Index: head/contrib/llvm/tools/lld/ELF/LinkerScript.cpp
===================================================================
--- head/contrib/llvm/tools/lld/ELF/LinkerScript.cpp	(revision 328545)
+++ head/contrib/llvm/tools/lld/ELF/LinkerScript.cpp	(revision 328546)
@@ -1,1023 +1,1030 @@
 //===- LinkerScript.cpp ---------------------------------------------------===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file contains the parser/evaluator of the linker script.
 //
 //===----------------------------------------------------------------------===//
 
 #include "LinkerScript.h"
 #include "Config.h"
 #include "InputSection.h"
 #include "OutputSections.h"
 #include "Strings.h"
 #include "SymbolTable.h"
 #include "Symbols.h"
 #include "SyntheticSections.h"
 #include "Target.h"
 #include "Writer.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/Threads.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
 #include <iterator>
 #include <limits>
 #include <string>
 #include <vector>
 
 using namespace llvm;
 using namespace llvm::ELF;
 using namespace llvm::object;
 using namespace llvm::support::endian;
 using namespace lld;
 using namespace lld::elf;
 
 LinkerScript *elf::Script;
 
 static uint64_t getOutputSectionVA(SectionBase *InputSec, StringRef Loc) {
   if (OutputSection *OS = InputSec->getOutputSection())
     return OS->Addr;
   error(Loc + ": unable to evaluate expression: input section " +
         InputSec->Name + " has no output section assigned");
   return 0;
 }
 
 uint64_t ExprValue::getValue() const {
   if (Sec)
     return alignTo(Sec->getOffset(Val) + getOutputSectionVA(Sec, Loc),
                    Alignment);
   return alignTo(Val, Alignment);
 }
 
 uint64_t ExprValue::getSecAddr() const {
   if (Sec)
     return Sec->getOffset(0) + getOutputSectionVA(Sec, Loc);
   return 0;
 }
 
 uint64_t ExprValue::getSectionOffset() const {
   // If the alignment is trivial, we don't have to compute the full
   // value to know the offset. This allows this function to succeed in
   // cases where the output section is not yet known.
   if (Alignment == 1)
     return Val;
   return getValue() - getSecAddr();
 }
 
 OutputSection *LinkerScript::createOutputSection(StringRef Name,
                                                  StringRef Location) {
   OutputSection *&SecRef = NameToOutputSection[Name];
   OutputSection *Sec;
   if (SecRef && SecRef->Location.empty()) {
     // There was a forward reference.
     Sec = SecRef;
   } else {
     Sec = make<OutputSection>(Name, SHT_NOBITS, 0);
     if (!SecRef)
       SecRef = Sec;
   }
   Sec->Location = Location;
   return Sec;
 }
 
 OutputSection *LinkerScript::getOrCreateOutputSection(StringRef Name) {
   OutputSection *&CmdRef = NameToOutputSection[Name];
   if (!CmdRef)
     CmdRef = make<OutputSection>(Name, SHT_PROGBITS, 0);
   return CmdRef;
 }
 
 void LinkerScript::setDot(Expr E, const Twine &Loc, bool InSec) {
   uint64_t Val = E().getValue();
   if (Val < Dot && InSec)
     error(Loc + ": unable to move location counter backward for: " +
           Ctx->OutSec->Name);
   Dot = Val;
 
   // Update to location counter means update to section size.
   if (InSec)
     Ctx->OutSec->Size = Dot - Ctx->OutSec->Addr;
 }
 
 // This function is called from processSectionCommands,
 // while we are fixing the output section layout.
 void LinkerScript::addSymbol(SymbolAssignment *Cmd) {
   if (Cmd->Name == ".")
     return;
 
   // If a symbol was in PROVIDE(), we need to define it only when
   // it is a referenced undefined symbol.
   Symbol *B = Symtab->find(Cmd->Name);
   if (Cmd->Provide && (!B || B->isDefined()))
     return;
 
   // Define a symbol.
   Symbol *Sym;
   uint8_t Visibility = Cmd->Hidden ? STV_HIDDEN : STV_DEFAULT;
   std::tie(Sym, std::ignore) = Symtab->insert(Cmd->Name, /*Type*/ 0, Visibility,
                                               /*CanOmitFromDynSym*/ false,
                                               /*File*/ nullptr);
   ExprValue Value = Cmd->Expression();
   SectionBase *Sec = Value.isAbsolute() ? nullptr : Value.Sec;
 
   // When this function is called, section addresses have not been
   // fixed yet. So, we may or may not know the value of the RHS
   // expression.
   //
   // For example, if an expression is `x = 42`, we know x is always 42.
   // However, if an expression is `x = .`, there's no way to know its
   // value at the moment.
   //
   // We want to set symbol values early if we can. This allows us to
   // use symbols as variables in linker scripts. Doing so allows us to
   // write expressions like this: `alignment = 16; . = ALIGN(., alignment)`.
   uint64_t SymValue = Value.Sec ? 0 : Value.getValue();
 
   replaceSymbol<Defined>(Sym, nullptr, Cmd->Name, STB_GLOBAL, Visibility,
                          STT_NOTYPE, SymValue, 0, Sec);
   Cmd->Sym = cast<Defined>(Sym);
 }
 
 // This function is called from assignAddresses, while we are
 // fixing the output section addresses. This function is supposed
 // to set the final value for a given symbol assignment.
 void LinkerScript::assignSymbol(SymbolAssignment *Cmd, bool InSec) {
   if (Cmd->Name == ".") {
     setDot(Cmd->Expression, Cmd->Location, InSec);
     return;
   }
 
   if (!Cmd->Sym)
     return;
 
   ExprValue V = Cmd->Expression();
   if (V.isAbsolute()) {
     Cmd->Sym->Section = nullptr;
     Cmd->Sym->Value = V.getValue();
   } else {
     Cmd->Sym->Section = V.Sec;
     Cmd->Sym->Value = V.getSectionOffset();
   }
 }
 
 static std::string getFilename(InputFile *File) {
   if (!File)
     return "";
   if (File->ArchiveName.empty())
     return File->getName();
   return (File->ArchiveName + "(" + File->getName() + ")").str();
 }
 
 bool LinkerScript::shouldKeep(InputSectionBase *S) {
   if (KeptSections.empty())
     return false;
   std::string Filename = getFilename(S->File);
   for (InputSectionDescription *ID : KeptSections)
     if (ID->FilePat.match(Filename))
       for (SectionPattern &P : ID->SectionPatterns)
         if (P.SectionPat.match(S->Name))
           return true;
   return false;
 }
 
 // A helper function for the SORT() command.
 static std::function<bool(InputSectionBase *, InputSectionBase *)>
 getComparator(SortSectionPolicy K) {
   switch (K) {
   case SortSectionPolicy::Alignment:
     return [](InputSectionBase *A, InputSectionBase *B) {
       // ">" is not a mistake. Sections with larger alignments are placed
       // before sections with smaller alignments in order to reduce the
       // amount of padding necessary. This is compatible with GNU.
       return A->Alignment > B->Alignment;
     };
   case SortSectionPolicy::Name:
     return [](InputSectionBase *A, InputSectionBase *B) {
       return A->Name < B->Name;
     };
   case SortSectionPolicy::Priority:
     return [](InputSectionBase *A, InputSectionBase *B) {
       return getPriority(A->Name) < getPriority(B->Name);
     };
   default:
     llvm_unreachable("unknown sort policy");
   }
 }
 
 // A helper function for the SORT() command.
 static bool matchConstraints(ArrayRef<InputSection *> Sections,
                              ConstraintKind Kind) {
   if (Kind == ConstraintKind::NoConstraint)
     return true;
 
   bool IsRW = llvm::any_of(
       Sections, [](InputSection *Sec) { return Sec->Flags & SHF_WRITE; });
 
   return (IsRW && Kind == ConstraintKind::ReadWrite) ||
          (!IsRW && Kind == ConstraintKind::ReadOnly);
 }
 
 static void sortSections(MutableArrayRef<InputSection *> Vec,
                          SortSectionPolicy K) {
   if (K != SortSectionPolicy::Default && K != SortSectionPolicy::None)
     std::stable_sort(Vec.begin(), Vec.end(), getComparator(K));
 }
 
 // Sort sections as instructed by SORT-family commands and --sort-section
 // option. Because SORT-family commands can be nested at most two depth
 // (e.g. SORT_BY_NAME(SORT_BY_ALIGNMENT(.text.*))) and because the command
 // line option is respected even if a SORT command is given, the exact
 // behavior we have here is a bit complicated. Here are the rules.
 //
 // 1. If two SORT commands are given, --sort-section is ignored.
 // 2. If one SORT command is given, and if it is not SORT_NONE,
 //    --sort-section is handled as an inner SORT command.
 // 3. If one SORT command is given, and if it is SORT_NONE, don't sort.
 // 4. If no SORT command is given, sort according to --sort-section.
 // 5. If no SORT commands are given and --sort-section is not specified,
 //    apply sorting provided by --symbol-ordering-file if any exist.
 static void sortInputSections(
     MutableArrayRef<InputSection *> Vec, const SectionPattern &Pat,
     const DenseMap<SectionBase *, int> &Order) {
   if (Pat.SortOuter == SortSectionPolicy::None)
     return;
 
   if (Pat.SortOuter == SortSectionPolicy::Default &&
       Config->SortSection == SortSectionPolicy::Default) {
     // If -symbol-ordering-file was given, sort accordingly.
     // Usually, Order is empty.
     if (!Order.empty())
       sortByOrder(Vec, [&](InputSectionBase *S) { return Order.lookup(S); });
     return;
   }
 
   if (Pat.SortInner == SortSectionPolicy::Default)
     sortSections(Vec, Config->SortSection);
   else
     sortSections(Vec, Pat.SortInner);
   sortSections(Vec, Pat.SortOuter);
 }
 
 // Compute and remember which sections the InputSectionDescription matches.
 std::vector<InputSection *>
 LinkerScript::computeInputSections(const InputSectionDescription *Cmd,
                                    const DenseMap<SectionBase *, int> &Order) {
   std::vector<InputSection *> Ret;
 
   // Collects all sections that satisfy constraints of Cmd.
   for (const SectionPattern &Pat : Cmd->SectionPatterns) {
     size_t SizeBefore = Ret.size();
 
     for (InputSectionBase *Sec : InputSections) {
       if (!Sec->Live || Sec->Assigned)
         continue;
 
       // For -emit-relocs we have to ignore entries like
       //   .rela.dyn : { *(.rela.data) }
       // which are common because they are in the default bfd script.
       if (Sec->Type == SHT_REL || Sec->Type == SHT_RELA)
         continue;
 
       std::string Filename = getFilename(Sec->File);
       if (!Cmd->FilePat.match(Filename) ||
           Pat.ExcludedFilePat.match(Filename) ||
           !Pat.SectionPat.match(Sec->Name))
         continue;
 
       // It is safe to assume that Sec is an InputSection
       // because mergeable or EH input sections have already been
       // handled and eliminated.
       Ret.push_back(cast<InputSection>(Sec));
       Sec->Assigned = true;
     }
 
     sortInputSections(MutableArrayRef<InputSection *>(Ret).slice(SizeBefore),
                       Pat, Order);
   }
   return Ret;
 }
 
 void LinkerScript::discard(ArrayRef<InputSection *> V) {
   for (InputSection *S : V) {
     if (S == InX::ShStrTab || S == InX::Dynamic || S == InX::DynSymTab ||
         S == InX::DynStrTab)
       error("discarding " + S->Name + " section is not allowed");
 
     S->Assigned = false;
     S->Live = false;
     discard(S->DependentSections);
   }
 }
 
 std::vector<InputSection *> LinkerScript::createInputSectionList(
     OutputSection &OutCmd, const DenseMap<SectionBase *, int> &Order) {
   std::vector<InputSection *> Ret;
 
   for (BaseCommand *Base : OutCmd.SectionCommands) {
     if (auto *Cmd = dyn_cast<InputSectionDescription>(Base)) {
       Cmd->Sections = computeInputSections(Cmd, Order);
       Ret.insert(Ret.end(), Cmd->Sections.begin(), Cmd->Sections.end());
     }
   }
   return Ret;
 }
 
 void LinkerScript::processSectionCommands() {
   // A symbol can be assigned before any section is mentioned in the linker
   // script. In an DSO, the symbol values are addresses, so the only important
   // section values are:
   // * SHN_UNDEF
   // * SHN_ABS
   // * Any value meaning a regular section.
   // To handle that, create a dummy aether section that fills the void before
   // the linker scripts switches to another section. It has an index of one
   // which will map to whatever the first actual section is.
   Aether = make<OutputSection>("", 0, SHF_ALLOC);
   Aether->SectionIndex = 1;
 
   // Ctx captures the local AddressState and makes it accessible deliberately.
   // This is needed as there are some cases where we cannot just
   // thread the current state through to a lambda function created by the
   // script parser.
   auto Deleter = make_unique<AddressState>();
   Ctx = Deleter.get();
   Ctx->OutSec = Aether;
 
   size_t I = 0;
   DenseMap<SectionBase *, int> Order = buildSectionOrder();
   // Add input sections to output sections.
   for (BaseCommand *Base : SectionCommands) {
     // Handle symbol assignments outside of any output section.
     if (auto *Cmd = dyn_cast<SymbolAssignment>(Base)) {
       addSymbol(Cmd);
       continue;
     }
 
     if (auto *Sec = dyn_cast<OutputSection>(Base)) {
       std::vector<InputSection *> V = createInputSectionList(*Sec, Order);
 
       // The output section name `/DISCARD/' is special.
       // Any input section assigned to it is discarded.
       if (Sec->Name == "/DISCARD/") {
         discard(V);
         continue;
       }
 
       // This is for ONLY_IF_RO and ONLY_IF_RW. An output section directive
       // ".foo : ONLY_IF_R[OW] { ... }" is handled only if all member input
       // sections satisfy a given constraint. If not, a directive is handled
       // as if it wasn't present from the beginning.
       //
       // Because we'll iterate over SectionCommands many more times, the easy
       // way to "make it as if it wasn't present" is to make it empty.
       if (!matchConstraints(V, Sec->Constraint)) {
         for (InputSectionBase *S : V)
           S->Assigned = false;
         Sec->SectionCommands.clear();
         continue;
       }
 
       // A directive may contain symbol definitions like this:
       // ".foo : { ...; bar = .; }". Handle them.
       for (BaseCommand *Base : Sec->SectionCommands)
         if (auto *OutCmd = dyn_cast<SymbolAssignment>(Base))
           addSymbol(OutCmd);
 
       // Handle subalign (e.g. ".foo : SUBALIGN(32) { ... }"). If subalign
       // is given, input sections are aligned to that value, whether the
       // given value is larger or smaller than the original section alignment.
       if (Sec->SubalignExpr) {
         uint32_t Subalign = Sec->SubalignExpr().getValue();
         for (InputSectionBase *S : V)
           S->Alignment = Subalign;
       }
 
       // Add input sections to an output section.
       for (InputSection *S : V)
         Sec->addSection(S);
 
       Sec->SectionIndex = I++;
       if (Sec->Noload)
         Sec->Type = SHT_NOBITS;
     }
   }
   Ctx = nullptr;
 }
 
 static OutputSection *findByName(ArrayRef<BaseCommand *> Vec,
                                  StringRef Name) {
   for (BaseCommand *Base : Vec)
     if (auto *Sec = dyn_cast<OutputSection>(Base))
       if (Sec->Name == Name)
         return Sec;
   return nullptr;
 }
 
 static OutputSection *createSection(InputSectionBase *IS,
                                     StringRef OutsecName) {
   OutputSection *Sec = Script->createOutputSection(OutsecName, "<internal>");
   Sec->addSection(cast<InputSection>(IS));
   return Sec;
 }
 
 static OutputSection *addInputSec(StringMap<OutputSection *> &Map,
                                   InputSectionBase *IS, StringRef OutsecName) {
   // Sections with SHT_GROUP or SHF_GROUP attributes reach here only when the -r
   // option is given. A section with SHT_GROUP defines a "section group", and
   // its members have SHF_GROUP attribute. Usually these flags have already been
   // stripped by InputFiles.cpp as section groups are processed and uniquified.
   // However, for the -r option, we want to pass through all section groups
   // as-is because adding/removing members or merging them with other groups
   // change their semantics.
   if (IS->Type == SHT_GROUP || (IS->Flags & SHF_GROUP))
     return createSection(IS, OutsecName);
 
