//===-- 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/DerivedTypes.h" #include "llvm/GlobalVariable.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCSectionELF.h" #include "llvm/Target/TargetData.h" #include "llvm/Target/TargetMachine.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/ELF.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); 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()); } // 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 { // Only use small section for non linux targets. const MipsSubtarget &Subtarget = TM.getSubtarget<MipsSubtarget>(); if (Subtarget.isLinux()) return false; // 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.getTargetData()->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); }