lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

   1 //===- llvm/CodeGen/DwarfCompileUnit.cpp - Dwarf Compile Units ------------===//
   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 support for constructing a dwarf compile unit.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "DwarfCompileUnit.h"
  14 #include "AddressPool.h"
  15 #include "DwarfDebug.h"
  16 #include "DwarfExpression.h"
  17 #include "DwarfUnit.h"
  18 #include "llvm/ADT/None.h"
  19 #include "llvm/ADT/STLExtras.h"
  20 #include "llvm/ADT/SmallString.h"
  21 #include "llvm/ADT/SmallVector.h"
  22 #include "llvm/ADT/StringRef.h"
  23 #include "llvm/BinaryFormat/Dwarf.h"
  24 #include "llvm/CodeGen/AsmPrinter.h"
  25 #include "llvm/CodeGen/DIE.h"
  26 #include "llvm/CodeGen/LexicalScopes.h"
  27 #include "llvm/CodeGen/MachineFunction.h"
  28 #include "llvm/CodeGen/MachineInstr.h"
  29 #include "llvm/CodeGen/MachineOperand.h"
  30 #include "llvm/CodeGen/TargetFrameLowering.h"
  31 #include "llvm/CodeGen/TargetRegisterInfo.h"
  32 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  33 #include "llvm/IR/DataLayout.h"
  34 #include "llvm/IR/DebugInfo.h"
  35 #include "llvm/IR/DebugInfoMetadata.h"
  36 #include "llvm/IR/GlobalVariable.h"
  37 #include "llvm/MC/MCSection.h"
  38 #include "llvm/MC/MCStreamer.h"
  39 #include "llvm/MC/MCSymbol.h"
  40 #include "llvm/MC/MachineLocation.h"
  41 #include "llvm/Support/Casting.h"
  42 #include "llvm/Target/TargetLoweringObjectFile.h"
  43 #include "llvm/Target/TargetMachine.h"
  44 #include "llvm/Target/TargetOptions.h"
  45 #include <algorithm>
  46 #include <cassert>
  47 #include <cstdint>
  48 #include <iterator>
  49 #include <memory>
  50 #include <string>
  51 #include <utility>
  52
  53 using namespace llvm;
  54
  55 DwarfCompileUnit::DwarfCompileUnit(unsigned UID, const DICompileUnit *Node,
  56                                    AsmPrinter *A, DwarfDebug *DW,
  57                                    DwarfFile *DWU)
  58     : DwarfUnit(dwarf::DW_TAG_compile_unit, Node, A, DW, DWU), UniqueID(UID) {
  59   insertDIE(Node, &getUnitDie());
  60   MacroLabelBegin = Asm->createTempSymbol("cu_macro_begin");
  61 }
  62
  63 /// addLabelAddress - Add a dwarf label attribute data and value using
  64 /// DW_FORM_addr or DW_FORM_GNU_addr_index.
  65 void DwarfCompileUnit::addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
  66                                        const MCSymbol *Label) {
  67   // Don't use the address pool in non-fission or in the skeleton unit itself.
  68   // FIXME: Once GDB supports this, it's probably worthwhile using the address
  69   // pool from the skeleton - maybe even in non-fission (possibly fewer
  70   // relocations by sharing them in the pool, but we have other ideas about how
  71   // to reduce the number of relocations as well/instead).
  72   if ((!DD->useSplitDwarf() || !Skeleton) && DD->getDwarfVersion() < 5)
  73     return addLocalLabelAddress(Die, Attribute, Label);
  74
  75   if (Label)
  76     DD->addArangeLabel(SymbolCU(this, Label));
  77
  78   unsigned idx = DD->getAddressPool().getIndex(Label);
  79   Die.addValue(DIEValueAllocator, Attribute,
  80                DD->getDwarfVersion() >= 5 ? dwarf::DW_FORM_addrx
  81                                           : dwarf::DW_FORM_GNU_addr_index,
  82                DIEInteger(idx));
  83 }
  84
  85 void DwarfCompileUnit::addLocalLabelAddress(DIE &Die,
  86                                             dwarf::Attribute Attribute,
  87                                             const MCSymbol *Label) {
  88   if (Label)
  89     DD->addArangeLabel(SymbolCU(this, Label));
  90
  91   if (Label)
  92     Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_addr,
  93                  DIELabel(Label));
  94   else
  95     Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_addr,
  96                  DIEInteger(0));
  97 }
  98
  99 unsigned DwarfCompileUnit::getOrCreateSourceID(const DIFile *File) {
 100   // If we print assembly, we can't separate .file entries according to
 101   // compile units. Thus all files will belong to the default compile unit.
 102
 103   // FIXME: add a better feature test than hasRawTextSupport. Even better,
 104   // extend .file to support this.
 105   unsigned CUID = Asm->OutStreamer->hasRawTextSupport() ? 0 : getUniqueID();
 106   if (!File)
 107     return Asm->OutStreamer->EmitDwarfFileDirective(0, "", "", None, None, CUID);
 108   return Asm->OutStreamer->EmitDwarfFileDirective(
 109       0, File->getDirectory(), File->getFilename(), getMD5AsBytes(File),
 110       File->getSource(), CUID);
 111 }
 112
 113 DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(
 114     const DIGlobalVariable *GV, ArrayRef<GlobalExpr> GlobalExprs) {
 115   // Check for pre-existence.
 116   if (DIE *Die = getDIE(GV))
 117     return Die;
 118
 119   assert(GV);
 120
 121   auto *GVContext = GV->getScope();
 122   const DIType *GTy = GV->getType();
 123
 124   // Construct the context before querying for the existence of the DIE in
 125   // case such construction creates the DIE.
 126   auto *CB = GVContext ? dyn_cast<DICommonBlock>(GVContext) : nullptr;
 127   DIE *ContextDIE = CB ? getOrCreateCommonBlock(CB, GlobalExprs)
 128     : getOrCreateContextDIE(GVContext);
 129
 130   // Add to map.
 131   DIE *VariableDIE = &createAndAddDIE(GV->getTag(), *ContextDIE, GV);
 132   DIScope *DeclContext;
 133   if (auto *SDMDecl = GV->getStaticDataMemberDeclaration()) {
 134     DeclContext = SDMDecl->getScope();
 135     assert(SDMDecl->isStaticMember() && "Expected static member decl");
 136     assert(GV->isDefinition());
 137     // We need the declaration DIE that is in the static member's class.
 138     DIE *VariableSpecDIE = getOrCreateStaticMemberDIE(SDMDecl);
 139     addDIEEntry(*VariableDIE, dwarf::DW_AT_specification, *VariableSpecDIE);
 140     // If the global variable's type is different from the one in the class
 141     // member type, assume that it's more specific and also emit it.
 142     if (GTy != SDMDecl->getBaseType())
 143       addType(*VariableDIE, GTy);
 144   } else {
 145     DeclContext = GV->getScope();
 146     // Add name and type.
 147     addString(*VariableDIE, dwarf::DW_AT_name, GV->getDisplayName());
 148     addType(*VariableDIE, GTy);
 149
 150     // Add scoping info.
 151     if (!GV->isLocalToUnit())
 152       addFlag(*VariableDIE, dwarf::DW_AT_external);
 153
 154     // Add line number info.
 155     addSourceLine(*VariableDIE, GV);
 156   }
 157
 158   if (!GV->isDefinition())
 159     addFlag(*VariableDIE, dwarf::DW_AT_declaration);
 160   else
 161     addGlobalName(GV->getName(), *VariableDIE, DeclContext);
 162
 163   if (uint32_t AlignInBytes = GV->getAlignInBytes())
 164     addUInt(*VariableDIE, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,
 165             AlignInBytes);
 166
 167   if (MDTuple *TP = GV->getTemplateParams())
 168     addTemplateParams(*VariableDIE, DINodeArray(TP));
 169
 170   // Add location.