   // Imagine .zed : { *(.foo) *(.bar) } script. Both foo and bar may have
   // relocation sections .rela.foo and .rela.bar for example. Most tools do
   // not allow multiple REL[A] sections for output section. Hence we
   // should combine these relocation sections into single output.
   // We skip synthetic sections because it can be .rela.dyn/.rela.plt or any
   // other REL[A] sections created by linker itself.
   if (!isa<SyntheticSection>(IS) &&
       (IS->Type == SHT_REL || IS->Type == SHT_RELA)) {
     auto *Sec = cast<InputSection>(IS);
     OutputSection *Out = Sec->getRelocatedSection()->getOutputSection();
 
     if (Out->RelocationSection) {
       Out->RelocationSection->addSection(Sec);
       return nullptr;
     }
 
     Out->RelocationSection = createSection(IS, OutsecName);
     return Out->RelocationSection;
   }
 
   // When control reaches here, mergeable sections have already been merged into
   // synthetic sections. For relocatable case we want to create one output
   // section per syntetic section so that they have a valid sh_entsize.
   if (Config->Relocatable && (IS->Flags & SHF_MERGE))
     return createSection(IS, OutsecName);
 
   //  The ELF spec just says
   // ----------------------------------------------------------------
   // In the first phase, input sections that match in name, type and
   // attribute flags should be concatenated into single sections.
   // ----------------------------------------------------------------
   //
   // However, it is clear that at least some flags have to be ignored for
   // section merging. At the very least SHF_GROUP and SHF_COMPRESSED have to be
   // ignored. We should not have two output .text sections just because one was
   // in a group and another was not for example.
   //
   // It also seems that that wording was a late addition and didn't get the
   // necessary scrutiny.
   //
   // Merging sections with different flags is expected by some users. One
   // reason is that if one file has
   //
   // int *const bar __attribute__((section(".foo"))) = (int *)0;
   //
   // gcc with -fPIC will produce a read only .foo section. But if another
   // file has
   //
   // int zed;
   // int *const bar __attribute__((section(".foo"))) = (int *)&zed;
   //
   // gcc with -fPIC will produce a read write section.
   //
   // Last but not least, when using linker script the merge rules are forced by
   // the script. Unfortunately, linker scripts are name based. This means that
   // expressions like *(.foo*) can refer to multiple input sections with
   // different flags. We cannot put them in different output sections or we
   // would produce wrong results for
   //
   // start = .; *(.foo.*) end = .; *(.bar)
   //
   // and a mapping of .foo1 and .bar1 to one section and .foo2 and .bar2 to
   // another. The problem is that there is no way to layout those output
   // sections such that the .foo sections are the only thing between the start
   // and end symbols.
   //
   // Given the above issues, we instead merge sections by name and error on
   // incompatible types and flags.
   OutputSection *&Sec = Map[OutsecName];
   if (Sec) {
     Sec->addSection(cast<InputSection>(IS));
     return nullptr;
   }
 
   Sec = createSection(IS, OutsecName);
   return Sec;
 }
 
 // Add sections that didn't match any sections command.
 void LinkerScript::addOrphanSections() {
   unsigned End = SectionCommands.size();
   StringMap<OutputSection *> Map;
 
   std::vector<OutputSection *> V;
   for (InputSectionBase *S : InputSections) {
     if (!S->Live || S->Parent)
       continue;
 
     StringRef Name = getOutputSectionName(S);
 
     if (Config->OrphanHandling == OrphanHandlingPolicy::Error)
       error(toString(S) + " is being placed in '" + Name + "'");
     else if (Config->OrphanHandling == OrphanHandlingPolicy::Warn)
       warn(toString(S) + " is being placed in '" + Name + "'");
 
     if (OutputSection *Sec =
             findByName(makeArrayRef(SectionCommands).slice(0, End), Name)) {
       Sec->addSection(cast<InputSection>(S));
       continue;
     }
 
     if (OutputSection *OS = addInputSec(Map, S, Name))
       V.push_back(OS);
     assert(S->getOutputSection()->SectionIndex == INT_MAX);
   }
 
   // If no SECTIONS command was given, we should insert sections commands
   // before others, so that we can handle scripts which refers them,
   // for example: "foo = ABSOLUTE(ADDR(.text)));".
   // When SECTIONS command is present we just add all orphans to the end.
   if (HasSectionsCommand)
     SectionCommands.insert(SectionCommands.end(), V.begin(), V.end());
   else
     SectionCommands.insert(SectionCommands.begin(), V.begin(), V.end());
 }
 
 uint64_t LinkerScript::advance(uint64_t Size, unsigned Alignment) {
   bool IsTbss =
       (Ctx->OutSec->Flags & SHF_TLS) && Ctx->OutSec->Type == SHT_NOBITS;
   uint64_t Start = IsTbss ? Dot + Ctx->ThreadBssOffset : Dot;
   Start = alignTo(Start, Alignment);
   uint64_t End = Start + Size;
 
   if (IsTbss)
     Ctx->ThreadBssOffset = End - Dot;
   else
     Dot = End;
   return End;
 }
 
 void LinkerScript::output(InputSection *S) {
   uint64_t Before = advance(0, 1);
   uint64_t Pos = advance(S->getSize(), S->Alignment);
   S->OutSecOff = Pos - S->getSize() - Ctx->OutSec->Addr;
 
   // Update output section size after adding each section. This is so that
   // SIZEOF works correctly in the case below:
   // .foo { *(.aaa) a = SIZEOF(.foo); *(.bbb) }
   Ctx->OutSec->Size = Pos - Ctx->OutSec->Addr;
 
   // If there is a memory region associated with this input section, then
   // place the section in that region and update the region index.
+  if (Ctx->LMARegion)
+    Ctx->LMARegion->CurPos += Pos - Before;
+  // FIXME: should we also produce overflow errors for LMARegion?
+
   if (Ctx->MemRegion) {
     uint64_t &CurOffset = Ctx->MemRegion->CurPos;
     CurOffset += Pos - Before;
     uint64_t CurSize = CurOffset - Ctx->MemRegion->Origin;
     if (CurSize > Ctx->MemRegion->Length) {
       uint64_t OverflowAmt = CurSize - Ctx->MemRegion->Length;
       error("section '" + Ctx->OutSec->Name + "' will not fit in region '" +
             Ctx->MemRegion->Name + "': overflowed by " + Twine(OverflowAmt) +
             " bytes");
     }
   }
 }
 
 void LinkerScript::switchTo(OutputSection *Sec) {
   if (Ctx->OutSec == Sec)
     return;
 
   Ctx->OutSec = Sec;
   Ctx->OutSec->Addr = advance(0, Ctx->OutSec->Alignment);
 }
 
 // This function searches for a memory region to place the given output
 // section in. If found, a pointer to the appropriate memory region is
 // returned. Otherwise, a nullptr is returned.
 MemoryRegion *LinkerScript::findMemoryRegion(OutputSection *Sec) {
   // If a memory region name was specified in the output section command,
   // then try to find that region first.
   if (!Sec->MemoryRegionName.empty()) {
     if (MemoryRegion *M = MemoryRegions.lookup(Sec->MemoryRegionName))
       return M;
     error("memory region '" + Sec->MemoryRegionName + "' not declared");
     return nullptr;
   }
 
   // If at least one memory region is defined, all sections must
   // belong to some memory region. Otherwise, we don't need to do
   // anything for memory regions.
   if (MemoryRegions.empty())
     return nullptr;
 
   // See if a region can be found by matching section flags.
   for (auto &Pair : MemoryRegions) {
     MemoryRegion *M = Pair.second;
     if ((M->Flags & Sec->Flags) && (M->NegFlags & Sec->Flags) == 0)
       return M;
   }
 
   // Otherwise, no suitable region was found.
   if (Sec->Flags & SHF_ALLOC)
     error("no memory region specified for section '" + Sec->Name + "'");
   return nullptr;
 }
 
 // This function assigns offsets to input sections and an output section
 // for a single sections command (e.g. ".text { *(.text); }").
 void LinkerScript::assignOffsets(OutputSection *Sec) {
   if (!(Sec->Flags & SHF_ALLOC))
     Dot = 0;
   else if (Sec->AddrExpr)
     setDot(Sec->AddrExpr, Sec->Location, false);
 
   Ctx->MemRegion = Sec->MemRegion;
+  Ctx->LMARegion = Sec->LMARegion;
   if (Ctx->MemRegion)
     Dot = Ctx->MemRegion->CurPos;
 
   switchTo(Sec);
 
   if (Sec->LMAExpr)
     Ctx->LMAOffset = Sec->LMAExpr().getValue() - Dot;
 
   if (MemoryRegion *MR = Sec->LMARegion)
-    Ctx->LMAOffset = MR->Origin - Dot;
+    Ctx->LMAOffset = MR->CurPos - Dot;
 
   // If neither AT nor AT> is specified for an allocatable section, the linker
   // will set the LMA such that the difference between VMA and LMA for the
   // section is the same as the preceding output section in the same region
   // https://sourceware.org/binutils/docs-2.20/ld/Output-Section-LMA.html
   if (Ctx->LMAOffset)
     Ctx->OutSec->LMAOffset = Ctx->LMAOffset;
 
   // The Size previously denoted how many InputSections had been added to this
   // section, and was used for sorting SHF_LINK_ORDER sections. Reset it to
   // compute the actual size value.
   Sec->Size = 0;
 
   // We visited SectionsCommands from processSectionCommands to
   // layout sections. Now, we visit SectionsCommands again to fix
   // section offsets.
   for (BaseCommand *Base : Sec->SectionCommands) {
     // This handles the assignments to symbol or to the dot.
     if (auto *Cmd = dyn_cast<SymbolAssignment>(Base)) {
       assignSymbol(Cmd, true);
       continue;
     }
 
     // Handle BYTE(), SHORT(), LONG(), or QUAD().
     if (auto *Cmd = dyn_cast<ByteCommand>(Base)) {
       Cmd->Offset = Dot - Ctx->OutSec->Addr;
       Dot += Cmd->Size;
       if (Ctx->MemRegion)
         Ctx->MemRegion->CurPos += Cmd->Size;
+      if (Ctx->LMARegion)
+        Ctx->LMARegion->CurPos += Cmd->Size;
       Ctx->OutSec->Size = Dot - Ctx->OutSec->Addr;
       continue;
     }
 
     // Handle ASSERT().
     if (auto *Cmd = dyn_cast<AssertCommand>(Base)) {
       Cmd->Expression();
       continue;
     }
 
     // Handle a single input section description command.
     // It calculates and assigns the offsets for each section and also
     // updates the output section size.
     auto *Cmd = cast<InputSectionDescription>(Base);
     for (InputSection *Sec : Cmd->Sections) {
       // We tentatively added all synthetic sections at the beginning and
       // removed empty ones afterwards (because there is no way to know
       // whether they were going be empty or not other than actually running
       // linker scripts.) We need to ignore remains of empty sections.
       if (auto *S = dyn_cast<SyntheticSection>(Sec))
         if (S->empty())
           continue;
 
       if (!Sec->Live)
         continue;
       assert(Ctx->OutSec == Sec->getParent());
       output(Sec);
     }
   }
 }
 
 void LinkerScript::removeEmptyCommands() {
   // It is common practice to use very generic linker scripts. So for any
   // given run some of the output sections in the script will be empty.
   // We could create corresponding empty output sections, but that would
   // clutter the output.
   // We instead remove trivially empty sections. The bfd linker seems even
   // more aggressive at removing them.
   llvm::erase_if(SectionCommands, [&](BaseCommand *Base) {
     if (auto *Sec = dyn_cast<OutputSection>(Base))
       return !Sec->Live;
     return false;
   });
 }
 
 static bool isAllSectionDescription(const OutputSection &Cmd) {
   for (BaseCommand *Base : Cmd.SectionCommands)
     if (!isa<InputSectionDescription>(*Base))
       return false;
   return true;
 }
 
 void LinkerScript::adjustSectionsBeforeSorting() {
   // If the output section contains only symbol assignments, create a
   // corresponding output section. The issue is what to do with linker script
   // like ".foo : { symbol = 42; }". One option would be to convert it to
   // "symbol = 42;". That is, move the symbol out of the empty section
   // description. That seems to be what bfd does for this simple case. The
   // problem is that this is not completely general. bfd will give up and
   // create a dummy section too if there is a ". = . + 1" inside the section
   // for example.
   // Given that we want to create the section, we have to worry what impact
   // it will have on the link. For example, if we just create a section with
   // 0 for flags, it would change which PT_LOADs are created.
   // We could remember that that particular section is dummy and ignore it in
   // other parts of the linker, but unfortunately there are quite a few places
   // that would need to change:
   //   * The program header creation.
   //   * The orphan section placement.
   //   * The address assignment.
   // The other option is to pick flags that minimize the impact the section
   // will have on the rest of the linker. That is why we copy the flags from
   // the previous sections. Only a few flags are needed to keep the impact low.
   uint64_t Flags = SHF_ALLOC;
 
   for (BaseCommand *Cmd : SectionCommands) {
     auto *Sec = dyn_cast<OutputSection>(Cmd);
     if (!Sec)
       continue;
     if (Sec->Live) {
       Flags = Sec->Flags & (SHF_ALLOC | SHF_WRITE | SHF_EXECINSTR);
       continue;
     }
 
     if (isAllSectionDescription(*Sec))
       continue;
 
     Sec->Live = true;
     Sec->Flags = Flags;
   }
 }
 
 void LinkerScript::adjustSectionsAfterSorting() {
   // Try and find an appropriate memory region to assign offsets in.
   for (BaseCommand *Base : SectionCommands) {
     if (auto *Sec = dyn_cast<OutputSection>(Base)) {
       if (!Sec->Live)
         continue;
       if (!Sec->LMARegionName.empty()) {
         if (MemoryRegion *M = MemoryRegions.lookup(Sec->LMARegionName))
           Sec->LMARegion = M;
         else
           error("memory region '" + Sec->LMARegionName + "' not declared");
       }
       Sec->MemRegion = findMemoryRegion(Sec);
       // Handle align (e.g. ".foo : ALIGN(16) { ... }").
       if (Sec->AlignExpr)
         Sec->Alignment =
             std::max<uint32_t>(Sec->Alignment, Sec->AlignExpr().getValue());
     }
   }
 
   // If output section command doesn't specify any segments,
   // and we haven't previously assigned any section to segment,
   // then we simply assign section to the very first load segment.
   // Below is an example of such linker script:
   // PHDRS { seg PT_LOAD; }
   // SECTIONS { .aaa : { *(.aaa) } }
   std::vector<StringRef> DefPhdrs;
   auto FirstPtLoad =
       std::find_if(PhdrsCommands.begin(), PhdrsCommands.end(),
                    [](const PhdrsCommand &Cmd) { return Cmd.Type == PT_LOAD; });
   if (FirstPtLoad != PhdrsCommands.end())
     DefPhdrs.push_back(FirstPtLoad->Name);
 
   // Walk the commands and propagate the program headers to commands that don't
   // explicitly specify them.
   for (BaseCommand *Base : SectionCommands) {
     auto *Sec = dyn_cast<OutputSection>(Base);
     if (!Sec)
       continue;
 
     if (Sec->Phdrs.empty()) {
       // To match the bfd linker script behaviour, only propagate program
       // headers to sections that are allocated.
       if (Sec->Flags & SHF_ALLOC)
         Sec->Phdrs = DefPhdrs;
     } else {
       DefPhdrs = Sec->Phdrs;
     }
   }
 }
 
 static OutputSection *findFirstSection(PhdrEntry *Load) {
   for (OutputSection *Sec : OutputSections)
     if (Sec->PtLoad == Load)
       return Sec;
   return nullptr;
 }
 
 // Try to find an address for the file and program headers output sections,
 // which were unconditionally added to the first PT_LOAD segment earlier.
 //
 // When using the default layout, we check if the headers fit below the first
 // allocated section. When using a linker script, we also check if the headers
 // are covered by the output section. This allows omitting the headers by not
 // leaving enough space for them in the linker script; this pattern is common
 // in embedded systems.
 //
 // If there isn't enough space for these sections, we'll remove them from the
 // PT_LOAD segment, and we'll also remove the PT_PHDR segment.
 void LinkerScript::allocateHeaders(std::vector<PhdrEntry *> &Phdrs) {
   uint64_t Min = std::numeric_limits<uint64_t>::max();
   for (OutputSection *Sec : OutputSections)
     if (Sec->Flags & SHF_ALLOC)
       Min = std::min<uint64_t>(Min, Sec->Addr);
 
   auto It = llvm::find_if(
       Phdrs, [](const PhdrEntry *E) { return E->p_type == PT_LOAD; });
   if (It == Phdrs.end())
     return;
   PhdrEntry *FirstPTLoad = *It;
 
   uint64_t HeaderSize = getHeaderSize();
   // When linker script with SECTIONS is being used, don't output headers
   // unless there's a space for them.
   uint64_t Base = HasSectionsCommand ? alignDown(Min, Config->MaxPageSize) : 0;
   if (HeaderSize <= Min - Base || Script->hasPhdrsCommands()) {
     Min = alignDown(Min - HeaderSize, Config->MaxPageSize);
     Out::ElfHeader->Addr = Min;
     Out::ProgramHeaders->Addr = Min + Out::ElfHeader->Size;
     return;
   }
 
