LLVM  16.0.0git
MCSectionMachO.cpp
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1 //===- lib/MC/MCSectionMachO.cpp - MachO Code Section Representation ------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
10 #include "llvm/MC/SectionKind.h"
12 
13 namespace llvm {
14 class MCAsmInfo;
15 class MCExpr;
16 class MCSymbol;
17 class Triple;
18 } // namespace llvm
19 
20 using namespace llvm;
21 
22 /// SectionTypeDescriptors - These are strings that describe the various section
23 /// types. This *must* be kept in order with and stay synchronized with the
24 /// section type list.
25 static constexpr struct {
28  {StringLiteral("regular"), StringLiteral("S_REGULAR")}, // 0x00
29  {StringLiteral("zerofill"), StringLiteral("S_ZEROFILL")}, // 0x01
30  {StringLiteral("cstring_literals"),
31  StringLiteral("S_CSTRING_LITERALS")}, // 0x02
32  {StringLiteral("4byte_literals"),
33  StringLiteral("S_4BYTE_LITERALS")}, // 0x03
34  {StringLiteral("8byte_literals"),
35  StringLiteral("S_8BYTE_LITERALS")}, // 0x04
36  {StringLiteral("literal_pointers"),
37  StringLiteral("S_LITERAL_POINTERS")}, // 0x05
38  {StringLiteral("non_lazy_symbol_pointers"),
39  StringLiteral("S_NON_LAZY_SYMBOL_POINTERS")}, // 0x06
40  {StringLiteral("lazy_symbol_pointers"),
41  StringLiteral("S_LAZY_SYMBOL_POINTERS")}, // 0x07
42  {StringLiteral("symbol_stubs"), StringLiteral("S_SYMBOL_STUBS")}, // 0x08
43  {StringLiteral("mod_init_funcs"),
44  StringLiteral("S_MOD_INIT_FUNC_POINTERS")}, // 0x09
45  {StringLiteral("mod_term_funcs"),
46  StringLiteral("S_MOD_TERM_FUNC_POINTERS")}, // 0x0A
47  {StringLiteral("coalesced"), StringLiteral("S_COALESCED")}, // 0x0B
48  {StringLiteral("") /*FIXME??*/, StringLiteral("S_GB_ZEROFILL")}, // 0x0C
49  {StringLiteral("interposing"), StringLiteral("S_INTERPOSING")}, // 0x0D
50  {StringLiteral("16byte_literals"),
51  StringLiteral("S_16BYTE_LITERALS")}, // 0x0E
52  {StringLiteral("") /*FIXME??*/, StringLiteral("S_DTRACE_DOF")}, // 0x0F
53  {StringLiteral("") /*FIXME??*/,
54  StringLiteral("S_LAZY_DYLIB_SYMBOL_POINTERS")}, // 0x10
55  {StringLiteral("thread_local_regular"),
56  StringLiteral("S_THREAD_LOCAL_REGULAR")}, // 0x11
57  {StringLiteral("thread_local_zerofill"),
58  StringLiteral("S_THREAD_LOCAL_ZEROFILL")}, // 0x12
59  {StringLiteral("thread_local_variables"),
60  StringLiteral("S_THREAD_LOCAL_VARIABLES")}, // 0x13
61  {StringLiteral("thread_local_variable_pointers"),
62  StringLiteral("S_THREAD_LOCAL_VARIABLE_POINTERS")}, // 0x14
63  {StringLiteral("thread_local_init_function_pointers"),
64  StringLiteral("S_THREAD_LOCAL_INIT_FUNCTION_POINTERS")}, // 0x15
65  {StringLiteral("") /* linker-synthesized */,
66  StringLiteral("S_INIT_FUNC_OFFSETS")}, // 0x16
67 };
68 
69 /// SectionAttrDescriptors - This is an array of descriptors for section
70 /// attributes. Unlike the SectionTypeDescriptors, this is not directly indexed
71 /// by attribute, instead it is searched.
