PTXAsmPrinter.cpp   [plain text]

//===-- PTXAsmPrinter.cpp - PTX LLVM assembly writer ----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a printer that converts from our internal representation
// of machine-dependent LLVM code to PTX assembly language.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "ptx-asm-printer"

#include "PTX.h"
#include "PTXMachineFunctionInfo.h"
#include "PTXTargetMachine.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Target/Mangler.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetRegistry.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"

using namespace llvm;

namespace {
class PTXAsmPrinter : public AsmPrinter {
public:
  explicit PTXAsmPrinter(TargetMachine &TM, MCStreamer &Streamer)
    : AsmPrinter(TM, Streamer) {}

  const char *getPassName() const { return "PTX Assembly Printer"; }

  bool doFinalization(Module &M);

  virtual void EmitStartOfAsmFile(Module &M);

  virtual bool runOnMachineFunction(MachineFunction &MF);

  virtual void EmitFunctionBodyStart();
  virtual void EmitFunctionBodyEnd() { OutStreamer.EmitRawText(Twine("}")); }

  virtual void EmitInstruction(const MachineInstr *MI);

  void printOperand(const MachineInstr *MI, int opNum, raw_ostream &OS);
  void printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &OS,
                       const char *Modifier = 0);
  void printParamOperand(const MachineInstr *MI, int opNum, raw_ostream &OS,
                         const char *Modifier = 0);
  void printPredicateOperand(const MachineInstr *MI, raw_ostream &O);

  // autogen'd.
  void printInstruction(const MachineInstr *MI, raw_ostream &OS);
  static const char *getRegisterName(unsigned RegNo);

private:
  void EmitVariableDeclaration(const GlobalVariable *gv);
  void EmitFunctionDeclaration();
}; // class PTXAsmPrinter
} // namespace

static const char PARAM_PREFIX[] = "__param_";

static const char *getRegisterTypeName(unsigned RegNo) {
#define TEST_REGCLS(cls, clsstr)                \
  if (PTX::cls ## RegisterClass->contains(RegNo)) return # clsstr;
  TEST_REGCLS(Preds, pred);
  TEST_REGCLS(RRegu16, u16);
  TEST_REGCLS(RRegu32, u32);
  TEST_REGCLS(RRegu64, u64);
  TEST_REGCLS(RRegf32, f32);
  TEST_REGCLS(RRegf64, f64);
#undef TEST_REGCLS

  llvm_unreachable("Not in any register class!");
  return NULL;
}

static const char *getStateSpaceName(unsigned addressSpace) {
  switch (addressSpace) {
  default: llvm_unreachable("Unknown state space");
  case PTX::GLOBAL:    return "global";
  case PTX::CONSTANT:  return "const";
  case PTX::LOCAL:     return "local";
  case PTX::PARAMETER: return "param";
  case PTX::SHARED:    return "shared";
  }
  return NULL;
}

static const char *getTypeName(const Type* type) {
  while (true) {
    switch (type->getTypeID()) {
      default: llvm_unreachable("Unknown type");
      case Type::FloatTyID: return ".f32";
      case Type::DoubleTyID: return ".f64";
      case Type::IntegerTyID:
        switch (type->getPrimitiveSizeInBits()) {
          default: llvm_unreachable("Unknown integer bit-width");
          case 16: return ".u16";
          case 32: return ".u32";
          case 64: return ".u64";
        }
      case Type::ArrayTyID:
      case Type::PointerTyID:
        type = dyn_cast<const SequentialType>(type)->getElementType();
        break;
    }
  }
  return NULL;
}

bool PTXAsmPrinter::doFinalization(Module &M) {
  // XXX Temproarily remove global variables so that doFinalization() will not
  // emit them again (global variables are emitted at beginning).

  Module::GlobalListType &global_list = M.getGlobalList();
  int i, n = global_list.size();
  GlobalVariable **gv_array = new GlobalVariable* [n];

  // first, back-up GlobalVariable in gv_array
  i = 0;
  for (Module::global_iterator I = global_list.begin(), E = global_list.end();
       I != E; ++I)
    gv_array[i++] = &*I;

  // second, empty global_list
  while (!global_list.empty())
    global_list.remove(global_list.begin());

  // call doFinalization
  bool ret = AsmPrinter::doFinalization(M);

  // now we restore global variables
  for (i = 0; i < n; i ++)
    global_list.insert(global_list.end(), gv_array[i]);

  delete[] gv_array;
  return ret;
}

void PTXAsmPrinter::EmitStartOfAsmFile(Module &M)
{
  const PTXSubtarget& ST = TM.getSubtarget<PTXSubtarget>();

  OutStreamer.EmitRawText(Twine("\t.version " + ST.getPTXVersionString()));
  OutStreamer.EmitRawText(Twine("\t.target " + ST.getTargetString() +
                                (ST.supportsDouble() ? ""
                                                     : ", map_f64_to_f32")));
  OutStreamer.AddBlankLine();

