+++ /dev/null
-//===-- X86/MachineCodeEmitter.cpp - Convert X86 code to machine code -----===//
-//
-// This file contains the pass that transforms the X86 machine instructions into
-// actual executable machine code.
-//
-//===----------------------------------------------------------------------===//
-
-#include "X86TargetMachine.h"
-#include "X86.h"
-#include "llvm/PassManager.h"
-#include "llvm/CodeGen/MachineCodeEmitter.h"
-#include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/CodeGen/MachineInstr.h"
-#include "llvm/Value.h"
-
-namespace {
- class JITResolver {
- MachineCodeEmitter &MCE;
-
- // LazyCodeGenMap - Keep track of call sites for functions that are to be
- // lazily resolved.
- std::map<unsigned, Function*> LazyCodeGenMap;
-
- // LazyResolverMap - Keep track of the lazy resolver created for a
- // particular function so that we can reuse them if necessary.
- std::map<Function*, unsigned> LazyResolverMap;
- public:
- JITResolver(MachineCodeEmitter &mce) : MCE(mce) {}
- unsigned getLazyResolver(Function *F);
- unsigned addFunctionReference(unsigned Address, Function *F);
-
- private:
- unsigned emitStubForFunction(Function *F);
- static void CompilationCallback();
- unsigned resolveFunctionReference(unsigned RetAddr);
- };
-
- JITResolver *TheJITResolver;
-}
-
-
-/// addFunctionReference - This method is called when we need to emit the
-/// address of a function that has not yet been emitted, so we don't know the
-/// address. Instead, we emit a call to the CompilationCallback method, and
-/// keep track of where we are.
-///
-unsigned JITResolver::addFunctionReference(unsigned Address, Function *F) {
- LazyCodeGenMap[Address] = F;
- return (intptr_t)&JITResolver::CompilationCallback;
-}
-
-unsigned JITResolver::resolveFunctionReference(unsigned RetAddr) {
- std::map<unsigned, Function*>::iterator I = LazyCodeGenMap.find(RetAddr);
- assert(I != LazyCodeGenMap.end() && "Not in map!");
- Function *F = I->second;
- LazyCodeGenMap.erase(I);
- return MCE.forceCompilationOf(F);
-}
-
-unsigned JITResolver::getLazyResolver(Function *F) {
- std::map<Function*, unsigned>::iterator I = LazyResolverMap.lower_bound(F);
- if (I != LazyResolverMap.end() && I->first == F) return I->second;
-
-//std::cerr << "Getting lazy resolver for : " << ((Value*)F)->getName() << "\n";
-
- unsigned Stub = emitStubForFunction(F);
- LazyResolverMap.insert(I, std::make_pair(F, Stub));
- return Stub;
-}
-
-void JITResolver::CompilationCallback() {
- unsigned *StackPtr = (unsigned*)__builtin_frame_address(0);
- unsigned RetAddr = (unsigned)__builtin_return_address(0);
-
- assert(StackPtr[1] == RetAddr &&
- "Could not find return address on the stack!");
- bool isStub = ((unsigned char*)RetAddr)[0] == 0xCD; // Interrupt marker?
-
- // The call instruction should have pushed the return value onto the stack...
- RetAddr -= 4; // Backtrack to the reference itself...
-
-#if 0
- DEBUG(std::cerr << "In callback! Addr=0x" << std::hex << RetAddr
- << " ESP=0x" << (unsigned)StackPtr << std::dec
- << ": Resolving call to function: "
- << TheVM->getFunctionReferencedName((void*)RetAddr) << "\n");
-#endif
-
- // Sanity check to make sure this really is a call instruction...
- assert(((unsigned char*)RetAddr)[-1] == 0xE8 && "Not a call instr!");
-
- unsigned NewVal = TheJITResolver->resolveFunctionReference(RetAddr);
-
- // Rewrite the call target... so that we don't fault every time we execute
- // the call.
- *(unsigned*)RetAddr = NewVal-RetAddr-4;
-
- if (isStub) {
- // If this is a stub, rewrite the call into an unconditional branch
- // instruction so that two return addresses are not pushed onto the stack
- // when the requested function finally gets called. This also makes the
- // 0xCD byte (interrupt) dead, so the marker doesn't effect anything.
