1 //===-- AVRAsmPrinter.cpp - AVR LLVM assembly writer ----------------------===//
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 GAS-format AVR assembly language.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "AVR.h"
15 #include "AVRMCInstLower.h"
16 #include "AVRSubtarget.h"
17 #include "AVRTargetMachine.h"
18 #include "MCTargetDesc/AVRInstPrinter.h"
19 #include "MCTargetDesc/AVRMCExpr.h"
20 #include "TargetInfo/AVRTargetInfo.h"
21
22 #include "llvm/BinaryFormat/ELF.h"
23 #include "llvm/CodeGen/AsmPrinter.h"
24 #include "llvm/CodeGen/MachineFunction.h"
25 #include "llvm/CodeGen/MachineInstr.h"
26 #include "llvm/CodeGen/MachineModuleInfo.h"
27 #include "llvm/CodeGen/TargetRegisterInfo.h"
28 #include "llvm/CodeGen/TargetSubtargetInfo.h"
29 #include "llvm/IR/Mangler.h"
30 #include "llvm/MC/MCContext.h"
31 #include "llvm/MC/MCInst.h"
32 #include "llvm/MC/MCSectionELF.h"
33 #include "llvm/MC/MCStreamer.h"
34 #include "llvm/MC/MCSymbol.h"
35 #include "llvm/MC/TargetRegistry.h"
36 #include "llvm/Support/ErrorHandling.h"
37 #include "llvm/Support/raw_ostream.h"
38 #include "llvm/Target/TargetLoweringObjectFile.h"
39
40 #define DEBUG_TYPE "avr-asm-printer"
41
42 namespace llvm {
43
44 /// An AVR assembly code printer.
45 class AVRAsmPrinter : public AsmPrinter {
46 public:
AVRAsmPrinter(TargetMachine & TM,std::unique_ptr<MCStreamer> Streamer)47 AVRAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
48 : AsmPrinter(TM, std::move(Streamer)), MRI(*TM.getMCRegisterInfo()) {}
49
getPassName() const50 StringRef getPassName() const override { return "AVR Assembly Printer"; }
51
52 void printOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);
53
54 bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
55 const char *ExtraCode, raw_ostream &O) override;
56
57 bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum,
58 const char *ExtraCode, raw_ostream &O) override;
59
60 void emitInstruction(const MachineInstr *MI) override;
61
62 const MCExpr *lowerConstant(const Constant *CV) override;
63
64 void emitXXStructor(const DataLayout &DL, const Constant *CV) override;
65
66 bool doFinalization(Module &M) override;
67
68 void emitStartOfAsmFile(Module &M) override;
69
70 private:
71 const MCRegisterInfo &MRI;
72 bool EmittedStructorSymbolAttrs = false;
73 };
74
printOperand(const MachineInstr * MI,unsigned OpNo,raw_ostream & O)75 void AVRAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo,
76 raw_ostream &O) {
77 const MachineOperand &MO = MI->getOperand(OpNo);
78
79 switch (MO.getType()) {
80 case MachineOperand::MO_Register:
81 O << AVRInstPrinter::getPrettyRegisterName(MO.getReg(), MRI);
82 break;
83 case MachineOperand::MO_Immediate:
84 O << MO.getImm();
85 break;
86 case MachineOperand::MO_GlobalAddress:
87 O << getSymbol(MO.getGlobal());
88 break;
89 case MachineOperand::MO_ExternalSymbol:
90 O << *GetExternalSymbolSymbol(MO.getSymbolName());
91 break;
92 case MachineOperand::MO_MachineBasicBlock:
93 O << *MO.getMBB()->getSymbol();
94 break;
95 default:
96 llvm_unreachable("Not implemented yet!");
97 }
98 }
99
PrintAsmOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)100 bool AVRAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
101 const char *ExtraCode, raw_ostream &O) {
102 // Default asm printer can only deal with some extra codes,
103 // so try it first.
104 if (!AsmPrinter::PrintAsmOperand(MI, OpNum, ExtraCode, O))
105 return false;
106
107 const MachineOperand &MO = MI->getOperand(OpNum);
108
109 if (ExtraCode && ExtraCode[0]) {
110 // Unknown extra code.
111 if (ExtraCode[1] != 0 || ExtraCode[0] < 'A' || ExtraCode[0] > 'Z')
112 return true;
113
114 // Operand must be a register when using 'A' ~ 'Z' extra code.
