1 //===- lib/MC/MCSectionMachO.cpp - MachO Code Section Representation ------===// 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 "llvm/MC/MCSectionMachO.h" 11 #include "llvm/MC/MCContext.h" 12 #include "llvm/Support/raw_ostream.h" 13 #include <cctype> 14 using namespace llvm; 15 16 /// SectionTypeDescriptors - These are strings that describe the various section 17 /// types. This *must* be kept in order with and stay synchronized with the 18 /// section type list. 19 static constexpr struct { 20 StringLiteral AssemblerName, EnumName; 21 } SectionTypeDescriptors[MachO::LAST_KNOWN_SECTION_TYPE + 1] = { 22 {StringLiteral("regular"), StringLiteral("S_REGULAR")}, // 0x00 23 {StringLiteral(""), StringLiteral("S_ZEROFILL")}, // 0x01 24 {StringLiteral("cstring_literals"), 25 StringLiteral("S_CSTRING_LITERALS")}, // 0x02 26 {StringLiteral("4byte_literals"), 27 StringLiteral("S_4BYTE_LITERALS")}, // 0x03 28 {StringLiteral("8byte_literals"), 29 StringLiteral("S_8BYTE_LITERALS")}, // 0x04 30 {StringLiteral("literal_pointers"), 31 StringLiteral("S_LITERAL_POINTERS")}, // 0x05 32 {StringLiteral("non_lazy_symbol_pointers"), 33 StringLiteral("S_NON_LAZY_SYMBOL_POINTERS")}, // 0x06 34 {StringLiteral("lazy_symbol_pointers"), 35 StringLiteral("S_LAZY_SYMBOL_POINTERS")}, // 0x07 36 {StringLiteral("symbol_stubs"), StringLiteral("S_SYMBOL_STUBS")}, // 0x08 37 {StringLiteral("mod_init_funcs"), 38 StringLiteral("S_MOD_INIT_FUNC_POINTERS")}, // 0x09 39 {StringLiteral("mod_term_funcs"), 40 StringLiteral("S_MOD_TERM_FUNC_POINTERS")}, // 0x0A 41 {StringLiteral("coalesced"), StringLiteral("S_COALESCED")}, // 0x0B 42 {StringLiteral("") /*FIXME??*/, StringLiteral("S_GB_ZEROFILL")}, // 0x0C 43 {StringLiteral("interposing"), StringLiteral("S_INTERPOSING")}, // 0x0D 44 {StringLiteral("16byte_literals"), 45 StringLiteral("S_16BYTE_LITERALS")}, // 0x0E 46 {StringLiteral("") /*FIXME??*/, StringLiteral("S_DTRACE_DOF")}, // 0x0F 47 {StringLiteral("") /*FIXME??*/, 48 StringLiteral("S_LAZY_DYLIB_SYMBOL_POINTERS")}, // 0x10 49 {StringLiteral("thread_local_regular"), 50 StringLiteral("S_THREAD_LOCAL_REGULAR")}, // 0x11 51 {StringLiteral("thread_local_zerofill"), 52 StringLiteral("S_THREAD_LOCAL_ZEROFILL")}, // 0x12 53 {StringLiteral("thread_local_variables"), 54 StringLiteral("S_THREAD_LOCAL_VARIABLES")}, // 0x13 55 {StringLiteral("thread_local_variable_pointers"), 56 StringLiteral("S_THREAD_LOCAL_VARIABLE_POINTERS")}, // 0x14 57 {StringLiteral("thread_local_init_function_pointers"), 58 StringLiteral("S_THREAD_LOCAL_INIT_FUNCTION_POINTERS")}, // 0x15 59 }; 60 61 /// SectionAttrDescriptors - This is an array of descriptors for section 62 /// attributes. Unlike the SectionTypeDescriptors, this is not directly indexed 63 /// by attribute, instead it is searched. 64 static constexpr struct { 65 unsigned AttrFlag; 66 StringLiteral AssemblerName, EnumName; 67 } SectionAttrDescriptors[] = { 68 #define ENTRY(ASMNAME, ENUM) \ 69 { MachO::ENUM, StringLiteral(ASMNAME), StringLiteral(#ENUM) }, 70 ENTRY("pure_instructions", S_ATTR_PURE_INSTRUCTIONS) 71 ENTRY("no_toc", S_ATTR_NO_TOC) 72 ENTRY("strip_static_syms", S_ATTR_STRIP_STATIC_SYMS) 73 ENTRY("no_dead_strip", S_ATTR_NO_DEAD_STRIP) 74 ENTRY("live_support", S_ATTR_LIVE_SUPPORT) 75 ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE) 76 ENTRY("debug", S_ATTR_DEBUG) 77 ENTRY("" /*FIXME*/, S_ATTR_SOME_INSTRUCTIONS) 78 ENTRY("" /*FIXME*/, S_ATTR_EXT_RELOC) 79 ENTRY("" /*FIXME*/, S_ATTR_LOC_RELOC) 80 #undef ENTRY 81 { 0, StringLiteral("none"), StringLiteral("") }, // used