LLVM  6.0.0svn
X86TargetObjectFile.cpp
Go to the documentation of this file.
1 //===-- X86TargetObjectFile.cpp - X86 Object Info -------------------------===//
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 "X86TargetObjectFile.h"
11 #include "llvm/ADT/StringExtras.h"
12 #include "llvm/BinaryFormat/COFF.h"
15 #include "llvm/IR/Mangler.h"
16 #include "llvm/IR/Operator.h"
17 #include "llvm/MC/MCContext.h"
18 #include "llvm/MC/MCExpr.h"
19 #include "llvm/MC/MCSectionCOFF.h"
20 #include "llvm/MC/MCSectionELF.h"
21 #include "llvm/MC/MCValue.h"
22 
23 using namespace llvm;
24 using namespace dwarf;
25 
27  const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
28  MachineModuleInfo *MMI, MCStreamer &Streamer) const {
29 
30  // On Darwin/X86-64, we can reference dwarf symbols with foo@GOTPCREL+4, which
31  // is an indirect pc-relative reference.
32  if ((Encoding & DW_EH_PE_indirect) && (Encoding & DW_EH_PE_pcrel)) {
33  const MCSymbol *Sym = TM.getSymbol(GV);
34  const MCExpr *Res =
36  const MCExpr *Four = MCConstantExpr::create(4, getContext());
37  return MCBinaryExpr::createAdd(Res, Four, getContext());
38  }
39 
41  GV, Encoding, TM, MMI, Streamer);
42 }
43 
45  const GlobalValue *GV, const TargetMachine &TM,
46  MachineModuleInfo *MMI) const {
47  return TM.getSymbol(GV);
48 }
49 
51  const MCSymbol *Sym, const MCValue &MV, int64_t Offset,
52  MachineModuleInfo *MMI, MCStreamer &Streamer) const {
53  // On Darwin/X86-64, we need to use foo@GOTPCREL+4 to access the got entry
54  // from a data section. In case there's an additional offset, then use
55  // foo@GOTPCREL+4+<offset>.
56  unsigned FinalOff = Offset+MV.getConstant()+4;
57  const MCExpr *Res =
59  const MCExpr *Off = MCConstantExpr::create(FinalOff, getContext());
60  return MCBinaryExpr::createAdd(Res, Off, getContext());
61 }
62 
64  const MCSymbol *Sym) const {
65  return MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_DTPOFF, getContext());
66 }
67 
68 void
69 X86FreeBSDTargetObjectFile::Initialize(MCContext &Ctx,
70  const TargetMachine &TM) {
72  InitializeELF(TM.Options.UseInitArray);
73 }
74 
75 void
76 X86FuchsiaTargetObjectFile::Initialize(MCContext &Ctx,
77  const TargetMachine &TM) {
79  InitializeELF(TM.Options.UseInitArray);
80 }
81 
82 void
83 X86LinuxNaClTargetObjectFile::Initialize(MCContext &Ctx,
84  const TargetMachine &TM) {
86  InitializeELF(TM.Options.UseInitArray);
87 }
88 
89 void X86SolarisTargetObjectFile::Initialize(MCContext &Ctx,
90  const TargetMachine &TM) {
92  InitializeELF(TM.Options.UseInitArray);
93 }
94 
95 const MCExpr *X86WindowsTargetObjectFile::lowerRelativeReference(
96  const GlobalValue *LHS, const GlobalValue *RHS,
97  const TargetMachine &TM) const {
98  // Our symbols should exist in address space zero, cowardly no-op if
99  // otherwise.
100  if (LHS->getType()->getPointerAddressSpace() != 0 ||
101  RHS->getType()->getPointerAddressSpace() != 0)
102  return nullptr;
103 
104  // Both ptrtoint instructions must wrap global objects:
105  // - Only global variables are eligible for image relative relocations.
106  // - The subtrahend refers to the special symbol __ImageBase, a GlobalVariable.
