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      1 //===-- NVPTXAsmPrinter.h - NVPTX LLVM assembly writer --------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file contains a printer that converts from our internal representation
     11 // of machine-dependent LLVM code to NVPTX assembly language.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
     16 #define LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
     17 
     18 #include "NVPTX.h"
     19 #include "NVPTXSubtarget.h"
     20 #include "NVPTXTargetMachine.h"
     21 #include "llvm/ADT/SmallString.h"
     22 #include "llvm/ADT/StringExtras.h"
     23 #include "llvm/CodeGen/AsmPrinter.h"
     24 #include "llvm/IR/Function.h"
     25 #include "llvm/MC/MCAsmInfo.h"
     26 #include "llvm/MC/MCExpr.h"
     27 #include "llvm/MC/MCSymbol.h"
     28 #include "llvm/Support/CommandLine.h"
     29 #include "llvm/Support/FormattedStream.h"
     30 #include "llvm/Target/TargetMachine.h"
     31 #include <fstream>
     32 
     33 // The ptx syntax and format is very different from that usually seem in a .s
     34 // file,
     35 // therefore we are not able to use the MCAsmStreamer interface here.
     36 //
     37 // We are handcrafting the output method here.
     38 //
     39 // A better approach is to clone the MCAsmStreamer to a MCPTXAsmStreamer
     40 // (subclass of MCStreamer).
     41 
     42 namespace llvm {
     43   class MCOperand;
     44 
     45 class LineReader {
     46 private:
     47   unsigned theCurLine;
     48   std::ifstream fstr;
     49   char buff[512];
     50   std::string theFileName;
     51   SmallVector<unsigned, 32> lineOffset;
     52 public:
     53   LineReader(std::string filename) {
     54     theCurLine = 0;
     55     fstr.open(filename.c_str());
     56     theFileName = filename;
     57   }
     58   std::string fileName() { return theFileName; }
     59   ~LineReader() { fstr.close(); }
     60   std::string readLine(unsigned line);
     61 };
     62 
     63 class LLVM_LIBRARY_VISIBILITY NVPTXAsmPrinter : public AsmPrinter {
     64 
     65   class AggBuffer {
     66     // Used to buffer the emitted string for initializing global
     67     // aggregates.
     68     //
     69     // Normally an aggregate (array, vector or structure) is emitted
     70     // as a u8[]. However, if one element/field of the aggregate
     71     // is a non-NULL address, then the aggregate is emitted as u32[]
     72     // or u64[].
     73     //
     74     // We first layout the aggregate in 'buffer' in bytes, except for
     75     // those symbol addresses. For the i-th symbol address in the
     76     //aggregate, its corresponding 4-byte or 8-byte elements in 'buffer'
     77     // are filled with 0s. symbolPosInBuffer[i-1] records its position
     78     // in 'buffer', and Symbols[i-1] records the Value*.
     79     //
     80     // Once we have this AggBuffer setup, we can choose how to print
     81     // it out.
     82   public:
     83     unsigned numSymbols;   // number of symbol addresses
     84 
     85   private:
     86     const unsigned size;   // size of the buffer in bytes
     87     std::vector<unsigned char> buffer; // the buffer
     88     SmallVector<unsigned, 4> symbolPosInBuffer;
     89     SmallVector<const Value *, 4> Symbols;
     90     // SymbolsBeforeStripping[i] is the original form of Symbols[i] before
     91     // stripping pointer casts, i.e.,
     92     // Symbols[i] == SymbolsBeforeStripping[i]->stripPointerCasts().
     93     //
     94     // We need to keep these values because AggBuffer::print decides whether to
     95     // emit a "generic()" cast for Symbols[i] depending on the address space of
     96     // SymbolsBeforeStripping[i].
