[lld] r248604 - Add support for creating the symbols __init_array_start and __init_array_end.
Rafael Espíndola via llvm-commits
llvm-commits at lists.llvm.org
Fri Sep 25 14:22:40 PDT 2015
r248615. Thanks
On 25 September 2015 at 15:04, Rui Ueyama <ruiu at google.com> wrote:
> On Fri, Sep 25, 2015 at 11:56 AM, Rafael Espindola via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>>
>> Author: rafael
>> Date: Fri Sep 25 13:56:53 2015
>> New Revision: 248604
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=248604&view=rev
>> Log:
>> Add support for creating the symbols __init_array_start and
>> __init_array_end.
>>
>> Added:
>> lld/trunk/test/elf2/init_array.s
>> Modified:
>> lld/trunk/ELF/OutputSections.cpp
>> lld/trunk/ELF/OutputSections.h
>> lld/trunk/ELF/SymbolTable.cpp
>> lld/trunk/ELF/SymbolTable.h
>> lld/trunk/ELF/Symbols.h
>> lld/trunk/ELF/Writer.cpp
>>
>> Modified: lld/trunk/ELF/OutputSections.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.cpp?rev=248604&r1=248603&r2=248604&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/ELF/OutputSections.cpp (original)
>> +++ lld/trunk/ELF/OutputSections.cpp Fri Sep 25 13:56:53 2015
>> @@ -295,6 +295,8 @@ typename ELFFile<ELFT>::uintX_t
>> lld::elf2::getSymVA(const ELFSymbolBody<ELFT> &S,
>> const OutputSection<ELFT> &BssSec) {
>> switch (S.kind()) {
>> + case SymbolBody::DefinedSyntheticKind:
>> + return cast<DefinedSynthetic<ELFT>>(S).Section.getVA() +
>> S.Sym.st_value;
>> case SymbolBody::DefinedAbsoluteKind:
>> return S.Sym.st_value;
>> case SymbolBody::DefinedRegularKind: {
>> @@ -434,6 +436,9 @@ template <class ELFT> void SymbolTableSe
>> const InputSection<ELFT> *Section = nullptr;
>>
>> switch (EBody.kind()) {
>> + case SymbolBody::DefinedSyntheticKind:
>> + Out = &cast<DefinedSynthetic<ELFT>>(Body)->Section;
>> + break;
>> case SymbolBody::DefinedRegularKind:
>> Section = &cast<DefinedRegular<ELFT>>(EBody).Section;
>> break;
>>
>> Modified: lld/trunk/ELF/OutputSections.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.h?rev=248604&r1=248603&r2=248604&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/ELF/OutputSections.h (original)
>> +++ lld/trunk/ELF/OutputSections.h Fri Sep 25 13:56:53 2015
>> @@ -165,7 +165,7 @@ public:
>>
>> void writeTo(uint8_t *Buf) override;
>>
>> - const SymbolTable &getSymTable() const { return Table; }
>> + SymbolTable &getSymTable() const { return Table; }
>>
>> void addSymbol(StringRef Name, bool isLocal = false) {
>> StrTabSec.add(Name);
>>
>> Modified: lld/trunk/ELF/SymbolTable.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.cpp?rev=248604&r1=248603&r2=248604&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/ELF/SymbolTable.cpp (original)
>> +++ lld/trunk/ELF/SymbolTable.cpp Fri Sep 25 13:56:53 2015
>> @@ -55,6 +55,17 @@ static TargetInfo *createTarget(uint16_t
>> error("Unknown target machine");
>> }
>>
>> +template <class ELFT>
>> +void SymbolTable::addSyntheticSym(StringRef Name, OutputSection<ELFT>
>> &Section,
>> + typename ELFFile<ELFT>::uintX_t Value)
>> {
>> + typedef typename DefinedSynthetic<ELFT>::Elf_Sym Elf_Sym;
>> + auto ESym = new (Alloc) Elf_Sym;