 171   addLocationAttribute(VariableDIE, GV, GlobalExprs);
 172
 173   return VariableDIE;
 174 }
 175
 176 void DwarfCompileUnit::addLocationAttribute(
 177     DIE *VariableDIE, const DIGlobalVariable *GV, ArrayRef<GlobalExpr> GlobalExprs) {
 178   bool addToAccelTable = false;
 179   DIELoc *Loc = nullptr;
 180   Optional<unsigned> NVPTXAddressSpace;
 181   std::unique_ptr<DIEDwarfExpression> DwarfExpr;
 182   for (const auto &GE : GlobalExprs) {
 183     const GlobalVariable *Global = GE.Var;
 184     const DIExpression *Expr = GE.Expr;
 185
 186     // For compatibility with DWARF 3 and earlier,
 187     // DW_AT_location(DW_OP_constu, X, DW_OP_stack_value) becomes
 188     // DW_AT_const_value(X).
 189     if (GlobalExprs.size() == 1 && Expr && Expr->isConstant()) {
 190       addToAccelTable = true;
 191       addConstantValue(*VariableDIE, /*Unsigned=*/true, Expr->getElement(1));
 192       break;
 193     }
 194
 195     // We cannot describe the location of dllimport'd variables: the
 196     // computation of their address requires loads from the IAT.
 197     if (Global && Global->hasDLLImportStorageClass())
 198       continue;
 199
 200     // Nothing to describe without address or constant.
 201     if (!Global && (!Expr || !Expr->isConstant()))
 202       continue;
 203
 204     if (Global && Global->isThreadLocal() &&
 205         !Asm->getObjFileLowering().supportDebugThreadLocalLocation())
 206       continue;
 207
 208     if (!Loc) {
 209       addToAccelTable = true;
 210       Loc = new (DIEValueAllocator) DIELoc;
 211       DwarfExpr = std::make_unique<DIEDwarfExpression>(*Asm, *this, *Loc);
 212     }
 213
 214     if (Expr) {
 215       // According to
 216       // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
 217       // cuda-gdb requires DW_AT_address_class for all variables to be able to
 218       // correctly interpret address space of the variable address.
 219       // Decode DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef
 220       // sequence for the NVPTX + gdb target.
 221       unsigned LocalNVPTXAddressSpace;
 222       if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
 223         const DIExpression *NewExpr =
 224             DIExpression::extractAddressClass(Expr, LocalNVPTXAddressSpace);
 225         if (NewExpr != Expr) {
 226           Expr = NewExpr;
 227           NVPTXAddressSpace = LocalNVPTXAddressSpace;
 228         }
 229       }
 230       DwarfExpr->addFragmentOffset(Expr);
 231     }
 232
 233     if (Global) {
 234       const MCSymbol *Sym = Asm->getSymbol(Global);
 235       if (Global->isThreadLocal()) {
 236         if (Asm->TM.useEmulatedTLS()) {
 237           // TODO: add debug info for emulated thread local mode.
 238         } else {
 239           // FIXME: Make this work with -gsplit-dwarf.
 240           unsigned PointerSize = Asm->getDataLayout().getPointerSize();
 241           assert((PointerSize == 4 || PointerSize == 8) &&
 242                  "Add support for other sizes if necessary");
 243           // Based on GCC's support for TLS:
 244           if (!DD->useSplitDwarf()) {
 245             // 1) Start with a constNu of the appropriate pointer size
 246             addUInt(*Loc, dwarf::DW_FORM_data1,
 247                     PointerSize == 4 ? dwarf::DW_OP_const4u
 248                                      : dwarf::DW_OP_const8u);
 249             // 2) containing the (relocated) offset of the TLS variable
 250             //    within the module's TLS block.
 251             addExpr(*Loc, dwarf::DW_FORM_udata,
 252                     Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
 253           } else {
 254             addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index);
 255             addUInt(*Loc, dwarf::DW_FORM_udata,
 256                     DD->getAddressPool().getIndex(Sym, /* TLS */ true));
 257           }
 258           // 3) followed by an OP to make the debugger do a TLS lookup.
 259           addUInt(*Loc, dwarf::DW_FORM_data1,
 260                   DD->useGNUTLSOpcode() ? dwarf::DW_OP_GNU_push_tls_address
 261                                         : dwarf::DW_OP_form_tls_address);
 262         }
 263       } else {
 264         DD->addArangeLabel(SymbolCU(this, Sym));
 265         addOpAddress(*Loc, Sym);
 266       }
 267     }
 268     // Global variables attached to symbols are memory locations.
 269     // It would be better if this were unconditional, but malformed input that
 270     // mixes non-fragments and fragments for the same variable is too expensive
 271     // to detect in the verifier.
 272     if (DwarfExpr->isUnknownLocation())
 273       DwarfExpr->setMemoryLocationKind();
 274     DwarfExpr->addExpression(Expr);
 275   }
 276   if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
 277     // According to
 278     // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
 279     // cuda-gdb requires DW_AT_address_class for all variables to be able to
 280     // correctly interpret address space of the variable address.
 281     const unsigned NVPTX_ADDR_global_space = 5;
 282     addUInt(*VariableDIE, dwarf::DW_AT_address_class, dwarf::DW_FORM_data1,
 283             NVPTXAddressSpace ? *NVPTXAddressSpace : NVPTX_ADDR_global_space);
 284   }
 285   if (Loc)
 286     addBlock(*VariableDIE, dwarf::DW_AT_location, DwarfExpr->finalize());
 287
 288   if (DD->useAllLinkageNames())
 289     addLinkageName(*VariableDIE, GV->getLinkageName());
 290
 291   if (addToAccelTable) {
 292     DD->addAccelName(*CUNode, GV->getName(), *VariableDIE);
 293
 294     // If the linkage name is different than the name, go ahead and output
 295     // that as well into the name table.
 296     if (GV->getLinkageName() != "" && GV->getName() != GV->getLinkageName() &&
 297         DD->useAllLinkageNames())
 298       DD->addAccelName(*CUNode, GV->getLinkageName(), *VariableDIE);
 299   }
 300 }
 301
 302 DIE *DwarfCompileUnit::getOrCreateCommonBlock(
 303     const DICommonBlock *CB, ArrayRef<GlobalExpr> GlobalExprs) {
 304   // Construct the context before querying for the existence of the DIE in case
 305   // such construction creates the DIE.
 306   DIE *ContextDIE = getOrCreateContextDIE(CB->getScope());
 307
 308   if (DIE *NDie = getDIE(CB))
 309     return NDie;
 310   DIE &NDie = createAndAddDIE(dwarf::DW_TAG_common_block, *ContextDIE, CB);
 311   StringRef Name = CB->getName().empty() ? "_BLNK_" : CB->getName();
 312   addString(NDie, dwarf::DW_AT_name, Name);
 313   addGlobalName(Name, NDie, CB->getScope());
 314   if (CB->getFile())
 315     addSourceLine(NDie, CB->getLineNo(), CB->getFile());
 316   if (DIGlobalVariable *V = CB->getDecl())
 317     getCU().addLocationAttribute(&NDie, V, GlobalExprs);
 318   return &NDie;
 319 }
 320
 321 void DwarfCompileUnit::addRange(RangeSpan Range) {
 322   bool SameAsPrevCU = this == DD->getPrevCU();
 323   DD->setPrevCU(this);
 324   // If we have no current ranges just add the range and return, otherwise,
 325   // check the current section and CU against the previous section and CU we
 326   // emitted into and the subprogram was contained within. If these are the
 327   // same then extend our current range, otherwise add this as a new range.
