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/AVRMCAsmInfo.h"
20 #include "TargetInfo/AVRTargetInfo.h"
21
22 #include "llvm/CodeGen/AsmPrinter.h"
23 #include "llvm/CodeGen/MachineFunction.h"
24 #include "llvm/CodeGen/MachineInstr.h"
25 #include "llvm/CodeGen/MachineModuleInfo.h"
26 #include "llvm/CodeGen/TargetRegisterInfo.h"
27 #include "llvm/CodeGen/TargetSubtargetInfo.h"
28 #include "llvm/IR/Mangler.h"
29 #include "llvm/IR/Module.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/Compiler.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 using namespace llvm;
44
45 namespace {
46
47 /// An AVR assembly code printer.
48 class AVRAsmPrinter : public AsmPrinter {
49 public:
AVRAsmPrinter(TargetMachine & TM,std::unique_ptr<MCStreamer> Streamer)50 AVRAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
51 : AsmPrinter(TM, std::move(Streamer), ID), MRI(*TM.getMCRegisterInfo()) {}
52
getPassName() const53 StringRef getPassName() const override { return "AVR Assembly Printer"; }
54
55 void printOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);
56
57 bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
58 const char *ExtraCode, raw_ostream &O) override;
59
60 bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum,
61 const char *ExtraCode, raw_ostream &O) override;
62
63 void emitInstruction(const MachineInstr *MI) override;
64
65 const MCExpr *lowerConstant(const Constant *CV, const Constant *BaseCV,
66 uint64_t Offset) override;
67
68 void emitXXStructor(const DataLayout &DL, const Constant *CV) override;
69
70 bool doFinalization(Module &M) override;
71
72 void emitStartOfAsmFile(Module &M) override;
73
74 static char ID;
75
76 private:
77 const MCRegisterInfo &MRI;
78 bool EmittedStructorSymbolAttrs = false;
79 };
80
81 } // namespace
82
printOperand(const MachineInstr * MI,unsigned OpNo,raw_ostream & O)83 void AVRAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo,
84 raw_ostream &O) {
85 const MachineOperand &MO = MI->getOperand(OpNo);
86
87 switch (MO.getType()) {
88 case MachineOperand::MO_Register:
89 O << AVRInstPrinter::getPrettyRegisterName(MO.getReg(), MRI);
90 break;
91 case MachineOperand::MO_Immediate:
92 O << MO.getImm();
93 break;
94 case MachineOperand::MO_GlobalAddress:
95 O << getSymbol(MO.getGlobal());
96 break;
97 case MachineOperand::MO_ExternalSymbol:
98 O << *GetExternalSymbolSymbol(MO.getSymbolName());
99 break;
100 case MachineOperand::MO_MachineBasicBlock:
101 O << *MO.getMBB()->getSymbol();
102 break;
103 default:
104 llvm_unreachable("Not implemented yet!");
105 }
106 }
107
PrintAsmOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)108 bool AVRAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
109 const char *ExtraCode, raw_ostream &O) {
110 // Default asm printer can only deal with some extra codes,
111 // so try it first.
112 if (!AsmPrinter::PrintAsmOperand(MI, OpNum, ExtraCode, O))
113 return false;
114
115 const MachineOperand &MO = MI->getOperand(OpNum);
116
117 if (ExtraCode && ExtraCode[0]) {
118 // Unknown extra code.
119 if (ExtraCode[1] != 0 || ExtraCode[0] < 'A' || ExtraCode[0] > 'Z')
120 return true;
121
122 // Operand must be a register when using 'A' ~ 'Z' extra code.
123 if (!MO.isReg())
124 return true;
125
126 Register Reg = MO.getReg();
127
128 unsigned ByteNumber = ExtraCode[0] - 'A';
129 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm());
130 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters();
131
132 const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>();
133 const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
134
135 const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg);
136 unsigned BytesPerReg = TRI.getRegSizeInBits(*RC) / 8;
137 assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported.");
138
139 unsigned RegIdx = ByteNumber / BytesPerReg;
140 if (RegIdx >= NumOpRegs)
141 return true;
142 Reg = MI->getOperand(OpNum + RegIdx).getReg();
143
144 if (BytesPerReg == 2) {
145 Reg = TRI.getSubReg(Reg, (ByteNumber % BytesPerReg) ? AVR::sub_hi
146 : AVR::sub_lo);
147 }
148
149 O << AVRInstPrinter::getPrettyRegisterName(Reg, MRI);
150 return false;
151 }
152
153 if (MO.getType() == MachineOperand::MO_GlobalAddress)
154 PrintSymbolOperand(MO, O); // Print global symbols.
155 else
156 printOperand(MI, OpNum, O); // Fallback to ordinary cases.
