diff --git a/asm/src/main/java/dev/openrs2/asm/InsnNodeUtils.java b/asm/src/main/java/dev/openrs2/asm/InsnNodeUtils.java
index 6ae5b323..370a89a5 100644
--- a/asm/src/main/java/dev/openrs2/asm/InsnNodeUtils.java
+++ b/asm/src/main/java/dev/openrs2/asm/InsnNodeUtils.java
@@ -112,6 +112,198 @@ public final class InsnNodeUtils {
 		}
 	}
 
+	public static boolean hasSideEffects(AbstractInsnNode insn) {
+		var opcode = insn.getOpcode();
+		switch (opcode) {
+		case Opcodes.NOP:
+		case Opcodes.ACONST_NULL:
+		case Opcodes.ICONST_M1:
+		case Opcodes.ICONST_0:
+		case Opcodes.ICONST_1:
+		case Opcodes.ICONST_2:
+		case Opcodes.ICONST_3:
+		case Opcodes.ICONST_4:
+		case Opcodes.ICONST_5:
+		case Opcodes.LCONST_0:
+		case Opcodes.LCONST_1:
+		case Opcodes.FCONST_0:
+		case Opcodes.FCONST_1:
+		case Opcodes.FCONST_2:
+		case Opcodes.DCONST_0:
+		case Opcodes.DCONST_1:
+		case Opcodes.BIPUSH:
+		case Opcodes.SIPUSH:
+		case Opcodes.LDC:
+		case Opcodes.ILOAD:
+		case Opcodes.LLOAD:
+		case Opcodes.FLOAD:
+		case Opcodes.DLOAD:
+		case Opcodes.ALOAD:
+			return false;
+		case Opcodes.IALOAD:
+		case Opcodes.LALOAD:
+		case Opcodes.FALOAD:
+		case Opcodes.DALOAD:
+		case Opcodes.AALOAD:
+		case Opcodes.BALOAD:
+		case Opcodes.CALOAD:
+		case Opcodes.SALOAD:
+			/* might throw NPE or index out of bounds exception */
+		case Opcodes.ISTORE:
+		case Opcodes.LSTORE:
+		case Opcodes.FSTORE:
+		case Opcodes.DSTORE:
+		case Opcodes.ASTORE:
+		case Opcodes.IASTORE:
+		case Opcodes.LASTORE:
+		case Opcodes.FASTORE:
+		case Opcodes.DASTORE:
+		case Opcodes.AASTORE:
+		case Opcodes.BASTORE:
+		case Opcodes.CASTORE:
+		case Opcodes.SASTORE:
+			return true;
+		case Opcodes.POP:
+		case Opcodes.POP2:
+		case Opcodes.DUP:
+		case Opcodes.DUP_X1:
+		case Opcodes.DUP_X2:
+		case Opcodes.DUP2:
+		case Opcodes.DUP2_X1:
+		case Opcodes.DUP2_X2:
+		case Opcodes.SWAP:
+		case Opcodes.IADD:
+		case Opcodes.LADD:
+		case Opcodes.FADD:
+		case Opcodes.DADD:
+		case Opcodes.ISUB:
+		case Opcodes.LSUB:
+		case Opcodes.FSUB:
+		case Opcodes.DSUB:
+		case Opcodes.IMUL:
+		case Opcodes.LMUL:
+		case Opcodes.FMUL:
+		case Opcodes.DMUL:
+		case Opcodes.IDIV:
+		case Opcodes.LDIV:
+		case Opcodes.FDIV:
+		case Opcodes.DDIV:
+		case Opcodes.IREM:
+		case Opcodes.LREM:
+		case Opcodes.FREM:
+		case Opcodes.DREM:
+			/*
+			 * XXX(gpe): strictly speaking the *DIV and *REM instructions have
+			 * side effects (unless we can prove that the second argument is
+			 * non-zero). However, treating them as having side effects reduces
+			 * the number of dummy variables we can remove, so we pretend they
+			 * don't have any side effects.
