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
25 using namespace llvm;
26
27 static 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
Initialize(MCContext & Ctx,const TargetMachine & TM)31 void 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.
IsInSmallSection(uint64_t Size)47 static bool IsInSmallSection(uint64_t Size) {
48 return Size > 0 && Size <= (uint64_t)SmallDataThreshold;
49 }
50
IsSmallDataEnabled() const51 bool 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.
IsGlobalInSmallSection(const GlobalValue * GV,const TargetMachine & TM) const57 bool 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.
72 bool HexagonTargetObjectFile::
IsGlobalInSmallSection(const GlobalValue * GV,const TargetMachine & TM,SectionKind Kind) const73 IsGlobalInSmallSection(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
88 const MCSection *
SelectSectionForGlobal(const GlobalValue * GV,SectionKind Kind,Mangler & Mang,const TargetMachine & TM) const89 HexagonTargetObjectFile::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