);
+					if (reg2 > 0 && reg2 != REG_LO)
+						return REG_LO;
+
+					if (!sync && !(old_mask & BIT(op->r.rd)))
+						return op->r.rd;
+					else
+						return REG_LO;
+				}
+				continue;
+			default:
+				break;
 			}
+
+			fallthrough;
 		default:
 			continue;
 		}
 	}
 
-	return last != NULL;
+	return reg;
 }
 
-static int lightrec_flag_mults(struct block *block)
+static void lightrec_replace_lo_hi(struct block *block, u16 offset,
+				   u16 last, bool lo)
 {
-	struct opcode *list, *prev;
+	unsigned int i;
+	u32 branch_offset;
 
-	for (list = block->opcode_list, prev = NULL; list;
-	     prev = list, list = list->next) {
-		if (list->i.op != OP_SPECIAL)
-			continue;
+	/* This function will remove the following MFLO/MFHI. It must be called
+	 * only if get_mfhi_mflo_reg() returned a non-zero value. */
 
-		switch (list->r.op) {
-		case OP_SPECIAL_MULT:
-		case OP_SPECIAL_MULTU:
+	for (i = offset; i < last; i++) {
+		struct opcode *op = &block->opcode_list[i];
+
+		switch (op->i.op) {
+		case OP_BEQ:
+		case OP_BNE:
+		case OP_BLEZ:
+		case OP_BGTZ:
+		case OP_REGIMM:
+			/* TODO: handle backwards branches too */
+			if (op_flag_local_branch(op->flags) && (s16)op->c.i.imm >= 0) {
+				branch_offset = i + 1 + (s16)op->c.i.imm
+					- !!op_flag_no_ds(op->flags);
+
+				lightrec_replace_lo_hi(block, branch_offset, last, lo);
+				lightrec_replace_lo_hi(block, i + 1, branch_offset, lo);
+			}
+			break;
+
+		case OP_SPECIAL:
+			if (lo && op->r.op == OP_SPECIAL_MFLO) {
+				pr_debug("Removing MFLO opcode at offset 0x%x\n",
+					 i << 2);
+				op->opcode = 0;
+				return;
+			} else if (!lo && op->r.op == OP_SPECIAL_MFHI) {
+				pr_debug("Removing MFHI opcode at offset 0x%x\n",
+					 i << 2);
+				op->opcode = 0;
+				return;
+			}
+
+			fallthrough;
+		default:
+			break;
+		}
+	}
+}
+
+static bool lightrec_always_skip_div_check(void)
+{
+#ifdef __mips__
+	return true;
+#else
+	return false;
+#endif
+}
+
+static int lightrec_flag_mults_divs(struct lightrec_state *state, struct block *block)
+{
+	struct opcode *prev, *list = NULL;
+	u8 reg_hi, reg_lo;
+	unsigned int i;
+	u32 known = BIT(0);
+	u32 values[32] = { 0 };
+
+	for (i = 0; i < block->nb_ops - 1; i++) {
+		prev = list;
+		list = &block->opcode_list[i];
+
+		if (prev)
+			known = lightrec_propagate_consts(list, prev, known, values);
+
+		switch (list->i.op) {
+		case OP_SPECIAL:
+			switch (list->r.op) {
+			case OP_SPECIAL_DIV:
+			case OP_SPECIAL_DIVU:
+				/* If we are dividing by a non-zero constant, don't
+				 * emit the div-by-zero check. */
+				if (lightrec_always_skip_div_check() ||
+				    ((known & BIT(list->c.r.rt)) && values[list->c.r.rt]))
+					list->flags |= LIGHTREC_NO_DIV_CHECK;
+				fallthrough;
+			case OP_SPECIAL_MULT:
+			case OP_SPECIAL_MULTU:
+				break;
+			default:
+				continue;
+			}
+			fallthrough;
+		case OP_META_MULT2:
+		case OP_META_MULTU2:
 			break;
 		default:
 			continue;
 		}
 