107  // We expect __ImageBase to be a global variable without a section, externally
108  // defined.
109  //
110  // It should look something like this: @__ImageBase = external constant i8
111  if (!isa<GlobalObject>(LHS) || !isa<GlobalVariable>(RHS) ||
112  LHS->isThreadLocal() || RHS->isThreadLocal() ||
113  RHS->getName() != "__ImageBase" || !RHS->hasExternalLinkage() ||
114  cast<GlobalVariable>(RHS)->hasInitializer() || RHS->hasSection())
115  return nullptr;
116 
117  return MCSymbolRefExpr::create(TM.getSymbol(LHS),
119  getContext());
120 }
121 
122 static std::string APIntToHexString(const APInt &AI) {
123  unsigned Width = (AI.getBitWidth() / 8) * 2;
124  std::string HexString = utohexstr(AI.getLimitedValue(), /*LowerCase=*/true);
125  unsigned Size = HexString.size();
126  assert(Width >= Size && "hex string is too large!");
127  HexString.insert(HexString.begin(), Width - Size, '0');
128 
129  return HexString;
130 }
131 
132 static std::string scalarConstantToHexString(const Constant *C) {
133  Type *Ty = C->getType();
134  if (isa<UndefValue>(C)) {
136  } else if (const auto *CFP = dyn_cast<ConstantFP>(C)) {
137  return APIntToHexString(CFP->getValueAPF().bitcastToAPInt());
138  } else if (const auto *CI = dyn_cast<ConstantInt>(C)) {
139  return APIntToHexString(CI->getValue());
140  } else {
141  unsigned NumElements;
142  if (isa<VectorType>(Ty))
143  NumElements = Ty->getVectorNumElements();
144  else
145  NumElements = Ty->getArrayNumElements();
146  std::string HexString;
147  for (int I = NumElements - 1, E = -1; I != E; --I)
149  return HexString;
150  }
151 }
152 
153 MCSection *X86WindowsTargetObjectFile::getSectionForConstant(
154  const DataLayout &DL, SectionKind Kind, const Constant *C,
155  unsigned &Align) const {
156  if (Kind.isMergeableConst() && C) {
160  std::string COMDATSymName;
161  if (Kind.isMergeableConst4()) {
162  if (Align <= 4) {
163  COMDATSymName = "__real@" + scalarConstantToHexString(C);
164  Align = 4;
165  }
166  } else if (Kind.isMergeableConst8()) {
167  if (Align <= 8) {
168  COMDATSymName = "__real@" + scalarConstantToHexString(C);
169  Align = 8;
170  }
171  } else if (Kind.isMergeableConst16()) {
172  if (Align <= 16) {
173  COMDATSymName = "__xmm@" + scalarConstantToHexString(C);
174  Align = 16;
175  }
176  } else if (Kind.isMergeableConst32()) {
177  if (Align <= 32) {
178  COMDATSymName = "__ymm@" + scalarConstantToHexString(C);
179  Align = 32;
180  }
181  }
182 
183  if (!COMDATSymName.empty())
184  return getContext().getCOFFSection(".rdata", Characteristics, Kind,
185  COMDATSymName,
187  }
188 
189  return TargetLoweringObjectFile::getSectionForConstant(DL, Kind, C, Align);
190 }
uint64_t CallInst * C
Instances of this class represent a uniqued identifier for a section in the current translation unit...
Definition: MCSection.h:39
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:109
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
static const MCSymbolRefExpr * create(const MCSymbol *Symbol, MCContext &Ctx)
Definition: MCExpr.h:305
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
This represents an "assembler immediate".
Definition: MCValue.h:40
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:42
MCSymbol * getCFIPersonalitySymbol(const GlobalValue *GV, const TargetMachine &TM, MachineModuleInfo *MMI) const override
static std::string scalarConstantToHexString(const Constant *C)
static std::string APIntToHexString(const APInt &AI)
const MCExpr * getTTypeGlobalReference(const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM, MachineModuleInfo *MMI, MCStreamer &Streamer) const override
The mach-o version of this method defaults to returning a stub reference.
bool isMergeableConst8() const
Definition: SectionKind.h:141
unsigned getPointerAddressSpace() const
Get the address space of this pointer or pointer vector type.
