1 //===-- llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp -------*- C++ -*--===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // Common functionality for different debug information format backends. 11 // LLVM currently supports DWARF and CodeView. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "DebugHandlerBase.h" 16 #include "llvm/ADT/Optional.h" 17 #include "llvm/ADT/Twine.h" 18 #include "llvm/CodeGen/AsmPrinter.h" 19 #include "llvm/CodeGen/MachineFunction.h" 20 #include "llvm/CodeGen/MachineInstr.h" 21 #include "llvm/CodeGen/MachineModuleInfo.h" 22 #include "llvm/CodeGen/TargetSubtargetInfo.h" 23 #include "llvm/IR/DebugInfo.h" 24 #include "llvm/MC/MCStreamer.h" 25 26 using namespace llvm; 27 28 #define DEBUG_TYPE "dwarfdebug" 29 30 Optional<DbgVariableLocation> 31 DbgVariableLocation::extractFromMachineInstruction( 32 const MachineInstr &Instruction) { 33 DbgVariableLocation Location; 34 if (!Instruction.isDebugValue()) 35 return None; 36 if (!Instruction.getOperand(0).isReg()) 37 return None; 38 Location.Register = Instruction.getOperand(0).getReg(); 39 Location.FragmentInfo.reset(); 40 // We only handle expressions generated by DIExpression::appendOffset, 41 // which doesn't require a full stack machine. 42 int64_t Offset = 0; 43 const DIExpression *DIExpr = Instruction.getDebugExpression(); 44 auto Op = DIExpr->expr_op_begin(); 45 while (Op != DIExpr->expr_op_end()) { 46 switch (Op->getOp()) { 47 case dwarf::DW_OP_constu: { 48 int Value = Op->getArg(0); 49 ++Op; 50 if (Op != DIExpr->expr_op_end()) { 51 switch (Op->getOp()) { 52 case dwarf::DW_OP_minus: 53 Offset -= Value; 54 break; 55 case dwarf::DW_OP_plus: 56 Offset += Value; 57 break; 58 default: 59 continue; 60 } 61 } 62 } break; 63 case dwarf::DW_OP_plus_uconst: 64 Offset += Op->getArg(0); 65 break; 66 case dwarf::DW_OP_LLVM_fragment: 67 Location.FragmentInfo = {Op->getArg(1), Op->getArg(0)}; 68 break; 69 case dwarf::DW_OP_deref: 70 Location.LoadChain.push_back(Offset); 71 Offset = 0; 72 break; 73 default: 74 return None; 75 } 76 ++Op; 77 } 78 79 // Do one final implicit DW_OP_deref if this was an indirect DBG_VALUE 80 // instruction. 81 // FIXME: Replace these with DIExpression. 82 if (Instruction.isIndirectDebugValue()) 83 Location.LoadChain.push_back(Offset); 84 85 return Location; 86 } 87 88 DebugHandlerBase::DebugHandlerBase(AsmPrinter *A) : Asm(A), MMI(Asm->MMI) {} 89 90 // Each LexicalScope has first instruction and last instruction to mark 91 // beginning and end of a scope respectively. Create an inverse map that list 92 // scopes starts (and ends) with an instruction. One instruction may start (or 93 // end) multiple scopes. Ignore scopes that are not reachable. 94 void DebugHandlerBase::identifyScopeMarkers() { 95 SmallVector<LexicalScope *, 4> WorkList; 96 WorkList.push_back(LScopes.getCurrentFunctionScope()); 97 while (!WorkList.empty()) { 98 LexicalScope *S = WorkList.pop_back_val(); 99 100 const SmallVectorImpl<LexicalScope *> &Children = S->getChildren(); 101 if (!Children.empty()) 102 WorkList.append(Children.begin(), Children.end()); 103 104 if (S->isAbstractScope()) 105 continue; 106 107 for (const InsnRange &R : S->getRanges()) { 108 assert(R.first && "InsnRange does not have first instruction!"); 109 assert(R.second && "InsnRange does not have second instruction!"); 110 requestLabelBeforeInsn(R.first); 111 requestLabelAfterInsn(R.second); 112 } 113 } 114 } 115 116 // Return Label preceding the instruction. 117 MCSymbol *DebugHandlerBase::getLabelBeforeInsn(const MachineInstr *MI) { 118 MCSymbol *Label = LabelsBeforeInsn.lookup(MI); 119 assert(Label && "Didn't insert label before instruction"); 120 return Label; 121 } 122 123 // Return Label immediately following the instruction. 124 MCSymbol *DebugHandlerBase::getLabelAfterInsn(const MachineInstr *MI) { 125 return LabelsAfterInsn.lookup(MI); 126 } 127 128 /// If this type is derived from a base type then return base type size. 129 uint64_t DebugHandlerBase::getBaseTypeSize(const DITypeRef TyRef) { 130 DIType *Ty = TyRef.resolve(); 131 assert(Ty); 132 DIDerivedType *DDTy = dyn_cast<DIDerivedType>(Ty); 133 if (!DDTy) 134 return Ty->getSizeInBits(); 135 136 unsigned Tag = DDTy->getTag(); 137 138 if (Tag != dwarf::DW_TAG_member && Tag != dwarf::DW_TAG_typedef && 139 Tag != dwarf::DW_TAG_const_type && Tag != dwarf::DW_TAG_volatile_type && 140 Tag != dwarf::DW_TAG_restrict_type && Tag != dwarf::DW_TAG_atomic_type) 141 return DDTy->getSizeInBits(); 142 143 DIType *BaseType = DDTy->getBaseType().resolve(); 144 145 if (!BaseType) 146 return 0; 147 