72 static constexpr struct {
73  unsigned AttrFlag;
76 #define ENTRY(ASMNAME, ENUM) \
77  { MachO::ENUM, StringLiteral(ASMNAME), StringLiteral(#ENUM) },
78 ENTRY("pure_instructions", S_ATTR_PURE_INSTRUCTIONS)
79 ENTRY("no_toc", S_ATTR_NO_TOC)
80 ENTRY("strip_static_syms", S_ATTR_STRIP_STATIC_SYMS)
81 ENTRY("no_dead_strip", S_ATTR_NO_DEAD_STRIP)
82 ENTRY("live_support", S_ATTR_LIVE_SUPPORT)
83 ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE)
84 ENTRY("debug", S_ATTR_DEBUG)
85 ENTRY("" /*FIXME*/, S_ATTR_SOME_INSTRUCTIONS)
86 ENTRY("" /*FIXME*/, S_ATTR_EXT_RELOC)
87 ENTRY("" /*FIXME*/, S_ATTR_LOC_RELOC)
88 #undef ENTRY
89  { 0, StringLiteral("none"), StringLiteral("") }, // used if section has no attributes but has a stub size
90 };
91 
92 MCSectionMachO::MCSectionMachO(StringRef Segment, StringRef Section,
93  unsigned TAA, unsigned reserved2, SectionKind K,
94  MCSymbol *Begin)
95  : MCSection(SV_MachO, Section, K, Begin), TypeAndAttributes(TAA),
96  Reserved2(reserved2) {
97  assert(Segment.size() <= 16 && Section.size() <= 16 &&
98  "Segment or section string too long");
99  for (unsigned i = 0; i != 16; ++i) {
100  if (i < Segment.size())
101  SegmentName[i] = Segment[i];
102  else
103  SegmentName[i] = 0;
104  }
105 }
106 
107 void MCSectionMachO::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
108  raw_ostream &OS,
109  const MCExpr *Subsection) const {
110  OS << "\t.section\t" << getSegmentName() << ',' << getName();
111 
112  // Get the section type and attributes.
113  unsigned TAA = getTypeAndAttributes();
114  if (TAA == 0) {
115  OS << '\n';
116  return;
117  }
118 
121  "Invalid SectionType specified!");
122 
124  OS << ',';
125  OS << SectionTypeDescriptors[SectionType].AssemblerName;
126  } else {
127  // If we have no name for the attribute, stop here.
128  OS << '\n';
129  return;
130  }
131 
132  // If we don't have any attributes, we're done.
133  unsigned SectionAttrs = TAA & MachO::SECTION_ATTRIBUTES;
134  if (SectionAttrs == 0) {
135  // If we have a S_SYMBOL_STUBS size specified, print it along with 'none' as
136  // the attribute specifier.
137  if (Reserved2 != 0)
138  OS << ",none," << Reserved2;
139  OS << '\n';
140  return;
141  }
142 
143  // Check each attribute to see if we have it.
144  char Separator = ',';
145  for (unsigned i = 0;
146  SectionAttrs != 0 && SectionAttrDescriptors[i].AttrFlag;
147  ++i) {
148  // Check to see if we have this attribute.
149  if ((SectionAttrDescriptors[i].AttrFlag & SectionAttrs) == 0)
150  continue;
151 
152  // Yep, clear it and print it.
153  SectionAttrs &= ~SectionAttrDescriptors[i].AttrFlag;
154 
155  OS << Separator;
157  OS << SectionAttrDescriptors[i].AssemblerName;
158  else
159  OS << "<<" << SectionAttrDescriptors[i].EnumName << ">>";
160  Separator = '+';
161  }
162 
163  assert(SectionAttrs == 0 && "Unknown section attributes!");
164 
165  // If we have a S_SYMBOL_STUBS size specified, print it.
166  if (Reserved2 != 0)
167  OS << ',' << Reserved2;
168  OS << '\n';
169 }
170 
173 }
174 
176  return (getType() == MachO::S_ZEROFILL ||
179 }
180 
181 /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
182 /// This is a string that can appear after a .section directive in a mach-o
183 /// flavored .s file. If successful, this fills in the specified Out
184 /// parameters and returns an empty string. When an invalid section
185 /// specifier is present, this returns a string indicating the problem.
