MCSectionMachO.cpp revision 219077
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> 14using 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. 19static const struct { 20 const char *AssemblerName, *EnumName; 21} SectionTypeDescriptors[MCSectionMachO::LAST_KNOWN_SECTION_TYPE+1] = { 22 { "regular", "S_REGULAR" }, // 0x00 23 { 0, "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 { 0, /*FIXME??*/ "S_GB_ZEROFILL" }, // 0x0C 35 { "interposing", "S_INTERPOSING" }, // 0x0D 36 { "16byte_literals", "S_16BYTE_LITERALS" }, // 0x0E 37 { 0, /*FIXME??*/ "S_DTRACE_DOF" }, // 0x0F 38 { 0, /*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. The last entry has an AttrFlagEnd 52/// AttrFlag value. 53static const struct { 54 unsigned AttrFlag; 55 const char *AssemblerName, *EnumName; 56} SectionAttrDescriptors[] = { 57#define ENTRY(ASMNAME, ENUM) \ 58 { MCSectionMachO::ENUM, ASMNAME, #ENUM }, 59ENTRY("pure_instructions", S_ATTR_PURE_INSTRUCTIONS) 60ENTRY("no_toc", S_ATTR_NO_TOC) 61ENTRY("strip_static_syms", S_ATTR_STRIP_STATIC_SYMS) 62ENTRY("no_dead_strip", S_ATTR_NO_DEAD_STRIP) 63ENTRY("live_support", S_ATTR_LIVE_SUPPORT) 64ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE) 65ENTRY("debug", S_ATTR_DEBUG) 66ENTRY(0 /*FIXME*/, S_ATTR_SOME_INSTRUCTIONS) 67ENTRY(0 /*FIXME*/, S_ATTR_EXT_RELOC) 68ENTRY(0 /*FIXME*/, S_ATTR_LOC_RELOC) 69#undef ENTRY 70 { 0, "none", 0 }, // used if section has no attributes but has a stub size 71#define AttrFlagEnd 0xffffffff // non legal value, multiple attribute bits set 72 { AttrFlagEnd, 0, 0 } 73}; 74 75MCSectionMachO::MCSectionMachO(StringRef Segment, StringRef Section, 76 unsigned TAA, unsigned reserved2, SectionKind K) 77 : MCSection(SV_MachO, K), TypeAndAttributes(TAA), Reserved2(reserved2) { 78 assert(Segment.size() <= 16 && Section.size() <= 16 && 79 "Segment or section string too long"); 80 for (unsigned i = 0; i != 16; ++i) { 81 if (i < Segment.size()) 82 SegmentName[i] = Segment[i]; 83 else 84 SegmentName[i] = 0; 85 86 if (i < Section.size()) 87 SectionName[i] = Section[i]; 88 else 89 SectionName[i] = 0; 90 } 91} 92 93void MCSectionMachO::PrintSwitchToSection(const MCAsmInfo &MAI, 94 raw_ostream &OS) const { 95 OS << "\t.section\t" << getSegmentName() << ',' << getSectionName(); 96 97 // Get the section type and attributes. 98 unsigned TAA = getTypeAndAttributes(); 99 if (TAA == 0) { 100 OS << '\n'; 101 return; 102 } 103 104 unsigned SectionType = TAA & MCSectionMachO::SECTION_TYPE; 105 assert(SectionType <= MCSectionMachO::LAST_KNOWN_SECTION_TYPE && 106 "Invalid SectionType specified!"); 107 108 if (SectionTypeDescriptors[SectionType].AssemblerName) { 109 OS << ','; 110 OS << SectionTypeDescriptors[SectionType].AssemblerName; 111 } else { 112 // If we have no name for the attribute, stop here. 113 OS << '\n'; 114 return; 115 } 116 117 // If we don't have any attributes, we're done. 118 unsigned SectionAttrs = TAA & MCSectionMachO::SECTION_ATTRIBUTES; 119 if (SectionAttrs == 0) { 120 // If we have a S_SYMBOL_STUBS size specified, print it along with 'none' as 121 // the attribute specifier. 122 if (Reserved2 != 0) 123 OS << ",none," << Reserved2; 124 OS << '\n'; 125 return; 126 } 127 128 // Check each attribute to see if we have it. 129 char Separator = ','; 130 for (unsigned i = 0; 131 SectionAttrs != 0 && SectionAttrDescriptors[i].AttrFlag; 132 ++i) { 133 // Check to see if we have this attribute. 