148 // If this is a derived type, go ahead and get the base type, unless it's a 149 // reference then it's just the size of the field. Pointer types have no need 150 // of this since they're a different type of qualification on the type. 151 if (BaseType->getTag() == dwarf::DW_TAG_reference_type || 152 BaseType->getTag() == dwarf::DW_TAG_rvalue_reference_type) 153 return Ty->getSizeInBits(); 154 155 return getBaseTypeSize(BaseType); 156 } 157 158 static bool hasDebugInfo(const MachineModuleInfo *MMI, 159 const MachineFunction *MF) { 160 if (!MMI->hasDebugInfo()) 161 return false; 162 auto *SP = MF->getFunction().getSubprogram(); 163 if (!SP) 164 return false; 165 assert(SP->getUnit()); 166 auto EK = SP->getUnit()->getEmissionKind(); 167 if (EK == DICompileUnit::NoDebug) 168 return false; 169 return true; 170 } 171 172 void DebugHandlerBase::beginFunction(const MachineFunction *MF) { 173 PrevInstBB = nullptr; 174 175 if (!Asm || !hasDebugInfo(MMI, MF)) { 176 skippedNonDebugFunction(); 177 return; 178 } 179 180 // Grab the lexical scopes for the function, if we don't have any of those 181 // then we're not going to be able to do anything. 182 LScopes.initialize(*MF); 183 if (LScopes.empty()) { 184 beginFunctionImpl(MF); 185 return; 186 } 187 188 // Make sure that each lexical scope will have a begin/end label. 189 identifyScopeMarkers(); 190 191 // Calculate history for local variables. 192 assert(DbgValues.empty() && "DbgValues map wasn't cleaned!"); 193 calculateDbgValueHistory(MF, Asm->MF->getSubtarget().getRegisterInfo(), 194 DbgValues); 195 LLVM_DEBUG(DbgValues.dump()); 196 197 // Request labels for the full history. 198 for (const auto &I : DbgValues) { 199 const auto &Ranges = I.second; 200 if (Ranges.empty()) 201 continue; 202 203 // The first mention of a function argument gets the CurrentFnBegin 204 // label, so arguments are visible when breaking at function entry. 205 const DILocalVariable *DIVar = Ranges.front().first->getDebugVariable(); 206 if (DIVar->isParameter() && 207 getDISubprogram(DIVar->getScope())->describes(&MF->getFunction())) { 208 LabelsBeforeInsn[Ranges.front().first] = Asm->getFunctionBegin(); 209 if (Ranges.front().first->getDebugExpression()->isFragment()) { 210 // Mark all non-overlapping initial fragments. 211 for (auto I = Ranges.begin(); I != Ranges.end(); ++I) { 212 const DIExpression *Fragment = I->first->getDebugExpression(); 213 if (std::all_of(Ranges.begin(), I, 214 [&](DbgValueHistoryMap::InstrRange Pred) { 215 return !Fragment->fragmentsOverlap( 216 Pred.first->getDebugExpression()); 217 })) 218 LabelsBeforeInsn[I->first] = Asm->getFunctionBegin(); 219 else 220 break; 221 } 222 } 223 } 224 225 for (const auto &Range : Ranges) { 226 requestLabelBeforeInsn(Range.first); 227 if (Range.second) 228 requestLabelAfterInsn(Range.second); 229 } 230 } 231 232 PrevInstLoc = DebugLoc(); 233 PrevLabel = Asm->getFunctionBegin(); 234 beginFunctionImpl(MF); 235 } 236 237 void DebugHandlerBase::beginInstruction(const MachineInstr *MI) { 238 if (!MMI->hasDebugInfo()) 239 return; 240 241 assert(CurMI == nullptr); 242 CurMI = MI; 243 244 // Insert labels where requested. 245 DenseMap<const MachineInstr *, MCSymbol *>::iterator I = 246 LabelsBeforeInsn.find(MI); 247 248 // No label needed. 249 if (I == LabelsBeforeInsn.end()) 250 return; 251 252 // Label already assigned. 253 if (I->second) 254 return; 255 256 if (!PrevLabel) { 257 PrevLabel = MMI->getContext().createTempSymbol(); 258 Asm->OutStreamer->EmitLabel(PrevLabel); 259 } 260 I->second = PrevLabel; 261 } 262 263 void DebugHandlerBase::endInstruction() { 264 if (!MMI->hasDebugInfo()) 265 return; 266 267 assert(CurMI != nullptr); 268 // Don't create a new label after DBG_VALUE and other instructions that don't 269 // generate code. 270 if (!CurMI->isMetaInstruction()) { 271 PrevLabel = nullptr; 272 PrevInstBB = CurMI->getParent(); 273 } 274 275 DenseMap<const MachineInstr *, MCSymbol *>::iterator I = 276 LabelsAfterInsn.find(CurMI); 277 CurMI = nullptr; 278 279 // No label needed. 280 if (I == LabelsAfterInsn.end()) 281 return; 282 283 // Label already assigned. 284 if (I->second) 285 return; 286 287 // We need a label after this instruction. 288 if (!PrevLabel) { 289 PrevLabel = MMI->getContext().createTempSymbol(); 290 Asm->OutStreamer->EmitLabel(PrevLabel); 291 } 292 I->second = PrevLabel; 293 } 294 295 void DebugHandlerBase::endFunction(const MachineFunction *MF) { 296 if (hasDebugInfo(MMI, MF)) 297 endFunctionImpl(MF); 298 DbgValues.clear(); 299 LabelsBeforeInsn.clear(); 300 LabelsAfterInsn.clear(); 301 } 302