   Out::ElfHeader->PtLoad = nullptr;
   Out::ProgramHeaders->PtLoad = nullptr;
   FirstPTLoad->FirstSec = findFirstSection(FirstPTLoad);
 
   llvm::erase_if(Phdrs,
                  [](const PhdrEntry *E) { return E->p_type == PT_PHDR; });
 }
 
 LinkerScript::AddressState::AddressState() {
   for (auto &MRI : Script->MemoryRegions) {
     MemoryRegion *MR = MRI.second;
     MR->CurPos = MR->Origin;
   }
 }
 
 static uint64_t getInitialDot() {
   // By default linker scripts use an initial value of 0 for '.',
   // but prefer -image-base if set.
   if (Script->HasSectionsCommand)
     return Config->ImageBase ? *Config->ImageBase : 0;
 
   uint64_t StartAddr = UINT64_MAX;
   // The Sections with -T<section> have been sorted in order of ascending
   // address. We must lower StartAddr if the lowest -T<section address> as
   // calls to setDot() must be monotonically increasing.
   for (auto &KV : Config->SectionStartMap)
     StartAddr = std::min(StartAddr, KV.second);
   return std::min(StartAddr, Target->getImageBase() + elf::getHeaderSize());
 }
 
 // Here we assign addresses as instructed by linker script SECTIONS
 // sub-commands. Doing that allows us to use final VA values, so here
 // we also handle rest commands like symbol assignments and ASSERTs.
 void LinkerScript::assignAddresses() {
   Dot = getInitialDot();
 
   auto Deleter = make_unique<AddressState>();
   Ctx = Deleter.get();
   ErrorOnMissingSection = true;
   switchTo(Aether);
 
   for (BaseCommand *Base : SectionCommands) {
     if (auto *Cmd = dyn_cast<SymbolAssignment>(Base)) {
       assignSymbol(Cmd, false);
       continue;
     }
 
     if (auto *Cmd = dyn_cast<AssertCommand>(Base)) {
       Cmd->Expression();
       continue;
     }
 
     assignOffsets(cast<OutputSection>(Base));
   }
   Ctx = nullptr;
 }
 
 // Creates program headers as instructed by PHDRS linker script command.
 std::vector<PhdrEntry *> LinkerScript::createPhdrs() {
   std::vector<PhdrEntry *> Ret;
 
   // Process PHDRS and FILEHDR keywords because they are not
   // real output sections and cannot be added in the following loop.
   for (const PhdrsCommand &Cmd : PhdrsCommands) {
     PhdrEntry *Phdr = make<PhdrEntry>(Cmd.Type, Cmd.Flags ? *Cmd.Flags : PF_R);
 
     if (Cmd.HasFilehdr)
       Phdr->add(Out::ElfHeader);
     if (Cmd.HasPhdrs)
       Phdr->add(Out::ProgramHeaders);
 
     if (Cmd.LMAExpr) {
       Phdr->p_paddr = Cmd.LMAExpr().getValue();
       Phdr->HasLMA = true;
     }
     Ret.push_back(Phdr);
   }
 
   // Add output sections to program headers.
   for (OutputSection *Sec : OutputSections) {
     // Assign headers specified by linker script
     for (size_t Id : getPhdrIndices(Sec)) {
       Ret[Id]->add(Sec);
       if (!PhdrsCommands[Id].Flags.hasValue())
         Ret[Id]->p_flags |= Sec->getPhdrFlags();
     }
   }
   return Ret;
 }
 
 // Returns true if we should emit an .interp section.
 //
 // We usually do. But if PHDRS commands are given, and
 // no PT_INTERP is there, there's no place to emit an
 // .interp, so we don't do that in that case.
 bool LinkerScript::needsInterpSection() {
   if (PhdrsCommands.empty())
     return true;
   for (PhdrsCommand &Cmd : PhdrsCommands)
     if (Cmd.Type == PT_INTERP)
       return true;
   return false;
 }
 
 ExprValue LinkerScript::getSymbolValue(StringRef Name, const Twine &Loc) {
   if (Name == ".") {
     if (Ctx)
       return {Ctx->OutSec, false, Dot - Ctx->OutSec->Addr, Loc};
     error(Loc + ": unable to get location counter value");
     return 0;
   }
 
   if (Symbol *Sym = Symtab->find(Name)) {
     if (auto *DS = dyn_cast<Defined>(Sym))
       return {DS->Section, false, DS->Value, Loc};
     if (auto *SS = dyn_cast<SharedSymbol>(Sym))
       if (!ErrorOnMissingSection || SS->CopyRelSec)
         return {SS->CopyRelSec, false, 0, Loc};
   }
 
   error(Loc + ": symbol not found: " + Name);
   return 0;
 }
 
 // Returns the index of the segment named Name.
 static Optional<size_t> getPhdrIndex(ArrayRef<PhdrsCommand> Vec,
                                      StringRef Name) {
   for (size_t I = 0; I < Vec.size(); ++I)
     if (Vec[I].Name == Name)
       return I;
   return None;
 }
 
 // Returns indices of ELF headers containing specific section. Each index is a
 // zero based number of ELF header listed within PHDRS {} script block.
 std::vector<size_t> LinkerScript::getPhdrIndices(OutputSection *Cmd) {
   std::vector<size_t> Ret;
 
   for (StringRef S : Cmd->Phdrs) {
     if (Optional<size_t> Idx = getPhdrIndex(PhdrsCommands, S))
       Ret.push_back(*Idx);
     else if (S != "NONE")
       error(Cmd->Location + ": section header '" + S +
             "' is not listed in PHDRS");
   }
   return Ret;
 }
Index: head/contrib/llvm/tools/lld/ELF/LinkerScript.h
===================================================================
--- head/contrib/llvm/tools/lld/ELF/LinkerScript.h	(revision 328545)
+++ head/contrib/llvm/tools/lld/ELF/LinkerScript.h	(revision 328546)
@@ -1,296 +1,297 @@
 //===- LinkerScript.h -------------------------------------------*- C++ -*-===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLD_ELF_LINKER_SCRIPT_H
 #define LLD_ELF_LINKER_SCRIPT_H
 
 #include "Config.h"
 #include "Strings.h"
 #include "Writer.h"
 #include "lld/Common/LLVM.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include <cstddef>
 #include <cstdint>
 #include <functional>
 #include <memory>
 #include <vector>
 
 namespace lld {
 namespace elf {
 
 class Defined;
 class Symbol;
 class InputSectionBase;
 class InputSection;
 class OutputSection;
 class InputSectionBase;
 class SectionBase;
 
 // This represents an r-value in the linker script.
 struct ExprValue {
   ExprValue(SectionBase *Sec, bool ForceAbsolute, uint64_t Val,
             const Twine &Loc)
       : Sec(Sec), ForceAbsolute(ForceAbsolute), Val(Val), Loc(Loc.str()) {}
 
   ExprValue(uint64_t Val) : ExprValue(nullptr, false, Val, "") {}
 
   bool isAbsolute() const { return ForceAbsolute || Sec == nullptr; }
   uint64_t getValue() const;
   uint64_t getSecAddr() const;
   uint64_t getSectionOffset() const;
 
   // If a value is relative to a section, it has a non-null Sec.
   SectionBase *Sec;
 
   // True if this expression is enclosed in ABSOLUTE().
   // This flag affects the return value of getValue().
   bool ForceAbsolute;
 
   uint64_t Val;
   uint64_t Alignment = 1;
 
   // Original source location. Used for error messages.
   std::string Loc;
 };
 
 // This represents an expression in the linker script.
 // ScriptParser::readExpr reads an expression and returns an Expr.
 // Later, we evaluate the expression by calling the function.
 typedef std::function<ExprValue()> Expr;
 
 // This enum is used to implement linker script SECTIONS command.
 // https://sourceware.org/binutils/docs/ld/SECTIONS.html#SECTIONS
 enum SectionsCommandKind {
   AssignmentKind, // . = expr or <sym> = expr
   OutputSectionKind,
   InputSectionKind,
   AssertKind, // ASSERT(expr)
   ByteKind    // BYTE(expr), SHORT(expr), LONG(expr) or QUAD(expr)
 };
 
 struct BaseCommand {
   BaseCommand(int K) : Kind(K) {}
   int Kind;
 };
 
 // This represents ". = <expr>" or "<symbol> = <expr>".
 struct SymbolAssignment : BaseCommand {
   SymbolAssignment(StringRef Name, Expr E, std::string Loc)
       : BaseCommand(AssignmentKind), Name(Name), Expression(E), Location(Loc) {}
 
   static bool classof(const BaseCommand *C) {
     return C->Kind == AssignmentKind;
   }
 
   // The LHS of an expression. Name is either a symbol name or ".".
   StringRef Name;
   Defined *Sym = nullptr;
 
   // The RHS of an expression.
   Expr Expression;
 
   // Command attributes for PROVIDE, HIDDEN and PROVIDE_HIDDEN.
   bool Provide = false;
   bool Hidden = false;
 
   // Holds file name and line number for error reporting.
   std::string Location;
 };
 
 // Linker scripts allow additional constraints to be put on ouput sections.
 // If an output section is marked as ONLY_IF_RO, the section is created
 // only if its input sections are read-only. Likewise, an output section
 // with ONLY_IF_RW is created if all input sections are RW.
 enum class ConstraintKind { NoConstraint, ReadOnly, ReadWrite };
 
 // This struct is used to represent the location and size of regions of
 // target memory. Instances of the struct are created by parsing the
 // MEMORY command.
 struct MemoryRegion {
   MemoryRegion(StringRef Name, uint64_t Origin, uint64_t Length, uint32_t Flags,
                uint32_t NegFlags)
       : Name(Name), Origin(Origin), Length(Length), Flags(Flags),
         NegFlags(NegFlags) {}
 
   std::string Name;
   uint64_t Origin;
   uint64_t Length;
   uint32_t Flags;
   uint32_t NegFlags;
   uint64_t CurPos = 0;
 };
 
 // This struct represents one section match pattern in SECTIONS() command.
 // It can optionally have negative match pattern for EXCLUDED_FILE command.
 // Also it may be surrounded with SORT() command, so contains sorting rules.
 struct SectionPattern {
   SectionPattern(StringMatcher &&Pat1, StringMatcher &&Pat2)
       : ExcludedFilePat(Pat1), SectionPat(Pat2) {}
 
   StringMatcher ExcludedFilePat;
   StringMatcher SectionPat;
   SortSectionPolicy SortOuter;
   SortSectionPolicy SortInner;
 };
 
 class ThunkSection;
 struct InputSectionDescription : BaseCommand {
   InputSectionDescription(StringRef FilePattern)
       : BaseCommand(InputSectionKind), FilePat(FilePattern) {}
 
   static bool classof(const BaseCommand *C) {
     return C->Kind == InputSectionKind;
   }
 
   StringMatcher FilePat;
 
   // Input sections that matches at least one of SectionPatterns
   // will be associated with this InputSectionDescription.
   std::vector<SectionPattern> SectionPatterns;
 
   std::vector<InputSection *> Sections;
 
   // Temporary record of synthetic ThunkSection instances and the pass that
   // they were created in. This is used to insert newly created ThunkSections
   // into Sections at the end of a createThunks() pass.
   std::vector<std::pair<ThunkSection *, uint32_t>> ThunkSections;
 };
 
 // Represents an ASSERT().
 struct AssertCommand : BaseCommand {
   AssertCommand(Expr E) : BaseCommand(AssertKind), Expression(E) {}
 
   static bool classof(const BaseCommand *C) { return C->Kind == AssertKind; }
 
   Expr Expression;
 };
 
 // Represents BYTE(), SHORT(), LONG(), or QUAD().
 struct ByteCommand : BaseCommand {
   ByteCommand(Expr E, unsigned Size)
       : BaseCommand(ByteKind), Expression(E), Size(Size) {}
 
   static bool classof(const BaseCommand *C) { return C->Kind == ByteKind; }
 
   Expr Expression;
   unsigned Offset;
   unsigned Size;
 };
 
 struct PhdrsCommand {
   StringRef Name;
   unsigned Type = llvm::ELF::PT_NULL;
   bool HasFilehdr = false;
   bool HasPhdrs = false;
   llvm::Optional<unsigned> Flags;
   Expr LMAExpr = nullptr;
 };
 
 class LinkerScript final {
   // Temporary state used in processSectionCommands() and assignAddresses()
   // that must be reinitialized for each call to the above functions, and must
   // not be used outside of the scope of a call to the above functions.
   struct AddressState {
     AddressState();
     uint64_t ThreadBssOffset = 0;
     OutputSection *OutSec = nullptr;
     MemoryRegion *MemRegion = nullptr;
+    MemoryRegion *LMARegion = nullptr;
     uint64_t LMAOffset = 0;
   };
 
   llvm::DenseMap<StringRef, OutputSection *> NameToOutputSection;
 
   void addSymbol(SymbolAssignment *Cmd);
   void assignSymbol(SymbolAssignment *Cmd, bool InSec);
   void setDot(Expr E, const Twine &Loc, bool InSec);
 
   std::vector<InputSection *>
   computeInputSections(const InputSectionDescription *,
                        const llvm::DenseMap<SectionBase *, int> &Order);
 
   std::vector<InputSection *>
   createInputSectionList(OutputSection &Cmd,
                          const llvm::DenseMap<SectionBase *, int> &Order);
 
   std::vector<size_t> getPhdrIndices(OutputSection *Sec);
 
   MemoryRegion *findMemoryRegion(OutputSection *Sec);
 
   void switchTo(OutputSection *Sec);
   uint64_t advance(uint64_t Size, unsigned Align);
   void output(InputSection *Sec);
 
   void assignOffsets(OutputSection *Sec);
 
   // Ctx captures the local AddressState and makes it accessible
   // deliberately. This is needed as there are some cases where we cannot just
   // thread the current state through to a lambda function created by the
   // script parser.
   // This should remain a plain pointer as its lifetime is smaller than
   // LinkerScript.
   AddressState *Ctx = nullptr;
 
   OutputSection *Aether;
 
   uint64_t Dot;
 
 public:
   OutputSection *createOutputSection(StringRef Name, StringRef Location);
   OutputSection *getOrCreateOutputSection(StringRef Name);
 
   bool hasPhdrsCommands() { return !PhdrsCommands.empty(); }
   uint64_t getDot() { return Dot; }
   void discard(ArrayRef<InputSection *> V);
 
   ExprValue getSymbolValue(StringRef Name, const Twine &Loc);
 
   void addOrphanSections();
   void removeEmptyCommands();
   void adjustSectionsBeforeSorting();
   void adjustSectionsAfterSorting();
 
   std::vector<PhdrEntry *> createPhdrs();
   bool needsInterpSection();
 
   bool shouldKeep(InputSectionBase *S);
   void assignAddresses();
   void allocateHeaders(std::vector<PhdrEntry *> &Phdrs);
   void processSectionCommands();
 
   // SECTIONS command list.
   std::vector<BaseCommand *> SectionCommands;
 
   // PHDRS command list.
   std::vector<PhdrsCommand> PhdrsCommands;
 
   bool HasSectionsCommand = false;
   bool ErrorOnMissingSection = false;
 
   // List of section patterns specified with KEEP commands. They will
   // be kept even if they are unused and --gc-sections is specified.
   std::vector<InputSectionDescription *> KeptSections;
 
   // A map from memory region name to a memory region descriptor.
   llvm::MapVector<llvm::StringRef, MemoryRegion *> MemoryRegions;
 
   // A list of symbols referenced by the script.
   std::vector<llvm::StringRef> ReferencedSymbols;
 };
 
 extern LinkerScript *Script;
 