- ((unsigned char*)RetAddr)[-1] = 0xE9;
- }
-
- // Change the return address to reexecute the call instruction...
- StackPtr[1] -= 5;
-}
-
-/// emitStubForFunction - This method is used by the JIT when it needs to emit
-/// the address of a function for a function whose code has not yet been
-/// generated. In order to do this, it generates a stub which jumps to the lazy
-/// function compiler, which will eventually get fixed to call the function
-/// directly.
-///
-unsigned JITResolver::emitStubForFunction(Function *F) {
- MCE.startFunctionStub(*F, 6);
- MCE.emitByte(0xE8); // Call with 32 bit pc-rel destination...
-
- unsigned Address = addFunctionReference(MCE.getCurrentPCValue(), F);
- MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
-
- MCE.emitByte(0xCD); // Interrupt - Just a marker identifying the stub!
- return (intptr_t)MCE.finishFunctionStub(*F);
-}
-
-
-
-namespace {
- class Emitter : public MachineFunctionPass {
- const X86InstrInfo *II;
- MachineCodeEmitter &MCE;
- std::map<BasicBlock*, unsigned> BasicBlockAddrs;
- std::vector<std::pair<BasicBlock*, unsigned> > BBRefs;
- public:
- Emitter(MachineCodeEmitter &mce) : II(0), MCE(mce) {}
-
- bool runOnMachineFunction(MachineFunction &MF);
-
- virtual const char *getPassName() const {
- return "X86 Machine Code Emitter";
- }
-
- private:
- void emitBasicBlock(MachineBasicBlock &MBB);
- void emitInstruction(MachineInstr &MI);
-
- void emitPCRelativeBlockAddress(BasicBlock *BB);
- void emitMaybePCRelativeValue(unsigned Address, bool isPCRelative);
- void emitGlobalAddressForCall(GlobalValue *GV);
- void emitGlobalAddressForPtr(GlobalValue *GV);
-
- void emitRegModRMByte(unsigned ModRMReg, unsigned RegOpcodeField);
- void emitSIBByte(unsigned SS, unsigned Index, unsigned Base);
- void emitConstant(unsigned Val, unsigned Size);
-
- void emitMemModRMByte(const MachineInstr &MI,
- unsigned Op, unsigned RegOpcodeField);
-
- };
-}
-
-/// addPassesToEmitMachineCode - Add passes to the specified pass manager to get
-/// machine code emitted. This uses a MAchineCodeEmitter object to handle
-/// actually outputting the machine code and resolving things like the address
-/// of functions. This method should returns true if machine code emission is
-/// not supported.
-///
-bool X86TargetMachine::addPassesToEmitMachineCode(PassManager &PM,
- MachineCodeEmitter &MCE) {
- PM.add(new Emitter(MCE));
- return false;
-}
-
-bool Emitter::runOnMachineFunction(MachineFunction &MF) {
- II = &((X86TargetMachine&)MF.getTarget()).getInstrInfo();
-
- MCE.startFunction(MF);
- MCE.emitConstantPool(MF.getConstantPool());
- for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
- emitBasicBlock(*I);
- MCE.finishFunction(MF);
-
- // Resolve all forward branches now...
- for (unsigned i = 0, e = BBRefs.size(); i != e; ++i) {
- unsigned Location = BasicBlockAddrs[BBRefs[i].first];
- unsigned Ref = BBRefs[i].second;
- *(unsigned*)Ref = Location-Ref-4;
- }
- BBRefs.clear();
- BasicBlockAddrs.clear();
- return false;
-}
-
-void Emitter::emitBasicBlock(MachineBasicBlock &MBB) {
- if (uint64_t Addr = MCE.getCurrentPCValue())
- BasicBlockAddrs[MBB.getBasicBlock()] = Addr;
-
- for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ++I)
- emitInstruction(**I);
-}
-
-
-/// emitPCRelativeBlockAddress - This method emits the PC relative address of
-/// the specified basic block, or if the basic block hasn't been emitted yet
-/// (because this is a forward branch), it keeps track of the information
-/// necessary to resolve this address later (and emits a dummy value).
