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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System;
using System.Diagnostics;
namespace ILCompiler.DependencyAnalysis.X86
{
public struct X86Emitter
{
public X86Emitter(NodeFactory factory, bool relocsOnly)
{
Builder = new ObjectDataBuilder(factory, relocsOnly);
TargetRegister = new TargetRegisterMap(factory.Target.OperatingSystem);
}
public ObjectDataBuilder Builder;
public TargetRegisterMap TargetRegister;
public void EmitCMP(ref AddrMode addrMode, sbyte immediate)
{
if (addrMode.Size == AddrModeSize.Int16)
Builder.EmitByte(0x66);
EmitIndirInstruction((byte)((addrMode.Size != AddrModeSize.Int8) ? 0x83 : 0x80), 0x7, ref addrMode);
Builder.EmitByte((byte)immediate);
}
public void EmitADD(ref AddrMode addrMode, sbyte immediate)
{
if (addrMode.Size == AddrModeSize.Int16)
Builder.EmitByte(0x66);
EmitIndirInstruction((byte)((addrMode.Size != AddrModeSize.Int8) ? 0x83 : 0x80), (byte)0, ref addrMode);
Builder.EmitByte((byte)immediate);
}
public void EmitJMP(ISymbolNode symbol)
{
if (symbol.RepresentsIndirectionCell)
{
Builder.EmitByte(0xff);
Builder.EmitByte(0x25);
Builder.EmitReloc(symbol, RelocType.IMAGE_REL_BASED_HIGHLOW);
}
else
{
Builder.EmitByte(0xE9);
Builder.EmitReloc(symbol, RelocType.IMAGE_REL_BASED_REL32);
}
}
public void EmitXOR(Register register1, Register register2)
{
Builder.EmitByte(0x33);
Builder.EmitByte((byte)(0xC0 | ((byte)register1 << 3) | (byte)register2));
}
public void EmitPUSH(sbyte imm8)
{
Builder.EmitByte(0x6A);
Builder.EmitByte(unchecked((byte)imm8));
}
public void EmitPUSH(ISymbolNode node)
{
if (node.RepresentsIndirectionCell)
{
// push [node address]
Builder.EmitByte(0xFF);
Builder.EmitByte(0x35);
}
else
{
// push <node address>
Builder.EmitByte(0x68);
}
Builder.EmitReloc(node, RelocType.IMAGE_REL_BASED_HIGHLOW);
}
public void EmitMOV(Register regDst, Register regSrc)
{
Builder.EmitByte(0x8B);
Builder.EmitByte((byte)(0xC0 | (((int)regDst & 0x07) << 3) | (((int)regSrc & 0x07))));
}
public void EmitMOV(Register register, ISymbolNode node, int delta = 0)
{
if (node.RepresentsIndirectionCell)
{
// mov register, [node address]
Builder.EmitByte(0x8B);
Builder.EmitByte((byte)(0x00 | ((byte)register << 3) | 0x5));
}
else
{
// mov register, immediate
Builder.EmitByte((byte)(0xB8 + (byte)register));
}
Builder.EmitReloc(node, RelocType.IMAGE_REL_BASED_HIGHLOW, delta);
}
public void EmitINT3()
{
Builder.EmitByte(0xCC);
}
public void EmitRET()
{
Builder.EmitByte(0xC3);
}
public void EmitRETIfEqual()
{
// jne @+1
Builder.EmitByte(0x75);
Builder.EmitByte(0x01);
// ret
Builder.EmitByte(0xC3);
}
private static bool InSignedByteRange(int i)
{
return i == (int)(sbyte)i;
}
private void EmitImmediate(int immediate, int size)
{
switch (size)
{
case 0:
break;
case 1:
Builder.EmitByte((byte)immediate);
break;
case 2:
Builder.EmitShort((short)immediate);
break;
case 4:
Builder.EmitInt(immediate);
break;
default:
throw new NotImplementedException();
}
}
private void EmitModRM(byte subOpcode, ref AddrMode addrMode)
{
byte modRM = (byte)((subOpcode & 0x07) << 3);
if (addrMode.BaseReg > Register.None)
{
Debug.Assert(addrMode.BaseReg >= Register.RegDirect);
Register reg = (Register)(addrMode.BaseReg - Register.RegDirect);
Builder.EmitByte((byte)(0xC0 | modRM | ((int)reg & 0x07)));
}
else
{
byte lowOrderBitsOfBaseReg = (byte)((int)addrMode.BaseReg & 0x07);
modRM |= lowOrderBitsOfBaseReg;
int offsetSize;
if (addrMode.Offset == 0 && (lowOrderBitsOfBaseReg != (byte)Register.EBP))
{
offsetSize = 0;
}
else if (InSignedByteRange(addrMode.Offset))
{
offsetSize = 1;
modRM |= 0x40;
}
else
{
offsetSize = 4;
modRM |= 0x80;
}
bool emitSibByte = false;
Register sibByteBaseRegister = addrMode.BaseReg;
if (addrMode.BaseReg == Register.None)
{
emitSibByte = (addrMode.IndexReg != Register.NoIndex);
modRM &= 0x38; // set Mod bits to 00 and clear out base reg
offsetSize = 4; // this forces 32-bit displacement
if (emitSibByte)
{
// EBP in SIB byte means no base
// ModRM base register forced to ESP in SIB code below
sibByteBaseRegister = Register.EBP;
}
else
{
// EBP in ModRM means no base
modRM |= (byte)(Register.EBP);
}
}
else if (lowOrderBitsOfBaseReg == (byte)Register.ESP || addrMode.IndexReg.HasValue)
{
emitSibByte = true;
}
if (!emitSibByte)
{
Builder.EmitByte(modRM);
}
else
{
modRM = (byte)((modRM & 0xF8) | (int)Register.ESP);
Builder.EmitByte(modRM);
int indexRegAsInt = (int)(addrMode.IndexReg ?? Register.ESP);
Builder.EmitByte((byte)((addrMode.Scale << 6) + ((indexRegAsInt & 0x07) << 3) + ((int)sibByteBaseRegister & 0x07)));
}
EmitImmediate(addrMode.Offset, offsetSize);
}
}
private void EmitExtendedOpcode(int opcode)
{
if ((opcode >> 16) != 0)
{
if ((opcode >> 24) != 0)
{
Builder.EmitByte((byte)(opcode >> 24));
}
Builder.EmitByte((byte)(opcode >> 16));
}
Builder.EmitByte((byte)(opcode >> 8));
}
private void EmitIndirInstruction(int opcode, byte subOpcode, ref AddrMode addrMode)
{
if ((opcode >> 8) != 0)
{
EmitExtendedOpcode(opcode);
}
Builder.EmitByte((byte)opcode);
EmitModRM(subOpcode, ref addrMode);
}
}
}
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