157
158 return false;
159 }
160
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)161 bool AVRAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
162 unsigned OpNum, const char *ExtraCode,
163 raw_ostream &O) {
164 if (ExtraCode && ExtraCode[0])
165 return true; // Unknown modifier
166
167 const MachineOperand &MO = MI->getOperand(OpNum);
168 (void)MO;
169 assert(MO.isReg() && "Unexpected inline asm memory operand");
170
171 // TODO: We should be able to look up the alternative name for
172 // the register if it's given.
173 // TableGen doesn't expose a way of getting retrieving names
174 // for registers.
175 if (MI->getOperand(OpNum).getReg() == AVR::R31R30) {
176 O << "Z";
177 } else if (MI->getOperand(OpNum).getReg() == AVR::R29R28) {
178 O << "Y";
179 } else if (MI->getOperand(OpNum).getReg() == AVR::R27R26) {
180 O << "X";
181 } else {
182 assert(false && "Wrong register class for memory operand.");
183 }
184
185 // If NumOpRegs == 2, then we assume it is product of a FrameIndex expansion
186 // and the second operand is an Imm.
187 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm());
188 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters();
189
190 if (NumOpRegs == 2) {
191 assert(MI->getOperand(OpNum).getReg() != AVR::R27R26 &&
192 "Base register X can not have offset/displacement.");
193 O << '+' << MI->getOperand(OpNum + 1).getImm();
194 }
195
196 return false;
197 }
198
emitInstruction(const MachineInstr * MI)199 void AVRAsmPrinter::emitInstruction(const MachineInstr *MI) {
200 AVR_MC::verifyInstructionPredicates(MI->getOpcode(),
201 getSubtargetInfo().getFeatureBits());
202
203 AVRMCInstLower MCInstLowering(OutContext, *this);
204
205 MCInst I;
206 MCInstLowering.lowerInstruction(*MI, I);
207 EmitToStreamer(*OutStreamer, I);
208 }
209
lowerConstant(const Constant * CV,const Constant * BaseCV,uint64_t Offset)210 const MCExpr *AVRAsmPrinter::lowerConstant(const Constant *CV,
211 const Constant *BaseCV,
212 uint64_t Offset) {
213 MCContext &Ctx = OutContext;
214
215 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
216 bool IsProgMem = GV->getAddressSpace() == AVR::ProgramMemory;
217 if (IsProgMem) {
218 const MCExpr *Expr = MCSymbolRefExpr::create(getSymbol(GV), Ctx);
219 return AVRMCExpr::create(AVR::S_PM, Expr, false, Ctx);
220 }
221 }
222
223 return AsmPrinter::lowerConstant(CV, BaseCV, Offset);
224 }
225
emitXXStructor(const DataLayout & DL,const Constant * CV)226 void AVRAsmPrinter::emitXXStructor(const DataLayout &DL, const Constant *CV) {
227 if (!EmittedStructorSymbolAttrs) {
228 OutStreamer->emitRawComment(
229 " Emitting these undefined symbol references causes us to link the"
230 " libgcc code that runs our constructors/destructors");
231 OutStreamer->emitRawComment(" This matches GCC's behavior");
232
233 MCSymbol *CtorsSym = OutContext.getOrCreateSymbol("__do_global_ctors");
234 OutStreamer->emitSymbolAttribute(CtorsSym, MCSA_Global);
235
236 MCSymbol *DtorsSym = OutContext.getOrCreateSymbol("__do_global_dtors");
237 OutStreamer->emitSymbolAttribute(DtorsSym, MCSA_Global);
238
239 EmittedStructorSymbolAttrs = true;
240 }
241
242 AsmPrinter::emitXXStructor(DL, CV);
243 }
244
doFinalization(Module & M)245 bool AVRAsmPrinter::doFinalization(Module &M) {
246 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
247 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
248 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
249
250 bool NeedsCopyData = false;
251 bool NeedsClearBSS = false;
252 for (const auto &GO : M.globals()) {
253 if (!GO.hasInitializer() || GO.hasAvailableExternallyLinkage())
254 // These globals aren't defined in the current object file.
