1 //===- lib/MC/MCSectionMachO.cpp - MachO Code Section Representation ------===//
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
7 //===----------------------------------------------------------------------===//
9 #include "llvm/MC/MCSectionMachO.h"
10 #include "llvm/MC/MCContext.h"
11 #include "llvm/Support/raw_ostream.h"
15 /// SectionTypeDescriptors - These are strings that describe the various section
16 /// types. This *must* be kept in order with and stay synchronized with the
17 /// section type list.
18 static constexpr struct {
19 StringLiteral AssemblerName
, EnumName
;
20 } SectionTypeDescriptors
[MachO::LAST_KNOWN_SECTION_TYPE
+ 1] = {
21 {StringLiteral("regular"), StringLiteral("S_REGULAR")}, // 0x00
22 {StringLiteral(""), StringLiteral("S_ZEROFILL")}, // 0x01
23 {StringLiteral("cstring_literals"),
24 StringLiteral("S_CSTRING_LITERALS")}, // 0x02
25 {StringLiteral("4byte_literals"),
26 StringLiteral("S_4BYTE_LITERALS")}, // 0x03
27 {StringLiteral("8byte_literals"),
28 StringLiteral("S_8BYTE_LITERALS")}, // 0x04
29 {StringLiteral("literal_pointers"),
30 StringLiteral("S_LITERAL_POINTERS")}, // 0x05
31 {StringLiteral("non_lazy_symbol_pointers"),
32 StringLiteral("S_NON_LAZY_SYMBOL_POINTERS")}, // 0x06
33 {StringLiteral("lazy_symbol_pointers"),
34 StringLiteral("S_LAZY_SYMBOL_POINTERS")}, // 0x07
35 {StringLiteral("symbol_stubs"), StringLiteral("S_SYMBOL_STUBS")}, // 0x08
36 {StringLiteral("mod_init_funcs"),
37 StringLiteral("S_MOD_INIT_FUNC_POINTERS")}, // 0x09
38 {StringLiteral("mod_term_funcs"),
39 StringLiteral("S_MOD_TERM_FUNC_POINTERS")}, // 0x0A
40 {StringLiteral("coalesced"), StringLiteral("S_COALESCED")}, // 0x0B
41 {StringLiteral("") /*FIXME??*/, StringLiteral("S_GB_ZEROFILL")}, // 0x0C
42 {StringLiteral("interposing"), StringLiteral("S_INTERPOSING")}, // 0x0D
43 {StringLiteral("16byte_literals"),
44 StringLiteral("S_16BYTE_LITERALS")}, // 0x0E
45 {StringLiteral("") /*FIXME??*/, StringLiteral("S_DTRACE_DOF")}, // 0x0F
46 {StringLiteral("") /*FIXME??*/,
47 StringLiteral("S_LAZY_DYLIB_SYMBOL_POINTERS")}, // 0x10
48 {StringLiteral("thread_local_regular"),
49 StringLiteral("S_THREAD_LOCAL_REGULAR")}, // 0x11
50 {StringLiteral("thread_local_zerofill"),
51 StringLiteral("S_THREAD_LOCAL_ZEROFILL")}, // 0x12
52 {StringLiteral("thread_local_variables"),
53 StringLiteral("S_THREAD_LOCAL_VARIABLES")}, // 0x13
54 {StringLiteral("thread_local_variable_pointers"),
55 StringLiteral("S_THREAD_LOCAL_VARIABLE_POINTERS")}, // 0x14
56 {StringLiteral("thread_local_init_function_pointers"),
57 StringLiteral("S_THREAD_LOCAL_INIT_FUNCTION_POINTERS")}, // 0x15
60 /// SectionAttrDescriptors - This is an array of descriptors for section
61 /// attributes. Unlike the SectionTypeDescriptors, this is not directly indexed
62 /// by attribute, instead it is searched.
