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 bool Error = AsmPrinter::PrintAsmOperand(MI, OpNum, ExtraCode, O);
105
106 if (Error && ExtraCode && ExtraCode[0]) {
107 if (ExtraCode[1] != 0)
108 return true; // Unknown modifier.
109
110 if (ExtraCode[0] >= 'A' && ExtraCode[0] <= 'Z') {
111 const MachineOperand &RegOp = MI->getOperand(OpNum);
112
113 assert(RegOp.isReg() && "Operand must be a register when you're"
114 "using 'A'..'Z' operand extracodes.");
115 Register Reg = RegOp.getReg();
116
117 unsigned ByteNumber = ExtraCode[0] - 'A';
118
119 unsigned OpFlags = MI->getOperand(OpNum - 1).getImm();
120 unsigned NumOpRegs = InlineAsm::getNumOperandRegisters(OpFlags);
121 (void)NumOpRegs;
122
123 const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>();
124 const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
125
126 const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg);
127 unsigned BytesPerReg = TRI.getRegSizeInBits(*RC) / 8;
128 assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported.");
129
130 unsigned RegIdx = ByteNumber / BytesPerReg;
131 if (RegIdx >= NumOpRegs)
132 return true;
133 Reg = MI->getOperand(OpNum + RegIdx).getReg();
134
135 if (BytesPerReg == 2) {
136 Reg = TRI.getSubReg(Reg, ByteNumber % BytesPerReg ? AVR::sub_hi
137 : AVR::sub_lo);
138 }
139
140 O << AVRInstPrinter::getPrettyRegisterName(Reg, MRI);
141 return false;
142 }
143 }
144
145 // Print global symbols.
146 const auto &MO = MI->getOperand(OpNum);
147 if (Error && MO.getType() == MachineOperand::MO_GlobalAddress) {
148 PrintSymbolOperand(MO, O);
149 return false;
150 }
151
152 if (Error)
153 printOperand(MI, OpNum, O);
154
155 return false;
156 }
157
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)158 bool AVRAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
159 unsigned OpNum, const char *ExtraCode,
160 raw_ostream &O) {
161 if (ExtraCode && ExtraCode[0])
162 return true; // Unknown modifier
163
164 const MachineOperand &MO = MI->getOperand(OpNum);
165 (void)MO;
166 assert(MO.isReg() && "Unexpected inline asm memory operand");
167
168 // TODO: We should be able to look up the alternative name for
169 // the register if it's given.
170 // TableGen doesn't expose a way of getting retrieving names
171 // for registers.
172 if (MI->getOperand(OpNum).getReg() == AVR::R31R30) {
173 O << "Z";
174 } else if (MI->getOperand(OpNum).getReg() == AVR::R29R28) {
175 O << "Y";
176 } else if (MI->getOperand(OpNum).getReg() == AVR::R27R26) {
177 O << "X";
178 } else {
179 assert(false && "Wrong register class for memory operand.");
180 }
181
182 // If NumOpRegs == 2, then we assume it is product of a FrameIndex expansion
183 // and the second operand is an Imm.
184 unsigned OpFlags = MI->getOperand(OpNum - 1).getImm();
185 unsigned NumOpRegs = InlineAsm::getNumOperandRegisters(OpFlags);
186
187 if (NumOpRegs == 2) {
188 assert(MI->getOperand(OpNum).getReg() != AVR::R27R26 &&
189 "Base register X can not have offset/displacement.");
190 O << '+' << MI->getOperand(OpNum + 1).getImm();
191 }
192
193 return false;
194 }
195
emitInstruction(const MachineInstr * MI)196 void AVRAsmPrinter::emitInstruction(const MachineInstr *MI) {
197 // FIXME: Enable feature predicate checks once all the test pass.
198 // AVR_MC::verifyInstructionPredicates(MI->getOpcode(),
199 // getSubtargetInfo().getFeatureBits());
200
201 AVRMCInstLower MCInstLowering(OutContext, *this);
202
203 MCInst I;
204 MCInstLowering.lowerInstruction(*MI, I);
205 EmitToStreamer(*OutStreamer, I);
206 }
207
lowerConstant(const Constant * CV)208 const MCExpr *AVRAsmPrinter::lowerConstant(const Constant *CV) {
209 MCContext &Ctx = OutContext;
210
211 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
212 bool IsProgMem = GV->getAddressSpace() == AVR::ProgramMemory;
213 if (IsProgMem) {
214 const MCExpr *Expr = MCSymbolRefExpr::create(getSymbol(GV), Ctx);
215 return AVRMCExpr::create(AVRMCExpr::VK_AVR_PM, Expr, false, Ctx);
216 }
217 }
218
219 return AsmPrinter::lowerConstant(CV);
220 }
221
emitXXStructor(const DataLayout & DL,const Constant * CV)222 void AVRAsmPrinter::emitXXStructor(const DataLayout &DL, const Constant *CV) {
223 if (!EmittedStructorSymbolAttrs) {
224 OutStreamer->emitRawComment(
225 " Emitting these undefined symbol references causes us to link the"
226 " libgcc code that runs our constructors/destructors");
227 OutStreamer->emitRawComment(" This matches GCC's behavior");
228
229 MCSymbol *CtorsSym = OutContext.getOrCreateSymbol("__do_global_ctors");
230 OutStreamer->emitSymbolAttribute(CtorsSym, MCSA_Global);
231
232 MCSymbol *DtorsSym = OutContext.getOrCreateSymbol("__do_global_dtors");
233 OutStreamer->emitSymbolAttribute(DtorsSym, MCSA_Global);
234
235 EmittedStructorSymbolAttrs = true;
236 }
237
238 AsmPrinter::emitXXStructor(DL, CV);
239 }
240
doFinalization(Module & M)241 bool AVRAsmPrinter::doFinalization(Module &M) {
242 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
243 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
244 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
245
246 bool NeedsCopyData = false;
247 bool NeedsClearBSS = false;
248 for (const auto &GO : M.globals()) {
249 if (!GO.hasInitializer() || GO.hasAvailableExternallyLinkage())
250 // These globals aren't defined in the current object file.