 328   if (CURanges.empty() || !SameAsPrevCU ||
 329       (&CURanges.back().End->getSection() !=
 330        &Range.End->getSection())) {
 331     CURanges.push_back(Range);
 332     return;
 333   }
 334
 335   CURanges.back().End = Range.End;
 336 }
 337
 338 void DwarfCompileUnit::initStmtList() {
 339   if (CUNode->isDebugDirectivesOnly())
 340     return;
 341
 342   // Define start line table label for each Compile Unit.
 343   MCSymbol *LineTableStartSym;
 344   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
 345   if (DD->useSectionsAsReferences()) {
 346     LineTableStartSym = TLOF.getDwarfLineSection()->getBeginSymbol();
 347   } else {
 348     LineTableStartSym =
 349         Asm->OutStreamer->getDwarfLineTableSymbol(getUniqueID());
 350   }
 351
 352   // DW_AT_stmt_list is a offset of line number information for this
 353   // compile unit in debug_line section. For split dwarf this is
 354   // left in the skeleton CU and so not included.
 355   // The line table entries are not always emitted in assembly, so it
 356   // is not okay to use line_table_start here.
 357   StmtListValue =
 358       addSectionLabel(getUnitDie(), dwarf::DW_AT_stmt_list, LineTableStartSym,
 359                       TLOF.getDwarfLineSection()->getBeginSymbol());
 360 }
 361
 362 void DwarfCompileUnit::applyStmtList(DIE &D) {
 363   D.addValue(DIEValueAllocator, *StmtListValue);
 364 }
 365
 366 void DwarfCompileUnit::attachLowHighPC(DIE &D, const MCSymbol *Begin,
 367                                        const MCSymbol *End) {
 368   assert(Begin && "Begin label should not be null!");
 369   assert(End && "End label should not be null!");
 370   assert(Begin->isDefined() && "Invalid starting label");
 371   assert(End->isDefined() && "Invalid end label");
 372
 373   addLabelAddress(D, dwarf::DW_AT_low_pc, Begin);
 374   if (DD->getDwarfVersion() < 4)
 375     addLabelAddress(D, dwarf::DW_AT_high_pc, End);
 376   else
 377     addLabelDelta(D, dwarf::DW_AT_high_pc, End, Begin);
 378 }
 379
 380 // Find DIE for the given subprogram and attach appropriate DW_AT_low_pc
 381 // and DW_AT_high_pc attributes. If there are global variables in this
 382 // scope then create and insert DIEs for these variables.
 383 DIE &DwarfCompileUnit::updateSubprogramScopeDIE(const DISubprogram *SP) {
 384   DIE *SPDie = getOrCreateSubprogramDIE(SP, includeMinimalInlineScopes());
 385
 386   attachLowHighPC(*SPDie, Asm->getFunctionBegin(), Asm->getFunctionEnd());
 387   if (DD->useAppleExtensionAttributes() &&
 388       !DD->getCurrentFunction()->getTarget().Options.DisableFramePointerElim(
 389           *DD->getCurrentFunction()))
 390     addFlag(*SPDie, dwarf::DW_AT_APPLE_omit_frame_ptr);
 391
 392   // Only include DW_AT_frame_base in full debug info
 393   if (!includeMinimalInlineScopes()) {
 394     if (Asm->MF->getTarget().getTargetTriple().isNVPTX()) {
 395       DIELoc *Loc = new (DIEValueAllocator) DIELoc;
 396       addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_call_frame_cfa);
 397       addBlock(*SPDie, dwarf::DW_AT_frame_base, Loc);
 398     } else {
 399       const TargetRegisterInfo *RI = Asm->MF->getSubtarget().getRegisterInfo();
 400       MachineLocation Location(RI->getFrameRegister(*Asm->MF));
 401       if (Register::isPhysicalRegister(Location.getReg()))
 402         addAddress(*SPDie, dwarf::DW_AT_frame_base, Location);
 403     }
 404   }
 405
 406   // Add name to the name table, we do this here because we're guaranteed
 407   // to have concrete versions of our DW_TAG_subprogram nodes.
 408   DD->addSubprogramNames(*CUNode, SP, *SPDie);
 409
 410   return *SPDie;
 411 }
 412
 413 // Construct a DIE for this scope.
 414 void DwarfCompileUnit::constructScopeDIE(
 415     LexicalScope *Scope, SmallVectorImpl<DIE *> &FinalChildren) {
 416   if (!Scope || !Scope->getScopeNode())
 417     return;
 418
 419   auto *DS = Scope->getScopeNode();
 420
 421   assert((Scope->getInlinedAt() || !isa<DISubprogram>(DS)) &&
 422          "Only handle inlined subprograms here, use "
 423          "constructSubprogramScopeDIE for non-inlined "
 424          "subprograms");
 425
 426   SmallVector<DIE *, 8> Children;
 427
 428   // We try to create the scope DIE first, then the children DIEs. This will
 429   // avoid creating un-used children then removing them later when we find out
 430   // the scope DIE is null.
 431   DIE *ScopeDIE;
 432   if (Scope->getParent() && isa<DISubprogram>(DS)) {
 433     ScopeDIE = constructInlinedScopeDIE(Scope);
 434     if (!ScopeDIE)
 435       return;
 436     // We create children when the scope DIE is not null.
 437     createScopeChildrenDIE(Scope, Children);
 438   } else {
 439     // Early exit when we know the scope DIE is going to be null.
 440     if (DD->isLexicalScopeDIENull(Scope))
 441       return;
 442
 443     bool HasNonScopeChildren = false;
 444
 445     // We create children here when we know the scope DIE is not going to be
 446     // null and the children will be added to the scope DIE.
 447     createScopeChildrenDIE(Scope, Children, &HasNonScopeChildren);
 448
 449     // If there are only other scopes as children, put them directly in the
 450     // parent instead, as this scope would serve no purpose.
 451     if (!HasNonScopeChildren) {
 452       FinalChildren.insert(FinalChildren.end(),
 453                            std::make_move_iterator(Children.begin()),
 454                            std::make_move_iterator(Children.end()));
 455       return;
 456     }
 457     ScopeDIE = constructLexicalScopeDIE(Scope);
 458     assert(ScopeDIE && "Scope DIE should not be null.");
 459   }
 460
 461   // Add children
 462   for (auto &I : Children)
 463     ScopeDIE->addChild(std::move(I));
 464
 465   FinalChildren.push_back(std::move(ScopeDIE));
 466 }
 467
 468 void DwarfCompileUnit::addScopeRangeList(DIE &ScopeDIE,
 469                                          SmallVector<RangeSpan, 2> Range) {
 470
 471   HasRangeLists = true;
 472
 473   // Add the range list to the set of ranges to be emitted.
 474   auto IndexAndList =
 475       (DD->getDwarfVersion() < 5 && Skeleton ? Skeleton->DU : DU)
 476           ->addRange(*(Skeleton ? Skeleton : this), std::move(Range));
 477
 478   uint32_t Index = IndexAndList.first;
 479   auto &List = *IndexAndList.second;
 480
 481   // Under fission, ranges are specified by constant offsets relative to the
 482   // CU's DW_AT_GNU_ranges_base.
 483   // FIXME: For DWARF v5, do not generate the DW_AT_ranges attribute under
 484   // fission until we support the forms using the .debug_addr section
 485   // (DW_RLE_startx_endx etc.).
