NVPTXAsmPrinter.h revision 360660 
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/PassAnalysisSupport.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
57namespace llvm {
58
59class MCOperand;
60
61class 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
197private:
198  StringRef 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 printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
216                       const char *Modifier = nullptr);
217  void printModuleLevelGV(const GlobalVariable *GVar, raw_ostream &O,
218                          bool = false);
219  void printParamName(Function::const_arg_iterator I, int paramIndex,
220                      raw_ostream &O);
221  void emitGlobals(const Module &M);
222  void emitHeader(Module &M, raw_ostream &O, const NVPTXSubtarget &STI);
223  void emitKernelFunctionDirectives(const Function &F, raw_ostream &O) const;
224  void emitVirtualRegister(unsigned int vr, raw_ostream &);
225  void emitFunctionParamList(const Function *, raw_ostream &O);
226  void emitFunctionParamList(const MachineFunction &MF, raw_ostream &O);
227  void setAndEmitFunctionVirtualRegisters(const MachineFunction &MF);
228  void printReturnValStr(const Function *, raw_ostream &O);
229  void printReturnValStr(const MachineFunction &MF, raw_ostream &O);
230  bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
231                       const char *ExtraCode, raw_ostream &) override;
232  void printOperand(const MachineInstr *MI, int opNum, raw_ostream &O);
233  bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
234                             const char *ExtraCode, raw_ostream &) override;
235
236  const MCExpr *lowerConstantForGV(const Constant *CV, bool ProcessingGeneric);
237  void printMCExpr(const MCExpr &Expr, raw_ostream &OS);
238
239protected:
240  bool doInitialization(Module &M) override;
241  bool doFinalization(Module &M) override;
242
243private:
244  bool GlobalsEmitted;
245
246  // This is specific per MachineFunction.
247  const MachineRegisterInfo *MRI;
248  // The contents are specific for each
249  // MachineFunction. But the size of the
250  // array is not.
251  typedef DenseMap<unsigned, unsigned> VRegMap;
252  typedef DenseMap<const TargetRegisterClass *, VRegMap> VRegRCMap;
253  VRegRCMap VRegMapping;
254
255  // List of variables demoted to a function scope.
256  std::map<const Function *, std::vector<const GlobalVariable *>> localDecls;
257
258  void emitPTXGlobalVariable(const GlobalVariable *GVar, raw_ostream &O);
259  void emitPTXAddressSpace(unsigned int AddressSpace, raw_ostream &O) const;
260  std::string getPTXFundamentalTypeStr(Type *Ty, bool = true) const;
261  void printScalarConstant(const Constant *CPV, raw_ostream &O);
262  void printFPConstant(const ConstantFP *Fp, raw_ostream &O);
263  void bufferLEByte(const Constant *CPV, int Bytes, AggBuffer *aggBuffer);
264  void bufferAggregateConstant(const Constant *CV, AggBuffer *aggBuffer);
265
266  void emitLinkageDirective(const GlobalValue *V, raw_ostream &O);
267  void emitDeclarations(const Module &, raw_ostream &O);
268  void emitDeclaration(const Function *, raw_ostream &O);
269  void emitDemotedVars(const Function *, raw_ostream &);
270
271  bool lowerImageHandleOperand(const MachineInstr *MI, unsigned OpNo,
272                               MCOperand &MCOp);
273  void lowerImageHandleSymbol(unsigned Index, MCOperand &MCOp);
274
275  bool isLoopHeaderOfNoUnroll(const MachineBasicBlock &MBB) const;
276
277  // Used to control the need to emit .generic() in the initializer of
278  // module scope variables.
279  // Although ptx supports the hybrid mode like the following,
280  //    .global .u32 a;
281  //    .global .u32 b;
282  //    .global .u32 addr[] = {a, generic(b)}
283  // we have difficulty representing the difference in the NVVM IR.
284  //
285  // Since the address value should always be generic in CUDA C and always
286  // be specific in OpenCL, we use this simple control here.
287  //
288  bool EmitGeneric;
289
290public:
291  NVPTXAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
292      : AsmPrinter(TM, std::move(Streamer)),
293        EmitGeneric(static_cast<NVPTXTargetMachine &>(TM).getDrvInterface() ==
294                    NVPTX::CUDA) {}
295
296  bool runOnMachineFunction(MachineFunction &F) override;
297
298  void getAnalysisUsage(AnalysisUsage &AU) const override {
299    AU.addRequired<MachineLoopInfo>();
300    AsmPrinter::getAnalysisUsage(AU);
301  }
302
303  std::string getVirtualRegisterName(unsigned) const;
304
305  const MCSymbol *getFunctionFrameSymbol() const override;
306};
307
308} // end namespace llvm
309
310#endif // LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
311