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   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
 471
 472   // Emit the offset into .debug_ranges or .debug_rnglists as a relocatable
 473   // label. emitDIE() will handle emitting it appropriately.
 474   const MCSymbol *RangeSectionSym =
 475       DD->getDwarfVersion() >= 5
 476           ? TLOF.getDwarfRnglistsSection()->getBeginSymbol()
 477           : TLOF.getDwarfRangesSection()->getBeginSymbol();
 478
 479   HasRangeLists = true;
 480
 481   // Add the range list to the set of ranges to be emitted.
 482   auto IndexAndList =
 483       (DD->getDwarfVersion() < 5 && Skeleton ? Skeleton->DU : DU)
 484           ->addRange(*(Skeleton ? Skeleton : this), std::move(Range));
 485
 486   uint32_t Index = IndexAndList.first;
 487   auto &List = *IndexAndList.second;
 488
 489   // Under fission, ranges are specified by constant offsets relative to the
 490   // CU's DW_AT_GNU_ranges_base.
 491   // FIXME: For DWARF v5, do not generate the DW_AT_ranges attribute under
 492   // fission until we support the forms using the .debug_addr section
 493   // (DW_RLE_startx_endx etc.).
 494   if (DD->getDwarfVersion() >= 5)
 495     addUInt(ScopeDIE, dwarf::DW_AT_ranges, dwarf::DW_FORM_rnglistx, Index);
 496   else if (isDwoUnit())
 497     addSectionDelta(ScopeDIE, dwarf::DW_AT_ranges, List.getSym(),
 498                     RangeSectionSym);
 499   else
 500     addSectionLabel(ScopeDIE, dwarf::DW_AT_ranges, List.getSym(),
 501                     RangeSectionSym);
 502 }
 503
 504 void DwarfCompileUnit::attachRangesOrLowHighPC(
 505     DIE &Die, SmallVector<RangeSpan, 2> Ranges) {
 506   if (Ranges.size() == 1 || !DD->useRangesSection()) {
 507     const RangeSpan &Front = Ranges.front();
 508     const RangeSpan &Back = Ranges.back();
 509     attachLowHighPC(Die, Front.Begin, Back.End);
 510   } else
 511     addScopeRangeList(Die, std::move(Ranges));
 512 }
 513
 514 void DwarfCompileUnit::attachRangesOrLowHighPC(
 515     DIE &Die, const SmallVectorImpl<InsnRange> &Ranges) {
 516   SmallVector<RangeSpan, 2> List;
 517   List.reserve(Ranges.size());
 518   for (const InsnRange &R : Ranges)
 519     List.push_back(
 520         {DD->getLabelBeforeInsn(R.first), DD->getLabelAfterInsn(R.second)});
 521   attachRangesOrLowHighPC(Die, std::move(List));
 522 }
 523
 524 // This scope represents inlined body of a function. Construct DIE to
 525 // represent this concrete inlined copy of the function.
 526 DIE *DwarfCompileUnit::constructInlinedScopeDIE(LexicalScope *Scope) {
 527   assert(Scope->getScopeNode());
 528   auto *DS = Scope->getScopeNode();
 529   auto *InlinedSP = getDISubprogram(DS);
 530   // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
 531   // was inlined from another compile unit.
 532   DIE *OriginDIE = getAbstractSPDies()[InlinedSP];
 533   assert(OriginDIE && "Unable to find original DIE for an inlined subprogram.");
 534
 535   auto ScopeDIE = DIE::get(DIEValueAllocator, dwarf::DW_TAG_inlined_subroutine);
 536   addDIEEntry(*ScopeDIE, dwarf::DW_AT_abstract_origin, *OriginDIE);
 537
 538   attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());
 539
 540   // Add the call site information to the DIE.
 541   const DILocation *IA = Scope->getInlinedAt();
 542   addUInt(*ScopeDIE, dwarf::DW_AT_call_file, None,
 543           getOrCreateSourceID(IA->getFile()));
 544   addUInt(*ScopeDIE, dwarf::DW_AT_call_line, None, IA->getLine());
 545   if (IA->getColumn())
 546     addUInt(*ScopeDIE, dwarf::DW_AT_call_column, None, IA->getColumn());
 547   if (IA->getDiscriminator() && DD->getDwarfVersion() >= 4)
 548     addUInt(*ScopeDIE, dwarf::DW_AT_GNU_discriminator, None,
 549             IA->getDiscriminator());
 550
 551   // Add name to the name table, we do this here because we're guaranteed
 552   // to have concrete versions of our DW_TAG_inlined_subprogram nodes.
 553   DD->addSubprogramNames(*CUNode, InlinedSP, *ScopeDIE);
 554
 555   return ScopeDIE;
 556 }
 557
 558 // Construct new DW_TAG_lexical_block for this scope and attach
 559 // DW_AT_low_pc/DW_AT_high_pc labels.