187  StringRef &Segment, // Out.
188  StringRef &Section, // Out.
189  unsigned &TAA, // Out.
190  bool &TAAParsed, // Out.
191  unsigned &StubSize) { // Out.
192  TAAParsed = false;
193 
194  SmallVector<StringRef, 5> SplitSpec;
195  Spec.split(SplitSpec, ',');
196  // Remove leading and trailing whitespace.
197  auto GetEmptyOrTrim = [&SplitSpec](size_t Idx) -> StringRef {
198  return SplitSpec.size() > Idx ? SplitSpec[Idx].trim() : StringRef();
199  };
200  Segment = GetEmptyOrTrim(0);
201  Section = GetEmptyOrTrim(1);
202  StringRef SectionType = GetEmptyOrTrim(2);
203  StringRef Attrs = GetEmptyOrTrim(3);
204  StringRef StubSizeStr = GetEmptyOrTrim(4);
205 
206  // Verify that the section is present.
207  if (Section.empty())
209  "mach-o section specifier requires a segment "
210  "and section separated by a comma");
211 
212  // Verify that the section is not too long.
213  if (Section.size() > 16)
215  "mach-o section specifier requires a section "
216  "whose length is between 1 and 16 characters");
217 
218  // If there is no comma after the section, we're done.
219  TAA = 0;
220  StubSize = 0;
221  if (SectionType.empty())
222  return Error::success();
223 
224  // Figure out which section type it is.
225  auto TypeDescriptor =
227  [&](decltype(*SectionTypeDescriptors) &Descriptor) {
228  return SectionType == Descriptor.AssemblerName;
229  });
230 
231  // If we didn't find the section type, reject it.
232  if (TypeDescriptor == std::end(SectionTypeDescriptors))
234  "mach-o section specifier uses an unknown "
235  "section type");
236 
237  // Remember the TypeID.
238  TAA = TypeDescriptor - std::begin(SectionTypeDescriptors);
239  TAAParsed = true;
240 
241  // If we have no comma after the section type, there are no attributes.
242  if (Attrs.empty()) {
243  // S_SYMBOL_STUBS always require a symbol stub size specifier.
244  if (TAA == MachO::S_SYMBOL_STUBS)
246  "mach-o section specifier of type "
247  "'symbol_stubs' requires a size specifier");
248  return Error::success();
249  }
250 
251  // The attribute list is a '+' separated list of attributes.
252  SmallVector<StringRef, 1> SectionAttrs;
253  Attrs.split(SectionAttrs, '+', /*MaxSplit=*/-1, /*KeepEmpty=*/false);
254 
255  for (StringRef &SectionAttr : SectionAttrs) {
256  auto AttrDescriptorI =
258  [&](decltype(*SectionAttrDescriptors) &Descriptor) {
259  return SectionAttr.trim() == Descriptor.AssemblerName;
260  });
261  if (AttrDescriptorI == std::end(SectionAttrDescriptors))
263  "mach-o section specifier has invalid "
264  "attribute");
265 
266  TAA |= AttrDescriptorI->AttrFlag;
267  }
268 
269  // Okay, we've parsed the section attributes, see if we have a stub size spec.
270  if (StubSizeStr.empty()) {
271  // S_SYMBOL_STUBS always require a symbol stub size specifier.
272  if (TAA == MachO::S_SYMBOL_STUBS)
274  "mach-o section specifier of type "
275  "'symbol_stubs' requires a size specifier");
276  return Error::success();
277  }
278 
279  // If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS.
282  "mach-o section specifier cannot have a stub "
283  "size specified because it does not have type "
284  "'symbol_stubs'");
285 
286  // Convert the stub size from a string to an integer.
287  if (StubSizeStr.getAsInteger(0, StubSize))
289  "mach-o section specifier has a malformed "
290  "stub size");
291 
292  return Error::success();
293 }
i
i
Definition: README.txt:29
llvm::MachO::S_ATTR_SOME_INSTRUCTIONS
@ S_ATTR_SOME_INSTRUCTIONS
S_ATTR_SOME_INSTRUCTIONS - Section contains some machine instructions.