  // declare global variables
  for (Module::const_global_iterator i = M.global_begin(), e = M.global_end();
       i != e; ++i)
    EmitVariableDeclaration(i);
}

bool PTXAsmPrinter::runOnMachineFunction(MachineFunction &MF) {
  SetupMachineFunction(MF);
  EmitFunctionDeclaration();
  EmitFunctionBody();
  return false;
}

void PTXAsmPrinter::EmitFunctionBodyStart() {
  OutStreamer.EmitRawText(Twine("{"));

  const PTXMachineFunctionInfo *MFI = MF->getInfo<PTXMachineFunctionInfo>();

  // Print local variable definition
  for (PTXMachineFunctionInfo::reg_iterator
       i = MFI->localVarRegBegin(), e = MFI->localVarRegEnd(); i != e; ++ i) {
    unsigned reg = *i;

    std::string def = "\t.reg .";
    def += getRegisterTypeName(reg);
    def += ' ';
    def += getRegisterName(reg);
    def += ';';
    OutStreamer.EmitRawText(Twine(def));
  }
}

void PTXAsmPrinter::EmitInstruction(const MachineInstr *MI) {
  std::string str;
  str.reserve(64);

  raw_string_ostream OS(str);

  // Emit predicate
  printPredicateOperand(MI, OS);

  // Write instruction to str
  printInstruction(MI, OS);
  OS << ';';
  OS.flush();

  StringRef strref = StringRef(str);
  OutStreamer.EmitRawText(strref);
}

void PTXAsmPrinter::printOperand(const MachineInstr *MI, int opNum,
                                 raw_ostream &OS) {
  const MachineOperand &MO = MI->getOperand(opNum);

  switch (MO.getType()) {
    default:
      llvm_unreachable("<unknown operand type>");
      break;
    case MachineOperand::MO_GlobalAddress:
      OS << *Mang->getSymbol(MO.getGlobal());
      break;
    case MachineOperand::MO_Immediate:
      OS << (long) MO.getImm();
      break;
    case MachineOperand::MO_MachineBasicBlock:
      OS << *MO.getMBB()->getSymbol();
      break;
    case MachineOperand::MO_Register:
      OS << getRegisterName(MO.getReg());
      break;
    case MachineOperand::MO_FPImmediate:
      APInt constFP = MO.getFPImm()->getValueAPF().bitcastToAPInt();
      bool  isFloat = MO.getFPImm()->getType()->getTypeID() == Type::FloatTyID;
      // Emit 0F for 32-bit floats and 0D for 64-bit doubles.
      if (isFloat) {
        OS << "0F";
      }
      else {
        OS << "0D";
      }
      // Emit the encoded floating-point value.
      if (constFP.getZExtValue() > 0) {
        OS << constFP.toString(16, false);
      }
      else {
        OS << "00000000";
        // If We have a double-precision zero, pad to 8-bytes.
        if (!isFloat) {
          OS << "00000000";
        }
      }
      break;
  }
}

void PTXAsmPrinter::printMemOperand(const MachineInstr *MI, int opNum,
                                    raw_ostream &OS, const char *Modifier) {
  printOperand(MI, opNum, OS);

  if (MI->getOperand(opNum+1).isImm() && MI->getOperand(opNum+1).getImm() == 0)
    return; // don't print "+0"

  OS << "+";
  printOperand(MI, opNum+1, OS);
}

void PTXAsmPrinter::printParamOperand(const MachineInstr *MI, int opNum,
                                      raw_ostream &OS, const char *Modifier) {
  OS << PARAM_PREFIX << (int) MI->getOperand(opNum).getImm() + 1;
}

void PTXAsmPrinter::EmitVariableDeclaration(const GlobalVariable *gv) {
  // Check to see if this is a special global used by LLVM, if so, emit it.
  if (EmitSpecialLLVMGlobal(gv))
    return;

  MCSymbol *gvsym = Mang->getSymbol(gv);

  assert(gvsym->isUndefined() && "Cannot define a symbol twice!");

  std::string decl;

  // check if it is defined in some other translation unit
  if (gv->isDeclaration())
    decl += ".extern ";

  // state space: e.g., .global
  decl += ".";
  decl += getStateSpaceName(gv->getType()->getAddressSpace());
  decl += " ";