-///
-void Emitter::emitPCRelativeBlockAddress(BasicBlock *BB) {
- // FIXME: Emit backward branches directly
- BBRefs.push_back(std::make_pair(BB, MCE.getCurrentPCValue()));
- MCE.emitWord(0); // Emit a dummy value
-}
-
-/// emitMaybePCRelativeValue - Emit a 32-bit address which may be PC relative.
-///
-void Emitter::emitMaybePCRelativeValue(unsigned Address, bool isPCRelative) {
- if (isPCRelative)
- MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
- else
- MCE.emitWord(Address);
-}
-
-/// emitGlobalAddressForCall - Emit the specified address to the code stream
-/// assuming this is part of a function call, which is PC relative.
-///
-void Emitter::emitGlobalAddressForCall(GlobalValue *GV) {
- // Get the address from the backend...
- unsigned Address = MCE.getGlobalValueAddress(GV);
-
- // If the machine code emitter doesn't know what the address IS yet, we have
- // to take special measures.
- //
- if (Address == 0) {
- // FIXME: this is JIT specific!
- if (TheJITResolver == 0)
- TheJITResolver = new JITResolver(MCE);
- Address = TheJITResolver->addFunctionReference(MCE.getCurrentPCValue(),
- (Function*)GV);
- }
- emitMaybePCRelativeValue(Address, true);
-}
-
-/// emitGlobalAddress - Emit the specified address to the code stream assuming
-/// this is part of a "take the address of a global" instruction, which is not
-/// PC relative.
-///
-void Emitter::emitGlobalAddressForPtr(GlobalValue *GV) {
- // Get the address from the backend...
- unsigned Address = MCE.getGlobalValueAddress(GV);
-
- // If the machine code emitter doesn't know what the address IS yet, we have
- // to take special measures.
- //
- if (Address == 0) {
- // FIXME: this is JIT specific!
- if (TheJITResolver == 0)
- TheJITResolver = new JITResolver(MCE);
- Address = TheJITResolver->getLazyResolver((Function*)GV);
- }
-
- emitMaybePCRelativeValue(Address, false);
-}
-
-
-
-
-namespace N86 { // Native X86 Register numbers...
- enum {
- EAX = 0, ECX = 1, EDX = 2, EBX = 3, ESP = 4, EBP = 5, ESI = 6, EDI = 7
- };
-}
-
-
-// getX86RegNum - This function maps LLVM register identifiers to their X86
-// specific numbering, which is used in various places encoding instructions.
-//
-static unsigned getX86RegNum(unsigned RegNo) {
- switch(RegNo) {
- case X86::EAX: case X86::AX: case X86::AL: return N86::EAX;
- case X86::ECX: case X86::CX: case X86::CL: return N86::ECX;
- case X86::EDX: case X86::DX: case X86::DL: return N86::EDX;
- case X86::EBX: case X86::BX: case X86::BL: return N86::EBX;
- case X86::ESP: case X86::SP: case X86::AH: return N86::ESP;
- case X86::EBP: case X86::BP: case X86::CH: return N86::EBP;
- case X86::ESI: case X86::SI: case X86::DH: return N86::ESI;
- case X86::EDI: case X86::DI: case X86::BH: return N86::EDI;
-
- case X86::ST0: case X86::ST1: case X86::ST2: case X86::ST3:
- case X86::ST4: case X86::ST5: case X86::ST6: case X86::ST7:
- return RegNo-X86::ST0;
- default:
- assert(RegNo >= MRegisterInfo::FirstVirtualRegister &&
- "Unknown physical register!");
- assert(0 && "Register allocator hasn't allocated reg correctly yet!");
- return 0;
- }
-}
-
-inline static unsigned char ModRMByte(unsigned Mod, unsigned RegOpcode,
- unsigned RM) {
- assert(Mod < 4 && RegOpcode < 8 && RM < 8 && "ModRM Fields out of range!");
- return RM | (RegOpcode << 3) | (Mod << 6);
-}
-
-void Emitter::emitRegModRMByte(unsigned ModRMReg, unsigned RegOpcodeFld){
- MCE.emitByte(ModRMByte(3, RegOpcodeFld, getX86RegNum(ModRMReg)));
-}
-
-void Emitter::emitSIBByte(unsigned SS, unsigned Index, unsigned Base) {
- // SIB byte is in the same format as the ModRMByte...