 } // end namespace elf
 } // end namespace lld
 
 #endif // LLD_ELF_LINKER_SCRIPT_H
Index: head/contrib/llvm/tools/lld/ELF/Writer.cpp
===================================================================
--- head/contrib/llvm/tools/lld/ELF/Writer.cpp	(revision 328545)
+++ head/contrib/llvm/tools/lld/ELF/Writer.cpp	(revision 328546)
@@ -1,2071 +1,2072 @@
 //===- Writer.cpp ---------------------------------------------------------===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "Writer.h"
 #include "AArch64ErrataFix.h"
 #include "Config.h"
 #include "Filesystem.h"
 #include "LinkerScript.h"
 #include "MapFile.h"
 #include "OutputSections.h"
 #include "Relocations.h"
 #include "Strings.h"
 #include "SymbolTable.h"
 #include "Symbols.h"
 #include "SyntheticSections.h"
 #include "Target.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/Threads.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringSwitch.h"
 #include <climits>
 
 using namespace llvm;
 using namespace llvm::ELF;
 using namespace llvm::object;
 using namespace llvm::support;
 using namespace llvm::support::endian;
 
 using namespace lld;
 using namespace lld::elf;
 
 namespace {
 // The writer writes a SymbolTable result to a file.
 template <class ELFT> class Writer {
 public:
   Writer() : Buffer(errorHandler().OutputBuffer) {}
   typedef typename ELFT::Shdr Elf_Shdr;
   typedef typename ELFT::Ehdr Elf_Ehdr;
   typedef typename ELFT::Phdr Elf_Phdr;
 
   void run();
 
 private:
   void copyLocalSymbols();
   void addSectionSymbols();
   void forEachRelSec(std::function<void(InputSectionBase &)> Fn);
   void sortSections();
   void resolveShfLinkOrder();
   void sortInputSections();
   void finalizeSections();
   void setReservedSymbolSections();
 
   std::vector<PhdrEntry *> createPhdrs();
   void removeEmptyPTLoad();
   void addPtArmExid(std::vector<PhdrEntry *> &Phdrs);
   void assignFileOffsets();
   void assignFileOffsetsBinary();
   void setPhdrs();
   void fixSectionAlignments();
   void openFile();
   void writeTrapInstr();
   void writeHeader();
   void writeSections();
   void writeSectionsBinary();
   void writeBuildId();
 
   std::unique_ptr<FileOutputBuffer> &Buffer;
 
   void addRelIpltSymbols();
   void addStartEndSymbols();
   void addStartStopSymbols(OutputSection *Sec);
   uint64_t getEntryAddr();
 
   std::vector<PhdrEntry *> Phdrs;
 
   uint64_t FileSize;
   uint64_t SectionHeaderOff;
 
   bool HasGotBaseSym = false;
 };
 } // anonymous namespace
 
 StringRef elf::getOutputSectionName(InputSectionBase *S) {
   // ".zdebug_" is a prefix for ZLIB-compressed sections.
   // Because we decompressed input sections, we want to remove 'z'.
   if (S->Name.startswith(".zdebug_"))
     return Saver.save("." + S->Name.substr(2));
 
   if (Config->Relocatable)
     return S->Name;
 
   // This is for --emit-relocs. If .text.foo is emitted as .text.bar, we want
   // to emit .rela.text.foo as .rela.text.bar for consistency (this is not
   // technically required, but not doing it is odd). This code guarantees that.
   if ((S->Type == SHT_REL || S->Type == SHT_RELA) &&
       !isa<SyntheticSection>(S)) {
     OutputSection *Out =
         cast<InputSection>(S)->getRelocatedSection()->getOutputSection();
     if (S->Type == SHT_RELA)
       return Saver.save(".rela" + Out->Name);
     return Saver.save(".rel" + Out->Name);
   }
 
   for (StringRef V :
        {".text.", ".rodata.", ".data.rel.ro.", ".data.", ".bss.rel.ro.",
         ".bss.", ".init_array.", ".fini_array.", ".ctors.", ".dtors.", ".tbss.",
         ".gcc_except_table.", ".tdata.", ".ARM.exidx.", ".ARM.extab."}) {
     StringRef Prefix = V.drop_back();
     if (S->Name.startswith(V) || S->Name == Prefix)
       return Prefix;
   }
 
   // CommonSection is identified as "COMMON" in linker scripts.
   // By default, it should go to .bss section.
   if (S->Name == "COMMON")
     return ".bss";
 
   return S->Name;
 }
 
 static bool needsInterpSection() {
   return !SharedFiles.empty() && !Config->DynamicLinker.empty() &&
          Script->needsInterpSection();
 }
 
 template <class ELFT> void elf::writeResult() { Writer<ELFT>().run(); }
 
 template <class ELFT> void Writer<ELFT>::removeEmptyPTLoad() {
   llvm::erase_if(Phdrs, [&](const PhdrEntry *P) {
     if (P->p_type != PT_LOAD)
       return false;
     if (!P->FirstSec)
       return true;
     uint64_t Size = P->LastSec->Addr + P->LastSec->Size - P->FirstSec->Addr;
     return Size == 0;
   });
 }
 
 template <class ELFT> static void combineEhFrameSections() {
   for (InputSectionBase *&S : InputSections) {
     EhInputSection *ES = dyn_cast<EhInputSection>(S);
     if (!ES || !ES->Live)
       continue;
 
     InX::EhFrame->addSection<ELFT>(ES);
     S = nullptr;
   }
 
   std::vector<InputSectionBase *> &V = InputSections;
   V.erase(std::remove(V.begin(), V.end(), nullptr), V.end());
 }
 
 static Defined *addOptionalRegular(StringRef Name, SectionBase *Sec,
                                    uint64_t Val, uint8_t StOther = STV_HIDDEN,
                                    uint8_t Binding = STB_GLOBAL) {
   Symbol *S = Symtab->find(Name);
   if (!S || S->isDefined())
     return nullptr;
   Symbol *Sym = Symtab->addRegular(Name, StOther, STT_NOTYPE, Val,
                                    /*Size=*/0, Binding, Sec,
                                    /*File=*/nullptr);
   return cast<Defined>(Sym);
 }
 
 // The linker is expected to define some symbols depending on
 // the linking result. This function defines such symbols.
 void elf::addReservedSymbols() {
   if (Config->EMachine == EM_MIPS) {
     // Define _gp for MIPS. st_value of _gp symbol will be updated by Writer
     // so that it points to an absolute address which by default is relative
     // to GOT. Default offset is 0x7ff0.
     // See "Global Data Symbols" in Chapter 6 in the following document:
     // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
     ElfSym::MipsGp = Symtab->addAbsolute("_gp", STV_HIDDEN, STB_GLOBAL);
 
     // On MIPS O32 ABI, _gp_disp is a magic symbol designates offset between
     // start of function and 'gp' pointer into GOT.
     if (Symtab->find("_gp_disp"))
       ElfSym::MipsGpDisp =
           Symtab->addAbsolute("_gp_disp", STV_HIDDEN, STB_GLOBAL);
 
     // The __gnu_local_gp is a magic symbol equal to the current value of 'gp'
     // pointer. This symbol is used in the code generated by .cpload pseudo-op
     // in case of using -mno-shared option.
     // https://sourceware.org/ml/binutils/2004-12/msg00094.html
     if (Symtab->find("__gnu_local_gp"))
       ElfSym::MipsLocalGp =
           Symtab->addAbsolute("__gnu_local_gp", STV_HIDDEN, STB_GLOBAL);
   }
 
   ElfSym::GlobalOffsetTable = addOptionalRegular(
       "_GLOBAL_OFFSET_TABLE_", Out::ElfHeader, Target->GotBaseSymOff);
 
   // __ehdr_start is the location of ELF file headers. Note that we define
   // this symbol unconditionally even when using a linker script, which
   // differs from the behavior implemented by GNU linker which only define
   // this symbol if ELF headers are in the memory mapped segment.
   // __executable_start is not documented, but the expectation of at
   // least the android libc is that it points to the elf header too.
   // __dso_handle symbol is passed to cxa_finalize as a marker to identify
   // each DSO. The address of the symbol doesn't matter as long as they are
   // different in different DSOs, so we chose the start address of the DSO.
   for (const char *Name :
        {"__ehdr_start", "__executable_start", "__dso_handle"})
     addOptionalRegular(Name, Out::ElfHeader, 0, STV_HIDDEN);
 
   // If linker script do layout we do not need to create any standart symbols.
   if (Script->HasSectionsCommand)
     return;
 
   auto Add = [](StringRef S, int64_t Pos) {
     return addOptionalRegular(S, Out::ElfHeader, Pos, STV_DEFAULT);
   };
 
   ElfSym::Bss = Add("__bss_start", 0);
   ElfSym::End1 = Add("end", -1);
   ElfSym::End2 = Add("_end", -1);
   ElfSym::Etext1 = Add("etext", -1);
   ElfSym::Etext2 = Add("_etext", -1);
   ElfSym::Edata1 = Add("edata", -1);
   ElfSym::Edata2 = Add("_edata", -1);
 }
 
 static OutputSection *findSection(StringRef Name) {
   for (BaseCommand *Base : Script->SectionCommands)
     if (auto *Sec = dyn_cast<OutputSection>(Base))
       if (Sec->Name == Name)
         return Sec;
   return nullptr;
 }
 
 // Initialize Out members.
 template <class ELFT> static void createSyntheticSections() {
   // Initialize all pointers with NULL. This is needed because
   // you can call lld::elf::main more than once as a library.
   memset(&Out::First, 0, sizeof(Out));
 
   auto Add = [](InputSectionBase *Sec) { InputSections.push_back(Sec); };
 
   InX::DynStrTab = make<StringTableSection>(".dynstr", true);
   InX::Dynamic = make<DynamicSection<ELFT>>();
   if (Config->AndroidPackDynRelocs) {
     InX::RelaDyn = make<AndroidPackedRelocationSection<ELFT>>(
         Config->IsRela ? ".rela.dyn" : ".rel.dyn");
   } else {
     InX::RelaDyn = make<RelocationSection<ELFT>>(
         Config->IsRela ? ".rela.dyn" : ".rel.dyn", Config->ZCombreloc);
   }
   InX::ShStrTab = make<StringTableSection>(".shstrtab", false);
 
   Out::ProgramHeaders = make<OutputSection>("", 0, SHF_ALLOC);
   Out::ProgramHeaders->Alignment = Config->Wordsize;
 
   if (needsInterpSection()) {
     InX::Interp = createInterpSection();
     Add(InX::Interp);
   } else {
     InX::Interp = nullptr;
   }
 
   if (Config->Strip != StripPolicy::All) {
     InX::StrTab = make<StringTableSection>(".strtab", false);
     InX::SymTab = make<SymbolTableSection<ELFT>>(*InX::StrTab);
   }
 
   if (Config->BuildId != BuildIdKind::None) {
     InX::BuildId = make<BuildIdSection>();
     Add(InX::BuildId);
   }
 
   InX::Bss = make<BssSection>(".bss", 0, 1);
   Add(InX::Bss);
 
   // If there is a SECTIONS command and a .data.rel.ro section name use name
   // .data.rel.ro.bss so that we match in the .data.rel.ro output section.
   // This makes sure our relro is contiguous.
   bool HasDataRelRo =
       Script->HasSectionsCommand && findSection(".data.rel.ro");
   InX::BssRelRo = make<BssSection>(
       HasDataRelRo ? ".data.rel.ro.bss" : ".bss.rel.ro", 0, 1);
   Add(InX::BssRelRo);
 
   // Add MIPS-specific sections.
   if (Config->EMachine == EM_MIPS) {
     if (!Config->Shared && Config->HasDynSymTab) {
       InX::MipsRldMap = make<MipsRldMapSection>();
       Add(InX::MipsRldMap);
     }
     if (auto *Sec = MipsAbiFlagsSection<ELFT>::create())
       Add(Sec);
     if (auto *Sec = MipsOptionsSection<ELFT>::create())
       Add(Sec);
     if (auto *Sec = MipsReginfoSection<ELFT>::create())
       Add(Sec);
   }
 
   if (Config->HasDynSymTab) {
     InX::DynSymTab = make<SymbolTableSection<ELFT>>(*InX::DynStrTab);
     Add(InX::DynSymTab);
 
     In<ELFT>::VerSym = make<VersionTableSection<ELFT>>();
     Add(In<ELFT>::VerSym);
 
     if (!Config->VersionDefinitions.empty()) {
       In<ELFT>::VerDef = make<VersionDefinitionSection<ELFT>>();
       Add(In<ELFT>::VerDef);
     }
 
     In<ELFT>::VerNeed = make<VersionNeedSection<ELFT>>();
     Add(In<ELFT>::VerNeed);
 
     if (Config->GnuHash) {
       InX::GnuHashTab = make<GnuHashTableSection>();
       Add(InX::GnuHashTab);
     }
 
     if (Config->SysvHash) {
       InX::HashTab = make<HashTableSection>();
       Add(InX::HashTab);
     }
 
     Add(InX::Dynamic);
     Add(InX::DynStrTab);
     Add(InX::RelaDyn);
   }
 
   // Add .got. MIPS' .got is so different from the other archs,
   // it has its own class.
   if (Config->EMachine == EM_MIPS) {
     InX::MipsGot = make<MipsGotSection>();
     Add(InX::MipsGot);
   } else {
     InX::Got = make<GotSection>();
     Add(InX::Got);
   }
 
   InX::GotPlt = make<GotPltSection>();
   Add(InX::GotPlt);
   InX::IgotPlt = make<IgotPltSection>();
   Add(InX::IgotPlt);
 
   if (Config->GdbIndex) {
     InX::GdbIndex = createGdbIndex<ELFT>();
     Add(InX::GdbIndex);
   }
 
   // We always need to add rel[a].plt to output if it has entries.
   // Even for static linking it can contain R_[*]_IRELATIVE relocations.
   InX::RelaPlt = make<RelocationSection<ELFT>>(
       Config->IsRela ? ".rela.plt" : ".rel.plt", false /*Sort*/);
   Add(InX::RelaPlt);
 
   // The RelaIplt immediately follows .rel.plt (.rel.dyn for ARM) to ensure
   // that the IRelative relocations are processed last by the dynamic loader.
   // We cannot place the iplt section in .rel.dyn when Android relocation
   // packing is enabled because that would cause a section type mismatch.
   // However, because the Android dynamic loader reads .rel.plt after .rel.dyn,
   // we can get the desired behaviour by placing the iplt section in .rel.plt.
   InX::RelaIplt = make<RelocationSection<ELFT>>(
       (Config->EMachine == EM_ARM && !Config->AndroidPackDynRelocs)
           ? ".rel.dyn"
           : InX::RelaPlt->Name,
       false /*Sort*/);
   Add(InX::RelaIplt);
 
   InX::Plt = make<PltSection>(Target->PltHeaderSize);
   Add(InX::Plt);
   InX::Iplt = make<PltSection>(0);
   Add(InX::Iplt);
 
   if (!Config->Relocatable) {
     if (Config->EhFrameHdr) {
       InX::EhFrameHdr = make<EhFrameHeader>();
       Add(InX::EhFrameHdr);
     }
     InX::EhFrame = make<EhFrameSection>();
     Add(InX::EhFrame);
   }
 
   if (InX::SymTab)
     Add(InX::SymTab);
   Add(InX::ShStrTab);
   if (InX::StrTab)
     Add(InX::StrTab);
 
   if (Config->EMachine == EM_ARM && !Config->Relocatable)
     // Add a sentinel to terminate .ARM.exidx. It helps an unwinder
     // to find the exact address range of the last entry.
     Add(make<ARMExidxSentinelSection>());
 }
 
 // The main function of the writer.
 template <class ELFT> void Writer<ELFT>::run() {
   // Create linker-synthesized sections such as .got or .plt.
   // Such sections are of type input section.
   createSyntheticSections<ELFT>();
 
   if (!Config->Relocatable)
     combineEhFrameSections<ELFT>();
 
   // We want to process linker script commands. When SECTIONS command
   // is given we let it create sections.
   Script->processSectionCommands();
 
   // Linker scripts controls how input sections are assigned to output sections.
   // Input sections that were not handled by scripts are called "orphans", and
   // they are assigned to output sections by the default rule. Process that.
   Script->addOrphanSections();
 
   if (Config->Discard != DiscardPolicy::All)
     copyLocalSymbols();
 
   if (Config->CopyRelocs)
     addSectionSymbols();
 
   // Now that we have a complete set of output sections. This function
   // completes section contents. For example, we need to add strings
   // to the string table, and add entries to .got and .plt.
   // finalizeSections does that.
   finalizeSections();
   if (errorCount())
     return;
 
   Script->assignAddresses();
 
   // If -compressed-debug-sections is specified, we need to compress
   // .debug_* sections. Do it right now because it changes the size of
   // output sections.
   for (OutputSection *Sec : OutputSections)
     Sec->maybeCompress<ELFT>();
 
