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105 lines
3.6 KiB
C++
105 lines
3.6 KiB
C++
//===-- MipsTargetObjectFile.cpp - Mips Object Files ----------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "MipsTargetObjectFile.h"
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#include "MipsSubtarget.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/GlobalVariable.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCSectionELF.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/ELF.h"
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#include "llvm/Target/TargetMachine.h"
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using namespace llvm;
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static cl::opt<unsigned>
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SSThreshold("mips-ssection-threshold", cl::Hidden,
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cl::desc("Small data and bss section threshold size (default=8)"),
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cl::init(8));
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void MipsTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM){
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TargetLoweringObjectFileELF::Initialize(Ctx, TM);
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InitializeELF(TM.Options.UseInitArray);
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SmallDataSection =
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getContext().getELFSection(".sdata", ELF::SHT_PROGBITS,
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ELF::SHF_WRITE |ELF::SHF_ALLOC,
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SectionKind::getDataRel());
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SmallBSSSection =
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getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
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ELF::SHF_WRITE |ELF::SHF_ALLOC,
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SectionKind::getBSS());
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}
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// A address must be loaded from a small section if its size is less than the
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// small section size threshold. Data in this section must be addressed using
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// gp_rel operator.
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static bool IsInSmallSection(uint64_t Size) {
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return Size > 0 && Size <= SSThreshold;
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}
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bool MipsTargetObjectFile::IsGlobalInSmallSection(const GlobalValue *GV,
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const TargetMachine &TM) const {
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if (GV->isDeclaration() || GV->hasAvailableExternallyLinkage())
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return false;
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return IsGlobalInSmallSection(GV, TM, getKindForGlobal(GV, TM));
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}
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/// IsGlobalInSmallSection - Return true if this global address should be
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/// placed into small data/bss section.
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bool MipsTargetObjectFile::
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IsGlobalInSmallSection(const GlobalValue *GV, const TargetMachine &TM,
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SectionKind Kind) const {
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const MipsSubtarget &Subtarget = TM.getSubtarget<MipsSubtarget>();
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// Return if small section is not available.
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if (!Subtarget.useSmallSection())
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return false;
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// Only global variables, not functions.
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const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GV);
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if (!GVA)
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return false;
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// We can only do this for datarel or BSS objects for now.
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if (!Kind.isBSS() && !Kind.isDataRel())
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return false;
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// If this is a internal constant string, there is a special
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// section for it, but not in small data/bss.
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if (Kind.isMergeable1ByteCString())
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return false;
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Type *Ty = GV->getType()->getElementType();
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return IsInSmallSection(
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TM.getSubtargetImpl()->getDataLayout()->getTypeAllocSize(Ty));
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}
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const MCSection *MipsTargetObjectFile::
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SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
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Mangler &Mang, const TargetMachine &TM) const {
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// TODO: Could also support "weak" symbols as well with ".gnu.linkonce.s.*"
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// sections?
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// Handle Small Section classification here.
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if (Kind.isBSS() && IsGlobalInSmallSection(GV, TM, Kind))
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return SmallBSSSection;
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if (Kind.isDataNoRel() && IsGlobalInSmallSection(GV, TM, Kind))
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return SmallDataSection;
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// Otherwise, we work the same as ELF.
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return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind, Mang,TM);
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}
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