 486   if (DD->getDwarfVersion() >= 5)
 487     addUInt(ScopeDIE, dwarf::DW_AT_ranges, dwarf::DW_FORM_rnglistx, Index);
 488   else {
 489     const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
 490     const MCSymbol *RangeSectionSym =
 491         TLOF.getDwarfRangesSection()->getBeginSymbol();
 492     if (isDwoUnit())
 493       addSectionDelta(ScopeDIE, dwarf::DW_AT_ranges, List.getSym(),
 494                       RangeSectionSym);
 495     else
 496       addSectionLabel(ScopeDIE, dwarf::DW_AT_ranges, List.getSym(),
 497                       RangeSectionSym);
 498   }
 499 }
 500
 501 void DwarfCompileUnit::attachRangesOrLowHighPC(
 502     DIE &Die, SmallVector<RangeSpan, 2> Ranges) {
 503   if (Ranges.size() == 1 || !DD->useRangesSection()) {
 504     const RangeSpan &Front = Ranges.front();
 505     const RangeSpan &Back = Ranges.back();
 506     attachLowHighPC(Die, Front.Begin, Back.End);
 507   } else
 508     addScopeRangeList(Die, std::move(Ranges));
 509 }
 510
 511 void DwarfCompileUnit::attachRangesOrLowHighPC(
 512     DIE &Die, const SmallVectorImpl<InsnRange> &Ranges) {
 513   SmallVector<RangeSpan, 2> List;
 514   List.reserve(Ranges.size());
 515   for (const InsnRange &R : Ranges)
 516     List.push_back(
 517         {DD->getLabelBeforeInsn(R.first), DD->getLabelAfterInsn(R.second)});
 518   attachRangesOrLowHighPC(Die, std::move(List));
 519 }
 520
 521 // This scope represents inlined body of a function. Construct DIE to
 522 // represent this concrete inlined copy of the function.
 523 DIE *DwarfCompileUnit::constructInlinedScopeDIE(LexicalScope *Scope) {
 524   assert(Scope->getScopeNode());
 525   auto *DS = Scope->getScopeNode();
 526   auto *InlinedSP = getDISubprogram(DS);
 527   // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
 528   // was inlined from another compile unit.
 529   DIE *OriginDIE = getAbstractSPDies()[InlinedSP];
 530   assert(OriginDIE && "Unable to find original DIE for an inlined subprogram.");
 531
 532   auto ScopeDIE = DIE::get(DIEValueAllocator, dwarf::DW_TAG_inlined_subroutine);
 533   addDIEEntry(*ScopeDIE, dwarf::DW_AT_abstract_origin, *OriginDIE);
 534
 535   attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());
 536
 537   // Add the call site information to the DIE.
 538   const DILocation *IA = Scope->getInlinedAt();
 539   addUInt(*ScopeDIE, dwarf::DW_AT_call_file, None,
 540           getOrCreateSourceID(IA->getFile()));
 541   addUInt(*ScopeDIE, dwarf::DW_AT_call_line, None, IA->getLine());
 542   if (IA->getColumn())
 543     addUInt(*ScopeDIE, dwarf::DW_AT_call_column, None, IA->getColumn());
 544   if (IA->getDiscriminator() && DD->getDwarfVersion() >= 4)
 545     addUInt(*ScopeDIE, dwarf::DW_AT_GNU_discriminator, None,
 546             IA->getDiscriminator());
 547
 548   // Add name to the name table, we do this here because we're guaranteed
 549   // to have concrete versions of our DW_TAG_inlined_subprogram nodes.
 550   DD->addSubprogramNames(*CUNode, InlinedSP, *ScopeDIE);
 551
 552   return ScopeDIE;
 553 }
 554
 555 // Construct new DW_TAG_lexical_block for this scope and attach
 556 // DW_AT_low_pc/DW_AT_high_pc labels.
 557 DIE *DwarfCompileUnit::constructLexicalScopeDIE(LexicalScope *Scope) {
 558   if (DD->isLexicalScopeDIENull(Scope))
 559     return nullptr;
 560
 561   auto ScopeDIE = DIE::get(DIEValueAllocator, dwarf::DW_TAG_lexical_block);
 562   if (Scope->isAbstractScope())
 563     return ScopeDIE;
 564
 565   attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());
 566
 567   return ScopeDIE;
 568 }
 569
 570 /// constructVariableDIE - Construct a DIE for the given DbgVariable.
 571 DIE *DwarfCompileUnit::constructVariableDIE(DbgVariable &DV, bool Abstract) {
 572   auto D = constructVariableDIEImpl(DV, Abstract);
 573   DV.setDIE(*D);
 574   return D;
 575 }
 576
 577 DIE *DwarfCompileUnit::constructLabelDIE(DbgLabel &DL,
 578                                          const LexicalScope &Scope) {
 579   auto LabelDie = DIE::get(DIEValueAllocator, DL.getTag());
 580   insertDIE(DL.getLabel(), LabelDie);
 581   DL.setDIE(*LabelDie);
 582
 583   if (Scope.isAbstractScope())
 584     applyLabelAttributes(DL, *LabelDie);
 585
 586   return LabelDie;
 587 }
 588
 589 DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
 590                                                 bool Abstract) {
 591   // Define variable debug information entry.
 592   auto VariableDie = DIE::get(DIEValueAllocator, DV.getTag());
 593   insertDIE(DV.getVariable(), VariableDie);
 594
 595   if (Abstract) {
 596     applyVariableAttributes(DV, *VariableDie);
 597     return VariableDie;
 598   }
 599
 600   // Add variable address.
 601
 602   unsigned Offset = DV.getDebugLocListIndex();
 603   if (Offset != ~0U) {
 604     addLocationList(*VariableDie, dwarf::DW_AT_location, Offset);
 605     return VariableDie;
 606   }
 607
 608   // Check if variable has a single location description.
 609   if (auto *DVal = DV.getValueLoc()) {
 610     if (DVal->isLocation())
 611       addVariableAddress(DV, *VariableDie, DVal->getLoc());
 612     else if (DVal->isInt()) {
 613       auto *Expr = DV.getSingleExpression();
 614       if (Expr && Expr->getNumElements()) {
 615         DIELoc *Loc = new (DIEValueAllocator) DIELoc;
 616         DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
 617         // If there is an expression, emit raw unsigned bytes.
 618         DwarfExpr.addFragmentOffset(Expr);
 619         DwarfExpr.addUnsignedConstant(DVal->getInt());
 620         DwarfExpr.addExpression(Expr);
 621         addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
 622       } else
 623         addConstantValue(*VariableDie, DVal->getInt(), DV.getType());
 624     } else if (DVal->isConstantFP()) {
 625       addConstantFPValue(*VariableDie, DVal->getConstantFP());
 626     } else if (DVal->isConstantInt()) {
 627       addConstantValue(*VariableDie, DVal->getConstantInt(), DV.getType());
 628     }
 629     return VariableDie;
 630   }
 631
 632   // .. else use frame index.
 633   if (!DV.hasFrameIndexExprs())
 634     return VariableDie;
 635
 636   Optional<unsigned> NVPTXAddressSpace;
 637   DIELoc *Loc = new (DIEValueAllocator) DIELoc;
 638   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
 639   for (auto &Fragment : DV.getFrameIndexExprs()) {
 640     unsigned FrameReg = 0;
 641     const DIExpression *Expr = Fragment.Expr;
 642     const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
 643     int Offset = TFI->getFrameIndexReference(*Asm->MF, Fragment.FI, FrameReg);
 644     DwarfExpr.addFragmentOffset(Expr);
 645     SmallVector<uint64_t, 8> Ops;
 646     DIExpression::appendOffset(Ops, Offset);
 647     // According to
 648     // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
 649     // cuda-gdb requires DW_AT_address_class for all variables to be able to
 650     // correctly interpret address space of the variable address.
 651     // Decode DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef
 652     // sequence for the NVPTX + gdb target.
