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
9#include "llvm/MC/MCSectionMachO.h"
10#include "llvm/MC/SectionKind.h"
11#include "llvm/Support/raw_ostream.h"
12
13namespace llvm {
14class MCAsmInfo;
15class MCExpr;
16class MCSymbol;
17class Triple;
18} // namespace llvm
19
20using 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.
25static constexpr struct {
26 StringLiteral AssemblerName, EnumName;
27} SectionTypeDescriptors[MachO::LAST_KNOWN_SECTION_TYPE + 1] = {
28 {.AssemblerName: StringLiteral("regular"), .EnumName: StringLiteral("S_REGULAR")}, // 0x00
29 {.AssemblerName: StringLiteral("zerofill"), .EnumName: StringLiteral("S_ZEROFILL")}, // 0x01
30 {.AssemblerName: StringLiteral("cstring_literals"),
31 .EnumName: StringLiteral("S_CSTRING_LITERALS")}, // 0x02
32 {.AssemblerName: StringLiteral("4byte_literals"),
33 .EnumName: StringLiteral("S_4BYTE_LITERALS")}, // 0x03
34 {.AssemblerName: StringLiteral("8byte_literals"),
35 .EnumName: StringLiteral("S_8BYTE_LITERALS")}, // 0x04
36 {.AssemblerName: StringLiteral("literal_pointers"),
37 .EnumName: StringLiteral("S_LITERAL_POINTERS")}, // 0x05
38 {.AssemblerName: StringLiteral("non_lazy_symbol_pointers"),
39 .EnumName: StringLiteral("S_NON_LAZY_SYMBOL_POINTERS")}, // 0x06
40 {.AssemblerName: StringLiteral("lazy_symbol_pointers"),
41 .EnumName: StringLiteral("S_LAZY_SYMBOL_POINTERS")}, // 0x07
42 {.AssemblerName: StringLiteral("symbol_stubs"), .EnumName: StringLiteral("S_SYMBOL_STUBS")}, // 0x08
43 {.AssemblerName: StringLiteral("mod_init_funcs"),
44 .EnumName: StringLiteral("S_MOD_INIT_FUNC_POINTERS")}, // 0x09
45 {.AssemblerName: StringLiteral("mod_term_funcs"),
46 .EnumName: StringLiteral("S_MOD_TERM_FUNC_POINTERS")}, // 0x0A
47 {.AssemblerName: StringLiteral("coalesced"), .EnumName: StringLiteral("S_COALESCED")}, // 0x0B
48 {.AssemblerName: StringLiteral("") /*FIXME??*/, .EnumName: StringLiteral("S_GB_ZEROFILL")}, // 0x0C
49 {.AssemblerName: StringLiteral("interposing"), .EnumName: StringLiteral("S_INTERPOSING")}, // 0x0D
50 {.AssemblerName: StringLiteral("16byte_literals"),
51 .EnumName: StringLiteral("S_16BYTE_LITERALS")}, // 0x0E
52 {.AssemblerName: StringLiteral("") /*FIXME??*/, .EnumName: StringLiteral("S_DTRACE_DOF")}, // 0x0F
53 {.AssemblerName: StringLiteral("") /*FIXME??*/,
54 .EnumName: StringLiteral("S_LAZY_DYLIB_SYMBOL_POINTERS")}, // 0x10
55 {.AssemblerName: StringLiteral("thread_local_regular"),
56 .EnumName: StringLiteral("S_THREAD_LOCAL_REGULAR")}, // 0x11
57 {.AssemblerName: StringLiteral("thread_local_zerofill"),
58 .EnumName: StringLiteral("S_THREAD_LOCAL_ZEROFILL")}, // 0x12
59 {.AssemblerName: StringLiteral("thread_local_variables"),
60 .EnumName: StringLiteral("S_THREAD_LOCAL_VARIABLES")}, // 0x13
61 {.AssemblerName: StringLiteral("thread_local_variable_pointers"),
62 .EnumName: StringLiteral("S_THREAD_LOCAL_VARIABLE_POINTERS")}, // 0x14
63 {.AssemblerName: StringLiteral("thread_local_init_function_pointers"),
64 .EnumName: StringLiteral("S_THREAD_LOCAL_INIT_FUNCTION_POINTERS")}, // 0x15
65 {.AssemblerName: StringLiteral("") /* linker-synthesized */,
66 .EnumName: 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.