     97     SmallVector<const Value *, 4> SymbolsBeforeStripping;
     98     unsigned curpos;
     99     raw_ostream &O;
    100     NVPTXAsmPrinter &AP;
    101     bool EmitGeneric;
    102 
    103   public:
    104     AggBuffer(unsigned size, raw_ostream &O, NVPTXAsmPrinter &AP)
    105         : size(size), buffer(size), O(O), AP(AP) {
    106       curpos = 0;
    107       numSymbols = 0;
    108       EmitGeneric = AP.EmitGeneric;
    109     }
    110     unsigned addBytes(unsigned char *Ptr, int Num, int Bytes) {
    111       assert((curpos + Num) <= size);
    112       assert((curpos + Bytes) <= size);
    113       for (int i = 0; i < Num; ++i) {
    114         buffer[curpos] = Ptr[i];
    115         curpos++;
    116       }
    117       for (int i = Num; i < Bytes; ++i) {
    118         buffer[curpos] = 0;
    119         curpos++;
    120       }
    121       return curpos;
    122     }
    123     unsigned addZeros(int Num) {
    124       assert((curpos + Num) <= size);
    125       for (int i = 0; i < Num; ++i) {
    126         buffer[curpos] = 0;
    127         curpos++;
    128       }
    129       return curpos;
    130     }
    131     void addSymbol(const Value *GVar, const Value *GVarBeforeStripping) {
    132       symbolPosInBuffer.push_back(curpos);
    133       Symbols.push_back(GVar);
    134       SymbolsBeforeStripping.push_back(GVarBeforeStripping);
    135       numSymbols++;
    136     }
    137     void print() {
    138       if (numSymbols == 0) {
    139         // print out in bytes
    140         for (unsigned i = 0; i < size; i++) {
    141           if (i)
    142             O << ", ";
    143           O << (unsigned int) buffer[i];
    144         }
    145       } else {
    146         // print out in 4-bytes or 8-bytes
    147         unsigned int pos = 0;
    148         unsigned int nSym = 0;
    149         unsigned int nextSymbolPos = symbolPosInBuffer[nSym];
    150         unsigned int nBytes = 4;
    151         if (static_cast<const NVPTXTargetMachine &>(AP.TM).is64Bit())
    152           nBytes = 8;
    153         for (pos = 0; pos < size; pos += nBytes) {
    154           if (pos)
    155             O << ", ";
    156           if (pos == nextSymbolPos) {
    157             const Value *v = Symbols[nSym];
    158             const Value *v0 = SymbolsBeforeStripping[nSym];
    159             if (const GlobalValue *GVar = dyn_cast<GlobalValue>(v)) {
    160               MCSymbol *Name = AP.getSymbol(GVar);
    161               PointerType *PTy = dyn_cast<PointerType>(v0->getType());
    162               bool IsNonGenericPointer = false; // Is v0 a non-generic pointer?
    163               if (PTy && PTy->getAddressSpace() != 0) {
    164                 IsNonGenericPointer = true;
    165               }
    166               if (EmitGeneric && !isa<Function>(v) && !IsNonGenericPointer) {
    167                 O << "generic(";
    168                 Name->print(O, AP.MAI);
    169                 O << ")";
    170               } else {
    171                 Name->print(O, AP.MAI);
    172               }
    173             } else if (const ConstantExpr *CExpr = dyn_cast<ConstantExpr>(v0)) {
    174               const MCExpr *Expr =
    175                 AP.lowerConstantForGV(cast<Constant>(CExpr), false);
    176               AP.printMCExpr(*Expr, O);
    177             } else
    178               llvm_unreachable("symbol type unknown");
    179             nSym++;
    180             if (nSym >= numSymbols)
    181               nextSymbolPos = size + 1;
    182             else
    183               nextSymbolPos = symbolPosInBuffer[nSym];
    184           } else if (nBytes == 4)
    185             O << *(unsigned int *)(&buffer[pos]);
    186           else
    187             O << *(unsigned long long *)(&buffer[pos]);
    188         }
    189       }
    190     }
    191   };
    192 
    193   friend class AggBuffer;
    194 
    195   void emitSrcInText(StringRef filename, unsigned line);
    196 
    197 private:
    198   const char *getPassName() const override { return "NVPTX Assembly Printer"; }
    199 
    200   const Function *F;
    201   std::string CurrentFnName;
    202 
    203   void EmitBasicBlockStart(const MachineBasicBlock &MBB) const override;
    204   void EmitFunctionEntryLabel() override;
    205   void EmitFunctionBodyStart() override;
    206   void EmitFunctionBodyEnd() override;
    207   void emitImplicitDef(const MachineInstr *MI) const override;
    208 
    209   void EmitInstruction(const MachineInstr *) override;
    210   void lowerToMCInst(const MachineInstr *MI, MCInst &OutMI);
    211   bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp);
    212   MCOperand GetSymbolRef(const MCSymbol *Symbol);
    213   unsigned encodeVirtualRegister(unsigned Reg);
    214 
    215   void printVecModifiedImmediate(const MachineOperand &MO, const char *Modifier,
    216                                  raw_ostream &O);
    217   void printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
    218                        const char *Modifier = nullptr);
    219   void printModuleLevelGV(const GlobalVariable *GVar, raw_ostream &O,
    220                           bool = false);
    221   void printParamName(Function::const_arg_iterator I, int paramIndex,
    222                       raw_ostream &O);
    223   void emitGlobals(const Module &M);
    224   void emitHeader(Module &M, raw_ostream &O, const NVPTXSubtarget &STI);
    225   void emitKernelFunctionDirectives(const Function &F, raw_ostream &O) const;
    226   void emitVirtualRegister(unsigned int vr, raw_ostream &);
    227   void emitFunctionParamList(const Function *, raw_ostream &O);
    228   void emitFunctionParamList(const MachineFunction &MF, raw_ostream &O);
    229   void setAndEmitFunctionVirtualRegisters(const MachineFunction &MF);
    230   void printReturnValStr(const Function *, raw_ostream &O);
    231   void printReturnValStr(const MachineFunction &MF, raw_ostream &O);
    232   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
    233                        unsigned AsmVariant, const char *ExtraCode,
    234                        raw_ostream &) override;
    235   void printOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
    236                     const char *Modifier = nullptr);
    237   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
    238                              unsigned AsmVariant, const char *ExtraCode,
    239                              raw_ostream &) override;
    240 
    241   const MCExpr *lowerConstantForGV(const Constant *CV, bool ProcessingGeneric);
    242   void printMCExpr(const MCExpr &Expr, raw_ostream &OS);
    243 
    244 protected:
    245   bool doInitialization(Module &M) override;
    246   bool doFinalization(Module &M) override;
    247 
    248 private:
    249   std::string CurrentBankselLabelInBasicBlock;
    250 
    251   bool GlobalsEmitted;
    252 
    253   // This is specific per MachineFunction.