 560 DIE *DwarfCompileUnit::constructLexicalScopeDIE(LexicalScope *Scope) {
 561   if (DD->isLexicalScopeDIENull(Scope))
 562     return nullptr;
 563
 564   auto ScopeDIE = DIE::get(DIEValueAllocator, dwarf::DW_TAG_lexical_block);
 565   if (Scope->isAbstractScope())
 566     return ScopeDIE;
 567
 568   attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());
 569
 570   return ScopeDIE;
 571 }
 572
 573 /// constructVariableDIE - Construct a DIE for the given DbgVariable.
 574 DIE *DwarfCompileUnit::constructVariableDIE(DbgVariable &DV, bool Abstract) {
 575   auto D = constructVariableDIEImpl(DV, Abstract);
 576   DV.setDIE(*D);
 577   return D;
 578 }
 579
 580 DIE *DwarfCompileUnit::constructLabelDIE(DbgLabel &DL,
 581                                          const LexicalScope &Scope) {
 582   auto LabelDie = DIE::get(DIEValueAllocator, DL.getTag());
 583   insertDIE(DL.getLabel(), LabelDie);
 584   DL.setDIE(*LabelDie);
 585
 586   if (Scope.isAbstractScope())
 587     applyLabelAttributes(DL, *LabelDie);
 588
 589   return LabelDie;
 590 }
 591
 592 DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
 593                                                 bool Abstract) {
 594   // Define variable debug information entry.
 595   auto VariableDie = DIE::get(DIEValueAllocator, DV.getTag());
 596   insertDIE(DV.getVariable(), VariableDie);
 597
 598   if (Abstract) {
 599     applyVariableAttributes(DV, *VariableDie);
 600     return VariableDie;
 601   }
 602
 603   // Add variable address.
 604
 605   unsigned Offset = DV.getDebugLocListIndex();
 606   if (Offset != ~0U) {
 607     addLocationList(*VariableDie, dwarf::DW_AT_location, Offset);
 608     return VariableDie;
 609   }
 610
 611   // Check if variable has a single location description.
 612   if (auto *DVal = DV.getValueLoc()) {
 613     if (DVal->isLocation())
 614       addVariableAddress(DV, *VariableDie, DVal->getLoc());
 615     else if (DVal->isInt()) {
 616       auto *Expr = DV.getSingleExpression();
 617       if (Expr && Expr->getNumElements()) {
 618         DIELoc *Loc = new (DIEValueAllocator) DIELoc;
 619         DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
 620         // If there is an expression, emit raw unsigned bytes.
 621         DwarfExpr.addFragmentOffset(Expr);
 622         DwarfExpr.addUnsignedConstant(DVal->getInt());
 623         DwarfExpr.addExpression(Expr);
 624         addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
 625       } else
 626         addConstantValue(*VariableDie, DVal->getInt(), DV.getType());
 627     } else if (DVal->isConstantFP()) {
 628       addConstantFPValue(*VariableDie, DVal->getConstantFP());
 629     } else if (DVal->isConstantInt()) {
 630       addConstantValue(*VariableDie, DVal->getConstantInt(), DV.getType());
 631     }
 632     return VariableDie;
 633   }
 634
 635   // .. else use frame index.
 636   if (!DV.hasFrameIndexExprs())
 637     return VariableDie;
 638
 639   Optional<unsigned> NVPTXAddressSpace;
 640   DIELoc *Loc = new (DIEValueAllocator) DIELoc;
 641   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
 642   for (auto &Fragment : DV.getFrameIndexExprs()) {
 643     unsigned FrameReg = 0;
 644     const DIExpression *Expr = Fragment.Expr;
 645     const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
 646     int Offset = TFI->getFrameIndexReference(*Asm->MF, Fragment.FI, FrameReg);
 647     DwarfExpr.addFragmentOffset(Expr);
 648     SmallVector<uint64_t, 8> Ops;
 649     DIExpression::appendOffset(Ops, Offset);
 650     // According to
 651     // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
 652     // cuda-gdb requires DW_AT_address_class for all variables to be able to
 653     // correctly interpret address space of the variable address.
 654     // Decode DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef
 655     // sequence for the NVPTX + gdb target.
 656     unsigned LocalNVPTXAddressSpace;
 657     if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
 658       const DIExpression *NewExpr =
 659           DIExpression::extractAddressClass(Expr, LocalNVPTXAddressSpace);
 660       if (NewExpr != Expr) {
 661         Expr = NewExpr;
 662         NVPTXAddressSpace = LocalNVPTXAddressSpace;
 663       }
 664     }
 665     if (Expr)
 666       Ops.append(Expr->elements_begin(), Expr->elements_end());
 667     DIExpressionCursor Cursor(Ops);
 668     DwarfExpr.setMemoryLocationKind();
 669     if (const MCSymbol *FrameSymbol = Asm->getFunctionFrameSymbol())
 670       addOpAddress(*Loc, FrameSymbol);
 671     else
 672       DwarfExpr.addMachineRegExpression(
 673           *Asm->MF->getSubtarget().getRegisterInfo(), Cursor, FrameReg);
 674     DwarfExpr.addExpression(std::move(Cursor));
 675   }
 676   if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
 677     // According to
 678     // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
 679     // cuda-gdb requires DW_AT_address_class for all variables to be able to
 680     // correctly interpret address space of the variable address.