- MCE.emitByte(ModRMByte(SS, Index, Base));
-}
-
-void Emitter::emitConstant(unsigned Val, unsigned Size) {
- // Output the constant in little endian byte order...
- for (unsigned i = 0; i != Size; ++i) {
- MCE.emitByte(Val & 255);
- Val >>= 8;
- }
-}
-
-static bool isDisp8(int Value) {
- return Value == (signed char)Value;
-}
-
-void Emitter::emitMemModRMByte(const MachineInstr &MI,
- unsigned Op, unsigned RegOpcodeField) {
- const MachineOperand &Disp = MI.getOperand(Op+3);
- if (MI.getOperand(Op).isConstantPoolIndex()) {
- // Emit a direct address reference [disp32] where the displacement of the
- // constant pool entry is controlled by the MCE.
- MCE.emitByte(ModRMByte(0, RegOpcodeField, 5));
- unsigned Index = MI.getOperand(Op).getConstantPoolIndex();
- unsigned Address = MCE.getConstantPoolEntryAddress(Index);
- MCE.emitWord(Address+Disp.getImmedValue());
- return;
- }
-
- const MachineOperand &BaseReg = MI.getOperand(Op);
- const MachineOperand &Scale = MI.getOperand(Op+1);
- const MachineOperand &IndexReg = MI.getOperand(Op+2);
-
- // Is a SIB byte needed?
- if (IndexReg.getReg() == 0 && BaseReg.getReg() != X86::ESP) {
- if (BaseReg.getReg() == 0) { // Just a displacement?
- // Emit special case [disp32] encoding
- MCE.emitByte(ModRMByte(0, RegOpcodeField, 5));
- emitConstant(Disp.getImmedValue(), 4);
- } else {
- unsigned BaseRegNo = getX86RegNum(BaseReg.getReg());
- if (Disp.getImmedValue() == 0 && BaseRegNo != N86::EBP) {
- // Emit simple indirect register encoding... [EAX] f.e.
- MCE.emitByte(ModRMByte(0, RegOpcodeField, BaseRegNo));
- } else if (isDisp8(Disp.getImmedValue())) {
- // Emit the disp8 encoding... [REG+disp8]
- MCE.emitByte(ModRMByte(1, RegOpcodeField, BaseRegNo));
- emitConstant(Disp.getImmedValue(), 1);
- } else {
- // Emit the most general non-SIB encoding: [REG+disp32]
- MCE.emitByte(ModRMByte(2, RegOpcodeField, BaseRegNo));
- emitConstant(Disp.getImmedValue(), 4);
- }
- }
-
- } else { // We need a SIB byte, so start by outputting the ModR/M byte first
- assert(IndexReg.getReg() != X86::ESP && "Cannot use ESP as index reg!");
-
- bool ForceDisp32 = false;
- bool ForceDisp8 = false;
- if (BaseReg.getReg() == 0) {
- // If there is no base register, we emit the special case SIB byte with
- // MOD=0, BASE=5, to JUST get the index, scale, and displacement.
- MCE.emitByte(ModRMByte(0, RegOpcodeField, 4));
- ForceDisp32 = true;
- } else if (Disp.getImmedValue() == 0 && BaseReg.getReg() != X86::EBP) {
- // Emit no displacement ModR/M byte
- MCE.emitByte(ModRMByte(0, RegOpcodeField, 4));
- } else if (isDisp8(Disp.getImmedValue())) {
- // Emit the disp8 encoding...
- MCE.emitByte(ModRMByte(1, RegOpcodeField, 4));
- ForceDisp8 = true; // Make sure to force 8 bit disp if Base=EBP
- } else {
- // Emit the normal disp32 encoding...
