openrs2/asm/src/main/java/dev/openrs2/asm/InsnNodeUtils.kt

package dev.openrs2.asm

import org.objectweb.asm.Opcodes
import org.objectweb.asm.tree.AbstractInsnNode
import org.objectweb.asm.tree.InsnNode
import org.objectweb.asm.tree.IntInsnNode
import org.objectweb.asm.tree.LdcInsnNode
import org.objectweb.asm.util.Textifier
import org.objectweb.asm.util.TraceMethodVisitor
import java.io.PrintWriter
import java.io.StringWriter

private val PURE_OPCODES = setOf(
    -1,
    Opcodes.NOP,
    Opcodes.ACONST_NULL,
    Opcodes.ICONST_M1,
    Opcodes.ICONST_0,
    Opcodes.ICONST_1,
    Opcodes.ICONST_2,
    Opcodes.ICONST_3,
    Opcodes.ICONST_4,
    Opcodes.ICONST_5,
    Opcodes.LCONST_0,
    Opcodes.LCONST_1,
    Opcodes.FCONST_0,
    Opcodes.FCONST_1,
    Opcodes.FCONST_2,
    Opcodes.DCONST_0,
    Opcodes.DCONST_1,
    Opcodes.BIPUSH,
    Opcodes.SIPUSH,
    Opcodes.LDC,
    Opcodes.ILOAD,
    Opcodes.LLOAD,
    Opcodes.FLOAD,
    Opcodes.DLOAD,
    Opcodes.ALOAD,
    Opcodes.POP,
    Opcodes.POP2,
    Opcodes.DUP,
    Opcodes.DUP_X1,
    Opcodes.DUP_X2,
    Opcodes.DUP2,
    Opcodes.DUP2_X1,
    Opcodes.DUP2_X2,
    Opcodes.SWAP,
    Opcodes.IADD,
    Opcodes.LADD,
    Opcodes.FADD,
    Opcodes.DADD,
    Opcodes.ISUB,
    Opcodes.LSUB,
    Opcodes.FSUB,
    Opcodes.DSUB,
    Opcodes.IMUL,
    Opcodes.LMUL,
    Opcodes.FMUL,
    Opcodes.DMUL,
    /*
     * XXX(gpe): strictly speaking the *DEV 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.
     */
    Opcodes.IDIV,
    Opcodes.LDIV,
    Opcodes.FDIV,
    Opcodes.DDIV,
    Opcodes.IREM,
    Opcodes.LREM,
    Opcodes.FREM,
    Opcodes.DREM,
    Opcodes.INEG,
    Opcodes.LNEG,
    Opcodes.FNEG,
    Opcodes.DNEG,
    Opcodes.ISHL,
    Opcodes.LSHL,
    Opcodes.ISHR,
    Opcodes.LSHR,
    Opcodes.IUSHR,
    Opcodes.LUSHR,
    Opcodes.IAND,
    Opcodes.LAND,
    Opcodes.IOR,
    Opcodes.LOR,
    Opcodes.IXOR,
    Opcodes.LXOR,
    Opcodes.I2L,
    Opcodes.I2F,
    Opcodes.I2D,
    Opcodes.L2I,
    Opcodes.L2F,
    Opcodes.L2D,
    Opcodes.F2I,
    Opcodes.F2L,
    Opcodes.F2D,
    Opcodes.D2I,
    Opcodes.D2L,
    Opcodes.D2F,
    Opcodes.I2B,
    Opcodes.I2C,
    Opcodes.I2S,
    Opcodes.LCMP,
    Opcodes.FCMPL,
    Opcodes.FCMPG,
    Opcodes.DCMPL,
    Opcodes.DCMPG,
    Opcodes.GETSTATIC,
    Opcodes.NEW,
    Opcodes.INSTANCEOF
)