 653     unsigned LocalNVPTXAddressSpace;
 654     if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
 655       const DIExpression *NewExpr =
 656           DIExpression::extractAddressClass(Expr, LocalNVPTXAddressSpace);
 657       if (NewExpr != Expr) {
 658         Expr = NewExpr;
 659         NVPTXAddressSpace = LocalNVPTXAddressSpace;
 660       }
 661     }
 662     if (Expr)
 663       Ops.append(Expr->elements_begin(), Expr->elements_end());
 664     DIExpressionCursor Cursor(Ops);
 665     DwarfExpr.setMemoryLocationKind();
 666     if (const MCSymbol *FrameSymbol = Asm->getFunctionFrameSymbol())
 667       addOpAddress(*Loc, FrameSymbol);
 668     else
 669       DwarfExpr.addMachineRegExpression(
 670           *Asm->MF->getSubtarget().getRegisterInfo(), Cursor, FrameReg);
 671     DwarfExpr.addExpression(std::move(Cursor));
 672   }
 673   if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
 674     // According to
 675     // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
 676     // cuda-gdb requires DW_AT_address_class for all variables to be able to
 677     // correctly interpret address space of the variable address.
 678     const unsigned NVPTX_ADDR_local_space = 6;
 679     addUInt(*VariableDie, dwarf::DW_AT_address_class, dwarf::DW_FORM_data1,
 680             NVPTXAddressSpace ? *NVPTXAddressSpace : NVPTX_ADDR_local_space);
 681   }
 682   addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
 683   if (DwarfExpr.TagOffset)
 684     addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
 685             *DwarfExpr.TagOffset);
 686
 687   return VariableDie;
 688 }
 689
 690 DIE *DwarfCompileUnit::constructVariableDIE(DbgVariable &DV,
 691                                             const LexicalScope &Scope,
 692                                             DIE *&ObjectPointer) {
 693   auto Var = constructVariableDIE(DV, Scope.isAbstractScope());
 694   if (DV.isObjectPointer())
 695     ObjectPointer = Var;
 696   return Var;
 697 }
 698
 699 /// Return all DIVariables that appear in count: expressions.
 700 static SmallVector<const DIVariable *, 2> dependencies(DbgVariable *Var) {
 701   SmallVector<const DIVariable *, 2> Result;
 702   auto *Array = dyn_cast<DICompositeType>(Var->getType());
 703   if (!Array || Array->getTag() != dwarf::DW_TAG_array_type)
 704     return Result;
 705   for (auto *El : Array->getElements()) {
 706     if (auto *Subrange = dyn_cast<DISubrange>(El)) {
 707       auto Count = Subrange->getCount();
 708       if (auto *Dependency = Count.dyn_cast<DIVariable *>())
 709         Result.push_back(Dependency);
 710     }
 711   }
 712   return Result;
 713 }
 714
 715 /// Sort local variables so that variables appearing inside of helper
 716 /// expressions come first.
 717 static SmallVector<DbgVariable *, 8>
 718 sortLocalVars(SmallVectorImpl<DbgVariable *> &Input) {
 719   SmallVector<DbgVariable *, 8> Result;
 720   SmallVector<PointerIntPair<DbgVariable *, 1>, 8> WorkList;
 721   // Map back from a DIVariable to its containing DbgVariable.
 722   SmallDenseMap<const DILocalVariable *, DbgVariable *> DbgVar;
 723   // Set of DbgVariables in Result.
 724   SmallDenseSet<DbgVariable *, 8> Visited;
 725   // For cycle detection.
 726   SmallDenseSet<DbgVariable *, 8> Visiting;
 727
 728   // Initialize the worklist and the DIVariable lookup table.
 729   for (auto Var : reverse(Input)) {
 730     DbgVar.insert({Var->getVariable(), Var});
 731     WorkList.push_back({Var, 0});
 732   }
 733
 734   // Perform a stable topological sort by doing a DFS.
 735   while (!WorkList.empty()) {
 736     auto Item = WorkList.back();
 737     DbgVariable *Var = Item.getPointer();
 738     bool visitedAllDependencies = Item.getInt();
 739     WorkList.pop_back();
 740
 741     // Dependency is in a different lexical scope or a global.
 742     if (!Var)
 743       continue;
 744
 745     // Already handled.
 746     if (Visited.count(Var))
 747       continue;
 748
 749     // Add to Result if all dependencies are visited.
 750     if (visitedAllDependencies) {
 751       Visited.insert(Var);
 752       Result.push_back(Var);
 753       continue;
 754     }
 755
 756     // Detect cycles.
 757     auto Res = Visiting.insert(Var);
 758     if (!Res.second) {
 759       assert(false && "dependency cycle in local variables");
 760       return Result;
 761     }
 762
 763     // Push dependencies and this node onto the worklist, so that this node is
 764     // visited again after all of its dependencies are handled.
 765     WorkList.push_back({Var, 1});
 766     for (auto *Dependency : dependencies(Var)) {
 767       auto Dep = dyn_cast_or_null<const DILocalVariable>(Dependency);
 768       WorkList.push_back({DbgVar[Dep], 0});
 769     }
 770   }
 771   return Result;
 772 }
 773
 774 DIE *DwarfCompileUnit::createScopeChildrenDIE(LexicalScope *Scope,
 775                                               SmallVectorImpl<DIE *> &Children,
 776                                               bool *HasNonScopeChildren) {
 777   assert(Children.empty());
 778   DIE *ObjectPointer = nullptr;
 779
 780   // Emit function arguments (order is significant).
 781   auto Vars = DU->getScopeVariables().lookup(Scope);
 782   for (auto &DV : Vars.Args)
 783     Children.push_back(constructVariableDIE(*DV.second, *Scope, ObjectPointer));
 784
 785   // Emit local variables.
 786   auto Locals = sortLocalVars(Vars.Locals);
 787   for (DbgVariable *DV : Locals)
 788     Children.push_back(constructVariableDIE(*DV, *Scope, ObjectPointer));
 789
 790   // Skip imported directives in gmlt-like data.
 791   if (!includeMinimalInlineScopes()) {
 792     // There is no need to emit empty lexical block DIE.
 793     for (const auto *IE : ImportedEntities[Scope->getScopeNode()])
 794       Children.push_back(
 795           constructImportedEntityDIE(cast<DIImportedEntity>(IE)));
 796   }
 797
 798   if (HasNonScopeChildren)
 799     *HasNonScopeChildren = !Children.empty();
 800
 801   for (DbgLabel *DL : DU->getScopeLabels().lookup(Scope))
 802     Children.push_back(constructLabelDIE(*DL, *Scope));
 803
 804   for (LexicalScope *LS : Scope->getChildren())
 805     constructScopeDIE(LS, Children);
 806
 807   return ObjectPointer;
 808 }
 809
 810 DIE &DwarfCompileUnit::constructSubprogramScopeDIE(const DISubprogram *Sub,
 811                                                    LexicalScope *Scope) {
 812   DIE &ScopeDIE = updateSubprogramScopeDIE(Sub);
 813
 814   if (Scope) {
 815     assert(!Scope->getInlinedAt());
 816     assert(!Scope->isAbstractScope());
 817     // Collect lexical scope children first.
 818     // ObjectPointer might be a local (non-argument) local variable if it's a
 819     // block's synthetic this pointer.
 820     if (DIE *ObjectPointer = createAndAddScopeChildren(Scope, ScopeDIE))
 821       addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
 822   }
 823
 824   // If this is a variadic function, add an unspecified parameter.
 825   DITypeRefArray FnArgs = Sub->getType()->getTypeArray();
 826
 827   // If we have a single element of null, it is a function that returns void.
 828   // If we have more than one elements and the last one is null, it is a
 829   // variadic function.
 830   if (FnArgs.size() > 1 && !FnArgs[FnArgs.size() - 1] &&
 831       !includeMinimalInlineScopes())
 832     ScopeDIE.addChild(
 833         DIE::get(DIEValueAllocator, dwarf::DW_TAG_unspecified_parameters));
 834
 835   return ScopeDIE;
 836 }
 837
 838 DIE *DwarfCompileUnit::createAndAddScopeChildren(LexicalScope *Scope,
 839                                                  DIE &ScopeDIE) {
 840   // We create children when the scope DIE is not null.