Definition: MachO.h:213
llvm::MachO::S_ATTR_NO_DEAD_STRIP
@ S_ATTR_NO_DEAD_STRIP
S_ATTR_NO_DEAD_STRIP - No dead stripping.
Definition: MachO.h:200
Attrs
Function Attrs
Definition: README_ALTIVEC.txt:215
llvm
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
llvm::MCSymbol
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
llvm::Function::empty
bool empty() const
Definition: Function.h:713
T
llvm::MCAsmInfo
This class is intended to be used as a base class for asm properties and features specific to the tar...
Definition: MCAsmInfo.h:56
llvm::SmallVector
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1199
llvm::MachO::S_ATTR_NO_TOC
@ S_ATTR_NO_TOC
S_ATTR_NO_TOC - Section contains coalesced symbols that are not to be in a ranlib table of contents.
Definition: MachO.h:195
llvm::Error::success
static ErrorSuccess success()
Create a success value.
Definition: Error.h:329
llvm::Triple
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:44
llvm::MachO::S_GB_ZEROFILL
@ S_GB_ZEROFILL
S_GB_ZEROFILL - Zero fill on demand section (that can be larger than 4 gigabytes).
Definition: MachO.h:155
llvm::sys::path::end
const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:235
llvm::sys::path::begin
const_iterator begin(StringRef path, Style style=Style::native)
Get begin iterator over path.
Definition: Path.cpp:226
llvm::MachO::S_ATTR_STRIP_STATIC_SYMS
@ S_ATTR_STRIP_STATIC_SYMS
S_ATTR_STRIP_STATIC_SYMS - Ok to strip static symbols in this section in files with the MY_DYLDLINK f...
Definition: MachO.h:198
llvm::MachO::S_ZEROFILL
@ S_ZEROFILL
S_ZEROFILL - Zero fill on demand section.
Definition: MachO.h:129
llvm::MachO::SECTION_TYPE
@ SECTION_TYPE
Definition: MachO.h:114
llvm::MachO::S_SYMBOL_STUBS
@ S_SYMBOL_STUBS
S_SYMBOL_STUBS - Section with symbol stubs, byte size of stub in the Reserved2 field.
Definition: MachO.h:144
llvm::ARMBuildAttrs::Section
@ Section
Legacy Tags.
Definition: ARMBuildAttributes.h:82
llvm::StringLiteral
A wrapper around a string literal that serves as a proxy for constructing global tables of StringRefs...
Definition: StringRef.h:846
llvm::MCSectionMachO::getType
MachO::SectionType getType() const
Definition: MCSectionMachO.h:50
llvm::MCSectionMachO::ParseSectionSpecifier
static Error ParseSectionSpecifier(StringRef Spec, StringRef &Segment, StringRef &Section, unsigned &TAA, bool &TAAParsed, unsigned &StubSize)
Parse the section specifier indicated by "Spec".
Definition: MCSectionMachO.cpp:186
MCSectionMachO.h
llvm::StringRef::getAsInteger
bool getAsInteger(unsigned Radix, T &Result) const
Parse the current string as an integer of the specified radix.
Definition: StringRef.h:474
llvm::MachO::S_ATTR_DEBUG
@ S_ATTR_DEBUG
S_ATTR_DEBUG - A debug section.
Definition: MachO.h:207
llvm::raw_ostream
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:53
llvm::MCSectionMachO::getTypeAndAttributes
unsigned getTypeAndAttributes() const
Definition: MCSectionMachO.h:47
llvm::MachO::SECTION_ATTRIBUTES
@ SECTION_ATTRIBUTES
Definition: MachO.h:115
AssemblerName
StringLiteral AssemblerName
Definition: MCSectionMachO.cpp:26
llvm::MCSectionMachO::hasAttribute
bool hasAttribute(unsigned Value) const
Definition: MCSectionMachO.h:54
llvm::MCSectionMachO::useCodeAlign
bool useCodeAlign() const override
Return true if a .align directive should use "optimized nops" to fill instead of 0s.