255 continue;
256
257 if (GO.hasCommonLinkage()) {
258 // COMMON symbols are put in .bss.
259 NeedsClearBSS = true;
260 continue;
261 }
262
263 auto *Section = cast<MCSectionELF>(TLOF.SectionForGlobal(&GO, TM));
264 if (Section->getName().starts_with(".data"))
265 NeedsCopyData = true;
266 else if (Section->getName().starts_with(".rodata") && SubTM->hasLPM())
267 // AVRs that have a separate program memory (that's most AVRs) store
268 // .rodata sections in RAM.
269 NeedsCopyData = true;
270 else if (Section->getName().starts_with(".bss"))
271 NeedsClearBSS = true;
272 }
273
274 MCSymbol *DoCopyData = OutContext.getOrCreateSymbol("__do_copy_data");
275 MCSymbol *DoClearBss = OutContext.getOrCreateSymbol("__do_clear_bss");
276
277 if (NeedsCopyData) {
278 OutStreamer->emitRawComment(
279 " Declaring this symbol tells the CRT that it should");
280 OutStreamer->emitRawComment(
281 "copy all variables from program memory to RAM on startup");
282 OutStreamer->emitSymbolAttribute(DoCopyData, MCSA_Global);
283 }
284
285 if (NeedsClearBSS) {
286 OutStreamer->emitRawComment(
287 " Declaring this symbol tells the CRT that it should");
288 OutStreamer->emitRawComment("clear the zeroed data section on startup");
289 OutStreamer->emitSymbolAttribute(DoClearBss, MCSA_Global);
290 }
291
292 return AsmPrinter::doFinalization(M);
293 }
294
emitStartOfAsmFile(Module & M)295 void AVRAsmPrinter::emitStartOfAsmFile(Module &M) {
296 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
297 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
298 if (!SubTM)
299 return;
300
301 // Emit __tmp_reg__.
302 OutStreamer->emitAssignment(
303 MMI->getContext().getOrCreateSymbol(StringRef("__tmp_reg__")),
304 MCConstantExpr::create(SubTM->getRegTmpIndex(), MMI->getContext()));
305 // Emit __zero_reg__.
306 OutStreamer->emitAssignment(
307 MMI->getContext().getOrCreateSymbol(StringRef("__zero_reg__")),
308 MCConstantExpr::create(SubTM->getRegZeroIndex(), MMI->getContext()));
309 // Emit __SREG__.
310 OutStreamer->emitAssignment(
311 MMI->getContext().getOrCreateSymbol(StringRef("__SREG__")),
312 MCConstantExpr::create(SubTM->getIORegSREG(), MMI->getContext()));
313 // Emit __SP_H__ if available.
314 if (!SubTM->hasSmallStack())
315 OutStreamer->emitAssignment(
316 MMI->getContext().getOrCreateSymbol(StringRef("__SP_H__")),
317 MCConstantExpr::create(SubTM->getIORegSPH(), MMI->getContext()));
318 // Emit __SP_L__.
319 OutStreamer->emitAssignment(
320 MMI->getContext().getOrCreateSymbol(StringRef("__SP_L__")),
321 MCConstantExpr::create(SubTM->getIORegSPL(), MMI->getContext()));
322 // Emit __EIND__ if available.
323 if (SubTM->hasEIJMPCALL())
324 OutStreamer->emitAssignment(
325 MMI->getContext().getOrCreateSymbol(StringRef("__EIND__")),
326 MCConstantExpr::create(SubTM->getIORegEIND(), MMI->getContext()));
327 // Emit __RAMPZ__ if available.
328 if (SubTM->hasELPM())
329 OutStreamer->emitAssignment(
330 MMI->getContext().getOrCreateSymbol(StringRef("__RAMPZ__")),
331 MCConstantExpr::create(SubTM->getIORegRAMPZ(), MMI->getContext()));
332 }
333
334 char AVRAsmPrinter::ID = 0;
335
336 INITIALIZE_PASS(AVRAsmPrinter, "avr-asm-printer", "AVR Assembly Printer", false,
337 false)
338
339 extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void
LLVMInitializeAVRAsmPrinter()340 LLVMInitializeAVRAsmPrinter() {
341 llvm::RegisterAsmPrinter<AVRAsmPrinter> X(getTheAVRTarget());
342 }
343