text: //===-- NVPTXAsmPrinter.h - NVPTX LLVM assembly writer ----------*- C++ -*-===//
  //
  //                     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 NVPTX assembly language.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
  #define LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
  
  #include "NVPTX.h"
  #include "NVPTXSubtarget.h"
  #include "NVPTXTargetMachine.h"
  #include "llvm/ADT/DenseMap.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/CodeGen/AsmPrinter.h"
  #include "llvm/CodeGen/MachineFunction.h"
  #include "llvm/CodeGen/MachineLoopInfo.h"
  #include "llvm/IR/Constants.h"
  #include "llvm/IR/DebugLoc.h"
  #include "llvm/IR/DerivedTypes.h"
  #include "llvm/IR/Function.h"
  #include "llvm/IR/GlobalValue.h"
  #include "llvm/IR/Value.h"
  #include "llvm/MC/MCExpr.h"
  #include "llvm/MC/MCStreamer.h"
  #include "llvm/MC/MCSymbol.h"
  #include "llvm/PassAnalysisSupport.h"
  #include "llvm/Support/Casting.h"
  #include "llvm/Support/Compiler.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/raw_ostream.h"
  #include "llvm/Target/TargetMachine.h"
  #include <algorithm>
  #include <cassert>
  #include <map>
  #include <memory>
  #include <string>
  #include <vector>
  
  // The ptx syntax and format is very different from that usually seem in a .s
  // file,
  // therefore we are not able to use the MCAsmStreamer interface here.
  //
  // We are handcrafting the output method here.
  //
  // A better approach is to clone the MCAsmStreamer to a MCPTXAsmStreamer
  // (subclass of MCStreamer).
  
  namespace llvm {
  
  class MCOperand;
  
  class LLVM_LIBRARY_VISIBILITY NVPTXAsmPrinter : public AsmPrinter {
  
    class AggBuffer {
      // Used to buffer the emitted string for initializing global
      // aggregates.
      //
      // Normally an aggregate (array, vector or structure) is emitted
      // as a u8[]. However, if one element/field of the aggregate
      // is a non-NULL address, then the aggregate is emitted as u32[]
      // or u64[].
      //
      // We first layout the aggregate in 'buffer' in bytes, except for
      // those symbol addresses. For the i-th symbol address in the
      //aggregate, its corresponding 4-byte or 8-byte elements in 'buffer'
      // are filled with 0s. symbolPosInBuffer[i-1] records its position
      // in 'buffer', and Symbols[i-1] records the Value*.
      //
      // Once we have this AggBuffer setup, we can choose how to print
      // it out.
    public:
      unsigned numSymbols;   // number of symbol addresses
  
    private:
      const unsigned size;   // size of the buffer in bytes
      std::vector<unsigned char> buffer; // the buffer
      SmallVector<unsigned, 4> symbolPosInBuffer;
      SmallVector<const Value *, 4> Symbols;
      // SymbolsBeforeStripping[i] is the original form of Symbols[i] before
      // stripping pointer casts, i.e.,
      // Symbols[i] == SymbolsBeforeStripping[i]->stripPointerCasts().
      //
      // We need to keep these values because AggBuffer::print decides whether to
      // emit a "generic()" cast for Symbols[i] depending on the address space of
      // SymbolsBeforeStripping[i].
      SmallVector<const Value *, 4> SymbolsBeforeStripping;
      unsigned curpos;
      raw_ostream &O;
      NVPTXAsmPrinter &AP;
      bool EmitGeneric;
  
    public:
      AggBuffer(unsigned size, raw_ostream &O, NVPTXAsmPrinter &AP)
          : size(size), buffer(size), O(O), AP(AP) {
        curpos = 0;
        numSymbols = 0;
        EmitGeneric = AP.EmitGeneric;
      }
  
      unsigned addBytes(unsigned char *Ptr, int Num, int Bytes) {
        assert((curpos + Num) <= size);
        assert((curpos + Bytes) <= size);
        for (int i = 0; i < Num; ++i) {
          buffer[curpos] = Ptr[i];
          curpos++;
        }
        for (int i = Num; i < Bytes; ++i) {
          buffer[curpos] = 0;
          curpos++;
        }
        return curpos;
      }
  
