1//===-- HexagonTargetObjectFile.cpp - Hexagon asm properties --------------===//
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// This file contains the declarations of the HexagonTargetAsmInfo properties.
11//
12//===----------------------------------------------------------------------===//
13
14#include "HexagonTargetObjectFile.h"
15#include "HexagonSubtarget.h"
16#include "HexagonTargetMachine.h"
17#include "llvm/IR/DataLayout.h"
18#include "llvm/IR/DerivedTypes.h"
19#include "llvm/IR/Function.h"
20#include "llvm/IR/GlobalVariable.h"
21#include "llvm/MC/MCContext.h"
22#include "llvm/Support/CommandLine.h"
23#include "llvm/Support/ELF.h"
24
25using namespace llvm;
26
27static cl::opt<int> SmallDataThreshold("hexagon-small-data-threshold",
28                                cl::init(8), cl::Hidden,
29                cl::desc("The maximum size of an object in the sdata section"));
30
31void HexagonTargetObjectFile::Initialize(MCContext &Ctx,
32                                         const TargetMachine &TM) {
33  TargetLoweringObjectFileELF::Initialize(Ctx, TM);
34
35
36  SmallDataSection =
37    getContext().getELFSection(".sdata", ELF::SHT_PROGBITS,
38                               ELF::SHF_WRITE | ELF::SHF_ALLOC,
39                               SectionKind::getDataRel());
40  SmallBSSSection =
41    getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
42                               ELF::SHF_WRITE | ELF::SHF_ALLOC,
43                               SectionKind::getBSS());
44}
45
46// sdata/sbss support taken largely from the MIPS Backend.
47static bool IsInSmallSection(uint64_t Size) {
48  return Size > 0 && Size <= (uint64_t)SmallDataThreshold;
49}
50
51bool HexagonTargetObjectFile::IsSmallDataEnabled () const {
52  return SmallDataThreshold > 0;
53}
54
55/// IsGlobalInSmallSection - Return true if this global value should be
56/// placed into small data/bss section.
57bool HexagonTargetObjectFile::IsGlobalInSmallSection(const GlobalValue *GV,
58                                                const TargetMachine &TM) const {
59  // If the primary definition of this global value is outside the current
60  // translation unit or the global value is available for inspection but not
61  // emission, then do nothing.
62  if (GV->isDeclaration() || GV->hasAvailableExternallyLinkage())
63    return false;
64
65  // Otherwise, Check if GV should be in sdata/sbss, when normally it would end
66  // up in getKindForGlobal(GV, TM).
67  return IsGlobalInSmallSection(GV, TM, getKindForGlobal(GV, TM));
68}
69
70/// IsGlobalInSmallSection - Return true if this global value should be
71/// placed into small data/bss section.
72bool HexagonTargetObjectFile::
73IsGlobalInSmallSection(const GlobalValue *GV, const TargetMachine &TM,
74                       SectionKind Kind) const {
75  // Only global variables, not functions.
76  const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GV);
77  if (!GVA)
78    return false;
79
80  if (Kind.isBSS() || Kind.isDataNoRel() || Kind.isCommon()) {
81    Type *Ty = GV->getType()->getElementType();
82    return IsInSmallSection(TM.getDataLayout()->getTypeAllocSize(Ty));
83  }
84
85  return false;
86}
87
88const MCSection *
89HexagonTargetObjectFile::SelectSectionForGlobal(const GlobalValue *GV,
90                                                SectionKind Kind, Mangler &Mang,
91                                                const TargetMachine &TM) const {
92
93  // Handle Small Section classification here.
94  if (Kind.isBSS() && IsGlobalInSmallSection(GV, TM, Kind))
95    return SmallBSSSection;
96  if (Kind.isDataNoRel() && IsGlobalInSmallSection(GV, TM, Kind))
97    return SmallDataSection;
98
99  // Otherwise, we work the same as ELF.
100  return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind, Mang,TM);
101}
102