 681     const unsigned NVPTX_ADDR_local_space = 6;
 682     addUInt(*VariableDie, dwarf::DW_AT_address_class, dwarf::DW_FORM_data1,
 683             NVPTXAddressSpace ? *NVPTXAddressSpace : NVPTX_ADDR_local_space);
 684   }
 685   addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
 686   if (DwarfExpr.TagOffset)
 687     addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
 688             *DwarfExpr.TagOffset);
 689
 690   return VariableDie;
 691 }
 692
 693 DIE *DwarfCompileUnit::constructVariableDIE(DbgVariable &DV,
 694                                             const LexicalScope &Scope,
 695                                             DIE *&ObjectPointer) {
 696   auto Var = constructVariableDIE(DV, Scope.isAbstractScope());
 697   if (DV.isObjectPointer())
 698     ObjectPointer = Var;
 699   return Var;
 700 }
 701
 702 /// Return all DIVariables that appear in count: expressions.
 703 static SmallVector<const DIVariable *, 2> dependencies(DbgVariable *Var) {
 704   SmallVector<const DIVariable *, 2> Result;
 705   auto *Array = dyn_cast<DICompositeType>(Var->getType());
 706   if (!Array || Array->getTag() != dwarf::DW_TAG_array_type)
 707     return Result;
 708   for (auto *El : Array->getElements()) {
 709     if (auto *Subrange = dyn_cast<DISubrange>(El)) {
 710       auto Count = Subrange->getCount();
 711       if (auto *Dependency = Count.dyn_cast<DIVariable *>())
 712         Result.push_back(Dependency);
 713     }
 714   }
 715   return Result;
 716 }
 717
 718 /// Sort local variables so that variables appearing inside of helper
 719 /// expressions come first.
 720 static SmallVector<DbgVariable *, 8>
 721 sortLocalVars(SmallVectorImpl<DbgVariable *> &Input) {
 722   SmallVector<DbgVariable *, 8> Result;
 723   SmallVector<PointerIntPair<DbgVariable *, 1>, 8> WorkList;
 724   // Map back from a DIVariable to its containing DbgVariable.
 725   SmallDenseMap<const DILocalVariable *, DbgVariable *> DbgVar;
 726   // Set of DbgVariables in Result.
 727   SmallDenseSet<DbgVariable *, 8> Visited;
 728   // For cycle detection.
 729   SmallDenseSet<DbgVariable *, 8> Visiting;
 730
 731   // Initialize the worklist and the DIVariable lookup table.
 732   for (auto Var : reverse(Input)) {
 733     DbgVar.insert({Var->getVariable(), Var});
 734     WorkList.push_back({Var, 0});
 735   }
 736
 737   // Perform a stable topological sort by doing a DFS.
 738   while (!WorkList.empty()) {
 739     auto Item = WorkList.back();
 740     DbgVariable *Var = Item.getPointer();
 741     bool visitedAllDependencies = Item.getInt();
 742     WorkList.pop_back();
 743
 744     // Dependency is in a different lexical scope or a global.
 745     if (!Var)
 746       continue;
 747
 748     // Already handled.
 749     if (Visited.count(Var))
 750       continue;
 751
 752     // Add to Result if all dependencies are visited.
 753     if (visitedAllDependencies) {
 754       Visited.insert(Var);
 755       Result.push_back(Var);
 756       continue;
 757     }
 758
 759     // Detect cycles.
 760     auto Res = Visiting.insert(Var);
 761     if (!Res.second) {
 762       assert(false && "dependency cycle in local variables");
 763       return Result;
 764     }
 765
 766     // Push dependencies and this node onto the worklist, so that this node is
 767     // visited again after all of its dependencies are handled.
 768     WorkList.push_back({Var, 1});
 769     for (auto *Dependency : dependencies(Var)) {
 770       auto Dep = dyn_cast_or_null<const DILocalVariable>(Dependency);
 771       WorkList.push_back({DbgVar[Dep], 0});
 772     }
 773   }
 774   return Result;
 775 }
 776
 777 DIE *DwarfCompileUnit::createScopeChildrenDIE(LexicalScope *Scope,
 778                                               SmallVectorImpl<DIE *> &Children,
 779                                               bool *HasNonScopeChildren) {
 780   assert(Children.empty());
 781   DIE *ObjectPointer = nullptr;
 782
 783   // Emit function arguments (order is significant).
 784   auto Vars = DU->getScopeVariables().lookup(Scope);
 785   for (auto &DV : Vars.Args)
 786     Children.push_back(constructVariableDIE(*DV.second, *Scope, ObjectPointer));
 787
 788   // Emit local variables.
 789   auto Locals = sortLocalVars(Vars.Locals);
 790   for (DbgVariable *DV : Locals)
 791     Children.push_back(constructVariableDIE(*DV, *Scope, ObjectPointer));
 792
 793   // Skip imported directives in gmlt-like data.
 794   if (!includeMinimalInlineScopes()) {
 795     // There is no need to emit empty lexical block DIE.