 841   SmallVector<DIE *, 8> Children;
 842   DIE *ObjectPointer = createScopeChildrenDIE(Scope, Children);
 843
 844   // Add children
 845   for (auto &I : Children)
 846     ScopeDIE.addChild(std::move(I));
 847
 848   return ObjectPointer;
 849 }
 850
 851 void DwarfCompileUnit::constructAbstractSubprogramScopeDIE(
 852     LexicalScope *Scope) {
 853   DIE *&AbsDef = getAbstractSPDies()[Scope->getScopeNode()];
 854   if (AbsDef)
 855     return;
 856
 857   auto *SP = cast<DISubprogram>(Scope->getScopeNode());
 858
 859   DIE *ContextDIE;
 860   DwarfCompileUnit *ContextCU = this;
 861
 862   if (includeMinimalInlineScopes())
 863     ContextDIE = &getUnitDie();
 864   // Some of this is duplicated from DwarfUnit::getOrCreateSubprogramDIE, with
 865   // the important distinction that the debug node is not associated with the
 866   // DIE (since the debug node will be associated with the concrete DIE, if
 867   // any). It could be refactored to some common utility function.
 868   else if (auto *SPDecl = SP->getDeclaration()) {
 869     ContextDIE = &getUnitDie();
 870     getOrCreateSubprogramDIE(SPDecl);
 871   } else {
 872     ContextDIE = getOrCreateContextDIE(SP->getScope());
 873     // The scope may be shared with a subprogram that has already been
 874     // constructed in another CU, in which case we need to construct this
 875     // subprogram in the same CU.
 876     ContextCU = DD->lookupCU(ContextDIE->getUnitDie());
 877   }
 878
 879   // Passing null as the associated node because the abstract definition
 880   // shouldn't be found by lookup.
 881   AbsDef = &ContextCU->createAndAddDIE(dwarf::DW_TAG_subprogram, *ContextDIE, nullptr);
 882   ContextCU->applySubprogramAttributesToDefinition(SP, *AbsDef);
 883
 884   if (!ContextCU->includeMinimalInlineScopes())
 885     ContextCU->addUInt(*AbsDef, dwarf::DW_AT_inline, None, dwarf::DW_INL_inlined);
 886   if (DIE *ObjectPointer = ContextCU->createAndAddScopeChildren(Scope, *AbsDef))
 887     ContextCU->addDIEEntry(*AbsDef, dwarf::DW_AT_object_pointer, *ObjectPointer);
 888 }
 889
 890 /// Whether to use the GNU analog for a DWARF5 tag, attribute, or location atom.
 891 static bool useGNUAnalogForDwarf5Feature(DwarfDebug *DD) {
 892   return DD->getDwarfVersion() == 4 && DD->tuneForGDB();
 893 }
 894
 895 dwarf::Tag DwarfCompileUnit::getDwarf5OrGNUTag(dwarf::Tag Tag) const {
 896   if (!useGNUAnalogForDwarf5Feature(DD))
 897     return Tag;
 898   switch (Tag) {
 899   case dwarf::DW_TAG_call_site:
 900     return dwarf::DW_TAG_GNU_call_site;
 901   case dwarf::DW_TAG_call_site_parameter:
 902     return dwarf::DW_TAG_GNU_call_site_parameter;
 903   default:
 904     llvm_unreachable("DWARF5 tag with no GNU analog");
 905   }
 906 }
 907
 908 dwarf::Attribute
 909 DwarfCompileUnit::getDwarf5OrGNUAttr(dwarf::Attribute Attr) const {
 910   if (!useGNUAnalogForDwarf5Feature(DD))
 911     return Attr;
 912   switch (Attr) {
 913   case dwarf::DW_AT_call_all_calls:
 914     return dwarf::DW_AT_GNU_all_call_sites;
 915   case dwarf::DW_AT_call_target:
 916     return dwarf::DW_AT_GNU_call_site_target;
 917   case dwarf::DW_AT_call_origin:
 918     return dwarf::DW_AT_abstract_origin;
 919   case dwarf::DW_AT_call_pc:
 920     return dwarf::DW_AT_low_pc;
 921   case dwarf::DW_AT_call_value:
 922     return dwarf::DW_AT_GNU_call_site_value;
 923   case dwarf::DW_AT_call_tail_call:
 924     return dwarf::DW_AT_GNU_tail_call;
 925   default:
 926     llvm_unreachable("DWARF5 attribute with no GNU analog");
 927   }
 928 }
 929
 930 dwarf::LocationAtom
 931 DwarfCompileUnit::getDwarf5OrGNULocationAtom(dwarf::LocationAtom Loc) const {
 932   if (!useGNUAnalogForDwarf5Feature(DD))
 933     return Loc;
 934   switch (Loc) {
 935   case dwarf::DW_OP_entry_value:
 936     return dwarf::DW_OP_GNU_entry_value;
 937   default:
 938     llvm_unreachable("DWARF5 location atom with no GNU analog");
 939   }
 940 }
 941
 942 DIE &DwarfCompileUnit::constructCallSiteEntryDIE(
 943     DIE &ScopeDIE, const DISubprogram *CalleeSP, bool IsTail,
 944     const MCSymbol *PCAddr, const MCExpr *PCOffset, unsigned CallReg) {
 945   // Insert a call site entry DIE within ScopeDIE.
 946   DIE &CallSiteDIE = createAndAddDIE(getDwarf5OrGNUTag(dwarf::DW_TAG_call_site),
 947                                      ScopeDIE, nullptr);
 948
 949   if (CallReg) {
 950     // Indirect call.
 951     addAddress(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_target),
 952                MachineLocation(CallReg));
 953   } else {
 954     DIE *CalleeDIE = getOrCreateSubprogramDIE(CalleeSP);
 955     assert(CalleeDIE && "Could not create DIE for call site entry origin");
 956     addDIEEntry(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_origin),
 957                 *CalleeDIE);
 958   }
 959
 960   if (IsTail)
 961     // Attach DW_AT_call_tail_call to tail calls for standards compliance.
 962     addFlag(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_tail_call));
 963
 964   // Attach the return PC to allow the debugger to disambiguate call paths
 965   // from one function to another.
