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Diffstat (limited to 'lib/Target/TargetLoweringObjectFile.cpp')
| -rw-r--r-- | lib/Target/TargetLoweringObjectFile.cpp | 1089 |
1 files changed, 1089 insertions, 0 deletions
diff --git a/lib/Target/TargetLoweringObjectFile.cpp b/lib/Target/TargetLoweringObjectFile.cpp new file mode 100644 index 0000000..c1aab99 --- /dev/null +++ b/lib/Target/TargetLoweringObjectFile.cpp @@ -0,0 +1,1089 @@ +//===-- llvm/Target/TargetLoweringObjectFile.cpp - Object File Info -------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements classes used to handle lowerings specific to common +// object file formats. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Target/TargetLoweringObjectFile.h" +#include "llvm/Constants.h" +#include "llvm/DerivedTypes.h" +#include "llvm/Function.h" +#include "llvm/GlobalVariable.h" +#include "llvm/MC/MCContext.h" +#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCSectionMachO.h" +#include "llvm/MC/MCSectionELF.h" +#include "llvm/Target/TargetData.h" +#include "llvm/Target/TargetMachine.h" +#include "llvm/Target/TargetOptions.h" +#include "llvm/Support/Mangler.h" +#include "llvm/ADT/SmallString.h" +#include "llvm/ADT/StringExtras.h" +using namespace llvm; + +//===----------------------------------------------------------------------===// +// Generic Code +//===----------------------------------------------------------------------===// + +TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) { + TextSection = 0; + DataSection = 0; + BSSSection = 0; + ReadOnlySection = 0; + StaticCtorSection = 0; + StaticDtorSection = 0; + LSDASection = 0; + EHFrameSection = 0; + + DwarfAbbrevSection = 0; + DwarfInfoSection = 0; + DwarfLineSection = 0; + DwarfFrameSection = 0; + DwarfPubNamesSection = 0; + DwarfPubTypesSection = 0; + DwarfDebugInlineSection = 0; + DwarfStrSection = 0; + DwarfLocSection = 0; + DwarfARangesSection = 0; + DwarfRangesSection = 0; + DwarfMacroInfoSection = 0; +} + +TargetLoweringObjectFile::~TargetLoweringObjectFile() { +} + +static bool isSuitableForBSS(const GlobalVariable *GV) { + Constant *C = GV->getInitializer(); + + // Must have zero initializer. + if (!C->isNullValue()) + return false; + + // Leave constant zeros in readonly constant sections, so they can be shared. + if (GV->isConstant()) + return false; + + // If the global has an explicit section specified, don't put it in BSS. + if (!GV->getSection().empty()) + return false; + + // If -nozero-initialized-in-bss is specified, don't ever use BSS. + if (NoZerosInBSS) + return false; + + // Otherwise, put it in BSS! + return true; +} + +/// IsNullTerminatedString - Return true if the specified constant (which is +/// known to have a type that is an array of 1/2/4 byte elements) ends with a +/// nul value and contains no other nuls in it. +static bool IsNullTerminatedString(const Constant *C) { + const ArrayType *ATy = cast<ArrayType>(C->getType()); + + // First check: is we have constant array of i8 terminated with zero + if (const ConstantArray *CVA = dyn_cast<ConstantArray>(C)) { + if (ATy->getNumElements() == 0) return false; + + ConstantInt *Null = + dyn_cast<ConstantInt>(CVA->getOperand(ATy->getNumElements()-1)); + if (Null == 0 || Null->getZExtValue() != 0) + return false; // Not null terminated. + + // Verify that the null doesn't occur anywhere else in the string. + for (unsigned i = 0, e = ATy->getNumElements()-1; i != e; ++i) + // Reject constantexpr elements etc. + if (!isa<ConstantInt>(CVA->getOperand(i)) || + CVA->getOperand(i) == Null) + return false; + return true; + } + + // Another possibility: [1 x i8] zeroinitializer + if (isa<ConstantAggregateZero>(C)) + return ATy->getNumElements() == 1; + + return false; +} + +/// getKindForGlobal - This is a top-level target-independent classifier for +/// a global variable. Given an global variable and information from TM, it +/// classifies the global in a variety of ways that make various target +/// implementations simpler. The target implementation is free to ignore this +/// extra info of course. +SectionKind TargetLoweringObjectFile::getKindForGlobal(const GlobalValue *GV, + const TargetMachine &TM){ + assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() && + "Can only be used for global definitions"); + + Reloc::Model ReloModel = TM.getRelocationModel(); + + // Early exit - functions should be always in text sections. + const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV); + if (GVar == 0) + return