 796     for (const auto *IE : ImportedEntities[Scope->getScopeNode()])
 797       Children.push_back(
 798           constructImportedEntityDIE(cast<DIImportedEntity>(IE)));
 799   }
 800
 801   if (HasNonScopeChildren)
 802     *HasNonScopeChildren = !Children.empty();
 803
 804   for (DbgLabel *DL : DU->getScopeLabels().lookup(Scope))
 805     Children.push_back(constructLabelDIE(*DL, *Scope));
 806
 807   for (LexicalScope *LS : Scope->getChildren())
 808     constructScopeDIE(LS, Children);
 809
 810   return ObjectPointer;
 811 }
 812
 813 DIE &DwarfCompileUnit::constructSubprogramScopeDIE(const DISubprogram *Sub,
 814                                                    LexicalScope *Scope) {
 815   DIE &ScopeDIE = updateSubprogramScopeDIE(Sub);
 816
 817   if (Scope) {
 818     assert(!Scope->getInlinedAt());
 819     assert(!Scope->isAbstractScope());
 820     // Collect lexical scope children first.
 821     // ObjectPointer might be a local (non-argument) local variable if it's a
 822     // block's synthetic this pointer.
 823     if (DIE *ObjectPointer = createAndAddScopeChildren(Scope, ScopeDIE))
 824       addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
 825   }
 826
 827   // If this is a variadic function, add an unspecified parameter.
 828   DITypeRefArray FnArgs = Sub->getType()->getTypeArray();
 829
 830   // If we have a single element of null, it is a function that returns void.
 831   // If we have more than one elements and the last one is null, it is a
 832   // variadic function.
 833   if (FnArgs.size() > 1 && !FnArgs[FnArgs.size() - 1] &&
 834       !includeMinimalInlineScopes())
 835     ScopeDIE.addChild(
 836         DIE::get(DIEValueAllocator, dwarf::DW_TAG_unspecified_parameters));
 837
 838   return ScopeDIE;
 839 }
 840
 841 DIE *DwarfCompileUnit::createAndAddScopeChildren(LexicalScope *Scope,
 842                                                  DIE &ScopeDIE) {
 843   // We create children when the scope DIE is not null.
 844   SmallVector<DIE *, 8> Children;
 845   DIE *ObjectPointer = createScopeChildrenDIE(Scope, Children);
 846
 847   // Add children
 848   for (auto &I : Children)
 849     ScopeDIE.addChild(std::move(I));
 850
 851   return ObjectPointer;
 852 }
 853
 854 void DwarfCompileUnit::constructAbstractSubprogramScopeDIE(
 855     LexicalScope *Scope) {
 856   DIE *&AbsDef = getAbstractSPDies()[Scope->getScopeNode()];
 857   if (AbsDef)
 858     return;
 859
 860   auto *SP = cast<DISubprogram>(Scope->getScopeNode());
 861
 862   DIE *ContextDIE;
 863   DwarfCompileUnit *ContextCU = this;
 864
 865   if (includeMinimalInlineScopes())
 866     ContextDIE = &getUnitDie();
 867   // Some of this is duplicated from DwarfUnit::getOrCreateSubprogramDIE, with
 868   // the important distinction that the debug node is not associated with the
 869   // DIE (since the debug node will be associated with the concrete DIE, if
 870   // any). It could be refactored to some common utility function.
 871   else if (auto *SPDecl = SP->getDeclaration()) {
 872     ContextDIE = &getUnitDie();
 873     getOrCreateSubprogramDIE(SPDecl);
 874   } else {
 875     ContextDIE = getOrCreateContextDIE(SP->getScope());
 876     // The scope may be shared with a subprogram that has already been
 877     // constructed in another CU, in which case we need to construct this
 878     // subprogram in the same CU.
 879     ContextCU = DD->lookupCU(ContextDIE->getUnitDie());
 880   }
 881
 882   // Passing null as the associated node because the abstract definition
 883   // shouldn't be found by lookup.
 884   AbsDef = &ContextCU->createAndAddDIE(dwarf::DW_TAG_subprogram, *ContextDIE, nullptr);
 885   ContextCU->applySubprogramAttributesToDefinition(SP, *AbsDef);
 886
 887   if (!ContextCU->includeMinimalInlineScopes())
 888     ContextCU->addUInt(*AbsDef, dwarf::DW_AT_inline, None, dwarf::DW_INL_inlined);
 889   if (DIE *ObjectPointer = ContextCU->createAndAddScopeChildren(Scope, *AbsDef))
 890     ContextCU->addDIEEntry(*AbsDef, dwarf::DW_AT_object_pointer, *ObjectPointer);
 891 }
 892
 893 /// Whether to use the GNU analog for a DWARF5 tag, attribute, or location atom.