Definition: DerivedTypes.h:503
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1488
bool hasSection() const
Definition: GlobalValue.h:261
int64_t getConstant() const
Definition: MCValue.h:47
uint64_t getArrayNumElements() const
Definition: DerivedTypes.h:388
virtual void Initialize(MCContext &ctx, const TargetMachine &TM)
This method must be called before any actual lowering is done.
const MCExpr * getDebugThreadLocalSymbol(const MCSymbol *Sym) const override
Describe a TLS variable address within debug info.
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:36
Context object for machine code objects.
Definition: MCContext.h:59
bool hasExternalLinkage() const
Definition: GlobalValue.h:413
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
bool isMergeableConst32() const
Definition: SectionKind.h:143
static const MCBinaryExpr * createAdd(const MCExpr *LHS, const MCExpr *RHS, MCContext &Ctx)
Definition: MCExpr.h:443
Constant * getAggregateElement(unsigned Elt) const
For aggregates (struct/array/vector) return the constant that corresponds to the specified element if...
Definition: Constants.cpp:277
Streaming machine code generation interface.
Definition: MCStreamer.h:169
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
This is an important base class in LLVM.
Definition: Constant.h:42
virtual MCSection * getSectionForConstant(const DataLayout &DL, SectionKind Kind, const Constant *C, unsigned &Align) const
Given a constant with the SectionKind, return a section that it should be placed in.
MCSymbol * getSymbol(const GlobalValue *GV) const
SectionKind - This is a simple POD value that classifies the properties of a section.
Definition: SectionKind.h:23
bool isMergeableConst16() const
Definition: SectionKind.h:142
const MCExpr * getTTypeGlobalReference(const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM, MachineModuleInfo *MMI, MCStreamer &Streamer) const override
The mach-o version of this method defaults to returning a stub reference.
bool isMergeableConst4() const
Definition: SectionKind.h:140
unsigned UseInitArray
UseInitArray - Use .init_array instead of .ctors for static constructors.
unsigned getVectorNumElements() const
Definition: DerivedTypes.h:462
This file contains constants used for implementing Dwarf debug support.
Class for arbitrary precision integers.
Definition: APInt.h:69
bool isMergeableConst() const
Definition: SectionKind.h:136
uint64_t getLimitedValue(uint64_t Limit=UINT64_MAX) const
If this value is smaller than the specified limit, return it, otherwise return the limit value...
Definition: APInt.h:475
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:220
TargetOptions Options
Definition: TargetMachine.h:96
#define I(x, y, z)
Definition: MD5.cpp:58
COFFYAML::WeakExternalCharacteristics Characteristics
Definition: COFFYAML.cpp:323
const MCExpr * getIndirectSymViaGOTPCRel(const MCSymbol *Sym, const MCValue &MV, int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const override
Get MachO PC relative GOT entry relocation.
const unsigned Kind
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:115
constexpr char Size[]
Key for Kernel::Arg::Metadata::mSize.
Primary interface to the complete machine description for the target machine.
Definition: TargetMachine.h:57
bool isThreadLocal() const
If the value is "Thread Local", its value isn&#39;t shared by the threads.
Definition: GlobalValue.h:238
static APInt getNullValue(unsigned numBits)
Get the &#39;0&#39; value.
Definition: APInt.h:562
static const MCConstantExpr * create(int64_t Value, MCContext &Ctx)
Definition: MCExpr.cpp:159
PointerType * getType() const
Global values are always pointers.
Definition: GlobalValue.h:265
This class contains meta information specific to a module.
This file describes how to lower LLVM code to machine code.
std::string utohexstr(uint64_t X, bool LowerCase=false)
Definition: StringExtras.h:76