if section has no attributes but has a stub size 82 }; 83 84 MCSectionMachO::MCSectionMachO(StringRef Segment, StringRef Section, 85 unsigned TAA, unsigned reserved2, SectionKind K, 86 MCSymbol *Begin) 87 : MCSection(SV_MachO, K, Begin), TypeAndAttributes(TAA), 88 Reserved2(reserved2) { 89 assert(Segment.size() <= 16 && Section.size() <= 16 && 90 "Segment or section string too long"); 91 for (unsigned i = 0; i != 16; ++i) { 92 if (i < Segment.size()) 93 SegmentName[i] = Segment[i]; 94 else 95 SegmentName[i] = 0; 96 97 if (i < Section.size()) 98 SectionName[i] = Section[i]; 99 else 100 SectionName[i] = 0; 101 } 102 } 103 104 void MCSectionMachO::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T, 105 raw_ostream &OS, 106 const MCExpr *Subsection) const { 107 OS << "\t.section\t" << getSegmentName() << ',' << getSectionName(); 108 109 // Get the section type and attributes. 110 unsigned TAA = getTypeAndAttributes(); 111 if (TAA == 0) { 112 OS << '\n'; 113 return; 114 } 115 116 MachO::SectionType SectionType = getType(); 117 assert(SectionType <= MachO::LAST_KNOWN_SECTION_TYPE && 118 "Invalid SectionType specified!"); 119 120 if (!SectionTypeDescriptors[SectionType].AssemblerName.empty()) { 121 OS << ','; 122 OS << SectionTypeDescriptors[SectionType].AssemblerName; 123 } else { 124 // If we have no name for the attribute, stop here. 125 OS << '\n'; 126 return; 127 } 128 129 // If we don't have any attributes, we're done. 130 unsigned SectionAttrs = TAA & MachO::SECTION_ATTRIBUTES; 131 if (SectionAttrs == 0) { 132 // If we have a S_SYMBOL_STUBS size specified, print it along with 'none' as 133 // the attribute specifier. 134 if (Reserved2 != 0) 135 OS << ",none," << Reserved2; 136 OS << '\n'; 137 return; 138 } 139 140 // Check each attribute to see if we have it. 141 char Separator = ','; 142 for (unsigned i = 0; 143 SectionAttrs != 0 && SectionAttrDescriptors[i].AttrFlag; 144 ++i) { 145 // Check to see if we have this attribute. 146 if ((SectionAttrDescriptors[i].AttrFlag & SectionAttrs) == 0) 147 continue; 148 149 // Yep, clear it and print it. 150 SectionAttrs &= ~SectionAttrDescriptors[i].AttrFlag; 151 152 OS << Separator; 153 if (!SectionAttrDescriptors[i].AssemblerName.empty()) 154 OS << SectionAttrDescriptors[i].AssemblerName; 155 else 156 OS << "<<" << SectionAttrDescriptors[i].EnumName << ">>"; 157 Separator = '+'; 158 } 159 160 assert(SectionAttrs == 0 && "Unknown section attributes!"); 161 162 // If we have a S_SYMBOL_STUBS size specified, print it. 163 if (Reserved2 != 0) 164 OS << ',' << Reserved2; 165 OS << '\n'; 166 } 167 168 bool MCSectionMachO::UseCodeAlign() const { 169 return hasAttribute(MachO::S_ATTR_PURE_INSTRUCTIONS); 170 } 171 172 bool MCSectionMachO::isVirtualSection() const { 173 return (getType() == MachO::S_ZEROFILL || 174 getType() == MachO::S_GB_ZEROFILL || 175 getType() == MachO::S_THREAD_LOCAL_ZEROFILL); 176 } 177 178 /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec". 179 /// This is a string that can appear after a .section directive in a mach-o 180 /// flavored .s file. If successful, this fills in the specified Out 181 /// parameters and returns an empty string. When an invalid section 182 /// specifier is present, this returns a string indicating the problem. 183 std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec, // In. 184 StringRef &Segment, // Out. 185 StringRef &Section, // Out. 186 unsigned &TAA, // Out. 187 bool &TAAParsed, // Out. 188 unsigned &StubSize) { // Out. 189 TAAParsed = false; 190 191 SmallVector<StringRef, 5> SplitSpec; 192 Spec.split(SplitSpec, ','); 193 // Remove leading and trailing whitespace. 