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
43using namespace llvm;
44
45namespace {
46
47/// An AVR assembly code printer.
48class AVRAsmPrinter : public AsmPrinter {
49public:
50 AVRAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
51 : AsmPrinter(TM, std::move(Streamer), ID), MRI(TM.getMCRegisterInfo()) {}
52
53 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
76private:
77 const MCRegisterInfo &MRI;
78 bool EmittedStructorSymbolAttrs = false;
79};
80
81} // namespace
82
83void AVRAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo,
84 raw_ostream &O) {
85 const MachineOperand &MO = MI->getOperand(i: OpNo);
86
87 switch (MO.getType()) {
88 case MachineOperand::MO_Register:
89 O << AVRInstPrinter::getPrettyRegisterName(Reg: MO.getReg(), MRI);
90 break;
91 case MachineOperand::MO_Immediate:
92 O << MO.getImm();
93 break;
94 case MachineOperand::MO_GlobalAddress:
95 O << getSymbol(GV: MO.getGlobal());
96 break;
97 case MachineOperand::MO_ExternalSymbol:
98 O << *GetExternalSymbolSymbol(Sym: 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
108bool 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, OpNo: OpNum, ExtraCode, OS&: O))
113 return false;
114
115 const MachineOperand &MO = MI->getOperand(i: OpNum);
116
117 // Operand must be a register when using 'A' ~ 'Z' extra code.
118 if (ExtraCode && ExtraCode[0] && MO.isReg()) {
119 // Unknown extra code.
120 if (ExtraCode[1] != 0 || ExtraCode[0] < 'A' || ExtraCode[0] > 'Z')
121 return true;
122
123 Register Reg = MO.getReg();
124
125 unsigned ByteNumber = ExtraCode[0] - 'A';
126 const InlineAsm::Flag OpFlags(MI->getOperand(i: OpNum - 1).getImm());
127 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters();
128
129 const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>();
130 const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
131
132 const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg);
133 unsigned BytesPerReg = TRI.getRegSizeInBits(RC: *RC) / 8;
134 assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported.");
135
136 unsigned RegIdx = ByteNumber / BytesPerReg;
137 if (RegIdx >= NumOpRegs)
138 return true;
139 Reg = MI->getOperand(i: OpNum + RegIdx).getReg();
140
141 if (BytesPerReg == 2) {
142 Reg = TRI.getSubReg(Reg, Idx: (ByteNumber % BytesPerReg) ? AVR::sub_hi
143 : AVR::sub_lo);
144 }
145
146 O << AVRInstPrinter::getPrettyRegisterName(Reg, MRI);
147 return false;
148 }
149
150 if (MO.getType() == MachineOperand::MO_GlobalAddress)
151 PrintSymbolOperand(MO, OS&: O); // Print global symbols.
152 else
153 printOperand(MI, OpNo: OpNum, O); // Fallback to ordinary cases.
154
155 return false;
156}
157
158bool 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(i: OpNum);
165
166 // Print direct memory operands.
167 if (MO.isGlobal() || MO.isSymbol() || MO.isMCSymbol()) {
168 PrintSymbolOperand(MO, OS&: O);
169 return false;
170 }
171
172 assert(MO.isReg() && "Unexpected inline asm memory operand");
173
174 // TODO: We should be able to look up the alternative name for
175 // the register if it's given.
176 // TableGen doesn't expose a way of getting retrieving names
177 // for registers.
178 if (MI->getOperand(i: OpNum).getReg() == AVR::R31R30) {
179 O << "Z";
180 } else if (MI->getOperand(i: OpNum).getReg() == AVR::R29R28) {
181 O << "Y";
182 } else if (MI->getOperand(i: OpNum).getReg() == AVR::R27R26) {
183 O << "X";
184 } else {
185 assert(false && "Wrong register class for memory operand.");
186 }
187
188 // If NumOpRegs == 2, then we assume it is product of a FrameIndex expansion
189 // and the second operand is an Imm.
