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/IR/DataLayout.h"
13#include "llvm/IR/DerivedTypes.h"
14#include "llvm/IR/GlobalVariable.h"
15#include "llvm/MC/MCContext.h"
16#include "llvm/MC/MCSectionELF.h"
17#include "llvm/Support/CommandLine.h"
18#include "llvm/Support/ELF.h"
19#include "llvm/Target/TargetMachine.h"
20using namespace llvm;
21
22void MBlazeTargetObjectFile::
23Initialize(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.
41static bool IsInSmallSection(uint64_t Size) {
42  return Size > 0 && Size <= 8;
43}
44
45bool MBlazeTargetObjectFile::
46IsGlobalInSmallSection(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.
55bool MBlazeTargetObjectFile::
56IsGlobalInSmallSection(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.getDataLayout()->getTypeAllocSize(Ty));
74}
75
76const MCSection *MBlazeTargetObjectFile::
77SelectSectionForGlobal(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