 894 static bool useGNUAnalogForDwarf5Feature(DwarfDebug *DD) {
 895   return DD->getDwarfVersion() == 4 && DD->tuneForGDB();
 896 }
 897
 898 dwarf::Tag DwarfCompileUnit::getDwarf5OrGNUTag(dwarf::Tag Tag) const {
 899   if (!useGNUAnalogForDwarf5Feature(DD))
 900     return Tag;
 901   switch (Tag) {
 902   case dwarf::DW_TAG_call_site:
 903     return dwarf::DW_TAG_GNU_call_site;
 904   case dwarf::DW_TAG_call_site_parameter:
 905     return dwarf::DW_TAG_GNU_call_site_parameter;
 906   default:
 907     llvm_unreachable("DWARF5 tag with no GNU analog");
 908   }
 909 }
 910
 911 dwarf::Attribute
 912 DwarfCompileUnit::getDwarf5OrGNUAttr(dwarf::Attribute Attr) const {
 913   if (!useGNUAnalogForDwarf5Feature(DD))
 914     return Attr;
 915   switch (Attr) {
 916   case dwarf::DW_AT_call_all_calls:
 917     return dwarf::DW_AT_GNU_all_call_sites;
 918   case dwarf::DW_AT_call_target:
 919     return dwarf::DW_AT_GNU_call_site_target;
 920   case dwarf::DW_AT_call_origin:
 921     return dwarf::DW_AT_abstract_origin;
 922   case dwarf::DW_AT_call_pc:
 923     return dwarf::DW_AT_low_pc;
 924   case dwarf::DW_AT_call_value:
 925     return dwarf::DW_AT_GNU_call_site_value;
 926   case dwarf::DW_AT_call_tail_call:
 927     return dwarf::DW_AT_GNU_tail_call;
 928   default:
 929     llvm_unreachable("DWARF5 attribute with no GNU analog");
 930   }
 931 }
 932
 933 dwarf::LocationAtom
 934 DwarfCompileUnit::getDwarf5OrGNULocationAtom(dwarf::LocationAtom Loc) const {
 935   if (!useGNUAnalogForDwarf5Feature(DD))
 936     return Loc;
 937   switch (Loc) {
 938   case dwarf::DW_OP_entry_value:
 939     return dwarf::DW_OP_GNU_entry_value;
 940   default:
 941     llvm_unreachable("DWARF5 location atom with no GNU analog");
 942   }
 943 }
 944
 945 DIE &DwarfCompileUnit::constructCallSiteEntryDIE(
 946     DIE &ScopeDIE, const DISubprogram *CalleeSP, bool IsTail,
 947     const MCSymbol *PCAddr, const MCExpr *PCOffset, unsigned CallReg) {
 948   // Insert a call site entry DIE within ScopeDIE.
 949   DIE &CallSiteDIE = createAndAddDIE(getDwarf5OrGNUTag(dwarf::DW_TAG_call_site),
 950                                      ScopeDIE, nullptr);
 951
 952   if (CallReg) {
 953     // Indirect call.
 954     addAddress(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_target),
 955                MachineLocation(CallReg));
 956   } else {
 957     DIE *CalleeDIE = getOrCreateSubprogramDIE(CalleeSP);
 958     assert(CalleeDIE && "Could not create DIE for call site entry origin");
 959     addDIEEntry(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_origin),
 960                 *CalleeDIE);
 961   }
 962
 963   if (IsTail)
 964     // Attach DW_AT_call_tail_call to tail calls for standards compliance.
 965     addFlag(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_tail_call));
 966
 967   // Attach the return PC to allow the debugger to disambiguate call paths
 968   // from one function to another.
 969   if (DD->getDwarfVersion() == 4 && DD->tuneForGDB()) {
 970     assert(PCAddr && "Missing PC information for a call");
 971     addLabelAddress(CallSiteDIE, dwarf::DW_AT_low_pc, PCAddr);
 972   } else if (!IsTail || DD->tuneForGDB()) {
 973     assert(PCOffset && "Missing return PC information for a call");
 974     addAddressExpr(CallSiteDIE, dwarf::DW_AT_call_return_pc, PCOffset);
 975   }
 976
 977   return CallSiteDIE;
 978 }
 979
 980 void DwarfCompileUnit::constructCallSiteParmEntryDIEs(
 981     DIE &CallSiteDIE, SmallVector<DbgCallSiteParam, 4> &Params) {
 982   for (const auto &Param : Params) {
 983     unsigned Register = Param.getRegister();
 984     auto CallSiteDieParam =
 985         DIE::get(DIEValueAllocator,
 986                  getDwarf5OrGNUTag(dwarf::DW_TAG_call_site_parameter));
 987     insertDIE(CallSiteDieParam);
 988     addAddress(*CallSiteDieParam, dwarf::DW_AT_location,
 989                MachineLocation(Register));
 990
 991     DIELoc *Loc = new (DIEValueAllocator) DIELoc;
 992     DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
 993     DwarfExpr.setCallSiteParamValueFlag();
 994
