llvm/lib/Target/NVPTX/NVPTXAsmPrinter.h

   1 //===-- NVPTXAsmPrinter.h - NVPTX LLVM assembly writer ----------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains a printer that converts from our internal representation
  10 // of machine-dependent LLVM code to NVPTX assembly language.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
  15 #define LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
  16
  17 #include "NVPTX.h"
  18 #include "NVPTXSubtarget.h"
  19 #include "NVPTXTargetMachine.h"
  20 #include "llvm/ADT/DenseMap.h"
  21 #include "llvm/ADT/SmallVector.h"
  22 #include "llvm/ADT/StringRef.h"
  23 #include "llvm/CodeGen/AsmPrinter.h"
  24 #include "llvm/CodeGen/MachineFunction.h"
  25 #include "llvm/CodeGen/MachineLoopInfo.h"
  26 #include "llvm/IR/Constants.h"
  27 #include "llvm/IR/DebugLoc.h"
  28 #include "llvm/IR/DerivedTypes.h"
  29 #include "llvm/IR/Function.h"
  30 #include "llvm/IR/GlobalValue.h"
  31 #include "llvm/IR/Value.h"
  32 #include "llvm/MC/MCExpr.h"
  33 #include "llvm/MC/MCStreamer.h"
  34 #include "llvm/MC/MCSymbol.h"
  35 #include "llvm/Pass.h"
  36 #include "llvm/Support/Casting.h"
  37 #include "llvm/Support/Compiler.h"
  38 #include "llvm/Support/ErrorHandling.h"
  39 #include "llvm/Support/raw_ostream.h"
  40 #include "llvm/Target/TargetMachine.h"
  41 #include <algorithm>
  42 #include <cassert>
  43 #include <map>
  44 #include <memory>
  45 #include <string>
  46 #include <vector>
  47
  48 // The ptx syntax and format is very different from that usually seem in a .s
  49 // file,
  50 // therefore we are not able to use the MCAsmStreamer interface here.
  51 //
  52 // We are handcrafting the output method here.
  53 //
  54 // A better approach is to clone the MCAsmStreamer to a MCPTXAsmStreamer
  55 // (subclass of MCStreamer).
  56
  57 namespace llvm {
  58
  59 class MCOperand;
  60
  61 class LLVM_LIBRARY_VISIBILITY NVPTXAsmPrinter : public AsmPrinter {
  62
  63   class AggBuffer {
  64     // Used to buffer the emitted string for initializing global
  65     // aggregates.
  66     //
  67     // Normally an aggregate (array, vector or structure) is emitted
  68     // as a u8[]. However, if one element/field of the aggregate
  69     // is a non-NULL address, then the aggregate is emitted as u32[]
  70     // or u64[].
  71     //
  72     // We first layout the aggregate in 'buffer' in bytes, except for
  73     // those symbol addresses. For the i-th symbol address in the
  74     //aggregate, its corresponding 4-byte or 8-byte elements in 'buffer'
  75     // are filled with 0s. symbolPosInBuffer[i-1] records its position
  76     // in 'buffer', and Symbols[i-1] records the Value*.
  77     //
  78     // Once we have this AggBuffer setup, we can choose how to print
  79     // it out.
  80   public:
  81     unsigned numSymbols;   // number of symbol addresses
  82
  83   private:
  84     const unsigned size;   // size of the buffer in bytes
  85     std::vector<unsigned char> buffer; // the buffer
  86     SmallVector<unsigned, 4> symbolPosInBuffer;
  87     SmallVector<const Value *, 4> Symbols;
  88     // SymbolsBeforeStripping[i] is the original form of Symbols[i] before
  89     // stripping pointer casts, i.e.,
  90     // Symbols[i] == SymbolsBeforeStripping[i]->stripPointerCasts().
  91     //
  92     // We need to keep these values because AggBuffer::print decides whether to
  93     // emit a "generic()" cast for Symbols[i] depending on the address space of
  94     // SymbolsBeforeStripping[i].