Definition: MCSectionMachO.cpp:171
llvm::StringRef::empty
constexpr bool empty() const
empty - Check if the string is empty.
Definition: StringRef.h:134
llvm::MachO::S_ATTR_LIVE_SUPPORT
@ S_ATTR_LIVE_SUPPORT
S_ATTR_LIVE_SUPPORT - Blocks are live if they reference live blocks.
Definition: MachO.h:202
llvm::MachO::S_ATTR_PURE_INSTRUCTIONS
@ S_ATTR_PURE_INSTRUCTIONS
S_ATTR_PURE_INSTRUCTIONS - Section contains only true machine instructions.
Definition: MachO.h:192
ENTRY
#define ENTRY(ASMNAME, ENUM)
assert
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
SectionAttrDescriptors
static constexpr struct @459 SectionAttrDescriptors[]
SectionAttrDescriptors - This is an array of descriptors for section attributes.
llvm::StringRef
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:50
llvm::MachO::S_ATTR_EXT_RELOC
@ S_ATTR_EXT_RELOC
S_ATTR_EXT_RELOC - Section has external relocation entries.
Definition: MachO.h:215
llvm::MCSection
Instances of this class represent a uniqued identifier for a section in the current translation unit.
Definition: MCSection.h:39
llvm::MCSectionMachO::isVirtualSection
bool isVirtualSection() const override
Check whether this section is "virtual", that is has no actual object file contents.
Definition: MCSectionMachO.cpp:175
llvm::MachO::LAST_KNOWN_SECTION_TYPE
@ LAST_KNOWN_SECTION_TYPE
Definition: MachO.h:183
llvm::find_if
auto find_if(R &&Range, UnaryPredicate P)
Provide wrappers to std::find_if which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1761
llvm::MCSection::getName
StringRef getName() const
Definition: MCSection.h:124
llvm::StringRef::size
constexpr size_t size() const
size - Get the string size.
Definition: StringRef.h:137
llvm::createStringError
Error createStringError(std::error_code EC, char const *Fmt, const Ts &... Vals)
Create formatted StringError object.
Definition: Error.h:1238
llvm::SectionKind
SectionKind - This is a simple POD value that classifies the properties of a section.
Definition: SectionKind.h:22
llvm::inconvertibleErrorCode
std::error_code inconvertibleErrorCode()
The value returned by this function can be returned from convertToErrorCode for Error values where no...
Definition: Error.cpp:79
llvm::Error
Lightweight error class with error context and mandatory checking.
Definition: Error.h:155
llvm::MCSectionMachO::getSegmentName
StringRef getSegmentName() const
Definition: MCSectionMachO.h:40
AttrFlag
unsigned AttrFlag
Definition: MCSectionMachO.cpp:73
llvm::MachO::S_THREAD_LOCAL_ZEROFILL
@ S_THREAD_LOCAL_ZEROFILL
S_THREAD_LOCAL_ZEROFILL - Thread local zerofill section.
Definition: MachO.h:169
SectionKind.h
llvm::MachO::S_ATTR_LOC_RELOC
@ S_ATTR_LOC_RELOC
S_ATTR_LOC_RELOC - Section has local relocation entries.
Definition: MachO.h:217
SectionTypeDescriptors
static constexpr struct @458 SectionTypeDescriptors[MachO::LAST_KNOWN_SECTION_TYPE+1]
SectionTypeDescriptors - These are strings that describe the various section types.
llvm::MachO::S_ATTR_SELF_MODIFYING_CODE
@ S_ATTR_SELF_MODIFYING_CODE
S_ATTR_SELF_MODIFYING_CODE - Used with i386 code stubs written on by dyld.
Definition: MachO.h:205
EnumName
StringLiteral EnumName
Definition: MCSectionMachO.cpp:26
raw_ostream.h
llvm::StringRef::split
std::pair< StringRef, StringRef > split(char Separator) const
Split into two substrings around the first occurrence of a separator character.
Definition: StringRef.h:693
llvm::MCExpr
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:35
llvm::MachO::SectionType
SectionType
These are the section type and attributes fields.
Definition: MachO.h:122