190 const InlineAsm::Flag OpFlags(MI->getOperand(i: OpNum - 1).getImm());
191 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters();
192
193 if (NumOpRegs == 2) {
194 assert(MI->getOperand(OpNum).getReg() != AVR::R27R26 &&
195 "Base register X can not have offset/displacement.");
196 O << '+' << MI->getOperand(i: OpNum + 1).getImm();
197 }
198
199 return false;
200}
201
202void AVRAsmPrinter::emitInstruction(const MachineInstr *MI) {
203 AVR_MC::verifyInstructionPredicates(Opcode: MI->getOpcode(),
204 Features: getSubtargetInfo().getFeatureBits());
205
206 AVRMCInstLower MCInstLowering(OutContext, *this);
207
208 MCInst I;
209 MCInstLowering.lowerInstruction(MI: *MI, OutMI&: I);
210 EmitToStreamer(S&: *OutStreamer, Inst: I);
211}
212
213const MCExpr *AVRAsmPrinter::lowerConstant(const Constant *CV,
214 const Constant *BaseCV,
215 uint64_t Offset) {
216 MCContext &Ctx = OutContext;
217
218 if (const GlobalValue *GV = dyn_cast<GlobalValue>(Val: CV)) {
219 bool IsProgMem = GV->getAddressSpace() == AVR::ProgramMemory;
220 if (IsProgMem) {
221 const MCExpr *Expr = MCSymbolRefExpr::create(Symbol: getSymbol(GV), Ctx);
222 return AVRMCExpr::create(S: AVR::S_PM, Expr, isNegated: false, Ctx);
223 }
224 }
225
226 return AsmPrinter::lowerConstant(CV, BaseCV, Offset);
227}
228
229void AVRAsmPrinter::emitXXStructor(const DataLayout &DL, const Constant *CV) {
230 if (!EmittedStructorSymbolAttrs) {
231 OutStreamer->emitRawComment(
232 T: " Emitting these undefined symbol references causes us to link the"
233 " libgcc code that runs our constructors/destructors");
234 OutStreamer->emitRawComment(T: " This matches GCC's behavior");
235
236 MCSymbol *CtorsSym = OutContext.getOrCreateSymbol(Name: "__do_global_ctors");
237 OutStreamer->emitSymbolAttribute(Symbol: CtorsSym, Attribute: MCSA_Global);
238
239 MCSymbol *DtorsSym = OutContext.getOrCreateSymbol(Name: "__do_global_dtors");
240 OutStreamer->emitSymbolAttribute(Symbol: DtorsSym, Attribute: MCSA_Global);
241
242 EmittedStructorSymbolAttrs = true;
243 }
244
245 AsmPrinter::emitXXStructor(DL, CV);
246}
247
248bool AVRAsmPrinter::doFinalization(Module &M) {
249 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
250 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
251 const AVRSubtarget *SubTM = TM.getSubtargetImpl();
252
253 bool NeedsCopyData = false;
254 bool NeedsClearBSS = false;
255 for (const auto &GO : M.globals()) {
256 if (!GO.hasInitializer() || GO.hasAvailableExternallyLinkage())
257 // These globals aren't defined in the current object file.
258 continue;
259
260 if (GO.hasCommonLinkage()) {
261 // COMMON symbols are put in .bss.
262 NeedsClearBSS = true;
263 continue;
264 }
265
266 auto *Section = static_cast<MCSectionELF *>(TLOF.SectionForGlobal(GO: &GO, TM));
267 if (Section->getName().starts_with(Prefix: ".data"))
268 NeedsCopyData = true;
269 else if (Section->getName().starts_with(Prefix: ".rodata") && SubTM->hasLPM())
270 // AVRs that have a separate program memory (that's most AVRs) store
271 // .rodata sections in RAM.