-		/* Don't support MULT(U) opcodes in delay slots */
-		if (prev && has_delay_slot(prev->c))
+		/* Don't support opcodes in delay slots */
+		if ((i && has_delay_slot(block->opcode_list[i - 1].c)) ||
+		    op_flag_no_ds(list->flags)) {
 			continue;
+		}
+
+		reg_lo = get_mfhi_mflo_reg(block, i + 1, NULL, 0, false, true, false);
+		if (reg_lo == 0) {
+			pr_debug("Mark MULT(U)/DIV(U) opcode at offset 0x%x as"
+				 " not writing LO\n", i << 2);
+			list->flags |= LIGHTREC_NO_LO;
+		}
+
+		reg_hi = get_mfhi_mflo_reg(block, i + 1, NULL, 0, false, false, false);
+		if (reg_hi == 0) {
+			pr_debug("Mark MULT(U)/DIV(U) opcode at offset 0x%x as"
+				 " not writing HI\n", i << 2);
+			list->flags |= LIGHTREC_NO_HI;
+		}
+
+		if (!reg_lo && !reg_hi) {
+			pr_debug("Both LO/HI unused in this block, they will "
+				 "probably be used in parent block - removing "
+				 "flags.\n");
+			list->flags &= ~(LIGHTREC_NO_LO | LIGHTREC_NO_HI);
+		}
+
+		if (reg_lo > 0 && reg_lo != REG_LO) {
+			pr_debug("Found register %s to hold LO (rs = %u, rt = %u)\n",
+				 lightrec_reg_name(reg_lo), list->r.rs, list->r.rt);
+
+			lightrec_replace_lo_hi(block, i + 1, block->nb_ops, true);
+			list->r.rd = reg_lo;
+		} else {
+			list->r.rd = 0;
+		}
+
+		if (reg_hi > 0 && reg_hi != REG_HI) {
+			pr_debug("Found register %s to hold HI (rs = %u, rt = %u)\n",
+				 lightrec_reg_name(reg_hi), list->r.rs, list->r.rt);
 
-		if (is_mult32(block, list)) {
-			pr_debug("Mark MULT(U) opcode at offset 0x%x as"
-				 " 32-bit\n", list->offset << 2);
-			list->flags |= LIGHTREC_MULT32;
+			lightrec_replace_lo_hi(block, i + 1, block->nb_ops, false);
+			list->r.imm = reg_hi;
+		} else {
+			list->r.imm = 0;
 		}
 	}
 
 	return 0;
 }
 
-static int (*lightrec_optimizers[])(struct block *) = {
-	&lightrec_detect_impossible_branches,
-	&lightrec_transform_ops,
-	&lightrec_local_branches,
-	&lightrec_switch_delay_slots,
-	&lightrec_flag_stores,
-	&lightrec_flag_mults,
-	&lightrec_early_unload,
+static bool remove_div_sequence(struct block *block, unsigned int offset)
+{
+	struct opcode *op;
+	unsigned int i, found = 0;
+
+	/*
+	 * Scan for the zero-checking sequence that GCC automatically introduced
+	 * after most DIV/DIVU opcodes. This sequence checks the value of the
+	 * divisor, and if zero, executes a BREAK opcode, causing the BIOS
+	 * handler to crash the PS1.
+	 *
+	 * For DIV opcodes, this sequence additionally checks that the signed
+	 * operation does not overflow.
+	 *
+	 * With the assumption that the games never crashed the PS1, we can
+	 * therefore assume that the games never divided by zero or overflowed,
+	 * and these sequences can be removed.
+	 */
+
+	for (i = offset; i < block->nb_ops; i++) {
+		op = &block->opcode_list[i];
+
+		if (!found) {
+			if (op->i.op == OP_SPECIAL &&
+			    (op->r.op == OP_SPECIAL_DIV || op->r.op == OP_SPECIAL_DIVU))
+				break;
+
+			if ((op->opcode & 0xfc1fffff) == 0x14000002) {
+				/* BNE ???, zero, +8 */
+				found++;
+			} else {
+				offset++;
+			}
+		} else if (found == 1 && !op->opcode) {
+			/* NOP */
+			found++;
+		} else if (found == 2 && op->opcode == 0x0007000d) {
+			/* BREAK 0x1c00 */
+			found++;
+		} else if (found == 3 && op->opcode == 0x2401ffff) {
+			/* LI at, -1 */
+			found++;
+		} else if (found == 4 && (op->opcode & 0xfc1fffff) == 0x14010004) {
+			/* BNE ???, at, +16 */
+			found++;
+		} else if (found == 5 && op->opcode == 0x3c018000) {
+			/* LUI at, 0x8000 */
+			found++;
+		} else if (found == 6 && (op->opcode & 0x141fffff) == 0x14010002) {
+			/* BNE ???, at, +16 */
+			found++;
+		} else if (found == 7 && !op->opcode) {
+			/* NOP */
+			found++;
+		} else if (found == 8 && op->opcode == 0x0006000d) {
+			/* BREAK 0x1800 */
+			found++;
+			break;
+		} else {
+			break;
+		}
+	}
+
+	if (found >= 3) {
+		if (found != 9)
+			found = 3;
+
+		pr_debug("Removing DIV%s sequence at offset 0x%x\n",
+			 found == 9 ? "" : "U", offset << 2);
+
+		for (i = 0; i < found; i++)
+			block->opcode_list[offset + i].opcode = 0;
+
+		return true;
+	}
+
+	return false;
+}
+
+static int lightrec_remove_div_by_zero_check_sequence(struct lightrec_state *state,
+						      struct block *block)
+{
+	struct opcode *op;
+	unsigned int i;
+
+	for (i = 0; i < block->nb_ops; i++) {
+		op = &block->opcode_list[i];
+
+		if (op->i.op == OP_SPECIAL &&
+		    (op->r.op == OP_SPECIAL_DIVU || op->r.op == OP_SPECIAL_DIV) &&
+		    remove_div_sequence(block, i + 1))
+			op->flags |= LIGHTREC_NO_DIV_CHECK;
+	}
+
+	return 0;
+}
+
+static const u32 memset_code[] = {
+	0x10a00006,	// beqz		a1, 2f
+	0x24a2ffff,	// addiu	v0,a1,-1
+	0x2403ffff,	// li		v1,-1
+	0xac800000,	// 1: sw	zero,0(a0)
+	0x2442ffff,	// addiu	v0,v0,-1
+	0x1443fffd,	// bne		v0,v1, 1b
+	0x24840004,	// addiu	a0,a0,4
+	0x03e00008,	// 2: jr	ra
+	0x00000000,	// nop
 };
 