   Script->allocateHeaders(Phdrs);
 
   // Remove empty PT_LOAD to avoid causing the dynamic linker to try to mmap a
   // 0 sized region. This has to be done late since only after assignAddresses
   // we know the size of the sections.
   removeEmptyPTLoad();
 
   if (!Config->OFormatBinary)
     assignFileOffsets();
   else
     assignFileOffsetsBinary();
 
   setPhdrs();
 
   if (Config->Relocatable) {
     for (OutputSection *Sec : OutputSections)
       Sec->Addr = 0;
   }
 
   // It does not make sense try to open the file if we have error already.
   if (errorCount())
     return;
   // Write the result down to a file.
   openFile();
   if (errorCount())
     return;
 
   if (!Config->OFormatBinary) {
     writeTrapInstr();
     writeHeader();
     writeSections();
   } else {
     writeSectionsBinary();
   }
 
   // Backfill .note.gnu.build-id section content. This is done at last
   // because the content is usually a hash value of the entire output file.
   writeBuildId();
   if (errorCount())
     return;
 
   // Handle -Map option.
   writeMapFile();
   if (errorCount())
     return;
 
   if (auto E = Buffer->commit())
     error("failed to write to the output file: " + toString(std::move(E)));
 }
 
 static bool shouldKeepInSymtab(SectionBase *Sec, StringRef SymName,
                                const Symbol &B) {
   if (B.isFile() || B.isSection())
     return false;
 
   // If sym references a section in a discarded group, don't keep it.
   if (Sec == &InputSection::Discarded)
     return false;
 
   if (Config->Discard == DiscardPolicy::None)
     return true;
 
   // In ELF assembly .L symbols are normally discarded by the assembler.
   // If the assembler fails to do so, the linker discards them if
   // * --discard-locals is used.
   // * The symbol is in a SHF_MERGE section, which is normally the reason for
   //   the assembler keeping the .L symbol.
   if (!SymName.startswith(".L") && !SymName.empty())
     return true;
 
   if (Config->Discard == DiscardPolicy::Locals)
     return false;
 
   return !Sec || !(Sec->Flags & SHF_MERGE);
 }
 
 static bool includeInSymtab(const Symbol &B) {
   if (!B.isLocal() && !B.IsUsedInRegularObj)
     return false;
 
   if (auto *D = dyn_cast<Defined>(&B)) {
     // Always include absolute symbols.
     SectionBase *Sec = D->Section;
     if (!Sec)
       return true;
     Sec = Sec->Repl;
     // Exclude symbols pointing to garbage-collected sections.
     if (isa<InputSectionBase>(Sec) && !Sec->Live)
       return false;
     if (auto *S = dyn_cast<MergeInputSection>(Sec))
       if (!S->getSectionPiece(D->Value)->Live)
         return false;
     return true;
   }
   return B.Used;
 }
 
 // Local symbols are not in the linker's symbol table. This function scans
 // each object file's symbol table to copy local symbols to the output.
 template <class ELFT> void Writer<ELFT>::copyLocalSymbols() {
   if (!InX::SymTab)
     return;
   for (InputFile *File : ObjectFiles) {
     ObjFile<ELFT> *F = cast<ObjFile<ELFT>>(File);
     for (Symbol *B : F->getLocalSymbols()) {
       if (!B->isLocal())
         fatal(toString(F) +
               ": broken object: getLocalSymbols returns a non-local symbol");
       auto *DR = dyn_cast<Defined>(B);
 
       // No reason to keep local undefined symbol in symtab.
       if (!DR)
         continue;
       if (!includeInSymtab(*B))
         continue;
 
       SectionBase *Sec = DR->Section;
       if (!shouldKeepInSymtab(Sec, B->getName(), *B))
         continue;
       InX::SymTab->addSymbol(B);
     }
   }
 }
 
 template <class ELFT> void Writer<ELFT>::addSectionSymbols() {
   // Create a section symbol for each output section so that we can represent
   // relocations that point to the section. If we know that no relocation is
   // referring to a section (that happens if the section is a synthetic one), we
   // don't create a section symbol for that section.
   for (BaseCommand *Base : Script->SectionCommands) {
     auto *Sec = dyn_cast<OutputSection>(Base);
     if (!Sec)
       continue;
     auto I = llvm::find_if(Sec->SectionCommands, [](BaseCommand *Base) {
       if (auto *ISD = dyn_cast<InputSectionDescription>(Base))
         return !ISD->Sections.empty();
       return false;
     });
     if (I == Sec->SectionCommands.end())
       continue;
     InputSection *IS = cast<InputSectionDescription>(*I)->Sections[0];
 
     // Relocations are not using REL[A] section symbols.
     if (IS->Type == SHT_REL || IS->Type == SHT_RELA)
       continue;
 
     // Unlike other synthetic sections, mergeable output sections contain data
     // copied from input sections, and there may be a relocation pointing to its
     // contents if -r or -emit-reloc are given.
     if (isa<SyntheticSection>(IS) && !(IS->Flags & SHF_MERGE))
       continue;
 
     auto *Sym =
         make<Defined>(IS->File, "", STB_LOCAL, /*StOther=*/0, STT_SECTION,
                       /*Value=*/0, /*Size=*/0, IS);
     InX::SymTab->addSymbol(Sym);
   }
 }
 
 // Today's loaders have a feature to make segments read-only after
 // processing dynamic relocations to enhance security. PT_GNU_RELRO
 // is defined for that.
 //
 // This function returns true if a section needs to be put into a
 // PT_GNU_RELRO segment.
 static bool isRelroSection(const OutputSection *Sec) {
   if (!Config->ZRelro)
     return false;
 
   uint64_t Flags = Sec->Flags;
 
   // Non-allocatable or non-writable sections don't need RELRO because
   // they are not writable or not even mapped to memory in the first place.
   // RELRO is for sections that are essentially read-only but need to
   // be writable only at process startup to allow dynamic linker to
   // apply relocations.
   if (!(Flags & SHF_ALLOC) || !(Flags & SHF_WRITE))
     return false;
 
   // Once initialized, TLS data segments are used as data templates
   // for a thread-local storage. For each new thread, runtime
   // allocates memory for a TLS and copy templates there. No thread
   // are supposed to use templates directly. Thus, it can be in RELRO.
   if (Flags & SHF_TLS)
     return true;
 
   // .init_array, .preinit_array and .fini_array contain pointers to
   // functions that are executed on process startup or exit. These
   // pointers are set by the static linker, and they are not expected
   // to change at runtime. But if you are an attacker, you could do
   // interesting things by manipulating pointers in .fini_array, for
   // example. So they are put into RELRO.
   uint32_t Type = Sec->Type;
   if (Type == SHT_INIT_ARRAY || Type == SHT_FINI_ARRAY ||
       Type == SHT_PREINIT_ARRAY)
     return true;
 
   // .got contains pointers to external symbols. They are resolved by
   // the dynamic linker when a module is loaded into memory, and after
   // that they are not expected to change. So, it can be in RELRO.
   if (InX::Got && Sec == InX::Got->getParent())
     return true;
 
   // .got.plt contains pointers to external function symbols. They are
   // by default resolved lazily, so we usually cannot put it into RELRO.
   // However, if "-z now" is given, the lazy symbol resolution is
   // disabled, which enables us to put it into RELRO.
   if (Sec == InX::GotPlt->getParent())
     return Config->ZNow;
 
   // .dynamic section contains data for the dynamic linker, and
   // there's no need to write to it at runtime, so it's better to put
   // it into RELRO.
   if (Sec == InX::Dynamic->getParent())
     return true;
 
   // Sections with some special names are put into RELRO. This is a
   // bit unfortunate because section names shouldn't be significant in
   // ELF in spirit. But in reality many linker features depend on
   // magic section names.
   StringRef S = Sec->Name;
   return S == ".data.rel.ro" || S == ".bss.rel.ro" || S == ".ctors" ||
          S == ".dtors" || S == ".jcr" || S == ".eh_frame" ||
          S == ".openbsd.randomdata";
 }
 
 // We compute a rank for each section. The rank indicates where the
 // section should be placed in the file.  Instead of using simple
 // numbers (0,1,2...), we use a series of flags. One for each decision
 // point when placing the section.
 // Using flags has two key properties:
 // * It is easy to check if a give branch was taken.
 // * It is easy two see how similar two ranks are (see getRankProximity).
 enum RankFlags {
   RF_NOT_ADDR_SET = 1 << 16,
   RF_NOT_INTERP = 1 << 15,
   RF_NOT_ALLOC = 1 << 14,
   RF_WRITE = 1 << 13,
   RF_EXEC_WRITE = 1 << 12,
   RF_EXEC = 1 << 11,
   RF_NON_TLS_BSS = 1 << 10,
   RF_NON_TLS_BSS_RO = 1 << 9,
   RF_NOT_TLS = 1 << 8,
   RF_BSS = 1 << 7,
   RF_PPC_NOT_TOCBSS = 1 << 6,
   RF_PPC_OPD = 1 << 5,
   RF_PPC_TOCL = 1 << 4,
   RF_PPC_TOC = 1 << 3,
   RF_PPC_BRANCH_LT = 1 << 2,
   RF_MIPS_GPREL = 1 << 1,
   RF_MIPS_NOT_GOT = 1 << 0
 };
 
 static unsigned getSectionRank(const OutputSection *Sec) {
   unsigned Rank = 0;
 
   // We want to put section specified by -T option first, so we
   // can start assigning VA starting from them later.
   if (Config->SectionStartMap.count(Sec->Name))
     return Rank;
   Rank |= RF_NOT_ADDR_SET;
 
   // Put .interp first because some loaders want to see that section
   // on the first page of the executable file when loaded into memory.
   if (Sec->Name == ".interp")
     return Rank;
   Rank |= RF_NOT_INTERP;
 
   // Allocatable sections go first to reduce the total PT_LOAD size and
   // so debug info doesn't change addresses in actual code.
   if (!(Sec->Flags & SHF_ALLOC))
     return Rank | RF_NOT_ALLOC;
 
   // Sort sections based on their access permission in the following
   // order: R, RX, RWX, RW.  This order is based on the following
   // considerations:
   // * Read-only sections come first such that they go in the
   //   PT_LOAD covering the program headers at the start of the file.
   // * Read-only, executable sections come next, unless the
   //   -no-rosegment option is used.
   // * Writable, executable sections follow such that .plt on
   //   architectures where it needs to be writable will be placed
   //   between .text and .data.
   // * Writable sections come last, such that .bss lands at the very
   //   end of the last PT_LOAD.
   bool IsExec = Sec->Flags & SHF_EXECINSTR;
   bool IsWrite = Sec->Flags & SHF_WRITE;
 
   if (IsExec) {
     if (IsWrite)
       Rank |= RF_EXEC_WRITE;
     else if (!Config->SingleRoRx)
       Rank |= RF_EXEC;
   } else {
     if (IsWrite)
       Rank |= RF_WRITE;
   }
 
   // If we got here we know that both A and B are in the same PT_LOAD.
 
   bool IsTls = Sec->Flags & SHF_TLS;
   bool IsNoBits = Sec->Type == SHT_NOBITS;
 
   // The first requirement we have is to put (non-TLS) nobits sections last. The
   // reason is that the only thing the dynamic linker will see about them is a
   // p_memsz that is larger than p_filesz. Seeing that it zeros the end of the
   // PT_LOAD, so that has to correspond to the nobits sections.
   bool IsNonTlsNoBits = IsNoBits && !IsTls;
   if (IsNonTlsNoBits)
     Rank |= RF_NON_TLS_BSS;
 
   // We place nobits RelRo sections before plain r/w ones, and non-nobits RelRo
   // sections after r/w ones, so that the RelRo sections are contiguous.
   bool IsRelRo = isRelroSection(Sec);
   if (IsNonTlsNoBits && !IsRelRo)
     Rank |= RF_NON_TLS_BSS_RO;
   if (!IsNonTlsNoBits && IsRelRo)
     Rank |= RF_NON_TLS_BSS_RO;
 
   // The TLS initialization block needs to be a single contiguous block in a R/W
   // PT_LOAD, so stick TLS sections directly before the other RelRo R/W
   // sections. The TLS NOBITS sections are placed here as they don't take up
   // virtual address space in the PT_LOAD.
   if (!IsTls)
     Rank |= RF_NOT_TLS;
 
   // Within the TLS initialization block, the non-nobits sections need to appear
   // first.
   if (IsNoBits)
     Rank |= RF_BSS;
 
   // Some architectures have additional ordering restrictions for sections
   // within the same PT_LOAD.
   if (Config->EMachine == EM_PPC64) {
     // PPC64 has a number of special SHT_PROGBITS+SHF_ALLOC+SHF_WRITE sections
     // that we would like to make sure appear is a specific order to maximize
     // their coverage by a single signed 16-bit offset from the TOC base
     // pointer. Conversely, the special .tocbss section should be first among
     // all SHT_NOBITS sections. This will put it next to the loaded special
     // PPC64 sections (and, thus, within reach of the TOC base pointer).
     StringRef Name = Sec->Name;
     if (Name != ".tocbss")
       Rank |= RF_PPC_NOT_TOCBSS;
 
     if (Name == ".opd")
       Rank |= RF_PPC_OPD;
 
     if (Name == ".toc1")
       Rank |= RF_PPC_TOCL;
 
     if (Name == ".toc")
       Rank |= RF_PPC_TOC;
 
     if (Name == ".branch_lt")
       Rank |= RF_PPC_BRANCH_LT;
   }
   if (Config->EMachine == EM_MIPS) {
     // All sections with SHF_MIPS_GPREL flag should be grouped together
     // because data in these sections is addressable with a gp relative address.
     if (Sec->Flags & SHF_MIPS_GPREL)
       Rank |= RF_MIPS_GPREL;
 
     if (Sec->Name != ".got")
       Rank |= RF_MIPS_NOT_GOT;
   }
 
   return Rank;
 }
 
 static bool compareSections(const BaseCommand *ACmd, const BaseCommand *BCmd) {
   const OutputSection *A = cast<OutputSection>(ACmd);
   const OutputSection *B = cast<OutputSection>(BCmd);
   if (A->SortRank != B->SortRank)
     return A->SortRank < B->SortRank;
   if (!(A->SortRank & RF_NOT_ADDR_SET))
     return Config->SectionStartMap.lookup(A->Name) <
            Config->SectionStartMap.lookup(B->Name);
   return false;
 }
 
 void PhdrEntry::add(OutputSection *Sec) {
   LastSec = Sec;
   if (!FirstSec)
     FirstSec = Sec;
   p_align = std::max(p_align, Sec->Alignment);
   if (p_type == PT_LOAD)
     Sec->PtLoad = this;
 }
 
 // The beginning and the ending of .rel[a].plt section are marked
 // with __rel[a]_iplt_{start,end} symbols if it is a statically linked
 // executable. The runtime needs these symbols in order to resolve
 // all IRELATIVE relocs on startup. For dynamic executables, we don't
 // need these symbols, since IRELATIVE relocs are resolved through GOT
 // and PLT. For details, see http://www.airs.com/blog/archives/403.
 template <class ELFT> void Writer<ELFT>::addRelIpltSymbols() {
   if (!Config->Static)
     return;
   StringRef S = Config->IsRela ? "__rela_iplt_start" : "__rel_iplt_start";
   addOptionalRegular(S, InX::RelaIplt, 0, STV_HIDDEN, STB_WEAK);
 
   S = Config->IsRela ? "__rela_iplt_end" : "__rel_iplt_end";
   addOptionalRegular(S, InX::RelaIplt, -1, STV_HIDDEN, STB_WEAK);
 }
 
 template <class ELFT>
 void Writer<ELFT>::forEachRelSec(std::function<void(InputSectionBase &)> Fn) {
   // Scan all relocations. Each relocation goes through a series
   // of tests to determine if it needs special treatment, such as
   // creating GOT, PLT, copy relocations, etc.
   // Note that relocations for non-alloc sections are directly
   // processed by InputSection::relocateNonAlloc.
   for (InputSectionBase *IS : InputSections)
     if (IS->Live && isa<InputSection>(IS) && (IS->Flags & SHF_ALLOC))
       Fn(*IS);
   for (EhInputSection *ES : InX::EhFrame->Sections)
     Fn(*ES);
 }
 