 995     DwarfDebug::emitDebugLocValue(*Asm, nullptr, Param.getValue(), DwarfExpr);
 996
 997     addBlock(*CallSiteDieParam, getDwarf5OrGNUAttr(dwarf::DW_AT_call_value),
 998              DwarfExpr.finalize());
 999
1000     CallSiteDIE.addChild(CallSiteDieParam);
1001   }
1002 }
1003
1004 DIE *DwarfCompileUnit::constructImportedEntityDIE(
1005     const DIImportedEntity *Module) {
1006   DIE *IMDie = DIE::get(DIEValueAllocator, (dwarf::Tag)Module->getTag());
1007   insertDIE(Module, IMDie);
1008   DIE *EntityDie;
1009   auto *Entity = Module->getEntity();
1010   if (auto *NS = dyn_cast<DINamespace>(Entity))
1011     EntityDie = getOrCreateNameSpace(NS);
1012   else if (auto *M = dyn_cast<DIModule>(Entity))
1013     EntityDie = getOrCreateModule(M);
1014   else if (auto *SP = dyn_cast<DISubprogram>(Entity))
1015     EntityDie = getOrCreateSubprogramDIE(SP);
1016   else if (auto *T = dyn_cast<DIType>(Entity))
1017     EntityDie = getOrCreateTypeDIE(T);
1018   else if (auto *GV = dyn_cast<DIGlobalVariable>(Entity))
1019     EntityDie = getOrCreateGlobalVariableDIE(GV, {});
1020   else
1021     EntityDie = getDIE(Entity);
1022   assert(EntityDie);
1023   addSourceLine(*IMDie, Module->getLine(), Module->getFile());
1024   addDIEEntry(*IMDie, dwarf::DW_AT_import, *EntityDie);
1025   StringRef Name = Module->getName();
1026   if (!Name.empty())
1027     addString(*IMDie, dwarf::DW_AT_name, Name);
1028
1029   return IMDie;
1030 }
1031
1032 void DwarfCompileUnit::finishSubprogramDefinition(const DISubprogram *SP) {
1033   DIE *D = getDIE(SP);
1034   if (DIE *AbsSPDIE = getAbstractSPDies().lookup(SP)) {
1035     if (D)
1036       // If this subprogram has an abstract definition, reference that
1037       addDIEEntry(*D, dwarf::DW_AT_abstract_origin, *AbsSPDIE);
1038   } else {
1039     assert(D || includeMinimalInlineScopes());
1040     if (D)
1041       // And attach the attributes
1042       applySubprogramAttributesToDefinition(SP, *D);
1043   }
1044 }
1045
1046 void DwarfCompileUnit::finishEntityDefinition(const DbgEntity *Entity) {
1047   DbgEntity *AbsEntity = getExistingAbstractEntity(Entity->getEntity());
1048
1049   auto *Die = Entity->getDIE();
1050   /// Label may be used to generate DW_AT_low_pc, so put it outside
1051   /// if/else block.
1052   const DbgLabel *Label = nullptr;
1053   if (AbsEntity && AbsEntity->getDIE()) {
1054     addDIEEntry(*Die, dwarf::DW_AT_abstract_origin, *AbsEntity->getDIE());
1055     Label = dyn_cast<const DbgLabel>(Entity);
1056   } else {
1057     if (const DbgVariable *Var = dyn_cast<const DbgVariable>(Entity))
1058       applyVariableAttributes(*Var, *Die);
1059     else if ((Label = dyn_cast<const DbgLabel>(Entity)))
1060       applyLabelAttributes(*Label, *Die);
1061     else
1062       llvm_unreachable("DbgEntity must be DbgVariable or DbgLabel.");
1063   }
1064
1065   if (Label)
1066     if (const auto *Sym = Label->getSymbol())
1067       addLabelAddress(*Die, dwarf::DW_AT_low_pc, Sym);
1068 }
1069
1070 DbgEntity *DwarfCompileUnit::getExistingAbstractEntity(const DINode *Node) {
1071   auto &AbstractEntities = getAbstractEntities();
1072   auto I = AbstractEntities.find(Node);
1073   if (I != AbstractEntities.end())
1074     return I->second.get();
1075   return nullptr;
1076 }
1077
1078 void DwarfCompileUnit::createAbstractEntity(const DINode *Node,
1079                                             LexicalScope *Scope) {
1080   assert(Scope && Scope->isAbstractScope());
1081   auto &Entity = getAbstractEntities()[Node];
1082   if (isa<const DILocalVariable>(Node)) {
1083     Entity = std::make_unique<DbgVariable>(
1084                         cast<const DILocalVariable>(Node), nullptr /* IA */);;
1085     DU->addScopeVariable(Scope, cast<DbgVariable>(Entity.get()));
1086   } else if (isa<const DILabel>(Node)) {
1087     Entity = std::make_unique<DbgLabel>(
1088                         cast<const DILabel>(Node), nullptr /* IA */);
1089     DU->addScopeLabel(Scope, cast<DbgLabel>(Entity.get()));
1090   }
1091 }
1092
1093 void DwarfCompileUnit::emitHeader(bool UseOffsets) {
1094   // Don't bother labeling the .dwo unit, as its offset isn't used.