>> + memset(ESym, 0, sizeof(Elf_Sym));
>> + ESym->st_value = Value;
>> + auto Sym = new (Alloc) DefinedSynthetic<ELFT>(Name, *ESym, Section);
>> + resolve<ELFT>(Sym);
>> +}
>> +
>> template <class ELFT> void SymbolTable::init(uint16_t EMachine) {
>> Target.reset(createTarget(EMachine));
>> if (Config->Shared)
>> @@ -205,3 +216,20 @@ void SymbolTable::addMemberFile(Lazy *Bo
>>
>> addFile(std::move(File));
>> }
>> +
>> +namespace lld {
>> +namespace elf2 {
>> +template void SymbolTable::addSyntheticSym(StringRef Name,
>> + OutputSection<ELF32LE>
>> &Section,
>> + ELFFile<ELF32LE>::uintX_t
>> Value);
>> +template void SymbolTable::addSyntheticSym(StringRef Name,
>> + OutputSection<ELF32BE>
>> &Section,
>> + ELFFile<ELF32BE>::uintX_t
>> Value);
>> +template void SymbolTable::addSyntheticSym(StringRef Name,
>> + OutputSection<ELF64LE>
>> &Section,
>> + ELFFile<ELF64LE>::uintX_t
>> Value);
>> +template void SymbolTable::addSyntheticSym(StringRef Name,
>> + OutputSection<ELF64BE>
>> &Section,
>> + ELFFile<ELF64BE>::uintX_t
>> Value);
>> +}
>> +}
>>
>> Modified: lld/trunk/ELF/SymbolTable.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.h?rev=248604&r1=248603&r2=248604&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/ELF/SymbolTable.h (original)
>> +++ lld/trunk/ELF/SymbolTable.h Fri Sep 25 13:56:53 2015
>> @@ -61,6 +61,10 @@ public:
>> return EntrySym->getReplacement();
>> }
>>
>> + template <class ELFT>
>> + void addSyntheticSym(StringRef Name, OutputSection<ELFT> &Section,
>> + typename llvm::object::ELFFile<ELFT>::uintX_t
>> Value);
>> +
>> private:
>> Symbol *insert(SymbolBody *New);
>> template <class ELFT> void addELFFile(ELFFileBase *File);
>>
>> Modified: lld/trunk/ELF/Symbols.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.h?rev=248604&r1=248603&r2=248604&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/ELF/Symbols.h (original)
>> +++ lld/trunk/ELF/Symbols.h Fri Sep 25 13:56:53 2015
>> @@ -41,10 +41,11 @@ public:
>> DefinedRegularKind = 0,
>> DefinedAbsoluteKind = 1,
>> DefinedCommonKind = 2,
>> - SharedKind = 3,
>> - DefinedLast = 3,
>> - UndefinedKind = 4,
>> - LazyKind = 5,
>> + DefinedSyntheticKind = 3,
>> + SharedKind = 4,
>> + DefinedLast = 4,
>
>
> Can you write DefinedLast = SharedKind and remove all explicit integers so
> that we don't have to update all the values when we add a new one?
>
>>
>> + UndefinedKind = 5,
>> + LazyKind = 6,
>> };
>>
>> Kind kind() const { return static_cast<Kind>(SymbolKind); }
>> @@ -213,6 +214,22 @@ public:
>> const InputSection<ELFT> &Section;
>> };
>>
>> +template <class ELFT> class DefinedSynthetic : public Defined<ELFT> {
>> + typedef Defined<ELFT> Base;
>> +
>> +public:
>> + typedef typename Base::Elf_Sym Elf_Sym;
>> + explicit DefinedSynthetic(StringRef N, const Elf_Sym &Sym,
>> + OutputSection<ELFT> &Section)
>> + : Defined<ELFT>(Base::DefinedSyntheticKind, N, Sym),
>> Section(Section) {}
>> +
>> + static bool classof(const SymbolBody *S) {
>> + return S->kind() == Base::DefinedSyntheticKind;
>> + }
>> +
>> + const OutputSection<ELFT> &Section;
>> +};
>> +
>> // Undefined symbol.