SectionKind::getText(); + + // Handle thread-local data first. + if (GVar->isThreadLocal()) { + if (isSuitableForBSS(GVar)) + return SectionKind::getThreadBSS(); + return SectionKind::getThreadData(); + } + + // Variable can be easily put to BSS section. + if (isSuitableForBSS(GVar)) + return SectionKind::getBSS(); + + Constant *C = GVar->getInitializer(); + + // If the global is marked constant, we can put it into a mergable section, + // a mergable string section, or general .data if it contains relocations. + if (GVar->isConstant()) { + // If the initializer for the global contains something that requires a + // relocation, then we may have to drop this into a wriable data section + // even though it is marked const. + switch (C->getRelocationInfo()) { + default: llvm_unreachable("unknown relocation info kind"); + case Constant::NoRelocation: + // If initializer is a null-terminated string, put it in a "cstring" + // section of the right width. + if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) { + if (const IntegerType *ITy = + dyn_cast<IntegerType>(ATy->getElementType())) { + if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 || + ITy->getBitWidth() == 32) && + IsNullTerminatedString(C)) { + if (ITy->getBitWidth() == 8) + return SectionKind::getMergeable1ByteCString(); + if (ITy->getBitWidth() == 16) + return SectionKind::getMergeable2ByteCString(); + + assert(ITy->getBitWidth() == 32 && "Unknown width"); + return SectionKind::getMergeable4ByteCString(); + } + } + } + + // Otherwise, just drop it into a mergable constant section. If we have + // a section for this size, use it, otherwise use the arbitrary sized + // mergable section. + switch (TM.getTargetData()->getTypeAllocSize(C->getType())) { + case 4: return SectionKind::getMergeableConst4(); + case 8: return SectionKind::getMergeableConst8(); + case 16: return SectionKind::getMergeableConst16(); + default: return SectionKind::getMergeableConst(); + } + + case Constant::LocalRelocation: + // In static relocation model, the linker will resolve all addresses, so + // the relocation entries will actually be constants by the time the app + // starts up. However, we can't put this into a mergable section, because + // the linker doesn't take relocations into consideration when it tries to + // merge entries in the section. + if (ReloModel == Reloc::Static) + return SectionKind::getReadOnly(); + + // Otherwise, the dynamic linker needs to fix it up, put it in the + // writable data.rel.local section. + return SectionKind::getReadOnlyWithRelLocal(); + + case Constant::GlobalRelocations: + // In static relocation model, the linker will resolve all addresses, so + // the relocation entries will actually be constants by the time the app + // starts up. However, we can't put this into a mergable section, because + // the linker doesn't take relocations into consideration when it tries to + // merge entries in the section. + if (ReloModel == Reloc::Static) + return SectionKind::getReadOnly(); + + // Otherwise, the dynamic linker needs to fix it up, put it in the + // writable data.rel section. + return SectionKind::getReadOnlyWithRel(); + } + } + + // Okay, this isn't a constant. If the initializer for the global is going + // to require a runtime relocation by the dynamic linker, put it into a more + // specific section to improve startup time of the app. This coalesces these + // globals together onto fewer pages, improving the locality of the dynamic + // linker. + if (ReloModel == Reloc::Static) + return SectionKind::getDataNoRel(); + + switch (C->getRelocationInfo()) { + default: llvm_unreachable("unknown relocation info kind"); + case Constant::NoRelocation: + return SectionKind::getDataNoRel(); + case Constant::LocalRelocation: + return SectionKind::getDataRelLocal(); + case Constant::GlobalRelocations: + return SectionKind::getDataRel(); + } +} + +/// SectionForGlobal - This method computes the appropriate section to emit +/// the specified global variable or function definition. This should not +/// be passed external (or available externally) globals. +const MCSection *TargetLoweringObjectFile:: +SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, + const TargetMachine &TM) const { + // Select section name. + if (GV->hasSection()) + return getExplicitSectionGlobal(GV, Kind, Mang, TM); + + + // Use default section depending on the 'type' of global + return SelectSectionForGlobal(GV, Kind, Mang, TM); +} + + +// Lame default implementation. Calculate the section name for global. +const