 // This function generates assignments for predefined symbols (e.g. _end or
 // _etext) and inserts them into the commands sequence to be processed at the
 // appropriate time. This ensures that the value is going to be correct by the
 // time any references to these symbols are processed and is equivalent to
 // defining these symbols explicitly in the linker script.
 template <class ELFT> void Writer<ELFT>::setReservedSymbolSections() {
   if (ElfSym::GlobalOffsetTable) {
     // The _GLOBAL_OFFSET_TABLE_ symbol is defined by target convention to
     // be at some offset from the base of the .got section, usually 0 or the end
     // of the .got
     InputSection *GotSection = InX::MipsGot ? cast<InputSection>(InX::MipsGot)
                                             : cast<InputSection>(InX::Got);
     ElfSym::GlobalOffsetTable->Section = GotSection;
   }
 
   PhdrEntry *Last = nullptr;
   PhdrEntry *LastRO = nullptr;
 
   for (PhdrEntry *P : Phdrs) {
     if (P->p_type != PT_LOAD)
       continue;
     Last = P;
     if (!(P->p_flags & PF_W))
       LastRO = P;
   }
 
   if (LastRO) {
     // _etext is the first location after the last read-only loadable segment.
     if (ElfSym::Etext1)
       ElfSym::Etext1->Section = LastRO->LastSec;
     if (ElfSym::Etext2)
       ElfSym::Etext2->Section = LastRO->LastSec;
   }
 
   if (Last) {
     // _edata points to the end of the last mapped initialized section.
     OutputSection *Edata = nullptr;
     for (OutputSection *OS : OutputSections) {
       if (OS->Type != SHT_NOBITS)
         Edata = OS;
       if (OS == Last->LastSec)
         break;
     }
 
     if (ElfSym::Edata1)
       ElfSym::Edata1->Section = Edata;
     if (ElfSym::Edata2)
       ElfSym::Edata2->Section = Edata;
 
     // _end is the first location after the uninitialized data region.
     if (ElfSym::End1)
       ElfSym::End1->Section = Last->LastSec;
     if (ElfSym::End2)
       ElfSym::End2->Section = Last->LastSec;
   }
 
   if (ElfSym::Bss)
     ElfSym::Bss->Section = findSection(".bss");
 
   // Setup MIPS _gp_disp/__gnu_local_gp symbols which should
   // be equal to the _gp symbol's value.
   if (ElfSym::MipsGp) {
     // Find GP-relative section with the lowest address
     // and use this address to calculate default _gp value.
     for (OutputSection *OS : OutputSections) {
       if (OS->Flags & SHF_MIPS_GPREL) {
         ElfSym::MipsGp->Section = OS;
         ElfSym::MipsGp->Value = 0x7ff0;
         break;
       }
     }
   }
 }
 
 // We want to find how similar two ranks are.
 // The more branches in getSectionRank that match, the more similar they are.
 // Since each branch corresponds to a bit flag, we can just use
 // countLeadingZeros.
 static int getRankProximityAux(OutputSection *A, OutputSection *B) {
   return countLeadingZeros(A->SortRank ^ B->SortRank);
 }
 
 static int getRankProximity(OutputSection *A, BaseCommand *B) {
   if (auto *Sec = dyn_cast<OutputSection>(B))
     if (Sec->Live)
       return getRankProximityAux(A, Sec);
   return -1;
 }
 
 // When placing orphan sections, we want to place them after symbol assignments
 // so that an orphan after
 //   begin_foo = .;
 //   foo : { *(foo) }
 //   end_foo = .;
 // doesn't break the intended meaning of the begin/end symbols.
 // We don't want to go over sections since findOrphanPos is the
 // one in charge of deciding the order of the sections.
 // We don't want to go over changes to '.', since doing so in
 //  rx_sec : { *(rx_sec) }
 //  . = ALIGN(0x1000);
 //  /* The RW PT_LOAD starts here*/
 //  rw_sec : { *(rw_sec) }
 // would mean that the RW PT_LOAD would become unaligned.
 static bool shouldSkip(BaseCommand *Cmd) {
   if (isa<OutputSection>(Cmd))
     return false;
   if (auto *Assign = dyn_cast<SymbolAssignment>(Cmd))
     return Assign->Name != ".";
   return true;
 }
 
 // We want to place orphan sections so that they share as much
 // characteristics with their neighbors as possible. For example, if
 // both are rw, or both are tls.
 template <typename ELFT>
 static std::vector<BaseCommand *>::iterator
 findOrphanPos(std::vector<BaseCommand *>::iterator B,
               std::vector<BaseCommand *>::iterator E) {
   OutputSection *Sec = cast<OutputSection>(*E);
 
   // Find the first element that has as close a rank as possible.
   auto I = std::max_element(B, E, [=](BaseCommand *A, BaseCommand *B) {
     return getRankProximity(Sec, A) < getRankProximity(Sec, B);
   });
   if (I == E)
     return E;
 
   // Consider all existing sections with the same proximity.
   int Proximity = getRankProximity(Sec, *I);
   for (; I != E; ++I) {
     auto *CurSec = dyn_cast<OutputSection>(*I);
     if (!CurSec || !CurSec->Live)
       continue;
     if (getRankProximity(Sec, CurSec) != Proximity ||
         Sec->SortRank < CurSec->SortRank)
       break;
   }
 
   auto IsLiveSection = [](BaseCommand *Cmd) {
     auto *OS = dyn_cast<OutputSection>(Cmd);
     return OS && OS->Live;
   };
 
   auto J = std::find_if(llvm::make_reverse_iterator(I),
                         llvm::make_reverse_iterator(B), IsLiveSection);
   I = J.base();
 
   // As a special case, if the orphan section is the last section, put
   // it at the very end, past any other commands.
   // This matches bfd's behavior and is convenient when the linker script fully
   // specifies the start of the file, but doesn't care about the end (the non
   // alloc sections for example).
   auto NextSec = std::find_if(I, E, IsLiveSection);
   if (NextSec == E)
     return E;
 
   while (I != E && shouldSkip(*I))
     ++I;
   return I;
 }
 
 // If no layout was provided by linker script, we want to apply default
 // sorting for special input sections and handle --symbol-ordering-file.
 template <class ELFT> void Writer<ELFT>::sortInputSections() {
   assert(!Script->HasSectionsCommand);
 
   // Sort input sections by priority using the list provided
   // by --symbol-ordering-file.
   DenseMap<SectionBase *, int> Order = buildSectionOrder();
   if (!Order.empty())
     for (BaseCommand *Base : Script->SectionCommands)
       if (auto *Sec = dyn_cast<OutputSection>(Base))
         if (Sec->Live)
           Sec->sort([&](InputSectionBase *S) { return Order.lookup(S); });
 
   // Sort input sections by section name suffixes for
   // __attribute__((init_priority(N))).
   if (OutputSection *Sec = findSection(".init_array"))
     Sec->sortInitFini();
   if (OutputSection *Sec = findSection(".fini_array"))
     Sec->sortInitFini();
 
   // Sort input sections by the special rule for .ctors and .dtors.
   if (OutputSection *Sec = findSection(".ctors"))
     Sec->sortCtorsDtors();
   if (OutputSection *Sec = findSection(".dtors"))
     Sec->sortCtorsDtors();
 }
 
 template <class ELFT> void Writer<ELFT>::sortSections() {
   Script->adjustSectionsBeforeSorting();
 
   // Don't sort if using -r. It is not necessary and we want to preserve the
   // relative order for SHF_LINK_ORDER sections.
   if (Config->Relocatable)
     return;
 
   for (BaseCommand *Base : Script->SectionCommands)
     if (auto *Sec = dyn_cast<OutputSection>(Base))
       Sec->SortRank = getSectionRank(Sec);
 
   if (!Script->HasSectionsCommand) {
     sortInputSections();
 
     // We know that all the OutputSections are contiguous in this case.
     auto E = Script->SectionCommands.end();
     auto I = Script->SectionCommands.begin();
     auto IsSection = [](BaseCommand *Base) { return isa<OutputSection>(Base); };
     I = std::find_if(I, E, IsSection);
     E = std::find_if(llvm::make_reverse_iterator(E),
                      llvm::make_reverse_iterator(I), IsSection)
             .base();
     std::stable_sort(I, E, compareSections);
     return;
   }
 
   // Orphan sections are sections present in the input files which are
   // not explicitly placed into the output file by the linker script.
   //
   // The sections in the linker script are already in the correct
   // order. We have to figuere out where to insert the orphan
   // sections.
   //
   // The order of the sections in the script is arbitrary and may not agree with
   // compareSections. This means that we cannot easily define a strict weak
   // ordering. To see why, consider a comparison of a section in the script and
   // one not in the script. We have a two simple options:
   // * Make them equivalent (a is not less than b, and b is not less than a).
   //   The problem is then that equivalence has to be transitive and we can
   //   have sections a, b and c with only b in a script and a less than c
   //   which breaks this property.
   // * Use compareSectionsNonScript. Given that the script order doesn't have
   //   to match, we can end up with sections a, b, c, d where b and c are in the
   //   script and c is compareSectionsNonScript less than b. In which case d
   //   can be equivalent to c, a to b and d < a. As a concrete example:
   //   .a (rx) # not in script
   //   .b (rx) # in script
   //   .c (ro) # in script
   //   .d (ro) # not in script
   //
   // The way we define an order then is:
   // *  Sort only the orphan sections. They are in the end right now.
   // *  Move each orphan section to its preferred position. We try
   //    to put each section in the last position where it it can share
   //    a PT_LOAD.
   //
   // There is some ambiguity as to where exactly a new entry should be
   // inserted, because Commands contains not only output section
   // commands but also other types of commands such as symbol assignment
   // expressions. There's no correct answer here due to the lack of the
   // formal specification of the linker script. We use heuristics to
   // determine whether a new output command should be added before or
   // after another commands. For the details, look at shouldSkip
   // function.
 
   auto I = Script->SectionCommands.begin();
   auto E = Script->SectionCommands.end();
   auto NonScriptI = std::find_if(I, E, [](BaseCommand *Base) {
     if (auto *Sec = dyn_cast<OutputSection>(Base))
       return Sec->Live && Sec->SectionIndex == INT_MAX;
     return false;
   });
 
   // Sort the orphan sections.
   std::stable_sort(NonScriptI, E, compareSections);
 
   // As a horrible special case, skip the first . assignment if it is before any
   // section. We do this because it is common to set a load address by starting
   // the script with ". = 0xabcd" and the expectation is that every section is
   // after that.
   auto FirstSectionOrDotAssignment =
       std::find_if(I, E, [](BaseCommand *Cmd) { return !shouldSkip(Cmd); });
   if (FirstSectionOrDotAssignment != E &&
       isa<SymbolAssignment>(**FirstSectionOrDotAssignment))
     ++FirstSectionOrDotAssignment;
   I = FirstSectionOrDotAssignment;
 
   while (NonScriptI != E) {
     auto Pos = findOrphanPos<ELFT>(I, NonScriptI);
     OutputSection *Orphan = cast<OutputSection>(*NonScriptI);
 
     // As an optimization, find all sections with the same sort rank
     // and insert them with one rotate.
     unsigned Rank = Orphan->SortRank;
     auto End = std::find_if(NonScriptI + 1, E, [=](BaseCommand *Cmd) {
       return cast<OutputSection>(Cmd)->SortRank != Rank;
     });
     std::rotate(Pos, NonScriptI, End);
     NonScriptI = End;
   }
 
   Script->adjustSectionsAfterSorting();
 }
 
 static bool compareByFilePosition(InputSection *A, InputSection *B) {
   // Synthetic, i. e. a sentinel section, should go last.
   if (A->kind() == InputSectionBase::Synthetic ||
       B->kind() == InputSectionBase::Synthetic)
     return A->kind() != InputSectionBase::Synthetic;
   InputSection *LA = A->getLinkOrderDep();
   InputSection *LB = B->getLinkOrderDep();
   OutputSection *AOut = LA->getParent();
   OutputSection *BOut = LB->getParent();
   if (AOut != BOut)
     return AOut->SectionIndex < BOut->SectionIndex;
   return LA->OutSecOff < LB->OutSecOff;
 }
 
 // This function is used by the --merge-exidx-entries to detect duplicate
 // .ARM.exidx sections. It is Arm only.
 //
 // The .ARM.exidx section is of the form:
 // | PREL31 offset to function | Unwind instructions for function |
 // where the unwind instructions are either a small number of unwind
 // instructions inlined into the table entry, the special CANT_UNWIND value of
 // 0x1 or a PREL31 offset into a .ARM.extab Section that contains unwind
 // instructions.
 //
 // We return true if all the unwind instructions in the .ARM.exidx entries of
 // Cur can be merged into the last entry of Prev.
 static bool isDuplicateArmExidxSec(InputSection *Prev, InputSection *Cur) {
 
   // References to .ARM.Extab Sections have bit 31 clear and are not the
   // special EXIDX_CANTUNWIND bit-pattern.
   auto IsExtabRef = [](uint32_t Unwind) {
     return (Unwind & 0x80000000) == 0 && Unwind != 0x1;
   };
 
   struct ExidxEntry {
     ulittle32_t Fn;
     ulittle32_t Unwind;
   };
 
   // Get the last table Entry from the previous .ARM.exidx section.
   const ExidxEntry &PrevEntry = *reinterpret_cast<const ExidxEntry *>(
       Prev->Data.data() + Prev->getSize() - sizeof(ExidxEntry));
   if (IsExtabRef(PrevEntry.Unwind))
     return false;
 
   // We consider the unwind instructions of an .ARM.exidx table entry
   // a duplicate if the previous unwind instructions if:
   // - Both are the special EXIDX_CANTUNWIND.
   // - Both are the same inline unwind instructions.
   // We do not attempt to follow and check links into .ARM.extab tables as
   // consecutive identical entries are rare and the effort to check that they
   // are identical is high.
 
   if (isa<SyntheticSection>(Cur))
     // Exidx sentinel section has implicit EXIDX_CANTUNWIND;
     return PrevEntry.Unwind == 0x1;
 
   ArrayRef<const ExidxEntry> Entries(
       reinterpret_cast<const ExidxEntry *>(Cur->Data.data()),
       Cur->getSize() / sizeof(ExidxEntry));
   for (const ExidxEntry &Entry : Entries)
     if (IsExtabRef(Entry.Unwind) || Entry.Unwind != PrevEntry.Unwind)
       return false;
   // All table entries in this .ARM.exidx Section can be merged into the
   // previous Section.
   return true;
 }
 
 template <class ELFT> void Writer<ELFT>::resolveShfLinkOrder() {
   for (OutputSection *Sec : OutputSections) {
     if (!(Sec->Flags & SHF_LINK_ORDER))
       continue;
 
     // Link order may be distributed across several InputSectionDescriptions
     // but sort must consider them all at once.
     std::vector<InputSection **> ScriptSections;
     std::vector<InputSection *> Sections;
     for (BaseCommand *Base : Sec->SectionCommands) {
       if (auto *ISD = dyn_cast<InputSectionDescription>(Base)) {
         for (InputSection *&IS : ISD->Sections) {
           ScriptSections.push_back(&IS);
           Sections.push_back(IS);
         }
       }
     }
     std::stable_sort(Sections.begin(), Sections.end(), compareByFilePosition);
 
     if (!Config->Relocatable && Config->EMachine == EM_ARM &&
         Sec->Type == SHT_ARM_EXIDX) {
 
       if (!Sections.empty() && isa<ARMExidxSentinelSection>(Sections.back())) {
         assert(Sections.size() >= 2 &&
                "We should create a sentinel section only if there are "
                "alive regular exidx sections.");
         // The last executable section is required to fill the sentinel.
         // Remember it here so that we don't have to find it again.
         auto *Sentinel = cast<ARMExidxSentinelSection>(Sections.back());
         Sentinel->Highest = Sections[Sections.size() - 2]->getLinkOrderDep();
       }
 
       if (Config->MergeArmExidx) {
         // The EHABI for the Arm Architecture permits consecutive identical
         // table entries to be merged. We use a simple implementation that
         // removes a .ARM.exidx Input Section if it can be merged into the
         // previous one. This does not require any rewriting of InputSection
         // contents but misses opportunities for fine grained deduplication
         // where only a subset of the InputSection contents can be merged.
         int Cur = 1;
         int Prev = 0;
         // The last one is a sentinel entry which should not be removed.
         int N = Sections.size() - 1;
         while (Cur < N) {
           if (isDuplicateArmExidxSec(Sections[Prev], Sections[Cur]))
             Sections[Cur] = nullptr;
           else
             Prev = Cur;
           ++Cur;
         }
       }
     }
 
     for (int I = 0, N = Sections.size(); I < N; ++I)
       *ScriptSections[I] = Sections[I];
 
