//===-- llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp -------*- C++ -*--===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // Common functionality for different debug information format backends. // LLVM currently supports DWARF and CodeView. // //===----------------------------------------------------------------------===// #include "DebugHandlerBase.h" #include "llvm/ADT/Optional.h" #include "llvm/ADT/Twine.h" #include "llvm/CodeGen/AsmPrinter.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineInstr.h" #include "llvm/CodeGen/MachineModuleInfo.h" #include "llvm/CodeGen/TargetSubtargetInfo.h" #include "llvm/IR/DebugInfo.h" #include "llvm/MC/MCStreamer.h" using namespace llvm; Optional DbgVariableLocation::extractFromMachineInstruction( const MachineInstr &Instruction) { DbgVariableLocation Location; if (!Instruction.isDebugValue()) return None; if (!Instruction.getOperand(0).isReg()) return None; Location.Register = Instruction.getOperand(0).getReg(); Location.FragmentInfo.reset(); // We only handle expressions generated by DIExpression::appendOffset, // which doesn't require a full stack machine. int64_t Offset = 0; const DIExpression *DIExpr = Instruction.getDebugExpression(); auto Op = DIExpr->expr_op_begin(); while (Op != DIExpr->expr_op_end()) { switch (Op->getOp()) { case dwarf::DW_OP_constu: { int Value = Op->getArg(0); ++Op; if (Op != DIExpr->expr_op_end()) { switch (Op->getOp()) { case dwarf::DW_OP_minus: Offset -= Value; break; case dwarf::DW_OP_plus: Offset += Value; break; default: continue; } } } break; case dwarf::DW_OP_plus_uconst: Offset += Op->getArg(0); break; case dwarf::DW_OP_LLVM_fragment: Location.FragmentInfo = {Op->getArg(1), Op->getArg(0)}; break; case dwarf::DW_OP_deref: Location.LoadChain.push_back(Offset); Offset = 0; break; default: return None; } ++Op; } // Do one final implicit DW_OP_deref if this was an indirect DBG_VALUE // instruction. // FIXME: Replace these with DIExpression. if (Instruction.isIndirectDebugValue()) Location.LoadChain.push_back(Offset); return Location; } DebugHandlerBase::DebugHandlerBase(AsmPrinter *A) : Asm(A), MMI(Asm->MMI) {} // Each LexicalScope has first instruction and last instruction to mark // beginning and end of a scope respectively. Create an inverse map that list // scopes starts (and ends) with an instruction. One instruction may start (or // end) multiple scopes. Ignore scopes that are not reachable. void DebugHandlerBase::identifyScopeMarkers() { SmallVector WorkList; WorkList.push_back(LScopes.getCurrentFunctionScope()); while (!WorkList.empty()) { LexicalScope *S = WorkList.pop_back_val(); const SmallVectorImpl &Children = S->getChildren(); if (!Children.empty()) WorkList.append(Children.begin(), Children.end()); if (S->isAbstractScope()) continue; for (const InsnRange &R : S->getRanges()) { assert(R.first && "InsnRange does not have first instruction!"); assert(R.second && "InsnRange does not have second instruction!"); requestLabelBeforeInsn(R.first); requestLabelAfterInsn(R.second); } } } // Return Label preceding the instruction. MCSymbol *DebugHandlerBase::getLabelBeforeInsn(const MachineInstr *MI) { MCSymbol *Label = LabelsBeforeInsn.lookup(MI); assert(Label && "Didn't insert label before instruction"); return Label; } // Return Label immediately following the instruction. MCSymbol *DebugHandlerBase::getLabelAfterInsn(const MachineInstr *MI) { return LabelsAfterInsn.lookup(MI); } int DebugHandlerBase::fragmentCmp(const DIExpression *P1, const DIExpression *P2) { auto Fragment1 = *P1->getFragmentInfo(); auto Fragment2 = *P2->getFragmentInfo(); unsigned l1 = Fragment1.OffsetInBits; unsigned l2 = Fragment2.OffsetInBits; unsigned r1 = l1 + Fragment1.SizeInBits; unsigned r2 = l2 + Fragment2.SizeInBits; if (r1 <= l2) return -1; else if (r2 <= l1) return 1; else return 0; } bool DebugHandlerBase::fragmentsOverlap(const DIExpression *P1, const DIExpression *P2) { if (!P1->isFragment() || !P2->isFragment()) return true; return fragmentCmp(P1, P2) == 0; } /// If this type is derived from a base type then return base type size. uint64_t DebugHandlerBase::getBaseTypeSize(const DITypeRef TyRef) { DIType *Ty = TyRef.resolve(); assert(Ty); DIDerivedType *DDTy = dyn_cast(Ty); if (!DDTy) return