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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/StringExtras.h"
22 #include "llvm/CodeGen/AsmPrinter.h"
23 #include "llvm/CodeGen/MachineLoopInfo.h"
24 #include "llvm/IR/Function.h"
25 #include "llvm/MC/MCAsmInfo.h"
26 #include "llvm/MC/MCExpr.h"
27 #include "llvm/MC/MCStreamer.h"
28 #include "llvm/MC/MCSymbol.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:
LineReader(std::string filename)53   LineReader(std::string filename) {
54     theCurLine = 0;
55     fstr.open(filename.c_str());
56     theFileName = filename;
57   }
fileName()58   std::string fileName() { return theFileName; }
~LineReader()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:
AggBuffer(unsigned size,raw_ostream & O,NVPTXAsmPrinter & AP)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     }
addBytes(unsigned char * Ptr,int Num,int Bytes)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     }
addZeros(int Num)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     }
addSymbol(const Value * GVar,const Value * GVarBeforeStripping)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     }
print()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:
getPassName()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(const 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:
NVPTXAsmPrinter(TargetMachine & TM,std::unique_ptr<MCStreamer> Streamer)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 
~NVPTXAsmPrinter()320   ~NVPTXAsmPrinter() {
321     if (!reader)
322       delete reader;
323   }
324 
runOnMachineFunction(MachineFunction & F)325   bool runOnMachineFunction(MachineFunction &F) override {
326     nvptxSubtarget = &F.getSubtarget<NVPTXSubtarget>();
327     return AsmPrinter::runOnMachineFunction(F);
328   }
getAnalysisUsage(AnalysisUsage & AU)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