194 auto GetEmptyOrTrim = [&SplitSpec](size_t Idx) -> StringRef { 195 return SplitSpec.size() > Idx ? SplitSpec[Idx].trim() : StringRef(); 196 }; 197 Segment = GetEmptyOrTrim(0); 198 Section = GetEmptyOrTrim(1); 199 StringRef SectionType = GetEmptyOrTrim(2); 200 StringRef Attrs = GetEmptyOrTrim(3); 201 StringRef StubSizeStr = GetEmptyOrTrim(4); 202 203 // Verify that the segment is present and not too long. 204 if (Segment.empty() || Segment.size() > 16) 205 return "mach-o section specifier requires a segment whose length is " 206 "between 1 and 16 characters"; 207 208 // Verify that the section is present and not too long. 209 if (Section.empty()) 210 return "mach-o section specifier requires a segment and section " 211 "separated by a comma"; 212 213 if (Section.size() > 16) 214 return "mach-o section specifier requires a section whose length is " 215 "between 1 and 16 characters"; 216 217 // If there is no comma after the section, we're done. 218 TAA = 0; 219 StubSize = 0; 220 if (SectionType.empty()) 221 return ""; 222 223 // Figure out which section type it is. 224 auto TypeDescriptor = std::find_if( 225 std::begin(SectionTypeDescriptors), std::end(SectionTypeDescriptors), 226 [&](decltype(*SectionTypeDescriptors) &Descriptor) { 227 return SectionType == Descriptor.AssemblerName; 228 }); 229 230 // If we didn't find the section type, reject it. 231 if (TypeDescriptor == std::end(SectionTypeDescriptors)) 232 return "mach-o section specifier uses an unknown section type"; 233 234 // Remember the TypeID. 235 TAA = TypeDescriptor - std::begin(SectionTypeDescriptors); 236 TAAParsed = true; 237 238 // If we have no comma after the section type, there are no attributes. 239 if (Attrs.empty()) { 240 // S_SYMBOL_STUBS always require a symbol stub size specifier. 241 if (TAA == MachO::S_SYMBOL_STUBS) 242 return "mach-o section specifier of type 'symbol_stubs' requires a size " 243 "specifier"; 244 return ""; 245 } 246 247 // The attribute list is a '+' separated list of attributes. 248 SmallVector<StringRef, 1> SectionAttrs; 249 Attrs.split(SectionAttrs, '+', /*MaxSplit=*/-1, /*KeepEmpty=*/false); 250 251 for (StringRef &SectionAttr : SectionAttrs) { 252 auto AttrDescriptorI = std::find_if( 253 std::begin(SectionAttrDescriptors), std::end(SectionAttrDescriptors), 254 [&](decltype(*SectionAttrDescriptors) &Descriptor) { 255 return SectionAttr.trim() == Descriptor.AssemblerName; 256 }); 257 if (AttrDescriptorI == std::end(SectionAttrDescriptors)) 258 return "mach-o section specifier has invalid attribute"; 259 260 TAA |= AttrDescriptorI->AttrFlag; 261 } 262 263 // Okay, we've parsed the section attributes, see if we have a stub size spec. 264 if (StubSizeStr.empty()) { 265 // S_SYMBOL_STUBS always require a symbol stub size specifier. 266 if (TAA == MachO::S_SYMBOL_STUBS) 267 return "mach-o section specifier of type 'symbol_stubs' requires a size " 268 "specifier"; 269 return ""; 270 } 271 272 // If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS. 273 if ((TAA & MachO::SECTION_TYPE) != MachO::S_SYMBOL_STUBS) 274 return "mach-o section specifier cannot have a stub size specified because " 275 "it does not have type 'symbol_stubs'"; 276 277 // Convert the stub size from a string to an integer. 278 if (StubSizeStr.getAsInteger(0, StubSize)) 279 return "mach-o section specifier has a malformed stub size"; 280 281 return ""; 282 } 283