>> template <class ELFT> class Undefined : public ELFSymbolBody<ELFT> {
>> typedef ELFSymbolBody<ELFT> Base;
>>
>> Modified: lld/trunk/ELF/Writer.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=248604&r1=248603&r2=248604&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/ELF/Writer.cpp (original)
>> +++ lld/trunk/ELF/Writer.cpp Fri Sep 25 13:56:53 2015
>> @@ -295,7 +295,7 @@ template <class ELFT> void Writer<ELFT>:
>> OutputSections.push_back(&BssSec);
>> Map[{BssSec.getName(), BssSec.getType(), BssSec.getFlags()}] = &BssSec;
>>
>> - const SymbolTable &Symtab = SymTabSec.getSymTable();
>> + SymbolTable &Symtab = SymTabSec.getSymTable();
>> for (const std::unique_ptr<ObjectFileBase> &FileB :
>> Symtab.getObjectFiles()) {
>> auto &File = cast<ObjectFile<ELFT>>(*FileB);
>> if (!Config->DiscardAll) {
>> @@ -323,6 +323,12 @@ template <class ELFT> void Writer<ELFT>:
>> }
>> }
>>
>> + if (OutputSection<ELFT> *OS =
>> + Map.lookup({".init_array", SHT_INIT_ARRAY, SHF_WRITE |
>> SHF_ALLOC})) {
>> + Symtab.addSyntheticSym<ELFT>("__init_array_start", *OS, 0);
>> + Symtab.addSyntheticSym<ELFT>("__init_array_end", *OS, OS->getSize());
>> + }
>> +
>> // FIXME: Try to avoid the extra walk over all global symbols.
>> std::vector<DefinedCommon<ELFT> *> CommonSymbols;
>> for (auto &P : Symtab.getSymbols()) {
>>
>> Added: lld/trunk/test/elf2/init_array.s
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf2/init_array.s?rev=248604&view=auto
>>
>> ==============================================================================
>> --- lld/trunk/test/elf2/init_array.s (added)
>> +++ lld/trunk/test/elf2/init_array.s Fri Sep 25 13:56:53 2015
>> @@ -0,0 +1,49 @@
>> +// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
>> +// RUN: lld -flavor gnu2 %t -o %t2
>> +// RUN: llvm-readobj -symbols -sections %t2 | FileCheck %s
>> +// RUN: llvm-objdump -d %t2 | FileCheck --check-prefix=DISASM %s
>> +// REQUIRES: x86
>> +
>> +.globl _start
>> +_start:
>> + call __init_array_start
>> + call __init_array_end
>> +
>> +
>> +.section .init_array,"aw", at init_array
>> + .quad 0
>> +
>> +
>> +// CHECK: Name: .init_array
>> +// CHECK-NEXT: Type: SHT_INIT_ARRAY
>> +// CHECK-NEXT: Flags [
>> +// CHECK-NEXT: SHF_ALLOC
>> +// CHECK-NEXT: SHF_WRITE
>> +// CHECK-NEXT: ]
>> +// CHECK-NEXT: Address: 0x12000
>> +// CHECK-NEXT: Offset:
>> +// CHECK-NEXT: Size: 8
>> +
>> +// CHECK: Name: __init_array_end
>> +// CHECK-NEXT: Value: 0x12008
>> +// CHECK-NEXT: Size: 0
>> +// CHECK-NEXT: Binding: Local
>> +// CHECK-NEXT: Type: None
>> +// CHECK-NEXT: Other: 0
>> +// CHECK-NEXT: Section: .init_array
>> +// CHECK-NEXT: }
>> +// CHECK-NEXT: Symbol {
>> +// CHECK-NEXT: Name: __init_array_start
>> +// CHECK-NEXT: Value: 0x12000
>> +// CHECK-NEXT: Size: 0
>> +// CHECK-NEXT: Binding: Local
>> +// CHECK-NEXT: Type: None
>> +// CHECK-NEXT: Other: 0
>> +// CHECK-NEXT: Section: .init_array
>> +// CHECK-NEXT: }
>> +
>> +// 0x12000 - (0x11000 + 5) = 4091
>> +// 0x12008 - (0x11005 + 5) = 4094
>> +// DISASM: _start:
>> +// DISASM-NEXT: 11000: e8 fb 0f 00 00 callq 4091
>> +// DISASM-NEXT: 11005: e8 fe 0f 00 00 callq 4094
>>
>>
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