1095   if (!Skeleton && !DD->useSectionsAsReferences()) {
1096     LabelBegin = Asm->createTempSymbol("cu_begin");
1097     Asm->OutStreamer->EmitLabel(LabelBegin);
1098   }
1099
1100   dwarf::UnitType UT = Skeleton ? dwarf::DW_UT_split_compile
1101                                 : DD->useSplitDwarf() ? dwarf::DW_UT_skeleton
1102                                                       : dwarf::DW_UT_compile;
1103   DwarfUnit::emitCommonHeader(UseOffsets, UT);
1104   if (DD->getDwarfVersion() >= 5 && UT != dwarf::DW_UT_compile)
1105     Asm->emitInt64(getDWOId());
1106 }
1107
1108 bool DwarfCompileUnit::hasDwarfPubSections() const {
1109   switch (CUNode->getNameTableKind()) {
1110   case DICompileUnit::DebugNameTableKind::None:
1111     return false;
1112     // Opting in to GNU Pubnames/types overrides the default to ensure these are
1113     // generated for things like Gold's gdb_index generation.
1114   case DICompileUnit::DebugNameTableKind::GNU:
1115     return true;
1116   case DICompileUnit::DebugNameTableKind::Default:
1117     return DD->tuneForGDB() && !includeMinimalInlineScopes() &&
1118            !CUNode->isDebugDirectivesOnly() &&
1119            DD->getAccelTableKind() != AccelTableKind::Apple &&
1120            DD->getDwarfVersion() < 5;
1121   }
1122   llvm_unreachable("Unhandled DICompileUnit::DebugNameTableKind enum");
1123 }
1124
1125 /// addGlobalName - Add a new global name to the compile unit.
1126 void DwarfCompileUnit::addGlobalName(StringRef Name, const DIE &Die,
1127                                      const DIScope *Context) {
1128   if (!hasDwarfPubSections())
1129     return;
1130   std::string FullName = getParentContextString(Context) + Name.str();
1131   GlobalNames[FullName] = &Die;
1132 }
1133
1134 void DwarfCompileUnit::addGlobalNameForTypeUnit(StringRef Name,
1135                                                 const DIScope *Context) {
1136   if (!hasDwarfPubSections())
1137     return;
1138   std::string FullName = getParentContextString(Context) + Name.str();
1139   // Insert, allowing the entry to remain as-is if it's already present
1140   // This way the CU-level type DIE is preferred over the "can't describe this
1141   // type as a unit offset because it's not really in the CU at all, it's only
1142   // in a type unit"
1143   GlobalNames.insert(std::make_pair(std::move(FullName), &getUnitDie()));
1144 }
1145
1146 /// Add a new global type to the unit.
1147 void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
1148                                      const DIScope *Context) {
1149   if (!hasDwarfPubSections())
1150     return;
1151   std::string FullName = getParentContextString(Context) + Ty->getName().str();
1152   GlobalTypes[FullName] = &Die;
1153 }
1154
1155 void DwarfCompileUnit::addGlobalTypeUnitType(const DIType *Ty,
1156                                              const DIScope *Context) {
1157   if (!hasDwarfPubSections())
1158     return;
1159   std::string FullName = getParentContextString(Context) + Ty->getName().str();
1160   // Insert, allowing the entry to remain as-is if it's already present
1161   // This way the CU-level type DIE is preferred over the "can't describe this
1162   // type as a unit offset because it's not really in the CU at all, it's only
1163   // in a type unit"
1164   GlobalTypes.insert(std::make_pair(std::move(FullName), &getUnitDie()));
1165 }
1166
1167 void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
1168                                           MachineLocation Location) {
1169   if (DV.hasComplexAddress())
1170     addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
1171   else
1172     addAddress(Die, dwarf::DW_AT_location, Location);
1173 }
1174
1175 /// Add an address attribute to a die based on the location provided.
1176 void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
1177                                   const MachineLocation &Location) {
1178   DIELoc *Loc = new (DIEValueAllocator) DIELoc;
1179   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
1180   if (Location.isIndirect())
1181     DwarfExpr.setMemoryLocationKind();
1182
1183   DIExpressionCursor Cursor({});
1184   const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
1185   if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
1186     return;
1187   DwarfExpr.addExpression(std::move(Cursor));
1188
1189   // Now attach the location information to the DIE.
1190   addBlock(Die, Attribute, DwarfExpr.finalize());
1191 }
1192
1193 /// Start with the address based on the location provided, and generate the
1194 /// DWARF information necessary to find the actual variable given the extra
1195 /// address information encoded in the DbgVariable, starting from the starting
1196 /// location.  Add the DWARF information to the die.
1197 void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
1198                                          dwarf::Attribute Attribute,
1199                                          const MachineLocation &Location) {
1200   DIELoc *Loc = new (DIEValueAllocator) DIELoc;
1201   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
1202   const DIExpression *DIExpr = DV.getSingleExpression();
1203   DwarfExpr.addFragmentOffset(DIExpr);
1204   if (Location.isIndirect())
1205     DwarfExpr.setMemoryLocationKind();
1206
1207   DIExpressionCursor Cursor(DIExpr);
1208
1209   if (DIExpr->isEntryValue()) {
1210     DwarfExpr.setEntryValueFlag();
1211     DwarfExpr.addEntryValueExpression(Cursor);
1212   }
1213
1214   const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
1215   if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
1216     return;
1217   DwarfExpr.addExpression(std::move(Cursor));
1218
1219   // Now attach the location information to the DIE.