 966   if (DD->getDwarfVersion() == 4 && DD->tuneForGDB()) {
 967     assert(PCAddr && "Missing PC information for a call");
 968     addLabelAddress(CallSiteDIE, dwarf::DW_AT_low_pc, PCAddr);
 969   } else if (!IsTail || DD->tuneForGDB()) {
 970     assert(PCOffset && "Missing return PC information for a call");
 971     addAddressExpr(CallSiteDIE, dwarf::DW_AT_call_return_pc, PCOffset);
 972   }
 973
 974   return CallSiteDIE;
 975 }
 976
 977 void DwarfCompileUnit::constructCallSiteParmEntryDIEs(
 978     DIE &CallSiteDIE, SmallVector<DbgCallSiteParam, 4> &Params) {
 979   for (const auto &Param : Params) {
 980     unsigned Register = Param.getRegister();
 981     auto CallSiteDieParam =
 982         DIE::get(DIEValueAllocator,
 983                  getDwarf5OrGNUTag(dwarf::DW_TAG_call_site_parameter));
 984     insertDIE(CallSiteDieParam);
 985     addAddress(*CallSiteDieParam, dwarf::DW_AT_location,
 986                MachineLocation(Register));
 987
 988     DIELoc *Loc = new (DIEValueAllocator) DIELoc;
 989     DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
 990     DwarfExpr.setCallSiteParamValueFlag();
 991
 992     DwarfDebug::emitDebugLocValue(*Asm, nullptr, Param.getValue(), DwarfExpr);
 993
 994     addBlock(*CallSiteDieParam, getDwarf5OrGNUAttr(dwarf::DW_AT_call_value),
 995              DwarfExpr.finalize());
 996
 997     CallSiteDIE.addChild(CallSiteDieParam);
 998   }
 999 }
1000
1001 DIE *DwarfCompileUnit::constructImportedEntityDIE(
1002     const DIImportedEntity *Module) {
1003   DIE *IMDie = DIE::get(DIEValueAllocator, (dwarf::Tag)Module->getTag());
1004   insertDIE(Module, IMDie);
1005   DIE *EntityDie;
1006   auto *Entity = Module->getEntity();
1007   if (auto *NS = dyn_cast<DINamespace>(Entity))
1008     EntityDie = getOrCreateNameSpace(NS);
1009   else if (auto *M = dyn_cast<DIModule>(Entity))
1010     EntityDie = getOrCreateModule(M);
1011   else if (auto *SP = dyn_cast<DISubprogram>(Entity))
1012     EntityDie = getOrCreateSubprogramDIE(SP);
1013   else if (auto *T = dyn_cast<DIType>(Entity))
1014     EntityDie = getOrCreateTypeDIE(T);
1015   else if (auto *GV = dyn_cast<DIGlobalVariable>(Entity))
1016     EntityDie = getOrCreateGlobalVariableDIE(GV, {});
1017   else
1018     EntityDie = getDIE(Entity);
1019   assert(EntityDie);
1020   addSourceLine(*IMDie, Module->getLine(), Module->getFile());
1021   addDIEEntry(*IMDie, dwarf::DW_AT_import, *EntityDie);
1022   StringRef Name = Module->getName();
1023   if (!Name.empty())
1024     addString(*IMDie, dwarf::DW_AT_name, Name);
1025
1026   return IMDie;
1027 }
1028
1029 void DwarfCompileUnit::finishSubprogramDefinition(const DISubprogram *SP) {
1030   DIE *D = getDIE(SP);
1031   if (DIE *AbsSPDIE = getAbstractSPDies().lookup(SP)) {
1032     if (D)
1033       // If this subprogram has an abstract definition, reference that
1034       addDIEEntry(*D, dwarf::DW_AT_abstract_origin, *AbsSPDIE);
1035   } else {
1036     assert(D || includeMinimalInlineScopes());
1037     if (D)
1038       // And attach the attributes
1039       applySubprogramAttributesToDefinition(SP, *D);
1040   }
1041 }
1042
1043 void DwarfCompileUnit::finishEntityDefinition(const DbgEntity *Entity) {
1044   DbgEntity *AbsEntity = getExistingAbstractEntity(Entity->getEntity());
1045
1046   auto *Die = Entity->getDIE();
1047   /// Label may be used to generate DW_AT_low_pc, so put it outside
1048   /// if/else block.
1049   const DbgLabel *Label = nullptr;
1050   if (AbsEntity && AbsEntity->getDIE()) {
1051     addDIEEntry(*Die, dwarf::DW_AT_abstract_origin, *AbsEntity->getDIE());
1052     Label = dyn_cast<const DbgLabel>(Entity);
1053   } else {
1054     if (const DbgVariable *Var = dyn_cast<const DbgVariable>(Entity))
1055       applyVariableAttributes(*Var, *Die);
1056     else if ((Label = dyn_cast<const DbgLabel>(Entity)))
1057       applyLabelAttributes(*Label, *Die);
1058     else
1059       llvm_unreachable("DbgEntity must be DbgVariable or DbgLabel.");
1060   }
1061
1062   if (Label)
1063     if (const auto *Sym = Label->getSymbol())
1064       addLabelAddress(*Die, dwarf::DW_AT_low_pc, Sym);
1065 }
1066
1067 DbgEntity *DwarfCompileUnit::getExistingAbstractEntity(const DINode *Node) {
1068   auto &AbstractEntities = getAbstractEntities();
1069   auto I = AbstractEntities.find(Node);
1070   if (I != AbstractEntities.end())
1071     return I->second.get();
1072   return nullptr;
1073 }
1074
1075 void DwarfCompileUnit::createAbstractEntity(const DINode *Node,
1076                                             LexicalScope *Scope) {
1077   assert(Scope && Scope->isAbstractScope());
1078   auto &Entity = getAbstractEntities()[Node];
1079   if (isa<const DILocalVariable>(Node)) {
1080     Entity = std::make_unique<DbgVariable>(
1081                         cast<const DILocalVariable>(Node), nullptr /* IA */);;
1082     DU->addScopeVariable(Scope, cast<DbgVariable>(Entity.get()));
1083   } else if (isa<const DILabel>(Node)) {
1084     Entity = std::make_unique<DbgLabel>(
1085                         cast<const DILabel>(Node), nullptr /* IA */);
1086     DU->addScopeLabel(Scope, cast<DbgLabel>(Entity.get()));
1087   }
1088 }
1089
1090 void DwarfCompileUnit::emitHeader(bool UseOffsets) {
1091   // Don't bother labeling the .dwo unit, as its offset isn't used.
1092   if (!Skeleton && !DD->useSectionsAsReferences()) {
1093     LabelBegin = Asm->createTempSymbol("cu_begin");
1094     Asm->OutStreamer->EmitLabel(LabelBegin);
1095   }
1096
1097   dwarf::UnitType UT = Skeleton ? dwarf::DW_UT_split_compile
1098                                 : DD->useSplitDwarf() ? dwarf::DW_UT_skeleton
1099                                                       : dwarf::DW_UT_compile;
1100   DwarfUnit::emitCommonHeader(UseOffsets, UT);
1101   if (DD->getDwarfVersion() >= 5 && UT != dwarf::DW_UT_compile)
1102     Asm->emitInt64(getDWOId());
1103 }
1104
1105 bool DwarfCompileUnit::hasDwarfPubSections() const {
1106   switch (CUNode->getNameTableKind()) {
1107   case DICompileUnit::DebugNameTableKind::None:
1108     return false;
1109     // Opting in to GNU Pubnames/types overrides the default to ensure these are
1110     // generated for things like Gold's gdb_index generation.
1111   case DICompileUnit::DebugNameTableKind::GNU:
1112     return true;
1113   case DICompileUnit::DebugNameTableKind::Default:
1114     return DD->tuneForGDB() && !includeMinimalInlineScopes() &&
1115            !CUNode->isDebugDirectivesOnly() &&
1116            DD->getAccelTableKind() != AccelTableKind::Apple &&
1117            DD->getDwarfVersion() < 5;
1118   }
1119   llvm_unreachable("Unhandled DICompileUnit::DebugNameTableKind enum");
1120 }
1121
1122 /// addGlobalName - Add a new global name to the compile unit.
1123 void DwarfCompileUnit::addGlobalName(StringRef Name, const DIE &Die,
1124                                      const DIScope *Context) {
1125   if (!hasDwarfPubSections())
1126     return;
1127   std::string FullName = getParentContextString(Context) + Name.str();
1128   GlobalNames[FullName] = &Die;
1129 }
1130
1131 void DwarfCompileUnit::addGlobalNameForTypeUnit(StringRef Name,
1132                                                 const DIScope *Context) {
1133   if (!hasDwarfPubSections())
1134     return;
1135   std::string FullName = getParentContextString(Context) + Name.str();
1136   // Insert, allowing the entry to remain as-is if it's already present
1137   // This way the CU-level type DIE is preferred over the "can't describe this
1138   // type as a unit offset because it's not really in the CU at all, it's only
1139   // in a type unit"
1140   GlobalNames.insert(std::make_pair(std::move(FullName), &getUnitDie()));
1141 }
1142
1143 /// Add a new global type to the unit.