- MCE.emitByte(ModRMByte(2, RegOpcodeField, 4));
- }
-
- // Calculate what the SS field value should be...
- static const unsigned SSTable[] = { ~0, 0, 1, ~0, 2, ~0, ~0, ~0, 3 };
- unsigned SS = SSTable[Scale.getImmedValue()];
-
- if (BaseReg.getReg() == 0) {
- // Handle the SIB byte for the case where there is no base. The
- // displacement has already been output.
- assert(IndexReg.getReg() && "Index register must be specified!");
- emitSIBByte(SS, getX86RegNum(IndexReg.getReg()), 5);
- } else {
- unsigned BaseRegNo = getX86RegNum(BaseReg.getReg());
- unsigned IndexRegNo;
- if (IndexReg.getReg())
- IndexRegNo = getX86RegNum(IndexReg.getReg());
- else
- IndexRegNo = 4; // For example [ESP+1*<noreg>+4]
- emitSIBByte(SS, IndexRegNo, BaseRegNo);
- }
-
- // Do we need to output a displacement?
- if (Disp.getImmedValue() != 0 || ForceDisp32 || ForceDisp8) {
- if (!ForceDisp32 && isDisp8(Disp.getImmedValue()))
- emitConstant(Disp.getImmedValue(), 1);
- else
- emitConstant(Disp.getImmedValue(), 4);
- }
- }
-}
-
-static unsigned sizeOfPtr(const TargetInstrDescriptor &Desc) {
- switch (Desc.TSFlags & X86II::ArgMask) {
- case X86II::Arg8: return 1;
- case X86II::Arg16: return 2;
- case X86II::Arg32: return 4;
- case X86II::ArgF32: return 4;
- case X86II::ArgF64: return 8;
- case X86II::ArgF80: return 10;
- default: assert(0 && "Memory size not set!");
- return 0;
- }
-}
-
-void Emitter::emitInstruction(MachineInstr &MI) {
- unsigned Opcode = MI.getOpcode();
- const TargetInstrDescriptor &Desc = II->get(Opcode);
-
- // Emit instruction prefixes if neccesary
- if (Desc.TSFlags & X86II::OpSize) MCE.emitByte(0x66);// Operand size...
-
- switch (Desc.TSFlags & X86II::Op0Mask) {
- case X86II::TB:
- MCE.emitByte(0x0F); // Two-byte opcode prefix
- break;
- case X86II::D8: case X86II::D9: case X86II::DA: case X86II::DB:
- case X86II::DC: case X86II::DD: case X86II::DE: case X86II::DF:
- MCE.emitByte(0xD8+
- (((Desc.TSFlags & X86II::Op0Mask)-X86II::D8)
- >> X86II::Op0Shift));
- break; // Two-byte opcode prefix
- default: assert(0 && "Invalid prefix!");
- case 0: break; // No prefix!
- }
-
- unsigned char BaseOpcode = II->getBaseOpcodeFor(Opcode);
- switch (Desc.TSFlags & X86II::FormMask) {
- default: assert(0 && "Unknown FormMask value in X86 MachineCodeEmitter!");
- case X86II::Pseudo:
- if (Opcode != X86::IMPLICIT_USE)
- std::cerr << "X86 Machine Code Emitter: No 'form', not emitting: " << MI;
- break;
-
- case X86II::RawFrm:
- MCE.emitByte(BaseOpcode);
- if (MI.getNumOperands() == 1) {
- MachineOperand &MO = MI.getOperand(0);
- if (MO.isPCRelativeDisp()) {
- // Conditional branch... FIXME: this should use an MBB destination!