63 static constexpr struct {
65 StringLiteral AssemblerName
, EnumName
;
66 } SectionAttrDescriptors
[] = {
67 #define ENTRY(ASMNAME, ENUM) \
68 { MachO::ENUM, StringLiteral(ASMNAME), StringLiteral(#ENUM) },
69 ENTRY("pure_instructions", S_ATTR_PURE_INSTRUCTIONS
)
70 ENTRY("no_toc", S_ATTR_NO_TOC
)
71 ENTRY("strip_static_syms", S_ATTR_STRIP_STATIC_SYMS
)
72 ENTRY("no_dead_strip", S_ATTR_NO_DEAD_STRIP
)
73 ENTRY("live_support", S_ATTR_LIVE_SUPPORT
)
74 ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE
)
75 ENTRY("debug", S_ATTR_DEBUG
)
76 ENTRY("" /*FIXME*/, S_ATTR_SOME_INSTRUCTIONS
)
77 ENTRY("" /*FIXME*/, S_ATTR_EXT_RELOC
)
78 ENTRY("" /*FIXME*/, S_ATTR_LOC_RELOC
)
80 { 0, StringLiteral("none"), StringLiteral("") }, // used if section has no attributes but has a stub size
83 MCSectionMachO::MCSectionMachO(StringRef Segment
, StringRef Section
,
84 unsigned TAA
, unsigned reserved2
, SectionKind K
,
86 : MCSection(SV_MachO
, Section
, K
, Begin
), TypeAndAttributes(TAA
),
87 Reserved2(reserved2
) {
88 assert(Segment
.size() <= 16 && Section
.size() <= 16 &&
89 "Segment or section string too long");
90 for (unsigned i
= 0; i
!= 16; ++i
) {
91 if (i
< Segment
.size())
92 SegmentName
[i
] = Segment
[i
];
98 void MCSectionMachO::PrintSwitchToSection(const MCAsmInfo
&MAI
, const Triple
&T
,
100 const MCExpr
*Subsection
) const {
101 OS
<< "\t.section\t" << getSegmentName() << ',' << getName();
103 // Get the section type and attributes.
104 unsigned TAA
= getTypeAndAttributes();
110 MachO::SectionType SectionType
= getType();
111 assert(SectionType
<= MachO::LAST_KNOWN_SECTION_TYPE
&&
112 "Invalid SectionType specified!");
114 if (!SectionTypeDescriptors
[SectionType
].AssemblerName
.empty()) {
116 OS
<< SectionTypeDescriptors
[SectionType
].AssemblerName
;
118 // If we have no name for the attribute, stop here.
123 // If we don't have any attributes, we're done.
124 unsigned SectionAttrs
= TAA
& MachO::SECTION_ATTRIBUTES
;
125 if (SectionAttrs
== 0) {
126 // If we have a S_SYMBOL_STUBS size specified, print it along with 'none' as
127 // the attribute specifier.
129 OS
<< ",none," << Reserved2
;
134 // Check each attribute to see if we have it.
135 char Separator
= ',';
137 SectionAttrs
!= 0 && SectionAttrDescriptors
[i
].AttrFlag
;
139 // Check to see if we have this attribute.
140 if ((SectionAttrDescriptors
[i
].AttrFlag
& SectionAttrs
) == 0)
143 // Yep, clear it and print it.
144 SectionAttrs
&= ~SectionAttrDescriptors
[i
].AttrFlag
;
147 if (!SectionAttrDescriptors
[i
].AssemblerName
.empty())
148 OS
<< SectionAttrDescriptors
[i
].AssemblerName
;
150 OS
<< "<<" << SectionAttrDescriptors
[i
].EnumName
<< ">>";
154 assert(SectionAttrs
== 0 && "Unknown section attributes!");
156 // If we have a S_SYMBOL_STUBS size specified, print it.
158 OS
<< ',' << Reserved2
;
162 bool MCSectionMachO::UseCodeAlign() const {
163 return hasAttribute(MachO::S_ATTR_PURE_INSTRUCTIONS
);
166 bool MCSectionMachO::isVirtualSection() const {
167 return (getType() == MachO::S_ZEROFILL
||
168 getType() == MachO::S_GB_ZEROFILL
||
169 getType() == MachO::S_THREAD_LOCAL_ZEROFILL
);
172 /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
173 /// This is a string that can appear after a .section directive in a mach-o
174 /// flavored .s file. If successful, this fills in the specified Out
175 /// parameters and returns an empty string. When an invalid section
176 /// specifier is present, this returns a string indicating the problem.
177 Error
MCSectionMachO::ParseSectionSpecifier(StringRef Spec
, // In.
