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/IR/Module.h"
31 #include "llvm/MC/MCContext.h"
32 #include "llvm/MC/MCInst.h"
33 #include "llvm/MC/MCSectionELF.h"
34 #include "llvm/MC/MCStreamer.h"
35 #include "llvm/MC/MCSymbol.h"
36 #include "llvm/MC/TargetRegistry.h"
37 #include "llvm/Support/ErrorHandling.h"
38 #include "llvm/Support/raw_ostream.h"
39 #include "llvm/Target/TargetLoweringObjectFile.h"
40
41 #define DEBUG_TYPE "avr-asm-printer"
42
43 namespace llvm {
44
45 /// An AVR assembly code printer.
46 class AVRAsmPrinter : public AsmPrinter {
47 public:
AVRAsmPrinter(TargetMachine & TM,std::unique_ptr<MCStreamer> Streamer)48 AVRAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
49 : AsmPrinter(TM, std::move(Streamer)), MRI(*TM.getMCRegisterInfo()) {}
50
getPassName() const51 StringRef getPassName() const override { return "AVR Assembly Printer"; }
52
53 void printOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);
54
55 bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
56 const char *ExtraCode, raw_ostream &O) override;
57
58 bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum,
59 const char *ExtraCode, raw_ostream &O) override;
60
61 void emitInstruction(const MachineInstr *MI) override;
62
63 const MCExpr *lowerConstant(const Constant *CV) override;
64
65 void emitXXStructor(const DataLayout &DL, const Constant *CV) override;
66
67 bool doFinalization(Module &M) override;
68
69 void emitStartOfAsmFile(Module &M) override;
70
71 private:
72 const MCRegisterInfo &MRI;
73 bool EmittedStructorSymbolAttrs = false;
74 };
75
printOperand(const MachineInstr * MI,unsigned OpNo,raw_ostream & O)76 void AVRAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo,
77 raw_ostream &O) {
78 const MachineOperand &MO = MI->getOperand(OpNo);
79
80 switch (MO.getType()) {
81 case MachineOperand::MO_Register:
82 O << AVRInstPrinter::getPrettyRegisterName(MO.getReg(), MRI);
83 break;
84 case MachineOperand::MO_Immediate:
85 O << MO.getImm();
86 break;
87 case MachineOperand::MO_GlobalAddress:
88 O << getSymbol(MO.getGlobal());
89 break;
90 case MachineOperand::MO_ExternalSymbol:
91 O << *GetExternalSymbolSymbol(MO.getSymbolName());
92 break;
93 case MachineOperand::MO_MachineBasicBlock:
94 O << *MO.getMBB()->getSymbol();
95 break;
96 default:
97 llvm_unreachable("Not implemented yet!");
98 }
99 }
100
PrintAsmOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)101 bool AVRAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
102 const char *ExtraCode, raw_ostream &O) {
103 // Default asm printer can only deal with some extra codes,
104 // so try it first.
105 if (!AsmPrinter::PrintAsmOperand(MI, OpNum, ExtraCode, O))
106 return false;
107
108 const MachineOperand &MO = MI->getOperand(OpNum);
109
110 if (ExtraCode && ExtraCode[0]) {
111 // Unknown extra code.
112 if (ExtraCode[1] != 0 || ExtraCode[0] < 'A' || ExtraCode[0] > 'Z')
113 return true;
114
115 // Operand must be a register when using 'A' ~ 'Z' extra code.
116 if (!MO.isReg())
117 return true;
118
119 Register Reg = MO.getReg();
120
121 unsigned ByteNumber = ExtraCode[0] - 'A';
122 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm());
123 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters();
124
125 const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>();
126 const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
127
128 const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg);
129 unsigned BytesPerReg = TRI.getRegSizeInBits(*RC) / 8;
130 assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported.");
131
132 unsigned RegIdx = ByteNumber / BytesPerReg;
133 if (RegIdx >= NumOpRegs)
134 return true;
135 Reg = MI->getOperand(OpNum + RegIdx).getReg();
136
137 if (BytesPerReg == 2) {
138 Reg = TRI.getSubReg(Reg, (ByteNumber % BytesPerReg) ? AVR::sub_hi
139 : AVR::sub_lo);
140 }
141
142 O << AVRInstPrinter::getPrettyRegisterName(Reg, MRI);
143 return false;
144 }
145
146 if (MO.getType() == MachineOperand::MO_GlobalAddress)
147 PrintSymbolOperand(MO, O); // Print global symbols.
148 else
149 printOperand(MI, OpNum, O); // Fallback to ordinary cases.
