1 //===-- llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp -------*- C++ -*--===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Common functionality for different debug information format backends.
11 // LLVM currently supports DWARF and CodeView.
13 //===----------------------------------------------------------------------===//
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"
28 Optional<DbgVariableLocation>
29 DbgVariableLocation::extractFromMachineInstruction(
30 const MachineInstr &Instruction) {
31 DbgVariableLocation Location;
32 if (!Instruction.isDebugValue())
34 if (!Instruction.getOperand(0).isReg())
36 Location.Register = Instruction.getOperand(0).getReg();
37 Location.FragmentInfo.reset();
38 // We only handle expressions generated by DIExpression::appendOffset,
39 // which doesn't require a full stack machine.
41 const DIExpression *DIExpr = Instruction.getDebugExpression();
42 auto Op = DIExpr->expr_op_begin();
43 while (Op != DIExpr->expr_op_end()) {
44 switch (Op->getOp()) {
45 case dwarf::DW_OP_constu: {
46 int Value = Op->getArg(0);
48 if (Op != DIExpr->expr_op_end()) {
49 switch (Op->getOp()) {
50 case dwarf::DW_OP_minus:
53 case dwarf::DW_OP_plus:
61 case dwarf::DW_OP_plus_uconst:
62 Offset += Op->getArg(0);
64 case dwarf::DW_OP_LLVM_fragment:
65 Location.FragmentInfo = {Op->getArg(1), Op->getArg(0)};
67 case dwarf::DW_OP_deref:
68 Location.LoadChain.push_back(Offset);
77 // Do one final implicit DW_OP_deref if this was an indirect DBG_VALUE
79 // FIXME: Replace these with DIExpression.
80 if (Instruction.isIndirectDebugValue())
81 Location.LoadChain.push_back(Offset);
86 DebugHandlerBase::DebugHandlerBase(AsmPrinter *A) : Asm(A), MMI(Asm->MMI) {}
88 // Each LexicalScope has first instruction and last instruction to mark
89 // beginning and end of a scope respectively. Create an inverse map that list
90 // scopes starts (and ends) with an instruction. One instruction may start (or
91 // end) multiple scopes. Ignore scopes that are not reachable.
92 void DebugHandlerBase::identifyScopeMarkers() {
93 SmallVector<LexicalScope *, 4> WorkList;
94 WorkList.push_back(LScopes.getCurrentFunctionScope());
95 while (!WorkList.empty()) {
96 LexicalScope *S = WorkList.pop_back_val();
98 const SmallVectorImpl<LexicalScope *> &Children = S->getChildren();
99 if (!Children.empty())
100 WorkList.append(Children.begin(), Children.end());
102 if (S->isAbstractScope())
105 for (const InsnRange &R : S->getRanges()) {
106 assert(R.first && "InsnRange does not have first instruction!");
107 assert(R.second && "InsnRange does not have second instruction!");
108 requestLabelBeforeInsn(R.first);
109 requestLabelAfterInsn(R.second);
114 // Return Label preceding the instruction.
115 MCSymbol *DebugHandlerBase::getLabelBeforeInsn(const MachineInstr *MI) {
116 MCSymbol *Label = LabelsBeforeInsn.lookup(MI);
117 assert(Label && "Didn't insert label before instruction");
121 // Return Label immediately following the instruction.
122 MCSymbol *DebugHandlerBase::getLabelAfterInsn(const MachineInstr *MI) {
123 return LabelsAfterInsn.lookup(MI);
126 int DebugHandlerBase::fragmentCmp(const DIExpression *P1,
127 const DIExpression *P2) {
128 auto Fragment1 = *P1->getFragmentInfo();
129 auto Fragment2 = *P2->getFragmentInfo();
130 unsigned l1 = Fragment1.OffsetInBits;
131 unsigned l2 = Fragment2.OffsetInBits;
132 unsigned r1 = l1 + Fragment1.SizeInBits;
133 unsigned r2 = l2 + Fragment2.SizeInBits;
142 bool DebugHandlerBase::fragmentsOverlap(const DIExpression *P1,
143 const DIExpression *P2) {
144 if (!P1->isFragment() || !P2->isFragment())
146 return fragmentCmp(P1, P2) == 0;
149 /// If this type is derived from a base type then return base type size.
150 uint64_t DebugHandlerBase::getBaseTypeSize(const DITypeRef TyRef) {
151 DIType *Ty = TyRef.resolve();
153 DIDerivedType *DDTy = dyn_cast<DIDerivedType>(Ty);
155 return Ty->getSizeInBits();
157 unsigned Tag = DDTy->getTag();
159 if (Tag != dwarf::DW_TAG_member && Tag != dwarf::DW_TAG_typedef &&
160 Tag != dwarf::DW_TAG_const_type && Tag != dwarf::DW_TAG_volatile_type &&
161 Tag != dwarf::DW_TAG_restrict_type && Tag != dwarf::DW_TAG_atomic_type)
162 return DDTy->getSizeInBits();
164 DIType *BaseType = DDTy->getBaseType().resolve();
169 // If this is a derived type, go ahead and get the base type, unless it's a
170 // reference then it's just the size of the field. Pointer types have no need
171 // of this since they're a different type of qualification on the type.