1144 void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
1145                                      const DIScope *Context) {
1146   if (!hasDwarfPubSections())
1147     return;
1148   std::string FullName = getParentContextString(Context) + Ty->getName().str();
1149   GlobalTypes[FullName] = &Die;
1150 }
1151
1152 void DwarfCompileUnit::addGlobalTypeUnitType(const DIType *Ty,
1153                                              const DIScope *Context) {
1154   if (!hasDwarfPubSections())
1155     return;
1156   std::string FullName = getParentContextString(Context) + Ty->getName().str();
1157   // Insert, allowing the entry to remain as-is if it's already present
1158   // This way the CU-level type DIE is preferred over the "can't describe this
1159   // type as a unit offset because it's not really in the CU at all, it's only
1160   // in a type unit"
1161   GlobalTypes.insert(std::make_pair(std::move(FullName), &getUnitDie()));
1162 }
1163
1164 void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
1165                                           MachineLocation Location) {
1166   if (DV.hasComplexAddress())
1167     addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
1168   else
1169     addAddress(Die, dwarf::DW_AT_location, Location);
1170 }
1171
1172 /// Add an address attribute to a die based on the location provided.
1173 void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
1174                                   const MachineLocation &Location) {
1175   DIELoc *Loc = new (DIEValueAllocator) DIELoc;
1176   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
1177   if (Location.isIndirect())
1178     DwarfExpr.setMemoryLocationKind();
1179
1180   DIExpressionCursor Cursor({});
1181   const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
1182   if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
1183     return;
1184   DwarfExpr.addExpression(std::move(Cursor));
1185
1186   // Now attach the location information to the DIE.
1187   addBlock(Die, Attribute, DwarfExpr.finalize());
1188 }
1189
1190 /// Start with the address based on the location provided, and generate the
1191 /// DWARF information necessary to find the actual variable given the extra
1192 /// address information encoded in the DbgVariable, starting from the starting
1193 /// location.  Add the DWARF information to the die.
1194 void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
1195                                          dwarf::Attribute Attribute,
1196                                          const MachineLocation &Location) {
1197   DIELoc *Loc = new (DIEValueAllocator) DIELoc;
1198   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
1199   const DIExpression *DIExpr = DV.getSingleExpression();
1200   DwarfExpr.addFragmentOffset(DIExpr);
1201   if (Location.isIndirect())
1202     DwarfExpr.setMemoryLocationKind();
1203
1204   DIExpressionCursor Cursor(DIExpr);
1205
1206   if (DIExpr->isEntryValue()) {
1207     DwarfExpr.setEntryValueFlag();
1208     DwarfExpr.beginEntryValueExpression(Cursor);
1209   }
1210
1211   const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
1212   if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
1213     return;
1214   DwarfExpr.addExpression(std::move(Cursor));
1215
1216   // Now attach the location information to the DIE.
1217   addBlock(Die, Attribute, DwarfExpr.finalize());
1218 }
1219
1220 /// Add a Dwarf loclistptr attribute data and value.
1221 void DwarfCompileUnit::addLocationList(DIE &Die, dwarf::Attribute Attribute,
1222                                        unsigned Index) {
1223   dwarf::Form Form = DD->getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
1224                                                 : dwarf::DW_FORM_data4;
1225   Die.addValue(DIEValueAllocator, Attribute, Form, DIELocList(Index));
1226 }
1227
1228 void DwarfCompileUnit::applyVariableAttributes(const DbgVariable &Var,
1229                                                DIE &VariableDie) {
1230   StringRef Name = Var.getName();
1231   if (!Name.empty())
1232     addString(VariableDie, dwarf::DW_AT_name, Name);
1233   const auto *DIVar = Var.getVariable();
1234   if (DIVar)
1235     if (uint32_t AlignInBytes = DIVar->getAlignInBytes())
1236       addUInt(VariableDie, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,
1237               AlignInBytes);
1238
1239   addSourceLine(VariableDie, DIVar);
1240   addType(VariableDie, Var.getType());
1241   if (Var.isArtificial())
1242     addFlag(VariableDie, dwarf::DW_AT_artificial);
1243 }
1244
1245 void DwarfCompileUnit::applyLabelAttributes(const DbgLabel &Label,
1246                                             DIE &LabelDie) {
1247   StringRef Name = Label.getName();
1248   if (!Name.empty())
1249     addString(LabelDie, dwarf::DW_AT_name, Name);
1250   const auto *DILabel = Label.getLabel();
1251   addSourceLine(LabelDie, DILabel);
1252 }
1253
1254 /// Add a Dwarf expression attribute data and value.
1255 void DwarfCompileUnit::addExpr(DIELoc &Die, dwarf::Form Form,
1256                                const MCExpr *Expr) {
1257   Die.addValue(DIEValueAllocator, (dwarf::Attribute)0, Form, DIEExpr(Expr));
1258 }
1259
1260 void DwarfCompileUnit::addAddressExpr(DIE &Die, dwarf::Attribute Attribute,
1261                                       const MCExpr *Expr) {
1262   Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_addr,
1263                DIEExpr(Expr));
1264 }
1265
1266 void DwarfCompileUnit::applySubprogramAttributesToDefinition(
1267     const DISubprogram *SP, DIE &SPDie) {
1268   auto *SPDecl = SP->getDeclaration();
1269   auto *Context = SPDecl ? SPDecl->getScope() : SP->getScope();
1270   applySubprogramAttributes(SP, SPDie, includeMinimalInlineScopes());
1271   addGlobalName(SP->getName(), SPDie, Context);
1272 }
1273
1274 bool DwarfCompileUnit::isDwoUnit() const {
1275   return DD->useSplitDwarf() && Skeleton;
1276 }
1277
1278 void DwarfCompileUnit::finishNonUnitTypeDIE(DIE& D, const DICompositeType *CTy) {
1279   constructTypeDIE(D, CTy);
1280 }
1281
1282 bool DwarfCompileUnit::includeMinimalInlineScopes() const {
1283   return getCUNode()->getEmissionKind() == DICompileUnit::LineTablesOnly ||
1284          (DD->useSplitDwarf() && !Skeleton);
1285 }
1286
1287 void DwarfCompileUnit::addAddrTableBase() {
1288   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
1289   MCSymbol *Label = DD->getAddressPool().getLabel();
1290   addSectionLabel(getUnitDie(),
1291                   getDwarfVersion() >= 5 ? dwarf::DW_AT_addr_base
1292                                          : dwarf::DW_AT_GNU_addr_base,
1293                   Label, TLOF.getDwarfAddrSection()->getBeginSymbol());
1294 }
1295
1296 void DwarfCompileUnit::addBaseTypeRef(DIEValueList &Die, int64_t Idx) {
1297   Die.addValue(DIEValueAllocator, (dwarf::Attribute)0, dwarf::DW_FORM_udata,
1298                new (DIEValueAllocator) DIEBaseTypeRef(this, Idx));
1299 }
1300
1301 void DwarfCompileUnit::createBaseTypeDIEs() {
1302   // Insert the base_type DIEs directly after the CU so that their offsets will
1303   // fit in the fixed size ULEB128 used inside the location expressions.
1304   // Maintain order by iterating backwards and inserting to the front of CU
1305   // child list.
1306   for (auto &Btr : reverse(ExprRefedBaseTypes)) {
1307     DIE &Die = getUnitDie().addChildFront(
1308       DIE::get(DIEValueAllocator, dwarf::DW_TAG_base_type));
1309     SmallString<32> Str;
1310     addString(Die, dwarf::DW_AT_name,
1311               Twine(dwarf::AttributeEncodingString(Btr.Encoding) +
1312                     "_" + Twine(Btr.BitSize)).toStringRef(Str));
1313     addUInt(Die, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1, Btr.Encoding);
1314     addUInt(Die, dwarf::DW_AT_byte_size, None, Btr.BitSize / 8);
1315
1316     Btr.Die = &Die;
1317   }
1318 }