      unsigned addZeros(int Num) {
        assert((curpos + Num) <= size);
        for (int i = 0; i < Num; ++i) {
          buffer[curpos] = 0;
          curpos++;
        }
        return curpos;
      }
  
      void addSymbol(const Value *GVar, const Value *GVarBeforeStripping) {
        symbolPosInBuffer.push_back(curpos);
        Symbols.push_back(GVar);
        SymbolsBeforeStripping.push_back(GVarBeforeStripping);
        numSymbols++;
      }
  
      void print() {
        if (numSymbols == 0) {
          // print out in bytes
          for (unsigned i = 0; i < size; i++) {
            if (i)
              O << ", ";
            O << (unsigned int) buffer[i];
          }
        } else {
          // print out in 4-bytes or 8-bytes
          unsigned int pos = 0;
          unsigned int nSym = 0;
          unsigned int nextSymbolPos = symbolPosInBuffer[nSym];
          unsigned int nBytes = 4;
          if (static_cast<const NVPTXTargetMachine &>(AP.TM).is64Bit())
            nBytes = 8;
          for (pos = 0; pos < size; pos += nBytes) {
            if (pos)
              O << ", ";
            if (pos == nextSymbolPos) {
              const Value *v = Symbols[nSym];
              const Value *v0 = SymbolsBeforeStripping[nSym];
              if (const GlobalValue *GVar = dyn_cast<GlobalValue>(v)) {
                MCSymbol *Name = AP.getSymbol(GVar);
                PointerType *PTy = dyn_cast<PointerType>(v0->getType());
                bool IsNonGenericPointer = false; // Is v0 a non-generic pointer?
                if (PTy && PTy->getAddressSpace() != 0) {
                  IsNonGenericPointer = true;
                }
                if (EmitGeneric && !isa<Function>(v) && !IsNonGenericPointer) {
                  O << "generic(";
                  Name->print(O, AP.MAI);
                  O << ")";
                } else {
                  Name->print(O, AP.MAI);
                }
              } else if (const ConstantExpr *CExpr = dyn_cast<ConstantExpr>(v0)) {
                const MCExpr *Expr =
                  AP.lowerConstantForGV(cast<Constant>(CExpr), false);
                AP.printMCExpr(*Expr, O);
              } else
                llvm_unreachable("symbol type unknown");
              nSym++;
              if (nSym >= numSymbols)
                nextSymbolPos = size + 1;
              else
                nextSymbolPos = symbolPosInBuffer[nSym];
            } else if (nBytes == 4)
              O << *(unsigned int *)(&buffer[pos]);
            else
              O << *(unsigned long long *)(&buffer[pos]);
          }
        }
      }
    };
  
    friend class AggBuffer;
  
  private:
    StringRef getPassName() const override { return "NVPTX Assembly Printer"; }
  
    const Function *F;
    std::string CurrentFnName;
  
    void EmitBasicBlockStart(const MachineBasicBlock &MBB) const override;
    void EmitFunctionEntryLabel() override;
    void EmitFunctionBodyStart() override;
    void EmitFunctionBodyEnd() override;
    void emitImplicitDef(const MachineInstr *MI) const override;
  
    void EmitInstruction(const MachineInstr *) override;
    void lowerToMCInst(const MachineInstr *MI, MCInst &OutMI);
    bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp);
    MCOperand GetSymbolRef(const MCSymbol *Symbol);
    unsigned encodeVirtualRegister(unsigned Reg);
  