150
151 return false;
152 }
153
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)154 bool AVRAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
155 unsigned OpNum, const char *ExtraCode,
156 raw_ostream &O) {
157 if (ExtraCode && ExtraCode[0])
158 return true; // Unknown modifier
159
160 const MachineOperand &MO = MI->getOperand(OpNum);
161 (void)MO;
162 assert(MO.isReg() && "Unexpected inline asm memory operand");
163
164 // TODO: We should be able to look up the alternative name for
165 // the register if it's given.
166 // TableGen doesn't expose a way of getting retrieving names
167 // for registers.
168 if (MI->getOperand(OpNum).getReg() == AVR::R31R30) {
169 O << "Z";
170 } else if (MI->getOperand(OpNum).getReg() == AVR::R29R28) {
171 O << "Y";
172 } else if (MI->getOperand(OpNum).getReg() == AVR::R27R26) {
173 O << "X";
174 } else {
175 assert(false && "Wrong register class for memory operand.");
176 }
177
178 // If NumOpRegs == 2, then we assume it is product of a FrameIndex expansion
179 // and the second operand is an Imm.
180 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm());
181 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters();
182
183 if (NumOpRegs == 2) {
184 assert(MI->getOperand(OpNum).getReg() != AVR::R27R26 &&
185 "Base register X can not have offset/displacement.");
186 O << '+' << MI->getOperand(OpNum + 1).getImm();
187 }
188
189 return false;
190 }
191
emitInstruction(const MachineInstr * MI)192 void AVRAsmPrinter::emitInstruction(const MachineInstr *MI) {
193 AVR_MC::verifyInstructionPredicates(MI->getOpcode(),
194 getSubtargetInfo().getFeatureBits());
195
196 AVRMCInstLower MCInstLowering(OutContext, *this);
197
198 MCInst I;
199 MCInstLowering.lowerInstruction(*MI, I);
200 EmitToStreamer(*OutStreamer, I);
201 }
202
lowerConstant(const Constant * CV)203 const MCExpr *AVRAsmPrinter::lowerConstant(const Constant *CV) {
204 MCContext &Ctx = OutContext;
205
206 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
207 bool IsProgMem = GV->getAddressSpace() == AVR::ProgramMemory;
208 if (IsProgMem) {
209 const MCExpr *Expr = MCSymbolRefExpr::create(getSymbol(GV), Ctx);
210 return AVRMCExpr::create(AVRMCExpr::VK_AVR_PM, Expr, false, Ctx);
211 }
212 }
213
214 return AsmPrinter::lowerConstant(CV);
215 }
216
emitXXStructor(const DataLayout & DL,const Constant * CV)217 void AVRAsmPrinter::emitXXStructor(const DataLayout &DL, const Constant *CV) {
218 if (!EmittedStructorSymbolAttrs) {
219 OutStreamer->emitRawComment(
220 " Emitting these undefined symbol references causes us to link the"
221 " libgcc code that runs our constructors/destructors");
222 OutStreamer->emitRawComment(" This matches GCC's behavior");
223
224 MCSymbol *CtorsSym = OutContext.getOrCreateSymbol("__do_global_ctors");
225 OutStreamer->emitSymbolAttribute(CtorsSym, MCSA_Global);
226
227 MCSymbol *DtorsSym = OutContext.getOrCreateSymbol("__do_global_dtors");
228 OutStreamer->emitSymbolAttribute(DtorsSym, MCSA_Global);
229
230 EmittedStructorSymbolAttrs = true;
231 }
232
233 AsmPrinter::emitXXStructor(DL, CV);
234 }
235
doFinalization(Module & M)236 bool AVRAsmPrinter::doFinalization(Module &M) {
237 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
238 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
239 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
240
241 bool NeedsCopyData = false;
242 bool NeedsClearBSS = false;
243 for (const auto &GO : M.globals()) {
244 if (!GO.hasInitializer() || GO.hasAvailableExternallyLinkage())
245 // These globals aren't defined in the current object file.