1220   addBlock(Die, Attribute, DwarfExpr.finalize());
1221 }
1222
1223 /// Add a Dwarf loclistptr attribute data and value.
1224 void DwarfCompileUnit::addLocationList(DIE &Die, dwarf::Attribute Attribute,
1225                                        unsigned Index) {
1226   dwarf::Form Form = DD->getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
1227                                                 : dwarf::DW_FORM_data4;
1228   Die.addValue(DIEValueAllocator, Attribute, Form, DIELocList(Index));
1229 }
1230
1231 void DwarfCompileUnit::applyVariableAttributes(const DbgVariable &Var,
1232                                                DIE &VariableDie) {
1233   StringRef Name = Var.getName();
1234   if (!Name.empty())
1235     addString(VariableDie, dwarf::DW_AT_name, Name);
1236   const auto *DIVar = Var.getVariable();
1237   if (DIVar)
1238     if (uint32_t AlignInBytes = DIVar->getAlignInBytes())
1239       addUInt(VariableDie, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,
1240               AlignInBytes);
1241
1242   addSourceLine(VariableDie, DIVar);
1243   addType(VariableDie, Var.getType());
1244   if (Var.isArtificial())
1245     addFlag(VariableDie, dwarf::DW_AT_artificial);
1246 }
1247
1248 void DwarfCompileUnit::applyLabelAttributes(const DbgLabel &Label,
1249                                             DIE &LabelDie) {
1250   StringRef Name = Label.getName();
1251   if (!Name.empty())
1252     addString(LabelDie, dwarf::DW_AT_name, Name);
1253   const auto *DILabel = Label.getLabel();
1254   addSourceLine(LabelDie, DILabel);
1255 }
1256
1257 /// Add a Dwarf expression attribute data and value.
1258 void DwarfCompileUnit::addExpr(DIELoc &Die, dwarf::Form Form,
1259                                const MCExpr *Expr) {
1260   Die.addValue(DIEValueAllocator, (dwarf::Attribute)0, Form, DIEExpr(Expr));
1261 }
1262
1263 void DwarfCompileUnit::addAddressExpr(DIE &Die, dwarf::Attribute Attribute,
1264                                       const MCExpr *Expr) {
1265   Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_addr,
1266                DIEExpr(Expr));
1267 }
1268
1269 void DwarfCompileUnit::applySubprogramAttributesToDefinition(
1270     const DISubprogram *SP, DIE &SPDie) {
1271   auto *SPDecl = SP->getDeclaration();
1272   auto *Context = SPDecl ? SPDecl->getScope() : SP->getScope();
1273   applySubprogramAttributes(SP, SPDie, includeMinimalInlineScopes());
1274   addGlobalName(SP->getName(), SPDie, Context);
1275 }
1276
1277 bool DwarfCompileUnit::isDwoUnit() const {
1278   return DD->useSplitDwarf() && Skeleton;
1279 }
1280
1281 void DwarfCompileUnit::finishNonUnitTypeDIE(DIE& D, const DICompositeType *CTy) {
1282   constructTypeDIE(D, CTy);
1283 }
1284
1285 bool DwarfCompileUnit::includeMinimalInlineScopes() const {
1286   return getCUNode()->getEmissionKind() == DICompileUnit::LineTablesOnly ||
1287          (DD->useSplitDwarf() && !Skeleton);
1288 }
1289
1290 void DwarfCompileUnit::addAddrTableBase() {
1291   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
1292   MCSymbol *Label = DD->getAddressPool().getLabel();
1293   addSectionLabel(getUnitDie(),
1294                   getDwarfVersion() >= 5 ? dwarf::DW_AT_addr_base
1295                                          : dwarf::DW_AT_GNU_addr_base,
1296                   Label, TLOF.getDwarfAddrSection()->getBeginSymbol());
1297 }
1298
1299 void DwarfCompileUnit::addBaseTypeRef(DIEValueList &Die, int64_t Idx) {
1300   Die.addValue(DIEValueAllocator, (dwarf::Attribute)0, dwarf::DW_FORM_udata,
1301                new (DIEValueAllocator) DIEBaseTypeRef(this, Idx));
1302 }
1303
1304 void DwarfCompileUnit::createBaseTypeDIEs() {
1305   // Insert the base_type DIEs directly after the CU so that their offsets will
1306   // fit in the fixed size ULEB128 used inside the location expressions.
1307   // Maintain order by iterating backwards and inserting to the front of CU
1308   // child list.
1309   for (auto &Btr : reverse(ExprRefedBaseTypes)) {
1310     DIE &Die = getUnitDie().addChildFront(
1311       DIE::get(DIEValueAllocator, dwarf::DW_TAG_base_type));
1312     SmallString<32> Str;
1313     addString(Die, dwarf::DW_AT_name,
1314               Twine(dwarf::AttributeEncodingString(Btr.Encoding) +
1315                     "_" + Twine(Btr.BitSize)).toStringRef(Str));
1316     addUInt(Die, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1, Btr.Encoding);
1317     addUInt(Die, dwarf::DW_AT_byte_size, None, Btr.BitSize / 8);
1318
1319     Btr.Die = &Die;
1320   }
1321 }