72static constexpr struct {
73 unsigned AttrFlag;
74 StringLiteral AssemblerName, EnumName;
75} SectionAttrDescriptors[] = {
76#define ENTRY(ASMNAME, ENUM) \
77 { MachO::ENUM, StringLiteral(ASMNAME), StringLiteral(#ENUM) },
78ENTRY("pure_instructions", S_ATTR_PURE_INSTRUCTIONS)
79ENTRY("no_toc", S_ATTR_NO_TOC)
80ENTRY("strip_static_syms", S_ATTR_STRIP_STATIC_SYMS)
81ENTRY("no_dead_strip", S_ATTR_NO_DEAD_STRIP)
82ENTRY("live_support", S_ATTR_LIVE_SUPPORT)
83ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE)
84ENTRY("debug", S_ATTR_DEBUG)
85ENTRY("" /*FIXME*/, S_ATTR_SOME_INSTRUCTIONS)
86ENTRY("" /*FIXME*/, S_ATTR_EXT_RELOC)
87ENTRY("" /*FIXME*/, S_ATTR_LOC_RELOC)
88#undef ENTRY
89 { .AttrFlag: 0, .AssemblerName: StringLiteral("none"), .EnumName: StringLiteral("") }, // used if section has no attributes but has a stub size
90};
91
92MCSectionMachO::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
107void 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
119 MachO::SectionType SectionType = getType();
120 assert(SectionType <= MachO::LAST_KNOWN_SECTION_TYPE &&
121 "Invalid SectionType specified!");
122
123 if (!SectionTypeDescriptors[SectionType].AssemblerName.empty()) {
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;
156 if (!SectionAttrDescriptors[i].AssemblerName.empty())
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
171bool MCSectionMachO::useCodeAlign() const {
172 return hasAttribute(Value: MachO::S_ATTR_PURE_INSTRUCTIONS);
173}
174
175bool MCSectionMachO::isVirtualSection() const {
176 return (getType() == MachO::S_ZEROFILL ||
177 getType() == MachO::S_GB_ZEROFILL ||
178 getType() == MachO::S_THREAD_LOCAL_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.
186Error MCSectionMachO::ParseSectionSpecifier(StringRef Spec, // In.
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(A&: SplitSpec, Separator: ',');
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())
208 return createStringError(EC: inconvertibleErrorCode(),
209 Msg: "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)
214 return createStringError(EC: inconvertibleErrorCode(),
215 Msg: "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 =
226 llvm::find_if(Range: SectionTypeDescriptors,
227 P: [&](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(arr: SectionTypeDescriptors))
233 return createStringError(EC: inconvertibleErrorCode(),
234 Msg: "mach-o section specifier uses an unknown "
235 "section type");
236
237 // Remember the TypeID.
238 TAA = TypeDescriptor - std::begin(arr: 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)
245 return createStringError(EC: inconvertibleErrorCode(),
246 Msg: "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(A&: SectionAttrs, Separator: '+', /*MaxSplit=*/-1, /*KeepEmpty=*/false);
254
255 for (StringRef &SectionAttr : SectionAttrs) {
256 auto AttrDescriptorI =
257 llvm::find_if(Range: SectionAttrDescriptors,
258 P: [&](decltype(*SectionAttrDescriptors) &Descriptor) {
259 return SectionAttr.trim() == Descriptor.AssemblerName;
260 });
261 if (AttrDescriptorI == std::end(arr: SectionAttrDescriptors))
262 return createStringError(EC: inconvertibleErrorCode(),
263 Msg: "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)
273 return createStringError(EC: inconvertibleErrorCode(),
274 Msg: "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.
280 if ((TAA & MachO::SECTION_TYPE) != MachO::S_SYMBOL_STUBS)
281 return createStringError(EC: inconvertibleErrorCode(),
282 Msg: "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(Radix: 0, Result&: StubSize))
288 return createStringError(EC: inconvertibleErrorCode(),
289 Msg: "mach-o section specifier has a malformed "
290 "stub size");
291
292 return Error::success();
293}
294

source code of llvm/lib/MC/MCSectionMachO.cpp