-int lightrec_optimize(struct block *block)
+static int lightrec_replace_memset(struct lightrec_state *state, struct block *block)
 {
 	unsigned int i;
+	union code c;
 
-	for (i = 0; i < ARRAY_SIZE(lightrec_optimizers); i++) {
-		int ret = lightrec_optimizers[i](block);
+	for (i = 0; i < block->nb_ops; i++) {
+		c = block->opcode_list[i].c;
+
+		if (c.opcode != memset_code[i])
+			return 0;
+
+		if (i == ARRAY_SIZE(memset_code) - 1) {
+			/* success! */
+			pr_debug("Block at PC 0x%x is a memset\n", block->pc);
+			block_set_flags(block,
+					BLOCK_IS_MEMSET | BLOCK_NEVER_COMPILE);
 
-		if (ret)
-			return ret;
+			/* Return non-zero to skip other optimizers. */
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int (*lightrec_optimizers[])(struct lightrec_state *state, struct block *) = {
+	IF_OPT(OPT_REMOVE_DIV_BY_ZERO_SEQ, &lightrec_remove_div_by_zero_check_sequence),
+	IF_OPT(OPT_REPLACE_MEMSET, &lightrec_replace_memset),
+	IF_OPT(OPT_DETECT_IMPOSSIBLE_BRANCHES, &lightrec_detect_impossible_branches),
+	IF_OPT(OPT_TRANSFORM_OPS, &lightrec_transform_branches),
+	IF_OPT(OPT_LOCAL_BRANCHES, &lightrec_local_branches),
+	IF_OPT(OPT_TRANSFORM_OPS, &lightrec_transform_ops),
+	IF_OPT(OPT_SWITCH_DELAY_SLOTS, &lightrec_switch_delay_slots),
+	IF_OPT(OPT_FLAG_IO || OPT_FLAG_STORES, &lightrec_flag_io),
+	IF_OPT(OPT_FLAG_MULT_DIV, &lightrec_flag_mults_divs),
+	IF_OPT(OPT_EARLY_UNLOAD, &lightrec_early_unload),
+};
+
+int lightrec_optimize(struct lightrec_state *state, struct block *block)
+{
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(lightrec_optimizers); i++) {
+		if (lightrec_optimizers[i]) {
+			ret = (*lightrec_optimizers[i])(state, block);
+			if (ret)
+				return ret;
+		}
 	}
 
 	return 0;