115 if (!MO.isReg())
116 return true;
117
118 Register Reg = MO.getReg();
119
120 unsigned ByteNumber = ExtraCode[0] - 'A';
121 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm());
122 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters();
123
124 const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>();
125 const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
126
127 const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg);
128 unsigned BytesPerReg = TRI.getRegSizeInBits(*RC) / 8;
129 assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported.");
130
131 unsigned RegIdx = ByteNumber / BytesPerReg;
132 if (RegIdx >= NumOpRegs)
133 return true;
134 Reg = MI->getOperand(OpNum + RegIdx).getReg();
135
136 if (BytesPerReg == 2) {
137 Reg = TRI.getSubReg(Reg,
138 ByteNumber % BytesPerReg ? AVR::sub_hi : AVR::sub_lo);
139 }
140
141 O << AVRInstPrinter::getPrettyRegisterName(Reg, MRI);
142 return false;
143 }
144
145 if (MO.getType() == MachineOperand::MO_GlobalAddress)
146 PrintSymbolOperand(MO, O); // Print global symbols.
147 else
148 printOperand(MI, OpNum, O); // Fallback to ordinary cases.
149
150 return false;
151 }
152
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)153 bool AVRAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
154 unsigned OpNum, const char *ExtraCode,
155 raw_ostream &O) {
156 if (ExtraCode && ExtraCode[0])
157 return true; // Unknown modifier
158
159 const MachineOperand &MO = MI->getOperand(OpNum);
160 (void)MO;
161 assert(MO.isReg() && "Unexpected inline asm memory operand");
162
163 // TODO: We should be able to look up the alternative name for
164 // the register if it's given.
165 // TableGen doesn't expose a way of getting retrieving names
166 // for registers.
167 if (MI->getOperand(OpNum).getReg() == AVR::R31R30) {
168 O << "Z";
169 } else if (MI->getOperand(OpNum).getReg() == AVR::R29R28) {
170 O << "Y";
171 } else if (MI->getOperand(OpNum).getReg() == AVR::R27R26) {
172 O << "X";
173 } else {
174 assert(false && "Wrong register class for memory operand.");
175 }
176
177 // If NumOpRegs == 2, then we assume it is product of a FrameIndex expansion
178 // and the second operand is an Imm.
179 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm());
180 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters();
181
182 if (NumOpRegs == 2) {
183 assert(MI->getOperand(OpNum).getReg() != AVR::R27R26 &&
184 "Base register X can not have offset/displacement.");
185 O << '+' << MI->getOperand(OpNum + 1).getImm();
186 }
187
188 return false;
189 }
190
emitInstruction(const MachineInstr * MI)191 void AVRAsmPrinter::emitInstruction(const MachineInstr *MI) {
192 AVR_MC::verifyInstructionPredicates(MI->getOpcode(),
193 getSubtargetInfo().getFeatureBits());
194
195 AVRMCInstLower MCInstLowering(OutContext, *this);
196
197 MCInst I;
198 MCInstLowering.lowerInstruction(*MI, I);
199 EmitToStreamer(*OutStreamer, I);
200 }
201
lowerConstant(const Constant * CV)202 const MCExpr *AVRAsmPrinter::lowerConstant(const Constant *CV) {
203 MCContext &Ctx = OutContext;
204
205 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
206 bool IsProgMem = GV->getAddressSpace() == AVR::ProgramMemory;
207 if (IsProgMem) {
208 const MCExpr *Expr = MCSymbolRefExpr::create(getSymbol(GV), Ctx);
209 return AVRMCExpr::create(AVRMCExpr::VK_AVR_PM, Expr, false, Ctx);
210 }
211 }
212
213 return AsmPrinter::lowerConstant(CV);
214 }
215
emitXXStructor(const DataLayout & DL,const Constant * CV)216 void AVRAsmPrinter::emitXXStructor(const DataLayout &DL, const Constant *CV) {
217 if (!EmittedStructorSymbolAttrs) {
218 OutStreamer->emitRawComment(
219 " Emitting these undefined symbol references causes us to link the"
220 " libgcc code that runs our constructors/destructors");
221 OutStreamer->emitRawComment(" This matches GCC's behavior");
222
223 MCSymbol *CtorsSym = OutContext.getOrCreateSymbol("__do_global_ctors");
224 OutStreamer->emitSymbolAttribute(CtorsSym, MCSA_Global);
225
226 MCSymbol *DtorsSym = OutContext.getOrCreateSymbol("__do_global_dtors");
227 OutStreamer->emitSymbolAttribute(DtorsSym, MCSA_Global);
228
229 EmittedStructorSymbolAttrs = true;
230 }
231
232 AsmPrinter::emitXXStructor(DL, CV);
233 }
234
doFinalization(Module & M)235 bool AVRAsmPrinter::doFinalization(Module &M) {
236 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
237 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
238 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
239
240 bool NeedsCopyData = false;
241 bool NeedsClearBSS = false;
242 for (const auto &GO : M.globals()) {
243 if (!GO.hasInitializer() || GO.hasAvailableExternallyLinkage())
244 // These globals aren't defined in the current object file.