- emitPCRelativeBlockAddress(cast<BasicBlock>(MO.getVRegValue()));
- } else if (MO.isGlobalAddress()) {
- assert(MO.isPCRelative() && "Call target is not PC Relative?");
- emitGlobalAddressForCall(MO.getGlobal());
- } else if (MO.isExternalSymbol()) {
- unsigned Address = MCE.getGlobalValueAddress(MO.getSymbolName());
- assert(Address && "Unknown external symbol!");
- emitMaybePCRelativeValue(Address, MO.isPCRelative());
- } else {
- assert(0 && "Unknown RawFrm operand!");
- }
- }
- break;
-
- case X86II::AddRegFrm:
- MCE.emitByte(BaseOpcode + getX86RegNum(MI.getOperand(0).getReg()));
- if (MI.getNumOperands() == 2) {
- MachineOperand &MO1 = MI.getOperand(1);
- if (MO1.isImmediate() || MO1.getVRegValueOrNull() ||
- MO1.isGlobalAddress() || MO1.isExternalSymbol()) {
- unsigned Size = sizeOfPtr(Desc);
- if (Value *V = MO1.getVRegValueOrNull()) {
- assert(Size == 4 && "Don't know how to emit non-pointer values!");
- emitGlobalAddressForPtr(cast<GlobalValue>(V));
- } else if (MO1.isGlobalAddress()) {
- assert(Size == 4 && "Don't know how to emit non-pointer values!");
- assert(!MO1.isPCRelative() && "Function pointer ref is PC relative?");
- emitGlobalAddressForPtr(MO1.getGlobal());
- } else if (MO1.isExternalSymbol()) {
- assert(Size == 4 && "Don't know how to emit non-pointer values!");
-
- unsigned Address = MCE.getGlobalValueAddress(MO1.getSymbolName());
- assert(Address && "Unknown external symbol!");
- emitMaybePCRelativeValue(Address, MO1.isPCRelative());
- } else {
- emitConstant(MO1.getImmedValue(), Size);
- }
- }
- }
- break;
-
- case X86II::MRMDestReg: {
- MCE.emitByte(BaseOpcode);
- MachineOperand &SrcOp = MI.getOperand(1+II->isTwoAddrInstr(Opcode));
- emitRegModRMByte(MI.getOperand(0).getReg(), getX86RegNum(SrcOp.getReg()));
- if (MI.getNumOperands() == 4)
- emitConstant(MI.getOperand(3).getImmedValue(), sizeOfPtr(Desc));
- break;
- }
- case X86II::MRMDestMem:
- MCE.emitByte(BaseOpcode);
- emitMemModRMByte(MI, 0, getX86RegNum(MI.getOperand(4).getReg()));
- break;
-
- case X86II::MRMSrcReg:
- MCE.emitByte(BaseOpcode);
- emitRegModRMByte(MI.getOperand(MI.getNumOperands()-1).getReg(),
- getX86RegNum(MI.getOperand(0).getReg()));
- break;
-
- case X86II::MRMSrcMem:
- MCE.emitByte(BaseOpcode);
- emitMemModRMByte(MI, MI.getNumOperands()-4,
- getX86RegNum(MI.getOperand(0).getReg()));
- break;
-
- case X86II::MRMS0r: case X86II::MRMS1r:
- case X86II::MRMS2r: case X86II::MRMS3r:
- case X86II::MRMS4r: case X86II::MRMS5r:
- case X86II::MRMS6r: case X86II::MRMS7r:
- MCE.emitByte(BaseOpcode);
- emitRegModRMByte(MI.getOperand(0).getReg(),
- (Desc.TSFlags & X86II::FormMask)-X86II::MRMS0r);
-
- if (MI.getOperand(MI.getNumOperands()-1).isImmediate()) {
- unsigned Size = sizeOfPtr(Desc);
- emitConstant(MI.getOperand(MI.getNumOperands()-1).getImmedValue(), Size);
- }
- break;
-
- case X86II::MRMS0m: case X86II::MRMS1m:
- case X86II::MRMS2m: case X86II::MRMS3m:
- case X86II::MRMS4m: case X86II::MRMS5m:
- case X86II::MRMS6m: case X86II::MRMS7m:
- MCE.emitByte(BaseOpcode);
- emitMemModRMByte(MI, 0, (Desc.TSFlags & X86II::FormMask)-X86II::MRMS0m);
-
- if (MI.getNumOperands() == 5) {
- unsigned Size = sizeOfPtr(Desc);
- emitConstant(MI.getOperand(4).getImmedValue(), Size);
- }
- break;
- }
-}
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