172 if (BaseType->getTag() == dwarf::DW_TAG_reference_type ||
173 BaseType->getTag() == dwarf::DW_TAG_rvalue_reference_type)
174 return Ty->getSizeInBits();
176 return getBaseTypeSize(BaseType);
179 static bool hasDebugInfo(const MachineModuleInfo *MMI,
180 const MachineFunction *MF) {
181 if (!MMI->hasDebugInfo())
183 auto *SP = MF->getFunction().getSubprogram();
186 assert(SP->getUnit());
187 auto EK = SP->getUnit()->getEmissionKind();
188 if (EK == DICompileUnit::NoDebug)
193 void DebugHandlerBase::beginFunction(const MachineFunction *MF) {
194 PrevInstBB = nullptr;
196 if (!Asm || !hasDebugInfo(MMI, MF)) {
197 skippedNonDebugFunction();
201 // Grab the lexical scopes for the function, if we don't have any of those
202 // then we're not going to be able to do anything.
203 LScopes.initialize(*MF);
204 if (LScopes.empty()) {
205 beginFunctionImpl(MF);
209 // Make sure that each lexical scope will have a begin/end label.
210 identifyScopeMarkers();
212 // Calculate history for local variables.
213 assert(DbgValues.empty() && "DbgValues map wasn't cleaned!");
214 calculateDbgValueHistory(MF, Asm->MF->getSubtarget().getRegisterInfo(),
217 // Request labels for the full history.
218 for (const auto &I : DbgValues) {
219 const auto &Ranges = I.second;
223 // The first mention of a function argument gets the CurrentFnBegin
224 // label, so arguments are visible when breaking at function entry.
225 const DILocalVariable *DIVar = Ranges.front().first->getDebugVariable();
226 if (DIVar->isParameter() &&
227 getDISubprogram(DIVar->getScope())->describes(&MF->getFunction())) {
228 LabelsBeforeInsn[Ranges.front().first] = Asm->getFunctionBegin();
229 if (Ranges.front().first->getDebugExpression()->isFragment()) {
230 // Mark all non-overlapping initial fragments.
231 for (auto I = Ranges.begin(); I != Ranges.end(); ++I) {
232 const DIExpression *Fragment = I->first->getDebugExpression();
233 if (std::all_of(Ranges.begin(), I,
234 [&](DbgValueHistoryMap::InstrRange Pred) {
235 return !fragmentsOverlap(
236 Fragment, Pred.first->getDebugExpression());
238 LabelsBeforeInsn[I->first] = Asm->getFunctionBegin();
245 for (const auto &Range : Ranges) {
246 requestLabelBeforeInsn(Range.first);
248 requestLabelAfterInsn(Range.second);
252 PrevInstLoc = DebugLoc();
253 PrevLabel = Asm->getFunctionBegin();
254 beginFunctionImpl(MF);
257 void DebugHandlerBase::beginInstruction(const MachineInstr *MI) {
258 if (!MMI->hasDebugInfo())
261 assert(CurMI == nullptr);
264 // Insert labels where requested.
265 DenseMap<const MachineInstr *, MCSymbol *>::iterator I =
266 LabelsBeforeInsn.find(MI);
269 if (I == LabelsBeforeInsn.end())
272 // Label already assigned.
277 PrevLabel = MMI->getContext().createTempSymbol();
278 Asm->OutStreamer->EmitLabel(PrevLabel);
280 I->second = PrevLabel;
283 void DebugHandlerBase::endInstruction() {
284 if (!MMI->hasDebugInfo())
287 assert(CurMI != nullptr);
288 // Don't create a new label after DBG_VALUE and other instructions that don't
290 if (!CurMI->isMetaInstruction()) {
292 PrevInstBB = CurMI->getParent();
295 DenseMap<const MachineInstr *, MCSymbol *>::iterator I =
296 LabelsAfterInsn.find(CurMI);
300 if (I == LabelsAfterInsn.end())
303 // Label already assigned.
307 // We need a label after this instruction.
309 PrevLabel = MMI->getContext().createTempSymbol();
310 Asm->OutStreamer->EmitLabel(PrevLabel);
312 I->second = PrevLabel;
315 void DebugHandlerBase::endFunction(const MachineFunction *MF) {
316 if (hasDebugInfo(MMI, MF))
319 LabelsBeforeInsn.clear();
320 LabelsAfterInsn.clear();