     // Remove the Sections we marked as duplicate earlier.
     for (BaseCommand *Base : Sec->SectionCommands)
       if (auto *ISD = dyn_cast<InputSectionDescription>(Base))
         ISD->Sections.erase(
             std::remove(ISD->Sections.begin(), ISD->Sections.end(), nullptr),
             ISD->Sections.end());
   }
 }
 
 static void applySynthetic(const std::vector<SyntheticSection *> &Sections,
                            std::function<void(SyntheticSection *)> Fn) {
   for (SyntheticSection *SS : Sections)
     if (SS && SS->getParent() && !SS->empty())
       Fn(SS);
 }
 
 // In order to allow users to manipulate linker-synthesized sections,
 // we had to add synthetic sections to the input section list early,
 // even before we make decisions whether they are needed. This allows
 // users to write scripts like this: ".mygot : { .got }".
 //
 // Doing it has an unintended side effects. If it turns out that we
 // don't need a .got (for example) at all because there's no
 // relocation that needs a .got, we don't want to emit .got.
 //
 // To deal with the above problem, this function is called after
 // scanRelocations is called to remove synthetic sections that turn
 // out to be empty.
 static void removeUnusedSyntheticSections() {
   // All input synthetic sections that can be empty are placed after
   // all regular ones. We iterate over them all and exit at first
   // non-synthetic.
   for (InputSectionBase *S : llvm::reverse(InputSections)) {
     SyntheticSection *SS = dyn_cast<SyntheticSection>(S);
     if (!SS)
       return;
     OutputSection *OS = SS->getParent();
     if (!SS->empty() || !OS)
       continue;
 
     std::vector<BaseCommand *>::iterator Empty = OS->SectionCommands.end();
     for (auto I = OS->SectionCommands.begin(), E = OS->SectionCommands.end();
          I != E; ++I) {
       BaseCommand *B = *I;
       if (auto *ISD = dyn_cast<InputSectionDescription>(B)) {
         llvm::erase_if(ISD->Sections,
                        [=](InputSection *IS) { return IS == SS; });
         if (ISD->Sections.empty())
           Empty = I;
       }
     }
     if (Empty != OS->SectionCommands.end())
       OS->SectionCommands.erase(Empty);
 
     // If there are no other sections in the output section, remove it from the
     // output.
     if (OS->SectionCommands.empty())
       OS->Live = false;
   }
 }
 
 // Returns true if a symbol can be replaced at load-time by a symbol
 // with the same name defined in other ELF executable or DSO.
 static bool computeIsPreemptible(const Symbol &B) {
   assert(!B.isLocal());
   // Only symbols that appear in dynsym can be preempted.
   if (!B.includeInDynsym())
     return false;
 
   // Only default visibility symbols can be preempted.
   if (B.Visibility != STV_DEFAULT)
     return false;
 
   // At this point copy relocations have not been created yet, so any
   // symbol that is not defined locally is preemptible.
   if (!B.isDefined())
     return true;
 
   // If we have a dynamic list it specifies which local symbols are preemptible.
   if (Config->HasDynamicList)
     return false;
 
   if (!Config->Shared)
     return false;
 
   // -Bsymbolic means that definitions are not preempted.
   if (Config->Bsymbolic || (Config->BsymbolicFunctions && B.isFunc()))
     return false;
   return true;
 }
 
 // Create output section objects and add them to OutputSections.
 template <class ELFT> void Writer<ELFT>::finalizeSections() {
   Out::DebugInfo = findSection(".debug_info");
   Out::PreinitArray = findSection(".preinit_array");
   Out::InitArray = findSection(".init_array");
   Out::FiniArray = findSection(".fini_array");
 
   // The linker needs to define SECNAME_start, SECNAME_end and SECNAME_stop
   // symbols for sections, so that the runtime can get the start and end
   // addresses of each section by section name. Add such symbols.
   if (!Config->Relocatable) {
     addStartEndSymbols();
     for (BaseCommand *Base : Script->SectionCommands)
       if (auto *Sec = dyn_cast<OutputSection>(Base))
         addStartStopSymbols(Sec);
   }
 
   // Add _DYNAMIC symbol. Unlike GNU gold, our _DYNAMIC symbol has no type.
   // It should be okay as no one seems to care about the type.
   // Even the author of gold doesn't remember why gold behaves that way.
   // https://sourceware.org/ml/binutils/2002-03/msg00360.html
   if (InX::DynSymTab)
     Symtab->addRegular("_DYNAMIC", STV_HIDDEN, STT_NOTYPE, 0 /*Value*/,
                        /*Size=*/0, STB_WEAK, InX::Dynamic,
                        /*File=*/nullptr);
 
   // Define __rel[a]_iplt_{start,end} symbols if needed.
   addRelIpltSymbols();
 
   // This responsible for splitting up .eh_frame section into
   // pieces. The relocation scan uses those pieces, so this has to be
   // earlier.
   applySynthetic({InX::EhFrame},
                  [](SyntheticSection *SS) { SS->finalizeContents(); });
 
   for (Symbol *S : Symtab->getSymbols())
     S->IsPreemptible |= computeIsPreemptible(*S);
 
   // Scan relocations. This must be done after every symbol is declared so that
   // we can correctly decide if a dynamic relocation is needed.
   if (!Config->Relocatable)
     forEachRelSec(scanRelocations<ELFT>);
 
   if (InX::Plt && !InX::Plt->empty())
     InX::Plt->addSymbols();
   if (InX::Iplt && !InX::Iplt->empty())
     InX::Iplt->addSymbols();
 
   // Now that we have defined all possible global symbols including linker-
   // synthesized ones. Visit all symbols to give the finishing touches.
   for (Symbol *Sym : Symtab->getSymbols()) {
     if (!includeInSymtab(*Sym))
       continue;
     if (InX::SymTab)
       InX::SymTab->addSymbol(Sym);
 
     if (InX::DynSymTab && Sym->includeInDynsym()) {
       InX::DynSymTab->addSymbol(Sym);
       if (auto *SS = dyn_cast<SharedSymbol>(Sym))
         if (cast<SharedFile<ELFT>>(Sym->File)->IsNeeded)
           In<ELFT>::VerNeed->addSymbol(SS);
     }
   }
 
   // Do not proceed if there was an undefined symbol.
   if (errorCount())
     return;
 
   removeUnusedSyntheticSections();
 
   sortSections();
   Script->removeEmptyCommands();
 
   // Now that we have the final list, create a list of all the
   // OutputSections for convenience.
   for (BaseCommand *Base : Script->SectionCommands)
     if (auto *Sec = dyn_cast<OutputSection>(Base))
       OutputSections.push_back(Sec);
 
   // Prefer command line supplied address over other constraints.
   for (OutputSection *Sec : OutputSections) {
     auto I = Config->SectionStartMap.find(Sec->Name);
     if (I != Config->SectionStartMap.end())
       Sec->AddrExpr = [=] { return I->second; };
   }
 
   // This is a bit of a hack. A value of 0 means undef, so we set it
   // to 1 t make __ehdr_start defined. The section number is not
   // particularly relevant.
   Out::ElfHeader->SectionIndex = 1;
 
   unsigned I = 1;
   for (OutputSection *Sec : OutputSections) {
     Sec->SectionIndex = I++;
     Sec->ShName = InX::ShStrTab->addString(Sec->Name);
   }
 
   // Binary and relocatable output does not have PHDRS.
   // The headers have to be created before finalize as that can influence the
   // image base and the dynamic section on mips includes the image base.
   if (!Config->Relocatable && !Config->OFormatBinary) {
     Phdrs = Script->hasPhdrsCommands() ? Script->createPhdrs() : createPhdrs();
     addPtArmExid(Phdrs);
     Out::ProgramHeaders->Size = sizeof(Elf_Phdr) * Phdrs.size();
   }
 
   // Some symbols are defined in term of program headers. Now that we
   // have the headers, we can find out which sections they point to.
   setReservedSymbolSections();
 
   // Dynamic section must be the last one in this list and dynamic
   // symbol table section (DynSymTab) must be the first one.
   applySynthetic(
       {InX::DynSymTab,   InX::Bss,          InX::BssRelRo, InX::GnuHashTab,
        InX::HashTab,     InX::SymTab,       InX::ShStrTab, InX::StrTab,
        In<ELFT>::VerDef, InX::DynStrTab,    InX::Got,      InX::MipsGot,
        InX::IgotPlt,     InX::GotPlt,       InX::RelaDyn,  InX::RelaIplt,
        InX::RelaPlt,     InX::Plt,          InX::Iplt,     InX::EhFrameHdr,
        In<ELFT>::VerSym, In<ELFT>::VerNeed, InX::Dynamic},
       [](SyntheticSection *SS) { SS->finalizeContents(); });
 
   if (!Script->HasSectionsCommand && !Config->Relocatable)
     fixSectionAlignments();
 
   // After link order processing .ARM.exidx sections can be deduplicated, which
   // needs to be resolved before any other address dependent operation.
   resolveShfLinkOrder();
 
   // Some architectures need to generate content that depends on the address
   // of InputSections. For example some architectures use small displacements
   // for jump instructions that is is the linker's responsibility for creating
   // range extension thunks for. As the generation of the content may also
   // alter InputSection addresses we must converge to a fixed point.
   if (Target->NeedsThunks || Config->AndroidPackDynRelocs) {
     ThunkCreator TC;
     AArch64Err843419Patcher A64P;
     bool Changed;
     do {
       Script->assignAddresses();
       Changed = false;
       if (Target->NeedsThunks)
         Changed |= TC.createThunks(OutputSections);
       if (Config->FixCortexA53Errata843419) {
         if (Changed)
           Script->assignAddresses();
         Changed |= A64P.createFixes();
       }
       if (InX::MipsGot)
         InX::MipsGot->updateAllocSize();
       Changed |= InX::RelaDyn->updateAllocSize();
     } while (Changed);
   }
 
   // Fill other section headers. The dynamic table is finalized
   // at the end because some tags like RELSZ depend on result
   // of finalizing other sections.
   for (OutputSection *Sec : OutputSections)
     Sec->finalize<ELFT>();
 
   // createThunks may have added local symbols to the static symbol table
   applySynthetic({InX::SymTab},
                  [](SyntheticSection *SS) { SS->postThunkContents(); });
 }
 
 // The linker is expected to define SECNAME_start and SECNAME_end
 // symbols for a few sections. This function defines them.
 template <class ELFT> void Writer<ELFT>::addStartEndSymbols() {
   auto Define = [&](StringRef Start, StringRef End, OutputSection *OS) {
     // These symbols resolve to the image base if the section does not exist.
     // A special value -1 indicates end of the section.
     if (OS) {
       addOptionalRegular(Start, OS, 0);
       addOptionalRegular(End, OS, -1);
     } else {
       if (Config->Pic)
         OS = Out::ElfHeader;
       addOptionalRegular(Start, OS, 0);
       addOptionalRegular(End, OS, 0);
     }
   };
 
   Define("__preinit_array_start", "__preinit_array_end", Out::PreinitArray);
   Define("__init_array_start", "__init_array_end", Out::InitArray);
   Define("__fini_array_start", "__fini_array_end", Out::FiniArray);
 
   if (OutputSection *Sec = findSection(".ARM.exidx"))
     Define("__exidx_start", "__exidx_end", Sec);
 }
 
 // If a section name is valid as a C identifier (which is rare because of
 // the leading '.'), linkers are expected to define __start_<secname> and
 // __stop_<secname> symbols. They are at beginning and end of the section,
 // respectively. This is not requested by the ELF standard, but GNU ld and
 // gold provide the feature, and used by many programs.
 template <class ELFT>
 void Writer<ELFT>::addStartStopSymbols(OutputSection *Sec) {
   StringRef S = Sec->Name;
   if (!isValidCIdentifier(S))
     return;
   addOptionalRegular(Saver.save("__start_" + S), Sec, 0, STV_DEFAULT);
   addOptionalRegular(Saver.save("__stop_" + S), Sec, -1, STV_DEFAULT);
 }
 
 static bool needsPtLoad(OutputSection *Sec) {
   if (!(Sec->Flags & SHF_ALLOC))
     return false;
 
   // Don't allocate VA space for TLS NOBITS sections. The PT_TLS PHDR is
   // responsible for allocating space for them, not the PT_LOAD that
   // contains the TLS initialization image.
   if (Sec->Flags & SHF_TLS && Sec->Type == SHT_NOBITS)
     return false;
   return true;
 }
 
 // Linker scripts are responsible for aligning addresses. Unfortunately, most
 // linker scripts are designed for creating two PT_LOADs only, one RX and one
 // RW. This means that there is no alignment in the RO to RX transition and we
 // cannot create a PT_LOAD there.
 static uint64_t computeFlags(uint64_t Flags) {
   if (Config->Omagic)
     return PF_R | PF_W | PF_X;
   if (Config->SingleRoRx && !(Flags & PF_W))
     return Flags | PF_X;
   return Flags;
 }
 
 // Decide which program headers to create and which sections to include in each
 // one.
 template <class ELFT> std::vector<PhdrEntry *> Writer<ELFT>::createPhdrs() {
   std::vector<PhdrEntry *> Ret;
   auto AddHdr = [&](unsigned Type, unsigned Flags) -> PhdrEntry * {
     Ret.push_back(make<PhdrEntry>(Type, Flags));
     return Ret.back();
   };
 
   // The first phdr entry is PT_PHDR which describes the program header itself.
   AddHdr(PT_PHDR, PF_R)->add(Out::ProgramHeaders);
 
   // PT_INTERP must be the second entry if exists.
   if (OutputSection *Cmd = findSection(".interp"))
     AddHdr(PT_INTERP, Cmd->getPhdrFlags())->add(Cmd);
 
   // Add the first PT_LOAD segment for regular output sections.
   uint64_t Flags = computeFlags(PF_R);
   PhdrEntry *Load = AddHdr(PT_LOAD, Flags);
 
   // Add the headers. We will remove them if they don't fit.
   Load->add(Out::ElfHeader);
   Load->add(Out::ProgramHeaders);
 
   for (OutputSection *Sec : OutputSections) {
     if (!(Sec->Flags & SHF_ALLOC))
       break;
     if (!needsPtLoad(Sec))
       continue;
 
     // Segments are contiguous memory regions that has the same attributes
     // (e.g. executable or writable). There is one phdr for each segment.
     // Therefore, we need to create a new phdr when the next section has
     // different flags or is loaded at a discontiguous address using AT linker
     // script command.
     uint64_t NewFlags = computeFlags(Sec->getPhdrFlags());
-    if (Sec->LMAExpr || Flags != NewFlags) {
+    if (Sec->LMAExpr || Sec->MemRegion != Load->FirstSec->MemRegion ||
+        Flags != NewFlags) {
       Load = AddHdr(PT_LOAD, NewFlags);
       Flags = NewFlags;
     }
 
     Load->add(Sec);
   }
 
   // Add a TLS segment if any.
   PhdrEntry *TlsHdr = make<PhdrEntry>(PT_TLS, PF_R);
   for (OutputSection *Sec : OutputSections)
     if (Sec->Flags & SHF_TLS)
       TlsHdr->add(Sec);
   if (TlsHdr->FirstSec)
     Ret.push_back(TlsHdr);
 
   // Add an entry for .dynamic.
   if (InX::DynSymTab)
     AddHdr(PT_DYNAMIC, InX::Dynamic->getParent()->getPhdrFlags())
         ->add(InX::Dynamic->getParent());
 
   // PT_GNU_RELRO includes all sections that should be marked as
   // read-only by dynamic linker after proccessing relocations.
   // Current dynamic loaders only support one PT_GNU_RELRO PHDR, give
   // an error message if more than one PT_GNU_RELRO PHDR is required.
   PhdrEntry *RelRo = make<PhdrEntry>(PT_GNU_RELRO, PF_R);
   bool InRelroPhdr = false;
   bool IsRelroFinished = false;
   for (OutputSection *Sec : OutputSections) {
     if (!needsPtLoad(Sec))
       continue;
     if (isRelroSection(Sec)) {
       InRelroPhdr = true;
       if (!IsRelroFinished)
         RelRo->add(Sec);
       else
         error("section: " + Sec->Name + " is not contiguous with other relro" +
               " sections");
     } else if (InRelroPhdr) {
       InRelroPhdr = false;
       IsRelroFinished = true;
     }
   }
   if (RelRo->FirstSec)
     Ret.push_back(RelRo);
 
   // PT_GNU_EH_FRAME is a special section pointing on .eh_frame_hdr.
   if (!InX::EhFrame->empty() && InX::EhFrameHdr && InX::EhFrame->getParent() &&
       InX::EhFrameHdr->getParent())
     AddHdr(PT_GNU_EH_FRAME, InX::EhFrameHdr->getParent()->getPhdrFlags())
         ->add(InX::EhFrameHdr->getParent());
 