Ty->getSizeInBits(); unsigned Tag = DDTy->getTag(); if (Tag != dwarf::DW_TAG_member && Tag != dwarf::DW_TAG_typedef && Tag != dwarf::DW_TAG_const_type && Tag != dwarf::DW_TAG_volatile_type && Tag != dwarf::DW_TAG_restrict_type && Tag != dwarf::DW_TAG_atomic_type) return DDTy->getSizeInBits(); DIType *BaseType = DDTy->getBaseType().resolve(); assert(BaseType && "Unexpected invalid base type"); // If this is a derived type, go ahead and get the base type, unless it's a // reference then it's just the size of the field. Pointer types have no need // of this since they're a different type of qualification on the type. if (BaseType->getTag() == dwarf::DW_TAG_reference_type || BaseType->getTag() == dwarf::DW_TAG_rvalue_reference_type) return Ty->getSizeInBits(); return getBaseTypeSize(BaseType); } static bool hasDebugInfo(const MachineModuleInfo *MMI, const MachineFunction *MF) { if (!MMI->hasDebugInfo()) return false; auto *SP = MF->getFunction()->getSubprogram(); if (!SP) return false; assert(SP->getUnit()); auto EK = SP->getUnit()->getEmissionKind(); if (EK == DICompileUnit::NoDebug) return false; return true; } void DebugHandlerBase::beginFunction(const MachineFunction *MF) { PrevInstBB = nullptr; if (!Asm || !hasDebugInfo(MMI, MF)) { skippedNonDebugFunction(); return; } // Grab the lexical scopes for the function, if we don't have any of those // then we're not going to be able to do anything. LScopes.initialize(*MF); if (LScopes.empty()) { beginFunctionImpl(MF); return; } // Make sure that each lexical scope will have a begin/end label. identifyScopeMarkers(); // Calculate history for local variables. assert(DbgValues.empty() && "DbgValues map wasn't cleaned!"); calculateDbgValueHistory(MF, Asm->MF->getSubtarget().getRegisterInfo(), DbgValues); // Request labels for the full history. for (const auto &I : DbgValues) { const auto &Ranges = I.second; if (Ranges.empty()) continue; // The first mention of a function argument gets the CurrentFnBegin // label, so arguments are visible when breaking at function entry. const DILocalVariable *DIVar = Ranges.front().first->getDebugVariable(); if (DIVar->isParameter() && getDISubprogram(DIVar->getScope())->describes(MF->getFunction())) { LabelsBeforeInsn[Ranges.front().first] = Asm->getFunctionBegin(); if (Ranges.front().first->getDebugExpression()->isFragment()) { // Mark all non-overlapping initial fragments. for (auto I = Ranges.begin(); I != Ranges.end(); ++I) { const DIExpression *Fragment = I->first->getDebugExpression(); if (std::all_of(Ranges.begin(), I, [&](DbgValueHistoryMap::InstrRange Pred) { return !fragmentsOverlap( Fragment, Pred.first->getDebugExpression()); })) LabelsBeforeInsn[I->first] = Asm->getFunctionBegin(); else break; } } } for (const auto &Range : Ranges) { requestLabelBeforeInsn(Range.first); if (Range.second) requestLabelAfterInsn(Range.second); } } PrevInstLoc = DebugLoc(); PrevLabel = Asm->getFunctionBegin(); beginFunctionImpl(MF); } void DebugHandlerBase::beginInstruction(const MachineInstr *MI) { if (!MMI->hasDebugInfo()) return; assert(CurMI == nullptr); CurMI = MI; // Insert labels where requested. DenseMap::iterator I = LabelsBeforeInsn.find(MI); // No label needed. if (I == LabelsBeforeInsn.end()) return; // Label already assigned. if (I->second) return; if (!PrevLabel) { PrevLabel = MMI->getContext().createTempSymbol(); Asm->OutStreamer->EmitLabel(PrevLabel); } I->second = PrevLabel; } void DebugHandlerBase::endInstruction() { if (!MMI->hasDebugInfo()) return; assert(CurMI != nullptr); // Don't create a new label after DBG_VALUE and other instructions that don't // generate code. if (!CurMI->isMetaInstruction()) { PrevLabel = nullptr; PrevInstBB = CurMI->getParent(); } DenseMap::iterator I = LabelsAfterInsn.find(CurMI); CurMI = nullptr; // No label needed. if (I == LabelsAfterInsn.end()) return; // Label already assigned. if (I->second) return; // We need a label after this instruction. if (!PrevLabel) { PrevLabel = MMI->getContext().createTempSymbol(); Asm->OutStreamer->EmitLabel(PrevLabel); } I->second = PrevLabel; } void DebugHandlerBase::endFunction(const MachineFunction *MF) { if (hasDebugInfo(MMI, MF)) endFunctionImpl(MF); DbgValues.clear(); LabelsBeforeInsn.clear(); LabelsAfterInsn.clear(); }