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/GlobalAlias.h"
31#include "llvm/IR/GlobalValue.h"
32#include "llvm/IR/Value.h"
33#include "llvm/MC/MCExpr.h"
34#include "llvm/MC/MCStreamer.h"
35#include "llvm/MC/MCSymbol.h"
36#include "llvm/Pass.h"
37#include "llvm/Support/Casting.h"
38#include "llvm/Support/Compiler.h"
39#include "llvm/Support/ErrorHandling.h"
40#include "llvm/Support/raw_ostream.h"
41#include "llvm/Target/TargetMachine.h"
42#include <algorithm>
43#include <cassert>
44#include <map>
45#include <memory>
46#include <string>
47#include <vector>
48
49// The ptx syntax and format is very different from that usually seem in a .s
50// file,
51// therefore we are not able to use the MCAsmStreamer interface here.
52//
53// We are handcrafting the output method here.
54//
55// A better approach is to clone the MCAsmStreamer to a MCPTXAsmStreamer
56// (subclass of MCStreamer).
57
58namespace llvm {
59
60class MCOperand;
61
62class LLVM_LIBRARY_VISIBILITY NVPTXAsmPrinter : public AsmPrinter {
63
64 class AggBuffer {
65 // Used to buffer the emitted string for initializing global aggregates.
66 //
67 // Normally an aggregate (array, vector, or structure) is emitted as a u8[].
68 // However, if either element/field of the aggregate is a non-NULL address,
69 // and all such addresses are properly aligned, then the aggregate is
70 // emitted as u32[] or u64[]. In the case of unaligned addresses, the
71 // aggregate is emitted as u8[], and the mask() operator is used for all
72 // pointers.
73 //
74 // We first layout the aggregate in 'buffer' in bytes, except for those
75 // symbol addresses. For the i-th symbol address in the aggregate, its
76 // corresponding 4-byte or 8-byte elements in 'buffer' are filled with 0s.
77 // symbolPosInBuffer[i-1] records its position in 'buffer', and Symbols[i-1]
78 // records the Value*.
79 //
80 // Once we have this AggBuffer setup, we can choose how to print it out.
81 public:
82 // number of symbol addresses
83 unsigned numSymbols() const { return Symbols.size(); }
84
85 bool allSymbolsAligned(unsigned ptrSize) const {
86 return llvm::all_of(Range: symbolPosInBuffer,
87 P: [=](unsigned pos) { return pos % ptrSize == 0; });
88 }
89
90 private:
91 const unsigned size; // size of the buffer in bytes
92 std::vector<unsigned char> buffer; // the buffer
93 SmallVector<unsigned, 4> symbolPosInBuffer;
94 SmallVector<const Value *, 4> Symbols;
95 // SymbolsBeforeStripping[i] is the original form of Symbols[i] before
96 // stripping pointer casts, i.e.,
97 // Symbols[i] == SymbolsBeforeStripping[i]->stripPointerCasts().
98 //
99 // We need to keep these values because AggBuffer::print decides whether to
100 // emit a "generic()" cast for Symbols[i] depending on the address space of
101 // SymbolsBeforeStripping[i].
102 SmallVector<const Value *, 4> SymbolsBeforeStripping;
103 unsigned curpos;
104 const NVPTXAsmPrinter &AP;
105 const bool EmitGeneric;
106
107 public:
108 AggBuffer(unsigned size, const NVPTXAsmPrinter &AP)
109 : size(size), buffer(size), curpos(0), AP(AP),
110 EmitGeneric(AP.EmitGeneric) {}
111
112 // Copy Num bytes from Ptr.
113 // if Bytes > Num, zero fill up to Bytes.
114 void addBytes(const unsigned char *Ptr, unsigned Num, unsigned Bytes) {
115 for (unsigned I : llvm::seq(Size: Num))
116 addByte(Byte: Ptr[I]);
117 if (Bytes > Num)
118 addZeros(Num: Bytes - Num);
119 }
120
121 void addByte(uint8_t Byte) {
122 assert(curpos < size);
123 buffer[curpos] = Byte;
124 curpos++;
125 }
126
127 void addZeros(unsigned Num) {
128 for ([[maybe_unused]] unsigned _ : llvm::seq(Size: Num)) {
129 addByte(Byte: 0);
130 }
131 }
132
133 void addSymbol(const Value *GVar, const Value *GVarBeforeStripping) {
134 symbolPosInBuffer.push_back(Elt: curpos);
135 Symbols.push_back(Elt: GVar);
136 SymbolsBeforeStripping.push_back(Elt: GVarBeforeStripping);
137 }
138
139 void printBytes(raw_ostream &os);
140 void printWords(raw_ostream &os);
141
142 private:
143 void printSymbol(unsigned nSym, raw_ostream &os);
144 };
145
146 friend class AggBuffer;
147
148public:
149 static char ID;
150
151 StringRef getPassName() const override { return "NVPTX Assembly Printer"; }
152
153private:
154 const Function *F;
155
156 void emitStartOfAsmFile(Module &M) override;
157 void emitBasicBlockStart(const MachineBasicBlock &MBB) override;
158 void emitFunctionEntryLabel() override;
159 void emitFunctionBodyStart() override;
160 void emitFunctionBodyEnd() override;
161 void emitImplicitDef(const MachineInstr *MI) const override;
162
163 void emitInstruction(const MachineInstr *) override;
164 void lowerToMCInst(const MachineInstr *MI, MCInst &OutMI);