272 NeedsCopyData = true;
273 else if (Section->getName().starts_with(Prefix: ".bss"))
274 NeedsClearBSS = true;
275 }
276
277 MCSymbol *DoCopyData = OutContext.getOrCreateSymbol(Name: "__do_copy_data");
278 MCSymbol *DoClearBss = OutContext.getOrCreateSymbol(Name: "__do_clear_bss");
279
280 if (NeedsCopyData) {
281 OutStreamer->emitRawComment(
282 T: " Declaring this symbol tells the CRT that it should");
283 OutStreamer->emitRawComment(
284 T: "copy all variables from program memory to RAM on startup");
285 OutStreamer->emitSymbolAttribute(Symbol: DoCopyData, Attribute: MCSA_Global);
286 }
287
288 if (NeedsClearBSS) {
289 OutStreamer->emitRawComment(
290 T: " Declaring this symbol tells the CRT that it should");
291 OutStreamer->emitRawComment(T: "clear the zeroed data section on startup");
292 OutStreamer->emitSymbolAttribute(Symbol: DoClearBss, Attribute: MCSA_Global);
293 }
294
295 return AsmPrinter::doFinalization(M);
296}
297
298void AVRAsmPrinter::emitStartOfAsmFile(Module &M) {
299 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
300 const AVRSubtarget *SubTM = TM.getSubtargetImpl();
301 if (!SubTM)
302 return;
303
304 // Emit __tmp_reg__.
305 OutStreamer->emitAssignment(
306 Symbol: MMI->getContext().getOrCreateSymbol(Name: StringRef("__tmp_reg__")),
307 Value: MCConstantExpr::create(Value: SubTM->getRegTmpIndex(), Ctx&: MMI->getContext()));
308 // Emit __zero_reg__.
309 OutStreamer->emitAssignment(
310 Symbol: MMI->getContext().getOrCreateSymbol(Name: StringRef("__zero_reg__")),
311 Value: MCConstantExpr::create(Value: SubTM->getRegZeroIndex(), Ctx&: MMI->getContext()));
312 // Emit __SREG__.
313 OutStreamer->emitAssignment(
314 Symbol: MMI->getContext().getOrCreateSymbol(Name: StringRef("__SREG__")),
315 Value: MCConstantExpr::create(Value: SubTM->getIORegSREG(), Ctx&: MMI->getContext()));
316 // Emit __SP_H__ if available.
317 if (!SubTM->hasSmallStack())
318 OutStreamer->emitAssignment(
319 Symbol: MMI->getContext().getOrCreateSymbol(Name: StringRef("__SP_H__")),
320 Value: MCConstantExpr::create(Value: SubTM->getIORegSPH(), Ctx&: MMI->getContext()));
321 // Emit __SP_L__.
322 OutStreamer->emitAssignment(
323 Symbol: MMI->getContext().getOrCreateSymbol(Name: StringRef("__SP_L__")),
324 Value: MCConstantExpr::create(Value: SubTM->getIORegSPL(), Ctx&: MMI->getContext()));
325 // Emit __EIND__ if available.
326 if (SubTM->hasEIJMPCALL())
327 OutStreamer->emitAssignment(
328 Symbol: MMI->getContext().getOrCreateSymbol(Name: StringRef("__EIND__")),
329 Value: MCConstantExpr::create(Value: SubTM->getIORegEIND(), Ctx&: MMI->getContext()));
330 // Emit __RAMPZ__ if available.
331 if (SubTM->hasELPM())
332 OutStreamer->emitAssignment(
333 Symbol: MMI->getContext().getOrCreateSymbol(Name: StringRef("__RAMPZ__")),
334 Value: MCConstantExpr::create(Value: SubTM->getIORegRAMPZ(), Ctx&: MMI->getContext()));
335}
336
337char AVRAsmPrinter::ID = 0;
338
339INITIALIZE_PASS(AVRAsmPrinter, "avr-asm-printer", "AVR Assembly Printer", false,
340 false)
341
342extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void
343LLVMInitializeAVRAsmPrinter() {
344 llvm::RegisterAsmPrinter<AVRAsmPrinter> X(getTheAVRTarget());
345}
346