    254   const MachineRegisterInfo *MRI;
    255   // The contents are specific for each
    256   // MachineFunction. But the size of the
    257   // array is not.
    258   typedef DenseMap<unsigned, unsigned> VRegMap;
    259   typedef DenseMap<const TargetRegisterClass *, VRegMap> VRegRCMap;
    260   VRegRCMap VRegMapping;
    261 
    262   // Cache the subtarget here.
    263   const NVPTXSubtarget *nvptxSubtarget;
    264 
    265   // Build the map between type name and ID based on module's type
    266   // symbol table.
    267   std::map<Type *, std::string> TypeNameMap;
    268 
    269   // List of variables demoted to a function scope.
    270   std::map<const Function *, std::vector<const GlobalVariable *> > localDecls;
    271 
    272   // To record filename to ID mapping
    273   std::map<std::string, unsigned> filenameMap;
    274   void recordAndEmitFilenames(Module &);
    275 
    276   void emitPTXGlobalVariable(const GlobalVariable *GVar, raw_ostream &O);
    277   void emitPTXAddressSpace(unsigned int AddressSpace, raw_ostream &O) const;
    278   std::string getPTXFundamentalTypeStr(Type *Ty, bool = true) const;
    279   void printScalarConstant(const Constant *CPV, raw_ostream &O);
    280   void printFPConstant(const ConstantFP *Fp, raw_ostream &O);
    281   void bufferLEByte(const Constant *CPV, int Bytes, AggBuffer *aggBuffer);
    282   void bufferAggregateConstant(const Constant *CV, AggBuffer *aggBuffer);
    283 
    284   void emitLinkageDirective(const GlobalValue *V, raw_ostream &O);
    285   void emitDeclarations(const Module &, raw_ostream &O);
    286   void emitDeclaration(const Function *, raw_ostream &O);
    287   void emitDemotedVars(const Function *, raw_ostream &);
    288 
    289   bool lowerImageHandleOperand(const MachineInstr *MI, unsigned OpNo,
    290                                MCOperand &MCOp);
    291   void lowerImageHandleSymbol(unsigned Index, MCOperand &MCOp);
    292 
    293   bool isLoopHeaderOfNoUnroll(const MachineBasicBlock &MBB) const;
    294 
    295   LineReader *reader;
    296   LineReader *getReader(std::string);
    297 
    298   // Used to control the need to emit .generic() in the initializer of
    299   // module scope variables.
    300   // Although ptx supports the hybrid mode like the following,
    301   //    .global .u32 a;
    302   //    .global .u32 b;
    303   //    .global .u32 addr[] = {a, generic(b)}
    304   // we have difficulty representing the difference in the NVVM IR.
    305   //
    306   // Since the address value should always be generic in CUDA C and always
    307   // be specific in OpenCL, we use this simple control here.
    308   //
    309   bool EmitGeneric;
    310 
    311 public:
    312   NVPTXAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
    313       : AsmPrinter(TM, std::move(Streamer)),
    314         EmitGeneric(static_cast<NVPTXTargetMachine &>(TM).getDrvInterface() ==
    315                     NVPTX::CUDA) {
    316     CurrentBankselLabelInBasicBlock = "";
    317     reader = nullptr;
    318   }
    319 
    320   ~NVPTXAsmPrinter() {
    321     if (!reader)
    322       delete reader;
    323   }
    324 
    325   bool runOnMachineFunction(MachineFunction &F) override {
    326     nvptxSubtarget = &F.getSubtarget<NVPTXSubtarget>();
    327     return AsmPrinter::runOnMachineFunction(F);
    328   }
    329   void getAnalysisUsage(AnalysisUsage &AU) const override {
    330     AU.addRequired<MachineLoopInfo>();
    331     AsmPrinter::getAnalysisUsage(AU);
    332   }
    333 
    334   bool ignoreLoc(const MachineInstr &);
    335 
    336   std::string getVirtualRegisterName(unsigned) const;
    337 
    338   DebugLoc prevDebugLoc;
    339   void emitLineNumberAsDotLoc(const MachineInstr &);
    340 };
    341 } // end of namespace
    342 
    343 #endif
    344