    void printVecModifiedImmediate(const MachineOperand &MO, const char *Modifier,
                                   raw_ostream &O);
    void printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
                         const char *Modifier = nullptr);
    void printModuleLevelGV(const GlobalVariable *GVar, raw_ostream &O,
                            bool = false);
    void printParamName(Function::const_arg_iterator I, int paramIndex,
                        raw_ostream &O);
    void emitGlobals(const Module &M);
    void emitHeader(Module &M, raw_ostream &O, const NVPTXSubtarget &STI);
    void emitKernelFunctionDirectives(const Function &F, raw_ostream &O) const;
    void emitVirtualRegister(unsigned int vr, raw_ostream &);
    void emitFunctionParamList(const Function *, raw_ostream &O);
    void emitFunctionParamList(const MachineFunction &MF, raw_ostream &O);
    void setAndEmitFunctionVirtualRegisters(const MachineFunction &MF);
    void printReturnValStr(const Function *, raw_ostream &O);
    void printReturnValStr(const MachineFunction &MF, raw_ostream &O);
    bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                         unsigned AsmVariant, const char *ExtraCode,
                         raw_ostream &) override;
    void printOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
                      const char *Modifier = nullptr);
    bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
                               unsigned AsmVariant, const char *ExtraCode,
                               raw_ostream &) override;
  
    const MCExpr *lowerConstantForGV(const Constant *CV, bool ProcessingGeneric);
    void printMCExpr(const MCExpr &Expr, raw_ostream &OS);
  
  protected:
    bool doInitialization(Module &M) override;
    bool doFinalization(Module &M) override;
  
  private:
    bool GlobalsEmitted;
  
    // This is specific per MachineFunction.
    const MachineRegisterInfo *MRI;
    // The contents are specific for each
    // MachineFunction. But the size of the
    // array is not.
    typedef DenseMap<unsigned, unsigned> VRegMap;
    typedef DenseMap<const TargetRegisterClass *, VRegMap> VRegRCMap;
    VRegRCMap VRegMapping;
  
    // List of variables demoted to a function scope.
    std::map<const Function *, std::vector<const GlobalVariable *>> localDecls;
  
    void emitPTXGlobalVariable(const GlobalVariable *GVar, raw_ostream &O);
    void emitPTXAddressSpace(unsigned int AddressSpace, raw_ostream &O) const;
    std::string getPTXFundamentalTypeStr(Type *Ty, bool = true) const;
    void printScalarConstant(const Constant *CPV, raw_ostream &O);
    void printFPConstant(const ConstantFP *Fp, raw_ostream &O);
    void bufferLEByte(const Constant *CPV, int Bytes, AggBuffer *aggBuffer);
    void bufferAggregateConstant(const Constant *CV, AggBuffer *aggBuffer);
  
    void emitLinkageDirective(const GlobalValue *V, raw_ostream &O);
    void emitDeclarations(const Module &, raw_ostream &O);
    void emitDeclaration(const Function *, raw_ostream &O);
    void emitDemotedVars(const Function *, raw_ostream &);
  
    bool lowerImageHandleOperand(const MachineInstr *MI, unsigned OpNo,
                                 MCOperand &MCOp);
    void lowerImageHandleSymbol(unsigned Index, MCOperand &MCOp);
  
    bool isLoopHeaderOfNoUnroll(const MachineBasicBlock &MBB) const;
  
    // Used to control the need to emit .generic() in the initializer of
    // module scope variables.
    // Although ptx supports the hybrid mode like the following,
    //    .global .u32 a;
    //    .global .u32 b;
    //    .global .u32 addr[] = {a, generic(b)}
    // we have difficulty representing the difference in the NVVM IR.
    //
    // Since the address value should always be generic in CUDA C and always
    // be specific in OpenCL, we use this simple control here.
    //
    bool EmitGeneric;
  
  public:
    NVPTXAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
        : AsmPrinter(TM, std::move(Streamer)),
          EmitGeneric(static_cast<NVPTXTargetMachine &>(TM).getDrvInterface() ==
                      NVPTX::CUDA) {}
  
    bool runOnMachineFunction(MachineFunction &F) override;
  
    void getAnalysisUsage(AnalysisUsage &AU) const override {
      AU.addRequired<MachineLoopInfo>();
      AsmPrinter::getAnalysisUsage(AU);
    }
  
    std::string getVirtualRegisterName(unsigned) const;
  
    const MCSymbol *getFunctionFrameSymbol() const override;
  };
  
  } // end namespace llvm
  
  #endif // LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
  