246 continue;
247
248 if (GO.hasCommonLinkage()) {
249 // COMMON symbols are put in .bss.
250 NeedsClearBSS = true;
251 continue;
252 }
253
254 auto *Section = cast<MCSectionELF>(TLOF.SectionForGlobal(&GO, TM));
255 if (Section->getName().starts_with(".data"))
256 NeedsCopyData = true;
257 else if (Section->getName().starts_with(".rodata") && SubTM->hasLPM())
258 // AVRs that have a separate program memory (that's most AVRs) store
259 // .rodata sections in RAM.
260 NeedsCopyData = true;
261 else if (Section->getName().starts_with(".bss"))
262 NeedsClearBSS = true;
263 }
264
265 MCSymbol *DoCopyData = OutContext.getOrCreateSymbol("__do_copy_data");
266 MCSymbol *DoClearBss = OutContext.getOrCreateSymbol("__do_clear_bss");
267
268 if (NeedsCopyData) {
269 OutStreamer->emitRawComment(
270 " Declaring this symbol tells the CRT that it should");
271 OutStreamer->emitRawComment(
272 "copy all variables from program memory to RAM on startup");
273 OutStreamer->emitSymbolAttribute(DoCopyData, MCSA_Global);
274 }
275
276 if (NeedsClearBSS) {
277 OutStreamer->emitRawComment(
278 " Declaring this symbol tells the CRT that it should");
279 OutStreamer->emitRawComment("clear the zeroed data section on startup");
280 OutStreamer->emitSymbolAttribute(DoClearBss, MCSA_Global);
281 }
282
283 return AsmPrinter::doFinalization(M);
284 }
285
emitStartOfAsmFile(Module & M)286 void AVRAsmPrinter::emitStartOfAsmFile(Module &M) {
287 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
288 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
289 if (!SubTM)
290 return;
291
292 // Emit __tmp_reg__.
293 OutStreamer->emitAssignment(
294 MMI->getContext().getOrCreateSymbol(StringRef("__tmp_reg__")),
295 MCConstantExpr::create(SubTM->getRegTmpIndex(), MMI->getContext()));
296 // Emit __zero_reg__.
297 OutStreamer->emitAssignment(
298 MMI->getContext().getOrCreateSymbol(StringRef("__zero_reg__")),
299 MCConstantExpr::create(SubTM->getRegZeroIndex(), MMI->getContext()));
300 // Emit __SREG__.
301 OutStreamer->emitAssignment(
302 MMI->getContext().getOrCreateSymbol(StringRef("__SREG__")),
303 MCConstantExpr::create(SubTM->getIORegSREG(), MMI->getContext()));
304 // Emit __SP_H__ if available.
305 if (!SubTM->hasSmallStack())
306 OutStreamer->emitAssignment(
307 MMI->getContext().getOrCreateSymbol(StringRef("__SP_H__")),
308 MCConstantExpr::create(SubTM->getIORegSPH(), MMI->getContext()));
309 // Emit __SP_L__.
310 OutStreamer->emitAssignment(
311 MMI->getContext().getOrCreateSymbol(StringRef("__SP_L__")),
312 MCConstantExpr::create(SubTM->getIORegSPL(), MMI->getContext()));
313 // Emit __EIND__ if available.
314 if (SubTM->hasEIJMPCALL())
315 OutStreamer->emitAssignment(
316 MMI->getContext().getOrCreateSymbol(StringRef("__EIND__")),
317 MCConstantExpr::create(SubTM->getIORegEIND(), MMI->getContext()));
318 // Emit __RAMPZ__ if available.
319 if (SubTM->hasELPM())
320 OutStreamer->emitAssignment(
321 MMI->getContext().getOrCreateSymbol(StringRef("__RAMPZ__")),
322 MCConstantExpr::create(SubTM->getIORegRAMPZ(), MMI->getContext()));
323 }
324
325 } // end of namespace llvm
326
LLVMInitializeAVRAsmPrinter()327 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeAVRAsmPrinter() {
328 llvm::RegisterAsmPrinter<llvm::AVRAsmPrinter> X(llvm::getTheAVRTarget());
329 }
330