   // PT_OPENBSD_RANDOMIZE is an OpenBSD-specific feature. That makes
   // the dynamic linker fill the segment with random data.
   if (OutputSection *Cmd = findSection(".openbsd.randomdata"))
     AddHdr(PT_OPENBSD_RANDOMIZE, Cmd->getPhdrFlags())->add(Cmd);
 
   // PT_GNU_STACK is a special section to tell the loader to make the
   // pages for the stack non-executable. If you really want an executable
   // stack, you can pass -z execstack, but that's not recommended for
   // security reasons.
   unsigned Perm;
   if (Config->ZExecstack)
     Perm = PF_R | PF_W | PF_X;
   else
     Perm = PF_R | PF_W;
   AddHdr(PT_GNU_STACK, Perm)->p_memsz = Config->ZStackSize;
 
   // PT_OPENBSD_WXNEEDED is a OpenBSD-specific header to mark the executable
   // is expected to perform W^X violations, such as calling mprotect(2) or
   // mmap(2) with PROT_WRITE | PROT_EXEC, which is prohibited by default on
   // OpenBSD.
   if (Config->ZWxneeded)
     AddHdr(PT_OPENBSD_WXNEEDED, PF_X);
 
   // Create one PT_NOTE per a group of contiguous .note sections.
   PhdrEntry *Note = nullptr;
   for (OutputSection *Sec : OutputSections) {
     if (Sec->Type == SHT_NOTE) {
       if (!Note || Sec->LMAExpr)
         Note = AddHdr(PT_NOTE, PF_R);
       Note->add(Sec);
     } else {
       Note = nullptr;
     }
   }
   return Ret;
 }
 
 template <class ELFT>
 void Writer<ELFT>::addPtArmExid(std::vector<PhdrEntry *> &Phdrs) {
   if (Config->EMachine != EM_ARM)
     return;
   auto I = llvm::find_if(OutputSections, [](OutputSection *Cmd) {
     return Cmd->Type == SHT_ARM_EXIDX;
   });
   if (I == OutputSections.end())
     return;
 
   // PT_ARM_EXIDX is the ARM EHABI equivalent of PT_GNU_EH_FRAME
   PhdrEntry *ARMExidx = make<PhdrEntry>(PT_ARM_EXIDX, PF_R);
   ARMExidx->add(*I);
   Phdrs.push_back(ARMExidx);
 }
 
 // The first section of each PT_LOAD, the first section in PT_GNU_RELRO and the
 // first section after PT_GNU_RELRO have to be page aligned so that the dynamic
 // linker can set the permissions.
 template <class ELFT> void Writer<ELFT>::fixSectionAlignments() {
   auto PageAlign = [](OutputSection *Cmd) {
     if (Cmd && !Cmd->AddrExpr)
       Cmd->AddrExpr = [=] {
         return alignTo(Script->getDot(), Config->MaxPageSize);
       };
   };
 
   for (const PhdrEntry *P : Phdrs)
     if (P->p_type == PT_LOAD && P->FirstSec)
       PageAlign(P->FirstSec);
 
   for (const PhdrEntry *P : Phdrs) {
     if (P->p_type != PT_GNU_RELRO)
       continue;
     if (P->FirstSec)
       PageAlign(P->FirstSec);
     // Find the first section after PT_GNU_RELRO. If it is in a PT_LOAD we
     // have to align it to a page.
     auto End = OutputSections.end();
     auto I = std::find(OutputSections.begin(), End, P->LastSec);
     if (I == End || (I + 1) == End)
       continue;
     OutputSection *Cmd = (*(I + 1));
     if (needsPtLoad(Cmd))
       PageAlign(Cmd);
   }
 }
 
 // Adjusts the file alignment for a given output section and returns
 // its new file offset. The file offset must be the same with its
 // virtual address (modulo the page size) so that the loader can load
 // executables without any address adjustment.
 static uint64_t getFileAlignment(uint64_t Off, OutputSection *Cmd) {
   OutputSection *First = Cmd->PtLoad ? Cmd->PtLoad->FirstSec : nullptr;
   // The first section in a PT_LOAD has to have congruent offset and address
   // module the page size.
   if (Cmd == First)
     return alignTo(Off, std::max<uint64_t>(Cmd->Alignment, Config->MaxPageSize),
                    Cmd->Addr);
 
   // For SHT_NOBITS we don't want the alignment of the section to impact the
   // offset of the sections that follow. Since nothing seems to care about the
   // sh_offset of the SHT_NOBITS section itself, just ignore it.
   if (Cmd->Type == SHT_NOBITS)
     return Off;
 
   // If the section is not in a PT_LOAD, we just have to align it.
   if (!Cmd->PtLoad)
     return alignTo(Off, Cmd->Alignment);
 
   // If two sections share the same PT_LOAD the file offset is calculated
   // using this formula: Off2 = Off1 + (VA2 - VA1).
   return First->Offset + Cmd->Addr - First->Addr;
 }
 
 static uint64_t setOffset(OutputSection *Cmd, uint64_t Off) {
   Off = getFileAlignment(Off, Cmd);
   Cmd->Offset = Off;
 
   // For SHT_NOBITS we should not count the size.
   if (Cmd->Type == SHT_NOBITS)
     return Off;
 
   return Off + Cmd->Size;
 }
 
 template <class ELFT> void Writer<ELFT>::assignFileOffsetsBinary() {
   uint64_t Off = 0;
   for (OutputSection *Sec : OutputSections)
     if (Sec->Flags & SHF_ALLOC)
       Off = setOffset(Sec, Off);
   FileSize = alignTo(Off, Config->Wordsize);
 }
 
 // Assign file offsets to output sections.
 template <class ELFT> void Writer<ELFT>::assignFileOffsets() {
   uint64_t Off = 0;
   Off = setOffset(Out::ElfHeader, Off);
   Off = setOffset(Out::ProgramHeaders, Off);
 
   PhdrEntry *LastRX = nullptr;
   for (PhdrEntry *P : Phdrs)
     if (P->p_type == PT_LOAD && (P->p_flags & PF_X))
       LastRX = P;
 
   for (OutputSection *Sec : OutputSections) {
     Off = setOffset(Sec, Off);
     if (Script->HasSectionsCommand)
       continue;
     // If this is a last section of the last executable segment and that
     // segment is the last loadable segment, align the offset of the
     // following section to avoid loading non-segments parts of the file.
     if (LastRX && LastRX->LastSec == Sec)
       Off = alignTo(Off, Target->PageSize);
   }
 
   SectionHeaderOff = alignTo(Off, Config->Wordsize);
   FileSize = SectionHeaderOff + (OutputSections.size() + 1) * sizeof(Elf_Shdr);
 }
 
 // Finalize the program headers. We call this function after we assign
 // file offsets and VAs to all sections.
 template <class ELFT> void Writer<ELFT>::setPhdrs() {
   for (PhdrEntry *P : Phdrs) {
     OutputSection *First = P->FirstSec;
     OutputSection *Last = P->LastSec;
     if (First) {
       P->p_filesz = Last->Offset - First->Offset;
       if (Last->Type != SHT_NOBITS)
         P->p_filesz += Last->Size;
       P->p_memsz = Last->Addr + Last->Size - First->Addr;
       P->p_offset = First->Offset;
       P->p_vaddr = First->Addr;
       if (!P->HasLMA)
         P->p_paddr = First->getLMA();
     }
     if (P->p_type == PT_LOAD)
       P->p_align = std::max<uint64_t>(P->p_align, Config->MaxPageSize);
     else if (P->p_type == PT_GNU_RELRO) {
       P->p_align = 1;
       // The glibc dynamic loader rounds the size down, so we need to round up
       // to protect the last page. This is a no-op on FreeBSD which always
       // rounds up.
       P->p_memsz = alignTo(P->p_memsz, Target->PageSize);
     }
 
     // The TLS pointer goes after PT_TLS. At least glibc will align it,
     // so round up the size to make sure the offsets are correct.
     if (P->p_type == PT_TLS) {
       Out::TlsPhdr = P;
       if (P->p_memsz)
         P->p_memsz = alignTo(P->p_memsz, P->p_align);
     }
   }
 }
 
 // The entry point address is chosen in the following ways.
 //
 // 1. the '-e' entry command-line option;
 // 2. the ENTRY(symbol) command in a linker control script;
 // 3. the value of the symbol _start, if present;
 // 4. the number represented by the entry symbol, if it is a number;
 // 5. the address of the first byte of the .text section, if present;
 // 6. the address 0.
 template <class ELFT> uint64_t Writer<ELFT>::getEntryAddr() {
   // Case 1, 2 or 3
   if (Symbol *B = Symtab->find(Config->Entry))
     return B->getVA();
 
   // Case 4
   uint64_t Addr;
   if (to_integer(Config->Entry, Addr))
     return Addr;
 
   // Case 5
   if (OutputSection *Sec = findSection(".text")) {
     if (Config->WarnMissingEntry)
       warn("cannot find entry symbol " + Config->Entry + "; defaulting to 0x" +
            utohexstr(Sec->Addr));
     return Sec->Addr;
   }
 
   // Case 6
   if (Config->WarnMissingEntry)
     warn("cannot find entry symbol " + Config->Entry +
          "; not setting start address");
   return 0;
 }
 
 static uint16_t getELFType() {
   if (Config->Pic)
     return ET_DYN;
   if (Config->Relocatable)
     return ET_REL;
   return ET_EXEC;
 }
 
 template <class ELFT> void Writer<ELFT>::writeHeader() {
   uint8_t *Buf = Buffer->getBufferStart();
   memcpy(Buf, "\177ELF", 4);
 
   // Write the ELF header.
   auto *EHdr = reinterpret_cast<Elf_Ehdr *>(Buf);
   EHdr->e_ident[EI_CLASS] = Config->Is64 ? ELFCLASS64 : ELFCLASS32;
   EHdr->e_ident[EI_DATA] = Config->IsLE ? ELFDATA2LSB : ELFDATA2MSB;
   EHdr->e_ident[EI_VERSION] = EV_CURRENT;
   EHdr->e_ident[EI_OSABI] = Config->OSABI;
   EHdr->e_type = getELFType();
   EHdr->e_machine = Config->EMachine;
   EHdr->e_version = EV_CURRENT;
   EHdr->e_entry = getEntryAddr();
   EHdr->e_shoff = SectionHeaderOff;
   EHdr->e_flags = Config->EFlags;
   EHdr->e_ehsize = sizeof(Elf_Ehdr);
   EHdr->e_phnum = Phdrs.size();
   EHdr->e_shentsize = sizeof(Elf_Shdr);
   EHdr->e_shnum = OutputSections.size() + 1;
   EHdr->e_shstrndx = InX::ShStrTab->getParent()->SectionIndex;
 
   if (!Config->Relocatable) {
     EHdr->e_phoff = sizeof(Elf_Ehdr);
     EHdr->e_phentsize = sizeof(Elf_Phdr);
   }
 
   // Write the program header table.
   auto *HBuf = reinterpret_cast<Elf_Phdr *>(Buf + EHdr->e_phoff);
   for (PhdrEntry *P : Phdrs) {
     HBuf->p_type = P->p_type;
     HBuf->p_flags = P->p_flags;
     HBuf->p_offset = P->p_offset;
     HBuf->p_vaddr = P->p_vaddr;
     HBuf->p_paddr = P->p_paddr;
     HBuf->p_filesz = P->p_filesz;
     HBuf->p_memsz = P->p_memsz;
     HBuf->p_align = P->p_align;
     ++HBuf;
   }
 
   // Write the section header table. Note that the first table entry is null.
   auto *SHdrs = reinterpret_cast<Elf_Shdr *>(Buf + EHdr->e_shoff);
   for (OutputSection *Sec : OutputSections)
     Sec->writeHeaderTo<ELFT>(++SHdrs);
 }
 
 // Open a result file.
 template <class ELFT> void Writer<ELFT>::openFile() {
   if (!Config->Is64 && FileSize > UINT32_MAX) {
     error("output file too large: " + Twine(FileSize) + " bytes");
     return;
   }
 
   unlinkAsync(Config->OutputFile);
   unsigned Flags = 0;
   if (!Config->Relocatable)
     Flags = FileOutputBuffer::F_executable;
   Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
       FileOutputBuffer::create(Config->OutputFile, FileSize, Flags);
 
   if (!BufferOrErr)
     error("failed to open " + Config->OutputFile + ": " +
           llvm::toString(BufferOrErr.takeError()));
   else
     Buffer = std::move(*BufferOrErr);
 }
 
 template <class ELFT> void Writer<ELFT>::writeSectionsBinary() {
   uint8_t *Buf = Buffer->getBufferStart();
   for (OutputSection *Sec : OutputSections)
     if (Sec->Flags & SHF_ALLOC)
       Sec->writeTo<ELFT>(Buf + Sec->Offset);
 }
 
 static void fillTrap(uint8_t *I, uint8_t *End) {
   for (; I + 4 <= End; I += 4)
     memcpy(I, &Target->TrapInstr, 4);
 }
 
 // Fill the last page of executable segments with trap instructions
 // instead of leaving them as zero. Even though it is not required by any
 // standard, it is in general a good thing to do for security reasons.
 //
 // We'll leave other pages in segments as-is because the rest will be
 // overwritten by output sections.
 template <class ELFT> void Writer<ELFT>::writeTrapInstr() {
   if (Script->HasSectionsCommand)
     return;
 
   // Fill the last page.
   uint8_t *Buf = Buffer->getBufferStart();
   for (PhdrEntry *P : Phdrs)
     if (P->p_type == PT_LOAD && (P->p_flags & PF_X))
       fillTrap(Buf + alignDown(P->p_offset + P->p_filesz, Target->PageSize),
                Buf + alignTo(P->p_offset + P->p_filesz, Target->PageSize));
 
   // Round up the file size of the last segment to the page boundary iff it is
   // an executable segment to ensure that other tools don't accidentally
   // trim the instruction padding (e.g. when stripping the file).
   PhdrEntry *Last = nullptr;
   for (PhdrEntry *P : Phdrs)
     if (P->p_type == PT_LOAD)
       Last = P;
 
   if (Last && (Last->p_flags & PF_X))
     Last->p_memsz = Last->p_filesz = alignTo(Last->p_filesz, Target->PageSize);
 }
 
 // Write section contents to a mmap'ed file.
 template <class ELFT> void Writer<ELFT>::writeSections() {
   uint8_t *Buf = Buffer->getBufferStart();
 
   // PPC64 needs to process relocations in the .opd section
   // before processing relocations in code-containing sections.
   if (auto *OpdCmd = findSection(".opd")) {
     Out::Opd = OpdCmd;
     Out::OpdBuf = Buf + Out::Opd->Offset;
     OpdCmd->template writeTo<ELFT>(Buf + Out::Opd->Offset);
   }
 
   OutputSection *EhFrameHdr = nullptr;
   if (InX::EhFrameHdr && !InX::EhFrameHdr->empty())
     EhFrameHdr = InX::EhFrameHdr->getParent();
 
   // In -r or -emit-relocs mode, write the relocation sections first as in
   // ELf_Rel targets we might find out that we need to modify the relocated
   // section while doing it.
   for (OutputSection *Sec : OutputSections)
     if (Sec->Type == SHT_REL || Sec->Type == SHT_RELA)
       Sec->writeTo<ELFT>(Buf + Sec->Offset);
 
   for (OutputSection *Sec : OutputSections)
     if (Sec != Out::Opd && Sec != EhFrameHdr && Sec->Type != SHT_REL &&
         Sec->Type != SHT_RELA)
       Sec->writeTo<ELFT>(Buf + Sec->Offset);
 
   // The .eh_frame_hdr depends on .eh_frame section contents, therefore
   // it should be written after .eh_frame is written.
   if (EhFrameHdr)
     EhFrameHdr->writeTo<ELFT>(Buf + EhFrameHdr->Offset);
 }
 
 template <class ELFT> void Writer<ELFT>::writeBuildId() {
   if (!InX::BuildId || !InX::BuildId->getParent())
     return;
 
   // Compute a hash of all sections of the output file.
   uint8_t *Start = Buffer->getBufferStart();
   uint8_t *End = Start + FileSize;
   InX::BuildId->writeBuildId({Start, End});
 }
 
 template void elf::writeResult<ELF32LE>();
 template void elf::writeResult<ELF32BE>();
 template void elf::writeResult<ELF64LE>();
 template void elf::writeResult<ELF64BE>();