  // alignment (optional)
  unsigned alignment = gv->getAlignment();
  if (alignment != 0) {
    decl += ".align ";
    decl += utostr(Log2_32(gv->getAlignment()));
    decl += " ";
  }


  if (PointerType::classof(gv->getType())) {
    const PointerType* pointerTy = dyn_cast<const PointerType>(gv->getType());
    const Type* elementTy = pointerTy->getElementType();

    decl += ".b8 ";
    decl += gvsym->getName();
    decl += "[";
    
    if (elementTy->isArrayTy())
    {
      assert(elementTy->isArrayTy() && "Only pointers to arrays are supported");

      const ArrayType* arrayTy = dyn_cast<const ArrayType>(elementTy);
      elementTy = arrayTy->getElementType();

      unsigned numElements = arrayTy->getNumElements();
      
      while (elementTy->isArrayTy()) {

        arrayTy = dyn_cast<const ArrayType>(elementTy);
        elementTy = arrayTy->getElementType();

        numElements *= arrayTy->getNumElements();
      }

      // FIXME: isPrimitiveType() == false for i16?
      assert(elementTy->isSingleValueType() &&
              "Non-primitive types are not handled");

      // Compute the size of the array, in bytes.
      uint64_t arraySize = (elementTy->getPrimitiveSizeInBits() >> 3)
                        * numElements;
  
      decl += utostr(arraySize);
    }
    
    decl += "]";
    
    // handle string constants (assume ConstantArray means string)
    
    if (gv->hasInitializer())
    {
      Constant *C = gv->getInitializer();  
      if (const ConstantArray *CA = dyn_cast<ConstantArray>(C))
      {
        decl += " = {";

        for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
        {
          if (i > 0)   decl += ",";
      
          decl += "0x" + utohexstr(cast<ConstantInt>(CA->getOperand(i))->getZExtValue());
        }
      
        decl += "}";
      }
    }
  }
  else {
    // Note: this is currently the fall-through case and most likely generates
    //       incorrect code.
    decl += getTypeName(gv->getType());
    decl += " ";

    decl += gvsym->getName();

    if (ArrayType::classof(gv->getType()) ||
        PointerType::classof(gv->getType()))
      decl += "[]";
  }

  decl += ";";

  OutStreamer.EmitRawText(Twine(decl));

  OutStreamer.AddBlankLine();
}

void PTXAsmPrinter::EmitFunctionDeclaration() {
  // The function label could have already been emitted if two symbols end up
  // conflicting due to asm renaming.  Detect this and emit an error.
  if (!CurrentFnSym->isUndefined()) {
    report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
                       "' label emitted multiple times to assembly file");
    return;
  }

  const PTXMachineFunctionInfo *MFI = MF->getInfo<PTXMachineFunctionInfo>();
  const bool isKernel = MFI->isKernel();
  unsigned reg;

  std::string decl = isKernel ? ".entry" : ".func";

  // Print return register
  reg = MFI->retReg();
  if (!isKernel && reg != PTX::NoRegister) {
    decl += " (.reg ."; // FIXME: could it return in .param space?
    decl += getRegisterTypeName(reg);
    decl += " ";
    decl += getRegisterName(reg);
    decl += ")";
  }

  // Print function name
  decl += " ";
  decl += CurrentFnSym->getName().str();

  // Print parameter list
  if (!MFI->argRegEmpty()) {
    decl += " (";
    if (isKernel) {
      unsigned cnt = 0;
      for(PTXMachineFunctionInfo::reg_iterator
          i = MFI->argRegBegin(), e = MFI->argRegEnd(), b = i;
          i != e; ++i) {
        reg = *i;
        assert(reg != PTX::NoRegister && "Not a valid register!");
        if (i != b)
          decl += ", ";
        decl += ".param .";
        decl += getRegisterTypeName(reg);
        decl += " ";
        decl += PARAM_PREFIX;
        decl += utostr(++cnt);
      }
    } else {
      for (PTXMachineFunctionInfo::reg_iterator
           i = MFI->argRegBegin(), e = MFI->argRegEnd(), b = i;
           i != e; ++i) {
        reg = *i;
        assert(reg != PTX::NoRegister && "Not a valid register!");
        if (i != b)
          decl += ", ";
        decl += ".reg .";
        decl += getRegisterTypeName(reg);
        decl += " ";
        decl += getRegisterName(reg);
      }
    }
    decl += ")";
  }

  OutStreamer.EmitRawText(Twine(decl));
}

void PTXAsmPrinter::
printPredicateOperand(const MachineInstr *MI, raw_ostream &O) {
  int i = MI->findFirstPredOperandIdx();
  if (i == -1)
    llvm_unreachable("missing predicate operand");

  unsigned reg = MI->getOperand(i).getReg();
  int predOp = MI->getOperand(i+1).getImm();

  DEBUG(dbgs() << "predicate: (" << reg << ", " << predOp << ")\n");

  if (reg != PTX::NoRegister) {
    O << '@';
    if (predOp == PTX::PRED_NEGATE)
      O << '!';
    O << getRegisterName(reg);
  }
}

#include "PTXGenAsmWriter.inc"

// Force static initialization.
extern "C" void LLVMInitializePTXAsmPrinter() {
  RegisterAsmPrinter<PTXAsmPrinter> X(ThePTX32Target);
  RegisterAsmPrinter<PTXAsmPrinter> Y(ThePTX64Target);
}