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 aggregates. 65 // 66 // Normally an aggregate (array, vector, or structure) is emitted as a u8[]. 67 // However, if either element/field of the aggregate is a non-NULL address, 68 // and all such addresses are properly aligned, then the aggregate is 69 // emitted as u32[] or u64[]. In the case of unaligned addresses, the 70 // aggregate is emitted as u8[], and the mask() operator is used for all 71 // pointers. 72 // 73 // We first layout the aggregate in 'buffer' in bytes, except for those 74 // symbol addresses. For the i-th symbol address in the aggregate, its 75 // corresponding 4-byte or 8-byte elements in 'buffer' are filled with 0s. 76 // symbolPosInBuffer[i-1] records its position in 'buffer', and Symbols[i-1] 77 // records the Value*. 78 // 79 // Once we have this AggBuffer setup, we can choose how to print it out. 80 public: 81 // number of symbol addresses 82 unsigned numSymbols() const { return Symbols.size(); } 83 84 bool allSymbolsAligned(unsigned ptrSize) const { 85 return llvm::all_of(symbolPosInBuffer, 86 [=](unsigned pos) { return pos % ptrSize == 0; }); 87 } 88 89 private: 90 const unsigned size; // size of the buffer in bytes 91 std::vector<unsigned char> buffer; // the buffer 92 SmallVector<unsigned, 4> symbolPosInBuffer; 93 SmallVector<const Value *, 4> Symbols; 94 // SymbolsBeforeStripping[i] is the original form of Symbols[i] before 95 // stripping pointer casts, i.e., 96 // Symbols[i] == SymbolsBeforeStripping[i]->stripPointerCasts(). 97 // 98 // We need to keep these values because AggBuffer::print decides whether to 99 // emit a "generic()" cast for Symbols[i] depending on the address space of 100 // SymbolsBeforeStripping[i]. 101 SmallVector<const Value *, 4> SymbolsBeforeStripping; 102 unsigned curpos; 103 NVPTXAsmPrinter &AP; 104 bool EmitGeneric; 105 106 public: 107 AggBuffer(unsigned size, NVPTXAsmPrinter &AP) 108 : size(size), buffer(size), AP(AP) { 109 curpos = 0; 110 EmitGeneric = AP.EmitGeneric; 111 } 112 113 // Copy Num bytes from Ptr. 114 // if Bytes > Num, zero fill up to Bytes. 115 unsigned addBytes(unsigned char *Ptr, int Num, int Bytes) { 116 assert((curpos + Num) <= size); 117 assert((curpos + Bytes) <= size); 118 for (int i = 0; i < Num; ++i) { 119 buffer[curpos] = Ptr[i]; 120 curpos++; 121 } 122 for (int i = Num; i < Bytes; ++i) { 123 buffer[curpos] = 0; 124 curpos++; 125 } 126 return curpos; 127 } 128 129 unsigned addZeros(int Num) { 130 assert((curpos + Num) <= size); 131 for (int i = 0; i < Num; ++i) { 132 buffer[curpos] = 0; 133 curpos++; 134 } 135 return curpos; 136 } 137 138 void addSymbol(const Value *GVar, const Value *GVarBeforeStripping) { 139 symbolPosInBuffer.push_back(curpos); 140 Symbols.push_back(GVar); 141 SymbolsBeforeStripping.push_back(GVarBeforeStripping); 142 } 143 144 void printBytes(raw_ostream &os); 145 void printWords(raw_ostream &os); 146 147 private: 148 void printSymbol(unsigned nSym, raw_ostream &os); 149 }; 150 151 friend class AggBuffer; 152 153 private: 154 StringRef getPassName() const override { return "NVPTX Assembly Printer"; } 155 156 const Function *F; 157 std::string CurrentFnName; 158 159 void emitStartOfAsmFile(Module &M) override; 160 void emitBasicBlockStart(const MachineBasicBlock &MBB) override; 161 void emitFunctionEntryLabel() override; 162 void emitFunctionBodyStart() override; 163 void emitFunctionBodyEnd() override; 164 void emitImplicitDef(const MachineInstr *MI) const override; 165 166 void emitInstruction(const MachineInstr *) override; 167 void lowerToMCInst(const MachineInstr *MI, MCInst &OutMI); 168 bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp); 169 MCOperand GetSymbolRef(const MCSymbol *Symbol); 170 unsigned encodeVirtualRegister(unsigned Reg); 171 172 void printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &O, 173 const char *Modifier = nullptr); 174 void printModuleLevelGV(const GlobalVariable *GVar, raw_ostream &O, 175 bool processDemoted, const NVPTXSubtarget &STI); 176 void emitGlobals(const Module &M); 177 void emitGlobalAlias(const Module &M, const GlobalAlias &GA); 178 void emitHeader(Module &M, raw_ostream &O, const NVPTXSubtarget &STI); 179 void emitKernelFunctionDirectives(const Function &F, raw_ostream &O) const; 180 void emitVirtualRegister(unsigned int vr, raw_ostream &); 181 void emitFunctionParamList(const Function *, raw_ostream &O); 182 void setAndEmitFunctionVirtualRegisters(const MachineFunction &MF); 183 void printReturnValStr(const Function *, raw_ostream &O); 184 void printReturnValStr(const MachineFunction &MF, raw_ostream &O); 185 bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo, 186 const char *ExtraCode, raw_ostream &) override; 187 void printOperand(const MachineInstr *MI, int opNum, raw_ostream &O); 188 bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo, 189 const char *ExtraCode, raw_ostream &) override; 190 191 const MCExpr *lowerConstantForGV(const Constant *CV, bool ProcessingGeneric); 192 void printMCExpr(const MCExpr &Expr, raw_ostream &OS); 193 194 protected: 195 bool doInitialization(Module &M) override; 196 bool doFinalization(Module &M) override; 197 198 private: 199 bool GlobalsEmitted; 200 201 // This is specific per MachineFunction. 202 const MachineRegisterInfo *MRI; 203 // The contents are specific for each 204 // MachineFunction. But the size of the 205 // array is not. 206 typedef DenseMap<unsigned, unsigned> VRegMap; 207 typedef DenseMap<const TargetRegisterClass *, VRegMap> VRegRCMap; 208 VRegRCMap VRegMapping; 209 210 // List of variables demoted to a function scope. 211 std::map<const Function *, std::vector<const GlobalVariable *>> localDecls; 212 213 void emitPTXGlobalVariable(const GlobalVariable *GVar, raw_ostream &O, 214 const NVPTXSubtarget &STI); 215 void emitPTXAddressSpace(unsigned int AddressSpace, raw_ostream &O) const; 216 std::string getPTXFundamentalTypeStr(Type *Ty, bool = true) const; 217 void printScalarConstant(const Constant *CPV, raw_ostream &O); 218 void printFPConstant(const ConstantFP *Fp, raw_ostream &O); 219 void bufferLEByte(const Constant *CPV, int Bytes, AggBuffer *aggBuffer); 220 void bufferAggregateConstant(const Constant *CV, AggBuffer *aggBuffer); 221 222 void emitLinkageDirective(const GlobalValue *V, raw_ostream &O); 223 void emitDeclarations(const Module &, raw_ostream &O); 224 void emitDeclaration(const Function *, raw_ostream &O); 225 void emitDemotedVars(const Function *, raw_ostream &); 226 227 bool lowerImageHandleOperand(const MachineInstr *MI, unsigned OpNo, 228 MCOperand &MCOp); 229 void lowerImageHandleSymbol(unsigned Index, MCOperand &MCOp); 230 231 bool isLoopHeaderOfNoUnroll(const MachineBasicBlock &MBB) const; 232 233 // Used to control the need to emit .generic() in the initializer of 234 // module scope variables. 235 // Although ptx supports the hybrid mode like the following, 236 // .global .u32 a; 237 // .global .u32 b; 238 // .global .u32 addr[] = {a, generic(b)} 239 // we have difficulty representing the difference in the NVVM IR. 240 // 241 // Since the address value should always be generic in CUDA C and always 242 // be specific in OpenCL, we use this simple control here. 243 // 244 bool EmitGeneric; 245 246 public: 247 NVPTXAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer) 248 : AsmPrinter(TM, std::move(Streamer)), 249 EmitGeneric(static_cast<NVPTXTargetMachine &>(TM).getDrvInterface() == 250 NVPTX::CUDA) {} 251 252 bool runOnMachineFunction(MachineFunction &F) override; 253 254 void getAnalysisUsage(AnalysisUsage &AU) const override { 255 AU.addRequired<MachineLoopInfo>(); 256 AsmPrinter::getAnalysisUsage(AU); 257 } 258 259 std::string getVirtualRegisterName(unsigned) const; 260 261 const MCSymbol *getFunctionFrameSymbol() const override; 262 263 // Make emitGlobalVariable() no-op for NVPTX. 264 // Global variables have been already emitted by the time the base AsmPrinter 265 // attempts to do so in doFinalization() (see NVPTXAsmPrinter::emitGlobals()). 266 void emitGlobalVariable(const GlobalVariable *GV) override {} 267 }; 268 269 } // end namespace llvm 270 271 #endif // LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H 272