MCSection * +TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV, + SectionKind Kind, + Mangler *Mang, + const TargetMachine &TM) const{ + assert(!Kind.isThreadLocal() && "Doesn't support TLS"); + + if (Kind.isText()) + return getTextSection(); + + if (Kind.isBSS() && BSSSection != 0) + return BSSSection; + + if (Kind.isReadOnly() && ReadOnlySection != 0) + return ReadOnlySection; + + return getDataSection(); +} + +/// getSectionForConstant - Given a mergable constant with the +/// specified size and relocation information, return a section that it +/// should be placed in. +const MCSection * +TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const { + if (Kind.isReadOnly() && ReadOnlySection != 0) + return ReadOnlySection; + + return DataSection; +} + +/// getSymbolForDwarfGlobalReference - Return an MCExpr to use for a +/// pc-relative reference to the specified global variable from exception +/// handling information. In addition to the symbol, this returns +/// by-reference: +/// +/// IsIndirect - True if the returned symbol is actually a stub that contains +/// the address of the symbol, false if the symbol is the global itself. +/// +/// IsPCRel - True if the symbol reference is already pc-relative, false if +/// the caller needs to subtract off the address of the reference from the +/// symbol. +/// +const MCExpr *TargetLoweringObjectFile:: +getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, + MachineModuleInfo *MMI, + bool &IsIndirect, bool &IsPCRel) const { + // The generic implementation of this just returns a direct reference to the + // symbol. + IsIndirect = false; + IsPCRel = false; + + SmallString<128> Name; + Mang->getNameWithPrefix(Name, GV, false); + return MCSymbolRefExpr::Create(Name.str(), getContext()); +} + + +//===----------------------------------------------------------------------===// +// ELF +//===----------------------------------------------------------------------===// +typedef StringMap<const MCSectionELF*> ELFUniqueMapTy; + +TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() { + // If we have the section uniquing map, free it. + delete (ELFUniqueMapTy*)UniquingMap; +} + +const MCSection *TargetLoweringObjectFileELF:: +getELFSection(StringRef Section, unsigned Type, unsigned Flags, + SectionKind Kind, bool IsExplicit) const { + if (UniquingMap == 0) + UniquingMap = new ELFUniqueMapTy(); + ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)UniquingMap; + + // Do the lookup, if we have a hit, return it. + const MCSectionELF *&Entry = Map[Section]; + if (Entry) return Entry; + + return Entry = MCSectionELF::Create(Section, Type, Flags, Kind, IsExplicit, + getContext()); +} + +void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx, + const TargetMachine &TM) { + if (UniquingMap != 0) + ((ELFUniqueMapTy*)UniquingMap)->clear(); + TargetLoweringObjectFile::Initialize(Ctx, TM); + + BSSSection = + getELFSection(".bss", MCSectionELF::SHT_NOBITS, + MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC, + SectionKind::getBSS()); + + TextSection = + getELFSection(".text", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC, + SectionKind::getText()); + + DataSection = + getELFSection(".data", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC, + SectionKind::getDataRel()); + + ReadOnlySection = + getELFSection(".rodata", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC, + SectionKind::getReadOnly()); + + TLSDataSection = + getELFSection(".tdata", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS | + MCSectionELF::SHF_WRITE, SectionKind::getThreadData()); + + TLSBSSSection = + getELFSection(".tbss", MCSectionELF::SHT_NOBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS | + MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS()); + + DataRelSection = + getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, + SectionKind::getDataRel()); + + DataRelLocalSection = + getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, + SectionKind::getDataRelLocal()); + + DataRelROSection = + getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, + SectionKind::getReadOnlyWithRel()); + + DataRelROLocalSection = + getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, + SectionKind::getReadOnlyWithRelLocal()); + + MergeableConst4Section = + getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE, + SectionKind::getMergeableConst4()); + + MergeableConst8Section = + getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE, + SectionKind::getMergeableConst8()); + + MergeableConst16Section = + getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE, + SectionKind::getMergeableConst16()); + + StaticCtorSection = + getELFSection(".ctors", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, + SectionKind::getDataRel()); + + StaticDtorSection = + getELFSection(".dtors", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, + SectionKind::getDataRel()); + + // Exception Handling Sections. + + // FIXME: We're emitting LSDA info into a readonly section on ELF, even though + // it contains relocatable pointers. In PIC mode, this is probably a big + // runtime hit for C++ apps. Either the contents of the LSDA need to be + // adjusted or this should be a data section. + LSDASection = + getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly()); + EHFrameSection = + getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, + SectionKind::getDataRel()); + + // Debug Info Sections. + DwarfAbbrevSection = + getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfInfoSection = + getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfLineSection = + getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfFrameSection = + getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfPubNamesSection = + getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfPubTypesSection = + getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfStrSection = + getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfLocSection = + getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfARangesSection = + getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfRangesSection = + getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); + DwarfMacroInfoSection = + getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0, + SectionKind::getMetadata()); +} + + +static SectionKind +getELFKindForNamedSection(const char *Name, SectionKind K) { + if (Name[0] != '.') return K; + + // Some lame default implementation based on some magic section names. + if (strcmp(Name, ".bss") == 0 || + strncmp(Name, ".bss.", 5) == 0 || + strncmp(Name, ".gnu.linkonce.b.", 16) == 0 || + strncmp(Name, ".llvm.linkonce.b.", 17) == 0 || + strcmp(Name, ".sbss") == 0 || + strncmp(Name, ".sbss.", 6) == 0 || + strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 || + strncmp(Name, ".llvm.linkonce.sb.", 18) == 0) + return SectionKind::getBSS(); + + if (strcmp(Name, ".tdata") == 0 || + strncmp(Name, ".tdata.", 7) == 0 || + strncmp(Name, ".gnu.linkonce.td.", 17) == 0 || + strncmp(Name, ".llvm.linkonce.td.", 18) == 0) + return SectionKind::getThreadData(); + + if (strcmp(Name, ".tbss") == 0 || + strncmp(Name, ".tbss.", 6) == 0 || + strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 || + strncmp(Name, ".llvm.linkonce.tb.", 18) == 0) + return SectionKind::getThreadBSS(); + + return K; +} + + +static unsigned +getELFSectionType(const char *Name, SectionKind K) { + + if (strcmp(Name, ".init_array") == 0) + return MCSectionELF::SHT_INIT_ARRAY; + + if (strcmp(Name, ".fini_array") == 0) + return MCSectionELF::SHT_FINI_ARRAY; + + if (strcmp(Name, ".preinit_array") == 0) + return MCSectionELF::SHT_PREINIT_ARRAY; + + if (K.isBSS() || K.isThreadBSS()) + return MCSectionELF::SHT_NOBITS; + + return MCSectionELF::SHT_PROGBITS; +} + + +static unsigned +getELFSectionFlags(SectionKind K) { + unsigned Flags = 0; + + if (!K.isMetadata()) + Flags |= MCSectionELF::SHF_ALLOC; + + if (K.isText()) + Flags |= MCSectionELF::SHF_EXECINSTR; + + if (K.isWriteable()) + Flags |= MCSectionELF::SHF_WRITE; + + if (K.isThreadLocal()) + Flags |= MCSectionELF::SHF_TLS; + + // K.isMergeableConst() is left out to honour PR4650 + if (K.isMergeableCString() || K.isMergeableConst4() || + K.isMergeableConst8() || K.isMergeableConst16()) + Flags |= MCSectionELF::SHF_MERGE; + + if (K.isMergeableCString()) + Flags |= MCSectionELF::SHF_STRINGS; + + return Flags; +} + + +const MCSection *TargetLoweringObjectFileELF:: +getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, + Mangler *Mang, const TargetMachine &TM) const { + const char *SectionName = GV->getSection().c_str(); + + // Infer section flags from the section name if we can. + Kind = getELFKindForNamedSection(SectionName, Kind); + + return getELFSection(SectionName, + getELFSectionType(SectionName, Kind), + getELFSectionFlags(Kind), Kind, true); +} + +static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) { + if (Kind.isText()) return ".gnu.linkonce.t."; + if (Kind.isReadOnly()) return ".gnu.linkonce.r."; + + if (Kind.isThreadData()) return ".gnu.linkonce.td."; + if (Kind.isThreadBSS()) return ".gnu.linkonce.tb."; + + if (Kind.isBSS()) return ".gnu.linkonce.b."; + if (Kind.isDataNoRel()) return ".gnu.linkonce.d."; + if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local."; + if (Kind.isDataRel()) return ".gnu.linkonce.d.rel."; + if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local."; + + assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); + return ".gnu.linkonce.d.rel.ro."; +} + +const MCSection *TargetLoweringObjectFileELF:: +SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, + Mangler *Mang, const TargetMachine &TM) const { + + // If this global is linkonce/weak and the target handles this by emitting it + // into a 'uniqued' section name, create and return the section now. + if (GV->isWeakForLinker()) { + const char *Prefix = getSectionPrefixForUniqueGlobal(Kind); + std::string Name = Mang->makeNameProper(GV->getNameStr()); + + return getELFSection((Prefix+Name).c_str(), + getELFSectionType((Prefix+Name).c_str(), Kind), + getELFSectionFlags(Kind), + Kind); + } + + if (Kind.isText()) return TextSection; + + if (Kind.isMergeable1ByteCString() || + Kind.isMergeable2ByteCString() || + Kind.isMergeable4ByteCString()) { + + // We also need alignment here. + // FIXME: this is getting the alignment of the character, not the + // alignment of the global! + unsigned Align = + TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); + + const char *SizeSpec = ".rodata.str1."; + if (Kind.isMergeable2ByteCString()) + SizeSpec = ".rodata.str2."; + else if (Kind.isMergeable4ByteCString()) + SizeSpec = ".rodata.str4."; + else + assert(Kind.isMergeable1ByteCString() && "unknown string width"); + + + std::string Name = SizeSpec + utostr(Align); + return getELFSection(Name.c_str(), MCSectionELF::SHT_PROGBITS, + MCSectionELF::SHF_ALLOC | + MCSectionELF::SHF_MERGE | + MCSectionELF::SHF_STRINGS, + Kind); + } + + if (Kind.isMergeableConst()) { + if (Kind.isMergeableConst4() && MergeableConst4Section) + return MergeableConst4Section; + if (Kind.isMergeableConst8() && MergeableConst8Section) + return MergeableConst8Section; + if (Kind.isMergeableConst16() && MergeableConst16Section) + return MergeableConst16Section; + return ReadOnlySection; // .const + } + + if (Kind.isReadOnly()) return ReadOnlySection; + + if (Kind.isThreadData()) return TLSDataSection; + if (Kind.isThreadBSS()) return TLSBSSSection; + + if (Kind.isBSS()) return BSSSection; + + if (Kind.isDataNoRel()) return DataSection; + if (Kind.isDataRelLocal()) return DataRelLocalSection; + if (Kind.isDataRel()) return DataRelSection; + if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; + + assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); + return DataRelROSection; +} + +/// getSectionForConstant - Given a mergeable constant with the +/// specified size and relocation information, return a section that it +/// should be placed in. +const MCSection *TargetLoweringObjectFileELF:: +getSectionForConstant(SectionKind Kind) const { + if (Kind.isMergeableConst4() && MergeableConst4Section) + return MergeableConst4Section; + if (Kind.isMergeableConst8() && MergeableConst8Section) + return MergeableConst8Section; + if (Kind.isMergeableConst16() && MergeableConst16Section) + return MergeableConst16Section; + if (Kind.isReadOnly()) + return ReadOnlySection; + + if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; + assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); + return DataRelROSection; +} + +//===----------------------------------------------------------------------===// +// MachO +//===----------------------------------------------------------------------===// + +typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy; + +TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() { + // If we have the MachO uniquing map, free it. + delete (MachOUniqueMapTy*)UniquingMap; +} + + +const MCSectionMachO *TargetLoweringObjectFileMachO:: +getMachOSection(const StringRef &Segment, const StringRef &Section, + unsigned TypeAndAttributes, + unsigned Reserved2, SectionKind Kind) const { + // We unique sections by their segment/section pair. The returned section + // may not have the same flags as the requested section, if so this should be + // diagnosed by the client as an error. + + // Create the map if it doesn't already exist. + if (UniquingMap == 0) + UniquingMap = new MachOUniqueMapTy(); + MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap; + + // Form the name to look up. + SmallString<64> Name; + Name += Segment; + Name.push_back(','); + Name += Section; + + // Do the lookup, if we have a hit, return it. + const MCSectionMachO *&Entry = Map[Name.str()]; + if (Entry) return Entry; + + // Otherwise, return a new section. + return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes, + Reserved2, Kind, getContext()); +} + + +void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, + const TargetMachine &TM) { + if (UniquingMap != 0) + ((MachOUniqueMapTy*)UniquingMap)->clear(); + TargetLoweringObjectFile::Initialize(Ctx, TM); + + TextSection // .text + = getMachOSection("__TEXT", "__text", + MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, + SectionKind::getText()); + DataSection // .data + = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel()); + + CStringSection // .cstring + = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS, + SectionKind::getMergeable1ByteCString()); + UStringSection + = getMachOSection("__TEXT","__ustring", 0, + SectionKind::getMergeable2ByteCString()); + FourByteConstantSection // .literal4 + = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS, + SectionKind::getMergeableConst4()); + EightByteConstantSection // .literal8 + = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS, + SectionKind::getMergeableConst8()); + + // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back + // to using it in -static mode. + SixteenByteConstantSection = 0; + if (TM.getRelocationModel() != Reloc::Static && + TM.getTargetData()->getPointerSize() == 32) + SixteenByteConstantSection = // .literal16 + getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS, + SectionKind::getMergeableConst16()); + + ReadOnlySection // .const + = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly()); + + TextCoalSection + = getMachOSection("__TEXT", "__textcoal_nt", + MCSectionMachO::S_COALESCED | + MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, + SectionKind::getText()); + ConstTextCoalSection + = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED, + SectionKind::getText()); + ConstDataCoalSection + = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED, + SectionKind::getText()); + ConstDataSection // .const_data + = getMachOSection("__DATA", "__const", 0, + SectionKind::getReadOnlyWithRel()); + DataCoalSection + = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED, + SectionKind::getDataRel()); + + + LazySymbolPointerSection + = getMachOSection("__DATA", "__la_symbol_ptr", + MCSectionMachO::S_LAZY_SYMBOL_POINTERS, + SectionKind::getMetadata()); + NonLazySymbolPointerSection + = getMachOSection("__DATA", "__nl_symbol_ptr", + MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS, + SectionKind::getMetadata()); + + if (TM.getRelocationModel() == Reloc::Static) { + StaticCtorSection + = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel()); + StaticDtorSection + = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel()); + } else { + StaticCtorSection + = getMachOSection("__DATA", "__mod_init_func", + MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, + SectionKind::getDataRel()); + StaticDtorSection + = getMachOSection("__DATA", "__mod_term_func", + MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, + SectionKind::getDataRel()); + } + + // Exception Handling. + LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0, + SectionKind::getDataRel()); + EHFrameSection = + getMachOSection("__TEXT", "__eh_frame", + MCSectionMachO::S_COALESCED | + MCSectionMachO::S_ATTR_NO_TOC | + MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | + MCSectionMachO::S_ATTR_LIVE_SUPPORT, + SectionKind::getReadOnly()); + + // Debug Information. + DwarfAbbrevSection = + getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfInfoSection = + getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfLineSection = + getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfFrameSection = + getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfPubNamesSection = + getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfPubTypesSection = + getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfStrSection = + getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfLocSection = + getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfARangesSection = + getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfRangesSection = + getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfMacroInfoSection = + getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); + DwarfDebugInlineSection = + getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG, + SectionKind::getMetadata()); +} + +const MCSection *TargetLoweringObjectFileMachO:: +getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, + Mangler *Mang, const TargetMachine &TM) const { + // Parse the section specifier and create it if valid. + StringRef Segment, Section; + unsigned TAA, StubSize; + std::string ErrorCode = + MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, + TAA, StubSize); + if (!ErrorCode.empty()) { + // If invalid, report the error with llvm_report_error. + llvm_report_error("Global variable '" + GV->getNameStr() + + "' has an invalid section specifier '" + GV->getSection()+ + "': " + ErrorCode + "."); + // Fall back to dropping it into the data section. + return DataSection; + } + + // Get the section. + const MCSectionMachO *S = + getMachOSection(Segment, Section, TAA, StubSize, Kind); + + // Okay, now that we got the section, verify that the TAA & StubSize agree. + // If the user declared multiple globals with different section flags, we need + // to reject it here. + if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { + // If invalid, report the error with llvm_report_error. + llvm_report_error("Global variable '" + GV->getNameStr() + + "' section type or attributes does not match previous" + " section specifier"); + } + + return S; +} + +const MCSection *TargetLoweringObjectFileMachO:: +SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, + Mangler *Mang, const TargetMachine &TM) const { + assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS"); + + if (Kind.isText()) + return GV->isWeakForLinker() ? TextCoalSection : TextSection; + + // If this is weak/linkonce, put this in a coalescable section, either in text + // or data depending on if it is writable. + if (GV->isWeakForLinker()) { + if (Kind.isReadOnly()) + return ConstTextCoalSection; + return DataCoalSection; + } + + // FIXME: Alignment check should be handled by section classifier. + if (Kind.isMergeable1ByteCString() || + Kind.isMergeable2ByteCString()) { + if (TM.getTargetData()->getPreferredAlignment( + cast<GlobalVariable>(GV)) < 32) { + if (Kind.isMergeable1ByteCString()) + return CStringSection; + assert(Kind.isMergeable2ByteCString()); + return UStringSection; + } + } + + if (Kind.isMergeableConst()) { + if (Kind.isMergeableConst4()) + return FourByteConstantSection; + if (Kind.isMergeableConst8()) + return EightByteConstantSection; + if (Kind.isMergeableConst16() && SixteenByteConstantSection) + return SixteenByteConstantSection; + } + + // Otherwise, if it is readonly, but not something we can specially optimize, + // just drop it in .const. + if (Kind.isReadOnly()) + return ReadOnlySection; + + // If this is marked const, put it into a const section. But if the dynamic + // linker needs to write to it, put it in the data segment. + if (Kind.isReadOnlyWithRel()) + return ConstDataSection; + + // Otherwise, just drop the variable in the normal data section. + return DataSection; +} + +const MCSection * +TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { + // If this constant requires a relocation, we have to put it in the data + // segment, not in the text segment. + if (Kind.isDataRel()) + return ConstDataSection; + + if (Kind.isMergeableConst4()) + return FourByteConstantSection; + if (Kind.isMergeableConst8()) + return EightByteConstantSection; + if (Kind.isMergeableConst16() && SixteenByteConstantSection) + return SixteenByteConstantSection; + return ReadOnlySection; // .const +} + +/// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide +/// not to emit the UsedDirective for some symbols in llvm.used. +// FIXME: REMOVE this (rdar://7071300) +bool TargetLoweringObjectFileMachO:: +shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { + /// On Darwin, internally linked data beginning with "L" or "l" does not have + /// the directive emitted (this occurs in ObjC metadata). + if (!GV) return false; + + // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. + if (GV->hasLocalLinkage() && !isa<Function>(GV)) { + // FIXME: ObjC metadata is currently emitted as internal symbols that have + // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and + // this horrible hack can go away. + const std::string &Name = Mang->getMangledName(GV); + if (Name[0] == 'L' || Name[0] == 'l') + return false; + } + + return true; +} + +const MCExpr *TargetLoweringObjectFileMachO:: +getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, + MachineModuleInfo *MMI, + bool &IsIndirect, bool &IsPCRel) const { + // The mach-o version of this method defaults to returning a stub reference. + IsIndirect = true; + IsPCRel = false; + + SmallString<128> Name; + Mang->getNameWithPrefix(Name, GV, true); + Name += "$non_lazy_ptr"; + return MCSymbolRefExpr::Create(Name.str(), getContext()); +} + + +//===----------------------------------------------------------------------===// +// COFF +//===----------------------------------------------------------------------===// + +typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy; + +TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() { + delete (COFFUniqueMapTy*)UniquingMap; +} + + +const MCSection *TargetLoweringObjectFileCOFF:: +getCOFFSection(const char *Name, bool isDirective, SectionKind Kind) const { + // Create the map if it doesn't already exist. + if (UniquingMap == 0) + UniquingMap = new MachOUniqueMapTy(); + COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap; + + // Do the lookup, if we have a hit, return it. + const MCSectionCOFF *&Entry = Map[Name]; + if (Entry) return Entry; + + return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext()); +} + +void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, + const TargetMachine &TM) { + if (UniquingMap != 0) + ((COFFUniqueMapTy*)UniquingMap)->clear(); + TargetLoweringObjectFile::Initialize(Ctx, TM); + TextSection = getCOFFSection("\t.text", true, SectionKind::getText()); + DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel()); + StaticCtorSection = + getCOFFSection(".ctors", false, SectionKind::getDataRel()); + StaticDtorSection = + getCOFFSection(".dtors", false, SectionKind::getDataRel()); + + // FIXME: We're emitting LSDA info into a readonly section on COFF, even + // though it contains relocatable pointers. In PIC mode, this is probably a + // big runtime hit for C++ apps. Either the contents of the LSDA need to be + // adjusted or this should be a data section. + LSDASection = + getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly()); + EHFrameSection = + getCOFFSection(".eh_frame", false, SectionKind::getDataRel()); + + // Debug info. + // FIXME: Don't use 'directive' mode here. + DwarfAbbrevSection = + getCOFFSection("\t.section\t.debug_abbrev,\"dr\"", + true, SectionKind::getMetadata()); + DwarfInfoSection = + getCOFFSection("\t.section\t.debug_info,\"dr\"", + true, SectionKind::getMetadata()); + DwarfLineSection = + getCOFFSection("\t.section\t.debug_line,\"dr\"", + true, SectionKind::getMetadata()); + DwarfFrameSection = + getCOFFSection("\t.section\t.debug_frame,\"dr\"", + true, SectionKind::getMetadata()); + DwarfPubNamesSection = + getCOFFSection("\t.section\t.debug_pubnames,\"dr\"", + true, SectionKind::getMetadata()); + DwarfPubTypesSection = + getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"", + true, SectionKind::getMetadata()); + DwarfStrSection = + getCOFFSection("\t.section\t.debug_str,\"dr\"", + true, SectionKind::getMetadata()); + DwarfLocSection = + getCOFFSection("\t.section\t.debug_loc,\"dr\"", + true, SectionKind::getMetadata()); + DwarfARangesSection = + getCOFFSection("\t.section\t.debug_aranges,\"dr\"", + true, SectionKind::getMetadata()); + DwarfRangesSection = + getCOFFSection("\t.section\t.debug_ranges,\"dr\"", + true, SectionKind::getMetadata()); + DwarfMacroInfoSection = + getCOFFSection("\t.section\t.debug_macinfo,\"dr\"", + true, SectionKind::getMetadata()); +} + +const MCSection *TargetLoweringObjectFileCOFF:: +getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, + Mangler *Mang, const TargetMachine &TM) const { + return getCOFFSection(GV->getSection().c_str(), false, Kind); +} + +static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { + if (Kind.isText()) + return ".text$linkonce"; + if (Kind.isWriteable()) + return ".data$linkonce"; + return ".rdata$linkonce"; +} + + +const MCSection *TargetLoweringObjectFileCOFF:: +SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, + Mangler *Mang, const TargetMachine &TM) const { + assert(!Kind.isThreadLocal() && "Doesn't support TLS"); + + // If this global is linkonce/weak and the target handles this by emitting it + // into a 'uniqued' section name, create and return the section now. + if (GV->isWeakForLinker()) { + const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); + std::string Name = Mang->makeNameProper(GV->getNameStr()); + return getCOFFSection((Prefix+Name).c_str(), false, Kind); + } + + if (Kind.isText()) + return getTextSection(); + + return getDataSection(); +} + |
