1 //===-- MBlazeTargetObjectFile.cpp - MBlaze object files ------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #include "MBlazeTargetObjectFile.h" 11 #include "MBlazeSubtarget.h" 12 #include "llvm/DerivedTypes.h" 13 #include "llvm/GlobalVariable.h" 14 #include "llvm/MC/MCContext.h" 15 #include "llvm/MC/MCSectionELF.h" 16 #include "llvm/Target/TargetData.h" 17 #include "llvm/Target/TargetMachine.h" 18 #include "llvm/Support/CommandLine.h" 19 #include "llvm/Support/ELF.h" 20 using namespace llvm; 21 22 void MBlazeTargetObjectFile:: 23 Initialize(MCContext &Ctx, const TargetMachine &TM) { 24 TargetLoweringObjectFileELF::Initialize(Ctx, TM); 25 26 SmallDataSection = 27 getContext().getELFSection(".sdata", ELF::SHT_PROGBITS, 28 ELF::SHF_WRITE |ELF::SHF_ALLOC, 29 SectionKind::getDataRel()); 30 31 SmallBSSSection = 32 getContext().getELFSection(".sbss", ELF::SHT_NOBITS, 33 ELF::SHF_WRITE |ELF::SHF_ALLOC, 34 SectionKind::getBSS()); 35 36 } 37 38 // A address must be loaded from a small section if its size is less than the 39 // small section size threshold. Data in this section must be addressed using 40 // gp_rel operator. 41 static bool IsInSmallSection(uint64_t Size) { 42 return Size > 0 && Size <= 8; 43 } 44 45 bool MBlazeTargetObjectFile:: 46 IsGlobalInSmallSection(const GlobalValue *GV, const TargetMachine &TM) const { 47 if (GV->isDeclaration() || GV->hasAvailableExternallyLinkage()) 48 return false; 49 50 return IsGlobalInSmallSection(GV, TM, getKindForGlobal(GV, TM)); 51 } 52 53 /// IsGlobalInSmallSection - Return true if this global address should be 54 /// placed into small data/bss section. 55 bool MBlazeTargetObjectFile:: 56 IsGlobalInSmallSection(const GlobalValue *GV, const TargetMachine &TM, 57 SectionKind Kind) const { 58 // Only global variables, not functions. 59 const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GV); 60 if (!GVA) 61 return false; 62 63 // We can only do this for datarel or BSS objects for now. 64 if (!Kind.isBSS() && !Kind.isDataRel()) 65 return false; 66 67 // If this is a internal constant string, there is a special 68 // section for it, but not in small data/bss. 69 if (Kind.isMergeable1ByteCString()) 70 return false; 71 72 Type *Ty = GV->getType()->getElementType(); 73 return IsInSmallSection(TM.getTargetData()->getTypeAllocSize(Ty)); 74 } 75 76 const MCSection *MBlazeTargetObjectFile:: 77 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 78 Mangler *Mang, const TargetMachine &TM) const { 79 // TODO: Could also support "weak" symbols as well with ".gnu.linkonce.s.*" 80 // sections? 81 82 // Handle Small Section classification here. 83 if (Kind.isBSS() && IsGlobalInSmallSection(GV, TM, Kind)) 84 return SmallBSSSection; 85 if (Kind.isDataNoRel() && IsGlobalInSmallSection(GV, TM, Kind)) 86 return SmallDataSection; 87 88 // Otherwise, we work the same as ELF. 89 return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind, Mang,TM); 90 } 91