  95     SmallVector<const Value *, 4> SymbolsBeforeStripping;
  96     unsigned curpos;
  97     raw_ostream &O;
  98     NVPTXAsmPrinter &AP;
  99     bool EmitGeneric;
 100
 101   public:
 102     AggBuffer(unsigned size, raw_ostream &O, NVPTXAsmPrinter &AP)
 103         : size(size), buffer(size), O(O), AP(AP) {
 104       curpos = 0;
 105       numSymbols = 0;
 106       EmitGeneric = AP.EmitGeneric;
 107     }
 108
 109     unsigned addBytes(unsigned char *Ptr, int Num, int Bytes) {
 110       assert((curpos + Num) <= size);
 111       assert((curpos + Bytes) <= size);
 112       for (int i = 0; i < Num; ++i) {
 113         buffer[curpos] = Ptr[i];
 114         curpos++;
 115       }
 116       for (int i = Num; i < Bytes; ++i) {
 117         buffer[curpos] = 0;
 118         curpos++;
 119       }
 120       return curpos;
 121     }
 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
 132     void addSymbol(const Value *GVar, const Value *GVarBeforeStripping) {
 133       symbolPosInBuffer.push_back(curpos);
 134       Symbols.push_back(GVar);
 135       SymbolsBeforeStripping.push_back(GVarBeforeStripping);
 136       numSymbols++;
 137     }
 138
 139     void print() {
 140       if (numSymbols == 0) {
 141         // print out in bytes
 142         for (unsigned i = 0; i < size; i++) {
 143           if (i)
 144             O << ", ";
 145           O << (unsigned int) buffer[i];
 146         }
 147       } else {
 148         // print out in 4-bytes or 8-bytes
 149         unsigned int pos = 0;
 150         unsigned int nSym = 0;
 151         unsigned int nextSymbolPos = symbolPosInBuffer[nSym];
 152         unsigned int nBytes = 4;
 153         if (static_cast<const NVPTXTargetMachine &>(AP.TM).is64Bit())
 154           nBytes = 8;
 155         for (pos = 0; pos < size; pos += nBytes) {
 156           if (pos)
 157             O << ", ";
 158           if (pos == nextSymbolPos) {
 159             const Value *v = Symbols[nSym];
 160             const Value *v0 = SymbolsBeforeStripping[nSym];
 161             if (const GlobalValue *GVar = dyn_cast<GlobalValue>(v)) {
 162               MCSymbol *Name = AP.getSymbol(GVar);
 163               PointerType *PTy = dyn_cast<PointerType>(v0->getType());
 164               bool IsNonGenericPointer = false; // Is v0 a non-generic pointer?
 165               if (PTy && PTy->getAddressSpace() != 0) {
 166                 IsNonGenericPointer = true;
 167               }
 168               if (EmitGeneric && !isa<Function>(v) && !IsNonGenericPointer) {
 169                 O << "generic(";
 170                 Name->print(O, AP.MAI);
 171                 O << ")";
 172               } else {
 173                 Name->print(O, AP.MAI);
 174               }
 175             } else if (const ConstantExpr *CExpr = dyn_cast<ConstantExpr>(v0)) {
 176               const MCExpr *Expr =
 177                 AP.lowerConstantForGV(cast<Constant>(CExpr), false);
 178               AP.printMCExpr(*Expr, O);
 179             } else
 180               llvm_unreachable("symbol type unknown");
 181             nSym++;
 182             if (nSym >= numSymbols)
 183               nextSymbolPos = size + 1;
 184             else
 185               nextSymbolPos = symbolPosInBuffer[nSym];
 186           } else if (nBytes == 4)
 187             O << *(unsigned int *)(&buffer[pos]);
 188           else
 189             O << *(unsigned long long *)(&buffer[pos]);
 190         }
 191       }
 192     }
 193   };
 194
 195   friend class AggBuffer;
 196
 197 private:
 198   StringRef getPassName() const override { return "NVPTX Assembly Printer"; }
 199
 200   const Function *F;
 201   std::string CurrentFnName;
 202
 203   void emitStartOfAsmFile(Module &M) override;
 204   void emitBasicBlockStart(const MachineBasicBlock &MBB) override;
 205   void emitFunctionEntryLabel() override;
 206   void emitFunctionBodyStart() override;
 207   void emitFunctionBodyEnd() override;
 208   void emitImplicitDef(const MachineInstr *MI) const override;
 209
 210   void emitInstruction(const MachineInstr *) override;
 211   void lowerToMCInst(const MachineInstr *MI, MCInst &OutMI);
 212   bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp);
 213   MCOperand GetSymbolRef(const MCSymbol *Symbol);
 214   unsigned encodeVirtualRegister(unsigned Reg);
 215
 216   void printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
 217                        const char *Modifier = nullptr);
