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//===-- ELFTargetAsmInfo.cpp - ELF asm properties ---------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines target asm properties related what form asm statements
// should take in general on ELF-based targets
//
//===----------------------------------------------------------------------===//
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Target/ELFTargetAsmInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetData.h"
using namespace llvm;
ELFTargetAsmInfo::ELFTargetAsmInfo(const TargetMachine &TM)
: TargetAsmInfo(TM) {
BSSSection_ = getUnnamedSection("\t.bss",
SectionFlags::Writeable | SectionFlags::BSS);
ReadOnlySection = getNamedSection("\t.rodata", SectionFlags::None);
TLSDataSection = getNamedSection("\t.tdata",
SectionFlags::Writeable | SectionFlags::TLS);
TLSBSSSection = getNamedSection("\t.tbss",
SectionFlags::Writeable | SectionFlags::TLS | SectionFlags::BSS);
DataRelSection = getNamedSection("\t.data.rel", SectionFlags::Writeable);
DataRelLocalSection = getNamedSection("\t.data.rel.local",
SectionFlags::Writeable);
DataRelROSection = getNamedSection("\t.data.rel.ro",
SectionFlags::Writeable);
DataRelROLocalSection = getNamedSection("\t.data.rel.ro.local",
SectionFlags::Writeable);
}
SectionKind::Kind
ELFTargetAsmInfo::SectionKindForGlobal(const GlobalValue *GV) const {
SectionKind::Kind Kind = TargetAsmInfo::SectionKindForGlobal(GV);
if (Kind != SectionKind::Data)
return Kind;
// Decide, whether we need data.rel stuff
const GlobalVariable* GVar = dyn_cast<GlobalVariable>(GV);
if (GVar->hasInitializer()) {
Constant *C = GVar->getInitializer();
bool isConstant = GVar->isConstant();
unsigned Reloc = RelocBehaviour();
if (Reloc != Reloc::None && C->ContainsRelocations(Reloc))
return (C->ContainsRelocations(Reloc::Global) ?
(isConstant ?
SectionKind::DataRelRO : SectionKind::DataRel) :
(isConstant ?
SectionKind::DataRelROLocal : SectionKind::DataRelLocal));
}
return Kind;
}
const Section*
ELFTargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV) const {
SectionKind::Kind Kind = SectionKindForGlobal(GV);
if (const Function *F = dyn_cast<Function>(GV)) {
switch (F->getLinkage()) {
default: llvm_unreachable("Unknown linkage type!");
case Function::PrivateLinkage:
case Function::InternalLinkage:
case Function::DLLExportLinkage:
case Function::ExternalLinkage:
return TextSection;
case Function::WeakAnyLinkage:
case Function::WeakODRLinkage:
case Function::LinkOnceAnyLinkage:
case Function::LinkOnceODRLinkage:
std::string Name = UniqueSectionForGlobal(GV, Kind);
unsigned Flags = SectionFlagsForGlobal(GV, Name.c_str());
return getNamedSection(Name.c_str(), Flags);
}
} else if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
if (GVar->isWeakForLinker()) {
std::string Name = UniqueSectionForGlobal(GVar, Kind);
unsigned Flags = SectionFlagsForGlobal(GVar, Name.c_str());
return getNamedSection(Name.c_str(), Flags);
} else {
switch (Kind) {
case SectionKind::Data:
case SectionKind::SmallData:
return DataSection;
case SectionKind::DataRel:
return DataRelSection;
case SectionKind::DataRelLocal:
return DataRelLocalSection;
case SectionKind::DataRelRO:
return DataRelROSection;
case SectionKind::DataRelROLocal:
return DataRelROLocalSection;
case SectionKind::BSS:
case SectionKind::SmallBSS:
// ELF targets usually have BSS sections
return getBSSSection_();
case SectionKind::ROData:
case SectionKind::SmallROData:
return getReadOnlySection();
case SectionKind::RODataMergeStr:
return MergeableStringSection(GVar);
case SectionKind::RODataMergeConst:
return MergeableConstSection(GVar);
case SectionKind::ThreadData:
// ELF targets usually support TLS stuff
return TLSDataSection;
case SectionKind::ThreadBSS:
return TLSBSSSection;
default:
llvm_unreachable("Unsuported section kind for global");
}
}
} else
llvm_unreachable("Unsupported global");
return NULL;
}
const Section*
ELFTargetAsmInfo::SelectSectionForMachineConst(const Type *Ty) const {
// FIXME: Support data.rel stuff someday
return MergeableConstSection(Ty);
}
const Section*
ELFTargetAsmInfo::MergeableConstSection(const GlobalVariable *GV) const {
Constant *C = GV->getInitializer();
return MergeableConstSection(C->getType());
}
inline const Section*
ELFTargetAsmInfo::MergeableConstSection(const Type *Ty) const {
const TargetData *TD = TM.getTargetData();
// FIXME: string here is temporary, until stuff will fully land in.
// We cannot use {Four,Eight,Sixteen}ByteConstantSection here, since it's
// currently directly used by asmprinter.
unsigned Size = TD->getTypeAllocSize(Ty);
if (Size == 4 || Size == 8 || Size == 16) {
std::string Name = ".rodata.cst" + utostr(Size);
return getNamedSection(Name.c_str(),
SectionFlags::setEntitySize(SectionFlags::Mergeable,
Size));
}
return getReadOnlySection();
}
const Section*
ELFTargetAsmInfo::MergeableStringSection(const GlobalVariable *GV) const {
const TargetData *TD = TM.getTargetData();
Constant *C = cast<GlobalVariable>(GV)->getInitializer();
const Type *Ty = cast<ArrayType>(C->getType())->getElementType();
unsigned Size = TD->getTypeAllocSize(Ty);
if (Size <= 16) {
assert(getCStringSection() && "Should have string section prefix");
// We also need alignment here
unsigned Align = TD->getPrefTypeAlignment(Ty);
if (Align < Size)
Align = Size;
std::string Name = getCStringSection() + utostr(Size) + '.' + utostr(Align);
unsigned Flags = SectionFlags::setEntitySize(SectionFlags::Mergeable |
SectionFlags::Strings,
Size);
return getNamedSection(Name.c_str(), Flags);
}
return getReadOnlySection();
}
std::string ELFTargetAsmInfo::printSectionFlags(unsigned flags) const {
std::string Flags = ",\"";
if (!(flags & SectionFlags::Debug))
Flags += 'a';
if (flags & SectionFlags::Code)
Flags += 'x';
if (flags & SectionFlags::Writeable)
Flags += 'w';
if (flags & SectionFlags::Mergeable)
Flags += 'M';
if (flags & SectionFlags::Strings)
Flags += 'S';
if (flags & SectionFlags::TLS)
Flags += 'T';
if (flags & SectionFlags::Small)
Flags += 's';
Flags += "\",";
// If comment string is '@', e.g. as on ARM - use '%' instead
if (strcmp(CommentString, "@") == 0)
Flags += '%';
else
Flags += '@';
// FIXME: There can be exceptions here
if (flags & SectionFlags::BSS)
Flags += "nobits";
else
Flags += "progbits";
if (unsigned entitySize = SectionFlags::getEntitySize(flags))
Flags += "," + utostr(entitySize);
return Flags;
}
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