private val IMPURE_OPCODES = setOf(
    Opcodes.IALOAD,
    Opcodes.LALOAD,
    Opcodes.FALOAD,
    Opcodes.DALOAD,
    Opcodes.AALOAD,
    Opcodes.BALOAD,
    Opcodes.CALOAD,
    Opcodes.SALOAD,
    Opcodes.ISTORE,
    Opcodes.LSTORE,
    Opcodes.FSTORE,
    Opcodes.DSTORE,
    Opcodes.ASTORE,
    Opcodes.IASTORE,
    Opcodes.LASTORE,
    Opcodes.FASTORE,
    Opcodes.DASTORE,
    Opcodes.AASTORE,
    Opcodes.BASTORE,
    Opcodes.CASTORE,
    Opcodes.SASTORE,
    Opcodes.IINC,
    Opcodes.IFEQ,
    Opcodes.IFNE,
    Opcodes.IFLT,
    Opcodes.IFGE,
    Opcodes.IFGT,
    Opcodes.IFLE,
    Opcodes.IF_ICMPEQ,
    Opcodes.IF_ICMPNE,
    Opcodes.IF_ICMPLT,
    Opcodes.IF_ICMPGE,
    Opcodes.IF_ICMPGT,
    Opcodes.IF_ICMPLE,
    Opcodes.IF_ACMPEQ,
    Opcodes.IF_ACMPNE,
    Opcodes.GOTO,
    Opcodes.JSR,
    Opcodes.RET,
    Opcodes.TABLESWITCH,
    Opcodes.LOOKUPSWITCH,
    Opcodes.IRETURN,
    Opcodes.LRETURN,
    Opcodes.FRETURN,
    Opcodes.DRETURN,
    Opcodes.ARETURN,
    Opcodes.RETURN,
    Opcodes.PUTSTATIC,
    Opcodes.GETFIELD,
    Opcodes.PUTFIELD,
    Opcodes.INVOKEVIRTUAL,
    Opcodes.INVOKESPECIAL,
    Opcodes.INVOKESTATIC,
    Opcodes.INVOKEINTERFACE,
    Opcodes.INVOKEDYNAMIC,
    Opcodes.NEWARRAY,
    Opcodes.ANEWARRAY,
    Opcodes.ARRAYLENGTH,
    Opcodes.ATHROW,
    Opcodes.CHECKCAST,
    Opcodes.MONITORENTER,
    Opcodes.MONITOREXIT,
    Opcodes.MULTIANEWARRAY,
    Opcodes.IFNULL,
    Opcodes.IFNONNULL
)

val AbstractInsnNode.nextReal: AbstractInsnNode?
    get() {
        var insn = next
        while (insn != null && insn.opcode == -1) {
            insn = insn.next
        }
        return insn
    }

val AbstractInsnNode.previousReal: AbstractInsnNode?
    get() {
        var insn = previous
        while (insn != null && insn.opcode == -1) {
            insn = insn.previous
        }
        return insn
    }

val AbstractInsnNode.nextVirtual: AbstractInsnNode?
    get() {
        var insn = next
        while (insn != null && insn.opcode != -1) {
            insn = insn.next
        }
        return insn
    }

val AbstractInsnNode.previousVirtual: AbstractInsnNode?
    get() {
        var insn = previous
        while (insn != null && insn.opcode != -1) {
            insn = insn.previous
        }
        return insn
    }

val AbstractInsnNode.intConstant: Int?
    get() = when (this) {
        is IntInsnNode -> {
            if (opcode == Opcodes.BIPUSH || opcode == Opcodes.SIPUSH) {
                operand
            } else {
                null
            }
        }
        is LdcInsnNode -> {
            val cst = cst
            if (cst is Int) {
                cst
            } else {
                null
            }
        }
        else -> when (opcode) {
            Opcodes.ICONST_M1 -> -1
            Opcodes.ICONST_0 -> 0
            Opcodes.ICONST_1 -> 1
            Opcodes.ICONST_2 -> 2
            Opcodes.ICONST_3 -> 3
            Opcodes.ICONST_4 -> 4
            Opcodes.ICONST_5 -> 5
            else -> null
        }
    }

val AbstractInsnNode.pure: Boolean
    get() = when (opcode) {
        in PURE_OPCODES -> true
        in IMPURE_OPCODES -> false
        else -> throw IllegalArgumentException()
    }

fun createIntConstant(value: Int): AbstractInsnNode = when (value) {
    -1 -> InsnNode(Opcodes.ICONST_M1)
    0 -> InsnNode(Opcodes.ICONST_0)
    1 -> InsnNode(Opcodes.ICONST_1)
    2 -> InsnNode(Opcodes.ICONST_2)
    3 -> InsnNode(Opcodes.ICONST_3)
    4 -> InsnNode(Opcodes.ICONST_4)
    5 -> InsnNode(Opcodes.ICONST_5)
    in Byte.MIN_VALUE..Byte.MAX_VALUE -> IntInsnNode(Opcodes.BIPUSH, value)
    in Short.MIN_VALUE..Short.MAX_VALUE -> IntInsnNode(Opcodes.SIPUSH, value)
    else -> LdcInsnNode(value)
}

fun AbstractInsnNode.toPrettyString(): String {
    val printer = Textifier()

    val visitor = TraceMethodVisitor(printer)
    accept(visitor)

    StringWriter().use { stringWriter ->
        PrintWriter(stringWriter).use { printWriter ->
            printer.print(printWriter)
            return stringWriter.toString().trim()
        }
    }
}