+			 *
+			 * This doesn't seem to cause any problems with the client, as it
+			 * doesn't deliberately try to trigger divide-by-zero exceptions.
+			 */
+		case Opcodes.INEG:
+		case Opcodes.LNEG:
+		case Opcodes.FNEG:
+		case Opcodes.DNEG:
+		case Opcodes.ISHL:
+		case Opcodes.LSHL:
+		case Opcodes.ISHR:
+		case Opcodes.LSHR:
+		case Opcodes.IUSHR:
+		case Opcodes.LUSHR:
+		case Opcodes.IAND:
+		case Opcodes.LAND:
+		case Opcodes.IOR:
+		case Opcodes.LOR:
+		case Opcodes.IXOR:
+		case Opcodes.LXOR:
+			return false;
+		case Opcodes.IINC:
+			return true;
+		case Opcodes.I2L:
+		case Opcodes.I2F:
+		case Opcodes.I2D:
+		case Opcodes.L2I:
+		case Opcodes.L2F:
+		case Opcodes.L2D:
+		case Opcodes.F2I:
+		case Opcodes.F2L:
+		case Opcodes.F2D:
+		case Opcodes.D2I:
+		case Opcodes.D2L:
+		case Opcodes.D2F:
+		case Opcodes.I2B:
+		case Opcodes.I2C:
+		case Opcodes.I2S:
+		case Opcodes.LCMP:
+		case Opcodes.FCMPL:
+		case Opcodes.FCMPG:
+		case Opcodes.DCMPL:
+		case Opcodes.DCMPG:
+			return false;
+		case Opcodes.IFEQ:
+		case Opcodes.IFNE:
+		case Opcodes.IFLT:
+		case Opcodes.IFGE:
+		case Opcodes.IFGT:
+		case Opcodes.IFLE:
+		case Opcodes.IF_ICMPEQ:
+		case Opcodes.IF_ICMPNE:
+		case Opcodes.IF_ICMPLT:
+		case Opcodes.IF_ICMPGE:
+		case Opcodes.IF_ICMPGT:
+		case Opcodes.IF_ICMPLE:
+		case Opcodes.IF_ACMPEQ:
+		case Opcodes.IF_ACMPNE:
+		case Opcodes.GOTO:
+		case Opcodes.JSR:
+		case Opcodes.RET:
+		case Opcodes.TABLESWITCH:
+		case Opcodes.LOOKUPSWITCH:
+		case Opcodes.IRETURN:
+		case Opcodes.LRETURN:
+		case Opcodes.FRETURN:
+		case Opcodes.DRETURN:
+		case Opcodes.ARETURN:
+		case Opcodes.RETURN:
+			return true;
+		case Opcodes.GETSTATIC:
+			return false;
+		case Opcodes.PUTSTATIC:
+		case Opcodes.GETFIELD:
+			/* might throw NPE */
+		case Opcodes.PUTFIELD:
+			return true;
+		case Opcodes.INVOKEVIRTUAL:
+		case Opcodes.INVOKESPECIAL:
+		case Opcodes.INVOKESTATIC:
+		case Opcodes.INVOKEINTERFACE:
+		case Opcodes.INVOKEDYNAMIC:
+			return true;
+		case Opcodes.NEW:
+			return false;
+		case Opcodes.NEWARRAY:
+		case Opcodes.ANEWARRAY:
+			/* arrays might be created with negative size */
+		case Opcodes.ARRAYLENGTH:
+			/* might throw NPE */
+		case Opcodes.ATHROW:
+		case Opcodes.CHECKCAST:
+			return true;
+		case Opcodes.INSTANCEOF:
+			return false;
+		case Opcodes.MONITORENTER:
+		case Opcodes.MONITOREXIT:
+		case Opcodes.MULTIANEWARRAY:
+		case Opcodes.IFNULL:
+		case Opcodes.IFNONNULL:
+			return true;
+		}
+
+		throw new IllegalArgumentException();
+	}
+
 	private InsnNodeUtils() {
 		/* empty */
 	}