245 continue;
246
247 if (GO.hasCommonLinkage()) {
248 // COMMON symbols are put in .bss.
249 NeedsClearBSS = true;
250 continue;
251 }
252
253 auto *Section = cast<MCSectionELF>(TLOF.SectionForGlobal(&GO, TM));
254 if (Section->getName().starts_with(".data"))
255 NeedsCopyData = true;
256 else if (Section->getName().starts_with(".rodata") && SubTM->hasLPM())
257 // AVRs that have a separate program memory (that's most AVRs) store
258 // .rodata sections in RAM.
259 NeedsCopyData = true;
260 else if (Section->getName().starts_with(".bss"))
261 NeedsClearBSS = true;
262 }
263
264 MCSymbol *DoCopyData = OutContext.getOrCreateSymbol("__do_copy_data");
265 MCSymbol *DoClearBss = OutContext.getOrCreateSymbol("__do_clear_bss");
266
267 if (NeedsCopyData) {
268 OutStreamer->emitRawComment(
269 " Declaring this symbol tells the CRT that it should");
270 OutStreamer->emitRawComment(
271 "copy all variables from program memory to RAM on startup");
272 OutStreamer->emitSymbolAttribute(DoCopyData, MCSA_Global);
273 }
274
275 if (NeedsClearBSS) {
276 OutStreamer->emitRawComment(
277 " Declaring this symbol tells the CRT that it should");
278 OutStreamer->emitRawComment("clear the zeroed data section on startup");
279 OutStreamer->emitSymbolAttribute(DoClearBss, MCSA_Global);
280 }
281
282 return AsmPrinter::doFinalization(M);
283 }
284
emitStartOfAsmFile(Module & M)285 void AVRAsmPrinter::emitStartOfAsmFile(Module &M) {
286 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
287 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
288 if (!SubTM)
289 return;
290
291 // Emit __tmp_reg__.
292 OutStreamer->emitAssignment(
293 MMI->getContext().getOrCreateSymbol(StringRef("__tmp_reg__")),
294 MCConstantExpr::create(SubTM->getRegTmpIndex(), MMI->getContext()));
295 // Emit __zero_reg__.
296 OutStreamer->emitAssignment(
297 MMI->getContext().getOrCreateSymbol(StringRef("__zero_reg__")),
298 MCConstantExpr::create(SubTM->getRegZeroIndex(), MMI->getContext()));
299 // Emit __SREG__.
300 OutStreamer->emitAssignment(
301 MMI->getContext().getOrCreateSymbol(StringRef("__SREG__")),
302 MCConstantExpr::create(SubTM->getIORegSREG(), MMI->getContext()));
303 // Emit __SP_H__ if available.
304 if (!SubTM->hasSmallStack())
305 OutStreamer->emitAssignment(
306 MMI->getContext().getOrCreateSymbol(StringRef("__SP_H__")),
307 MCConstantExpr::create(SubTM->getIORegSPH(), MMI->getContext()));
308 // Emit __SP_L__.
309 OutStreamer->emitAssignment(
310 MMI->getContext().getOrCreateSymbol(StringRef("__SP_L__")),
311 MCConstantExpr::create(SubTM->getIORegSPL(), MMI->getContext()));
312 // Emit __EIND__ if available.
313 if (SubTM->hasEIJMPCALL())
314 OutStreamer->emitAssignment(
315 MMI->getContext().getOrCreateSymbol(StringRef("__EIND__")),
316 MCConstantExpr::create(SubTM->getIORegEIND(), MMI->getContext()));
317 // Emit __RAMPZ__ if available.
318 if (SubTM->hasELPM())
319 OutStreamer->emitAssignment(
320 MMI->getContext().getOrCreateSymbol(StringRef("__RAMPZ__")),
321 MCConstantExpr::create(SubTM->getIORegRAMPZ(), MMI->getContext()));
322 }
323
324 } // end of namespace llvm
325
LLVMInitializeAVRAsmPrinter()326 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeAVRAsmPrinter() {
327 llvm::RegisterAsmPrinter<llvm::AVRAsmPrinter> X(llvm::getTheAVRTarget());
328 }
329