MSP430AsmPrinter.cpp

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//===-- MSP430AsmPrinter.cpp - MSP430 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 the MSP430 assembly language.
//
//===----------------------------------------------------------------------===//

#include "InstPrinter/MSP430InstPrinter.h"
#include "MSP430.h"
#include "MSP430InstrInfo.h"
#include "MSP430MCInstLower.h"
#include "MSP430TargetMachine.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;

#define DEBUG_TYPE "asm-printer"

namespace {
  class MSP430AsmPrinter : public AsmPrinter {
  public:
    MSP430AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
        : AsmPrinter(TM, std::move(Streamer)) {}

    StringRef getPassName() const override { return "MSP430 Assembly Printer"; }

    bool runOnMachineFunction(MachineFunction &MF) override;

    void printOperand(const MachineInstr *MI, int OpNum,
                      raw_ostream &O, const char* Modifier = nullptr);
    void printSrcMemOperand(const MachineInstr *MI, int OpNum,
                            raw_ostream &O);
    bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                         unsigned AsmVariant, const char *ExtraCode,
                         raw_ostream &O) override;
    bool PrintAsmMemoryOperand(const MachineInstr *MI,
                               unsigned OpNo, unsigned AsmVariant,
                               const char *ExtraCode, raw_ostream &O) override;
    void EmitInstruction(const MachineInstr *MI) override;

    void EmitInterruptVectorSection(MachineFunction &ISR);
  };
} // end of anonymous namespace


void MSP430AsmPrinter::printOperand(const MachineInstr *MI, int OpNum,
                                    raw_ostream &O, const char *Modifier) {
  const MachineOperand &MO = MI->getOperand(OpNum);
  switch (MO.getType()) {
  default: llvm_unreachable("Not implemented yet!");
  case MachineOperand::MO_Register:
    O << MSP430InstPrinter::getRegisterName(MO.getReg());
    return;
  case MachineOperand::MO_Immediate:
    if (!Modifier || strcmp(Modifier, "nohash"))
      O << '#';
    O << MO.getImm();
    return;
  case MachineOperand::MO_MachineBasicBlock:
    MO.getMBB()->getSymbol()->print(O, MAI);
    return;
  case MachineOperand::MO_GlobalAddress: {
    bool isMemOp  = Modifier && !strcmp(Modifier, "mem");
    uint64_t Offset = MO.getOffset();

    // If the global address expression is a part of displacement field with a
    // register base, we should not emit any prefix symbol here, e.g.
    //   mov.w &foo, r1
    // vs
    //   mov.w glb(r1), r2
    // Otherwise (!) msp430-as will silently miscompile the output :(
    if (!Modifier || strcmp(Modifier, "nohash"))
      O << (isMemOp ? '&' : '#');
    if (Offset)
      O << '(' << Offset << '+';

    getSymbol(MO.getGlobal())->print(O, MAI);

    if (Offset)
      O << ')';

    return;
  }
  }
}

void MSP430AsmPrinter::printSrcMemOperand(const MachineInstr *MI, int OpNum,
                                          raw_ostream &O) {
  const MachineOperand &Base = MI->getOperand(OpNum);
  const MachineOperand &Disp = MI->getOperand(OpNum+1);

  // Print displacement first

  // Imm here is in fact global address - print extra modifier.
  if (Disp.isImm() && !Base.getReg())
    O << '&';
  printOperand(MI, OpNum+1, O, "nohash");

  // Print register base field
  if (Base.getReg()) {
    O << '(';
    printOperand(MI, OpNum, O);
    O << ')';
  }
}

/// PrintAsmOperand - Print out an operand for an inline asm expression.
///
bool MSP430AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                                       unsigned AsmVariant,
                                       const char *ExtraCode, raw_ostream &O) {
  // Does this asm operand have a single letter operand modifier?
  if (ExtraCode && ExtraCode[0])
    return true; // Unknown modifier.

  printOperand(MI, OpNo, O);
  return false;
}

bool MSP430AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
                                             unsigned OpNo, unsigned AsmVariant,
                                             const char *ExtraCode,
                                             raw_ostream &O) {
  if (ExtraCode && ExtraCode[0]) {
    return true; // Unknown modifier.
  }
  printSrcMemOperand(MI, OpNo, O);
  return false;
}

//===----------------------------------------------------------------------===//
void MSP430AsmPrinter::EmitInstruction(const MachineInstr *MI) {
  MSP430MCInstLower MCInstLowering(OutContext, *this);

  MCInst TmpInst;
  MCInstLowering.Lower(MI, TmpInst);
  EmitToStreamer(*OutStreamer, TmpInst);
}

void MSP430AsmPrinter::EmitInterruptVectorSection(MachineFunction &ISR) {
  MCSection *Cur = OutStreamer->getCurrentSectionOnly();
  const auto *F = &ISR.getFunction();
  assert(F->hasFnAttribute("interrupt") &&
         "Functions with MSP430_INTR CC should have 'interrupt' attribute");
  StringRef IVIdx = F->getFnAttribute("interrupt").getValueAsString();
  MCSection *IV = OutStreamer->getContext().getELFSection(
    "__interrupt_vector_" + IVIdx,
    ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_EXECINSTR);
  OutStreamer->SwitchSection(IV);

  const MCSymbol *FunctionSymbol = getSymbol(F);
  OutStreamer->EmitSymbolValue(FunctionSymbol, TM.getProgramPointerSize());
  OutStreamer->SwitchSection(Cur);
}

bool MSP430AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
  // Emit separate section for an interrupt vector if ISR
  if (MF.getFunction().getCallingConv() == CallingConv::MSP430_INTR)
    EmitInterruptVectorSection(MF);

  SetupMachineFunction(MF);
  EmitFunctionBody();
  return false;
}

// Force static initialization.
extern "C" void LLVMInitializeMSP430AsmPrinter() {
  RegisterAsmPrinter<MSP430AsmPrinter> X(getTheMSP430Target());
}