178 StringRef
&Segment
, // Out.
179 StringRef
&Section
, // Out.
180 unsigned &TAA
, // Out.
181 bool &TAAParsed
, // Out.
182 unsigned &StubSize
) { // Out.
185 SmallVector
<StringRef
, 5> SplitSpec
;
186 Spec
.split(SplitSpec
, ',');
187 // Remove leading and trailing whitespace.
188 auto GetEmptyOrTrim
= [&SplitSpec
](size_t Idx
) -> StringRef
{
189 return SplitSpec
.size() > Idx
? SplitSpec
[Idx
].trim() : StringRef();
191 Segment
= GetEmptyOrTrim(0);
192 Section
= GetEmptyOrTrim(1);
193 StringRef SectionType
= GetEmptyOrTrim(2);
194 StringRef Attrs
= GetEmptyOrTrim(3);
195 StringRef StubSizeStr
= GetEmptyOrTrim(4);
197 // Verify that the section is present.
199 return createStringError(inconvertibleErrorCode(),
200 "mach-o section specifier requires a segment "
201 "and section separated by a comma");
203 // Verify that the section is not too long.
204 if (Section
.size() > 16)
205 return createStringError(inconvertibleErrorCode(),
206 "mach-o section specifier requires a section "
207 "whose length is between 1 and 16 characters");
209 // If there is no comma after the section, we're done.
212 if (SectionType
.empty())
213 return Error::success();
215 // Figure out which section type it is.
216 auto TypeDescriptor
=
217 llvm::find_if(SectionTypeDescriptors
,
218 [&](decltype(*SectionTypeDescriptors
) &Descriptor
) {
219 return SectionType
== Descriptor
.AssemblerName
;
222 // If we didn't find the section type, reject it.
223 if (TypeDescriptor
== std::end(SectionTypeDescriptors
))
224 return createStringError(inconvertibleErrorCode(),
225 "mach-o section specifier uses an unknown "
228 // Remember the TypeID.
229 TAA
= TypeDescriptor
- std::begin(SectionTypeDescriptors
);
232 // If we have no comma after the section type, there are no attributes.
234 // S_SYMBOL_STUBS always require a symbol stub size specifier.
235 if (TAA
== MachO::S_SYMBOL_STUBS
)
236 return createStringError(inconvertibleErrorCode(),
237 "mach-o section specifier of type "
238 "'symbol_stubs' requires a size specifier");
239 return Error::success();
242 // The attribute list is a '+' separated list of attributes.
243 SmallVector
<StringRef
, 1> SectionAttrs
;
244 Attrs
.split(SectionAttrs
, '+', /*MaxSplit=*/-1, /*KeepEmpty=*/false);
246 for (StringRef
&SectionAttr
: SectionAttrs
) {
247 auto AttrDescriptorI
=
248 llvm::find_if(SectionAttrDescriptors
,
249 [&](decltype(*SectionAttrDescriptors
) &Descriptor
) {
250 return SectionAttr
.trim() == Descriptor
.AssemblerName
;
252 if (AttrDescriptorI
== std::end(SectionAttrDescriptors
))
253 return createStringError(inconvertibleErrorCode(),
254 "mach-o section specifier has invalid "
257 TAA
|= AttrDescriptorI
->AttrFlag
;
260 // Okay, we've parsed the section attributes, see if we have a stub size spec.
261 if (StubSizeStr
.empty()) {
262 // S_SYMBOL_STUBS always require a symbol stub size specifier.
263 if (TAA
== MachO::S_SYMBOL_STUBS
)
264 return createStringError(inconvertibleErrorCode(),
265 "mach-o section specifier of type "
266 "'symbol_stubs' requires a size specifier");
267 return Error::success();
270 // If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS.
271 if ((TAA
& MachO::SECTION_TYPE
) != MachO::S_SYMBOL_STUBS
)
272 return createStringError(inconvertibleErrorCode(),
273 "mach-o section specifier cannot have a stub "
274 "size specified because it does not have type "
277 // Convert the stub size from a string to an integer.
278 if (StubSizeStr
.getAsInteger(0, StubSize
))
279 return createStringError(inconvertibleErrorCode(),
280 "mach-o section specifier has a malformed "
283 return Error::success();