 218   void printModuleLevelGV(const GlobalVariable *GVar, raw_ostream &O,
 219                           bool = false);
 220   void printParamName(Function::const_arg_iterator I, int paramIndex,
 221                       raw_ostream &O);
 222   void emitGlobals(const Module &M);
 223   void emitHeader(Module &M, raw_ostream &O, const NVPTXSubtarget &STI);
 224   void emitKernelFunctionDirectives(const Function &F, raw_ostream &O) const;
 225   void emitVirtualRegister(unsigned int vr, raw_ostream &);
 226   void emitFunctionParamList(const Function *, raw_ostream &O);
 227   void emitFunctionParamList(const MachineFunction &MF, raw_ostream &O);
 228   void setAndEmitFunctionVirtualRegisters(const MachineFunction &MF);
 229   void printReturnValStr(const Function *, raw_ostream &O);
 230   void printReturnValStr(const MachineFunction &MF, raw_ostream &O);
 231   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 232                        const char *ExtraCode, raw_ostream &) override;
 233   void printOperand(const MachineInstr *MI, int opNum, raw_ostream &O);
 234   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
 235                              const char *ExtraCode, raw_ostream &) override;
 236
 237   const MCExpr *lowerConstantForGV(const Constant *CV, bool ProcessingGeneric);
 238   void printMCExpr(const MCExpr &Expr, raw_ostream &OS);
 239
 240 protected:
 241   bool doInitialization(Module &M) override;
 242   bool doFinalization(Module &M) override;
 243
 244 private:
 245   bool GlobalsEmitted;
 246
 247   // This is specific per MachineFunction.
 248   const MachineRegisterInfo *MRI;
 249   // The contents are specific for each
 250   // MachineFunction. But the size of the
 251   // array is not.
 252   typedef DenseMap<unsigned, unsigned> VRegMap;
 253   typedef DenseMap<const TargetRegisterClass *, VRegMap> VRegRCMap;
 254   VRegRCMap VRegMapping;
 255
 256   // List of variables demoted to a function scope.
 257   std::map<const Function *, std::vector<const GlobalVariable *>> localDecls;
 258
 259   void emitPTXGlobalVariable(const GlobalVariable *GVar, raw_ostream &O);
 260   void emitPTXAddressSpace(unsigned int AddressSpace, raw_ostream &O) const;
 261   std::string getPTXFundamentalTypeStr(Type *Ty, bool = true) const;
 262   void printScalarConstant(const Constant *CPV, raw_ostream &O);
 263   void printFPConstant(const ConstantFP *Fp, raw_ostream &O);
 264   void bufferLEByte(const Constant *CPV, int Bytes, AggBuffer *aggBuffer);
 265   void bufferAggregateConstant(const Constant *CV, AggBuffer *aggBuffer);
 266
 267   void emitLinkageDirective(const GlobalValue *V, raw_ostream &O);
 268   void emitDeclarations(const Module &, raw_ostream &O);
 269   void emitDeclaration(const Function *, raw_ostream &O);
 270   void emitDemotedVars(const Function *, raw_ostream &);
 271
 272   bool lowerImageHandleOperand(const MachineInstr *MI, unsigned OpNo,
 273                                MCOperand &MCOp);
 274   void lowerImageHandleSymbol(unsigned Index, MCOperand &MCOp);
 275
 276   bool isLoopHeaderOfNoUnroll(const MachineBasicBlock &MBB) const;
 277
 278   // Used to control the need to emit .generic() in the initializer of
 279   // module scope variables.
 280   // Although ptx supports the hybrid mode like the following,
 281   //    .global .u32 a;
 282   //    .global .u32 b;
 283   //    .global .u32 addr[] = {a, generic(b)}
 284   // we have difficulty representing the difference in the NVVM IR.
 285   //
 286   // Since the address value should always be generic in CUDA C and always
 287   // be specific in OpenCL, we use this simple control here.
 288   //
 289   bool EmitGeneric;
 290
 291 public:
 292   NVPTXAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
 293       : AsmPrinter(TM, std::move(Streamer)),
 294         EmitGeneric(static_cast<NVPTXTargetMachine &>(TM).getDrvInterface() ==
 295                     NVPTX::CUDA) {}
 296
 297   bool runOnMachineFunction(MachineFunction &F) override;
 298
 299   void getAnalysisUsage(AnalysisUsage &AU) const override {
 300     AU.addRequired<MachineLoopInfo>();
 301     AsmPrinter::getAnalysisUsage(AU);
 302   }
 303
 304   std::string getVirtualRegisterName(unsigned) const;
 305
 306   const MCSymbol *getFunctionFrameSymbol() const override;
 307 };
 308
 309 } // end namespace llvm
 310
 311 #endif // LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H