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