251 continue;
252
253 if (GO.hasCommonLinkage()) {
254 // COMMON symbols are put in .bss.
255 NeedsClearBSS = true;
256 continue;
257 }
258
259 auto *Section = cast<MCSectionELF>(TLOF.SectionForGlobal(&GO, TM));
260 if (Section->getName().startswith(".data"))
261 NeedsCopyData = true;
262 else if (Section->getName().startswith(".rodata") && SubTM->hasPROGMEM())
263 // AVRs that have a separate PROGMEM (that's most AVRs) store .rodata
264 // sections in RAM.
265 NeedsCopyData = true;
266 else if (Section->getName().startswith(".bss"))
267 NeedsClearBSS = true;
268 }
269
270 MCSymbol *DoCopyData = OutContext.getOrCreateSymbol("__do_copy_data");
271 MCSymbol *DoClearBss = OutContext.getOrCreateSymbol("__do_clear_bss");
272
273 if (NeedsCopyData) {
274 OutStreamer->emitRawComment(
275 " Declaring this symbol tells the CRT that it should");
276 OutStreamer->emitRawComment(
277 "copy all variables from program memory to RAM on startup");
278 OutStreamer->emitSymbolAttribute(DoCopyData, MCSA_Global);
279 }
280
281 if (NeedsClearBSS) {
282 OutStreamer->emitRawComment(
283 " Declaring this symbol tells the CRT that it should");
284 OutStreamer->emitRawComment("clear the zeroed data section on startup");
285 OutStreamer->emitSymbolAttribute(DoClearBss, MCSA_Global);
286 }
287
288 return AsmPrinter::doFinalization(M);
289 }
290
emitStartOfAsmFile(Module & M)291 void AVRAsmPrinter::emitStartOfAsmFile(Module &M) {
292 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
293 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
294 if (!SubTM)
295 return;
296
297 // Emit __tmp_reg__.
298 OutStreamer->emitAssignment(
299 MMI->getContext().getOrCreateSymbol(StringRef("__tmp_reg__")),
300 MCConstantExpr::create(SubTM->getRegTmpIndex(), MMI->getContext()));
301 // Emit __zero_reg__.
302 OutStreamer->emitAssignment(
303 MMI->getContext().getOrCreateSymbol(StringRef("__zero_reg__")),
304 MCConstantExpr::create(SubTM->getRegZeroIndex(), MMI->getContext()));
305 // Emit __SREG__.
306 OutStreamer->emitAssignment(
307 MMI->getContext().getOrCreateSymbol(StringRef("__SREG__")),
308 MCConstantExpr::create(SubTM->getIORegSREG(), MMI->getContext()));
309 // Emit __SP_H__ if available.
310 if (!SubTM->hasSmallStack())
311 OutStreamer->emitAssignment(
312 MMI->getContext().getOrCreateSymbol(StringRef("__SP_H__")),
313 MCConstantExpr::create(SubTM->getIORegSPH(), MMI->getContext()));
314 // Emit __SP_L__.
315 OutStreamer->emitAssignment(
316 MMI->getContext().getOrCreateSymbol(StringRef("__SP_L__")),
317 MCConstantExpr::create(SubTM->getIORegSPL(), MMI->getContext()));
318 // Emit __EIND__ if available.
319 if (SubTM->hasEIJMPCALL())
320 OutStreamer->emitAssignment(
321 MMI->getContext().getOrCreateSymbol(StringRef("__EIND__")),
322 MCConstantExpr::create(SubTM->getIORegEIND(), MMI->getContext()));
323 // Emit __RAMPZ__ if available.
324 if (SubTM->hasELPM())
325 OutStreamer->emitAssignment(
326 MMI->getContext().getOrCreateSymbol(StringRef("__RAMPZ__")),
327 MCConstantExpr::create(SubTM->getIORegRAMPZ(), MMI->getContext()));
328 }
329
330 } // end of namespace llvm
331
LLVMInitializeAVRAsmPrinter()332 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeAVRAsmPrinter() {
333 llvm::RegisterAsmPrinter<llvm::AVRAsmPrinter> X(llvm::getTheAVRTarget());
334 }
335