165 MCOperand lowerOperand(const MachineOperand &MO);
166 MCOperand GetSymbolRef(const MCSymbol *Symbol);
167 unsigned encodeVirtualRegister(unsigned Reg);
168
169 void printMemOperand(const MachineInstr *MI, unsigned OpNum, raw_ostream &O,
170 const char *Modifier = nullptr);
171 void printModuleLevelGV(const GlobalVariable *GVar, raw_ostream &O,
172 bool processDemoted, const NVPTXSubtarget &STI);
173 void emitGlobals(const Module &M);
174 void emitGlobalAlias(const Module &M, const GlobalAlias &GA) override;
175 void emitHeader(Module &M, raw_ostream &O, const NVPTXSubtarget &STI);
176 void emitKernelFunctionDirectives(const Function &F, raw_ostream &O) const;
177 void emitVirtualRegister(unsigned int vr, raw_ostream &);
178 void emitFunctionParamList(const Function *, raw_ostream &O);
179 void setAndEmitFunctionVirtualRegisters(const MachineFunction &MF);
180 void encodeDebugInfoRegisterNumbers(const MachineFunction &MF);
181 void printReturnValStr(const Function *, raw_ostream &O);
182 void printReturnValStr(const MachineFunction &MF, raw_ostream &O);
183 bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
184 const char *ExtraCode, raw_ostream &) override;
185 void printOperand(const MachineInstr *MI, unsigned OpNum, raw_ostream &O);
186 bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
187 const char *ExtraCode, raw_ostream &) override;
188
189 const MCExpr *lowerConstantForGV(const Constant *CV,
190 bool ProcessingGeneric) const;
191 void printMCExpr(const MCExpr &Expr, raw_ostream &OS) const;
192
193protected:
194 bool doInitialization(Module &M) override;
195 bool doFinalization(Module &M) override;
196
197private:
198 bool GlobalsEmitted;
199
200 // This is specific per MachineFunction.
201 const MachineRegisterInfo *MRI;
202 // The contents are specific for each
203 // MachineFunction. But the size of the
204 // array is not.
205 typedef DenseMap<unsigned, unsigned> VRegMap;
206 typedef DenseMap<const TargetRegisterClass *, VRegMap> VRegRCMap;
207 VRegRCMap VRegMapping;
208
209 // List of variables demoted to a function scope.
210 std::map<const Function *, std::vector<const GlobalVariable *>> localDecls;
211
212 void emitPTXGlobalVariable(const GlobalVariable *GVar, raw_ostream &O,
213 const NVPTXSubtarget &STI);
214 void emitPTXAddressSpace(unsigned int AddressSpace, raw_ostream &O) const;
215 std::string getPTXFundamentalTypeStr(Type *Ty, bool = true) const;
216 void printScalarConstant(const Constant *CPV, raw_ostream &O);
217 void printFPConstant(const ConstantFP *Fp, raw_ostream &O) const;
218 void bufferLEByte(const Constant *CPV, int Bytes, AggBuffer *aggBuffer);
219 void bufferAggregateConstant(const Constant *CV, AggBuffer *aggBuffer);
220
221 void emitLinkageDirective(const GlobalValue *V, raw_ostream &O);
222 void emitDeclarations(const Module &, raw_ostream &O);
223 void emitDeclaration(const Function *, raw_ostream &O);
224 void emitAliasDeclaration(const GlobalAlias *, raw_ostream &O);
225 void emitDeclarationWithName(const Function *, MCSymbol *, raw_ostream &O);
226 void emitDemotedVars(const Function *, raw_ostream &);
227
228 bool isLoopHeaderOfNoUnroll(const MachineBasicBlock &MBB) const;
229
230 // Used to control the need to emit .generic() in the initializer of
231 // module scope variables.
232 // Although ptx supports the hybrid mode like the following,
233 // .global .u32 a;
234 // .global .u32 b;
235 // .global .u32 addr[] = {a, generic(b)}
236 // we have difficulty representing the difference in the NVVM IR.
237 //
238 // Since the address value should always be generic in CUDA C and always
239 // be specific in OpenCL, we use this simple control here.
240 //
241 const bool EmitGeneric;
242
243public:
244 NVPTXAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
245 : AsmPrinter(TM, std::move(Streamer), ID),
246 EmitGeneric(static_cast<NVPTXTargetMachine &>(TM).getDrvInterface() ==
247 NVPTX::CUDA) {}
248
249 bool runOnMachineFunction(MachineFunction &F) override;
250
251 void getAnalysisUsage(AnalysisUsage &AU) const override {
252 AU.addRequired<MachineLoopInfoWrapperPass>();
253 AsmPrinter::getAnalysisUsage(AU);
254 }
255
256 std::string getVirtualRegisterName(unsigned) const;
257
258 const MCSymbol *getFunctionFrameSymbol() const override;
259
260 // Make emitGlobalVariable() no-op for NVPTX.
261 // Global variables have been already emitted by the time the base AsmPrinter
262 // attempts to do so in doFinalization() (see NVPTXAsmPrinter::emitGlobals()).
263 void emitGlobalVariable(const GlobalVariable *GV) override {}
264};
265
266} // end namespace llvm
267
268#endif // LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
269