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//===-- MipsTargetObjectFile.cpp - Mips Object Files ----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "MipsTargetObjectFile.h"
#include "MipsSubtarget.h"
#include "llvm/DataLayout.h"
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ELF.h"
#include "llvm/Target/TargetMachine.h"
using namespace llvm;
static cl::opt<unsigned>
SSThreshold("mips-ssection-threshold", cl::Hidden,
cl::desc("Small data and bss section threshold size (default=8)"),
cl::init(8));
void MipsTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM){
TargetLoweringObjectFileELF::Initialize(Ctx, TM);
InitializeELF(TM.Options.UseInitArray);
SmallDataSection =
getContext().getELFSection(".sdata", ELF::SHT_PROGBITS,
ELF::SHF_WRITE |ELF::SHF_ALLOC,
SectionKind::getDataRel());
SmallBSSSection =
getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
ELF::SHF_WRITE |ELF::SHF_ALLOC,
SectionKind::getBSS());
// @LOCALMOD-BEGIN
// Without this the linker defined symbols __fini_array_start and
// __fini_array_end do not have useful values. c.f.:
// http://code.google.com/p/nativeclient/issues/detail?id=805
if (TM.getSubtarget<MipsSubtarget>().isTargetNaCl()) {
StaticCtorSection =
getContext().getELFSection(".init_array", ELF::SHT_INIT_ARRAY,
ELF::SHF_WRITE |
ELF::SHF_ALLOC,
SectionKind::getDataRel());
StaticDtorSection =
getContext().getELFSection(".fini_array", ELF::SHT_FINI_ARRAY,
ELF::SHF_WRITE |
ELF::SHF_ALLOC,
SectionKind::getDataRel());
}
// @LOCALMOD-END
}
// A address must be loaded from a small section if its size is less than the
// small section size threshold. Data in this section must be addressed using
// gp_rel operator.
static bool IsInSmallSection(uint64_t Size) {
return Size > 0 && Size <= SSThreshold;
}
bool MipsTargetObjectFile::IsGlobalInSmallSection(const GlobalValue *GV,
const TargetMachine &TM) const {
if (GV->isDeclaration() || GV->hasAvailableExternallyLinkage())
return false;
return IsGlobalInSmallSection(GV, TM, getKindForGlobal(GV, TM));
}
/// IsGlobalInSmallSection - Return true if this global address should be
/// placed into small data/bss section.
bool MipsTargetObjectFile::
IsGlobalInSmallSection(const GlobalValue *GV, const TargetMachine &TM,
SectionKind Kind) const {
const MipsSubtarget &Subtarget = TM.getSubtarget<MipsSubtarget>();
// Return if small section is not available.
if (!Subtarget.useSmallSection())
return false;
// @LOCALMOD-BEGIN
// Do not use small section for NaCl.
if (Subtarget.isTargetNaCl())
return false;
// @LOCALMOD-BEGIN
// Only global variables, not functions.
const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GV);
if (!GVA)
return false;
// We can only do this for datarel or BSS objects for now.
if (!Kind.isBSS() && !Kind.isDataRel())
return false;
// If this is a internal constant string, there is a special
// section for it, but not in small data/bss.
if (Kind.isMergeable1ByteCString())
return false;
Type *Ty = GV->getType()->getElementType();
return IsInSmallSection(TM.getDataLayout()->getTypeAllocSize(Ty));
}
const MCSection *MipsTargetObjectFile::
SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
Mangler *Mang, const TargetMachine &TM) const {
// TODO: Could also support "weak" symbols as well with ".gnu.linkonce.s.*"
// sections?
// Handle Small Section classification here.
if (Kind.isBSS() && IsGlobalInSmallSection(GV, TM, Kind))
return SmallBSSSection;
if (Kind.isDataNoRel() && IsGlobalInSmallSection(GV, TM, Kind))
return SmallDataSection;
// Otherwise, we work the same as ELF.
return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind, Mang,TM);
}
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