134 if ((SectionAttrDescriptors[i].AttrFlag & SectionAttrs) == 0) 135 continue; 136 137 // Yep, clear it and print it. 138 SectionAttrs &= ~SectionAttrDescriptors[i].AttrFlag; 139 140 OS << Separator; 141 if (SectionAttrDescriptors[i].AssemblerName) 142 OS << SectionAttrDescriptors[i].AssemblerName; 143 else 144 OS << "<<" << SectionAttrDescriptors[i].EnumName << ">>"; 145 Separator = '+'; 146 } 147 148 assert(SectionAttrs == 0 && "Unknown section attributes!"); 149 150 // If we have a S_SYMBOL_STUBS size specified, print it. 151 if (Reserved2 != 0) 152 OS << ',' << Reserved2; 153 OS << '\n'; 154} 155 156bool MCSectionMachO::UseCodeAlign() const { 157 return hasAttribute(MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS); 158} 159 160bool MCSectionMachO::isVirtualSection() const { 161 return (getType() == MCSectionMachO::S_ZEROFILL || 162 getType() == MCSectionMachO::S_GB_ZEROFILL || 163 getType() == MCSectionMachO::S_THREAD_LOCAL_ZEROFILL); 164} 165 166/// StripSpaces - This removes leading and trailing spaces from the StringRef. 167static void StripSpaces(StringRef &Str) { 168 while (!Str.empty() && isspace(Str[0])) 169 Str = Str.substr(1); 170 while (!Str.empty() && isspace(Str.back())) 171 Str = Str.substr(0, Str.size()-1); 172} 173 174/// ParseSectionSpecifier - Parse the section specifier indicated by "Spec". 175/// This is a string that can appear after a .section directive in a mach-o 176/// flavored .s file. If successful, this fills in the specified Out 177/// parameters and returns an empty string. When an invalid section 178/// specifier is present, this returns a string indicating the problem. 179std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec, // In. 180 StringRef &Segment, // Out. 181 StringRef &Section, // Out. 182 unsigned &TAA, // Out. 183 unsigned &StubSize) { // Out. 184 // Find the first comma. 185 std::pair<StringRef, StringRef> Comma = Spec.split(','); 186 187 // If there is no comma, we fail. 188 if (Comma.second.empty()) 189 return "mach-o section specifier requires a segment and section " 190 "separated by a comma"; 191 192 // Capture segment, remove leading and trailing whitespace. 193 Segment = Comma.first; 194 StripSpaces(Segment); 195 196 // Verify that the segment is present and not too long. 197 if (Segment.empty() || Segment.size() > 16) 198 return "mach-o section specifier requires a segment whose length is " 199 "between 1 and 16 characters"; 200 201 // Split the section name off from any attributes if present. 202 Comma = Comma.second.split(','); 203 204 // Capture section, remove leading and trailing whitespace. 205 Section = Comma.first; 206 StripSpaces(Section); 207 208 // Verify that the section is present and not too long. 209 if (Section.empty() || Section.size() > 16) 210 return "mach-o section specifier requires a section whose length is " 211 "between 1 and 16 characters"; 212 213 // If there is no comma after the section, we're done. 214 StubSize = 0; 215 if (Comma.second.empty()) 216 return ""; 217 218 // Otherwise, we need to parse the section type and attributes. 219 Comma = Comma.second.split(','); 220 221 // Get the section type. 222 StringRef SectionType = Comma.first; 223 StripSpaces(SectionType); 224 225 // Figure out which section type it is. 226 unsigned TypeID; 227 for (TypeID = 0; TypeID !=MCSectionMachO::LAST_KNOWN_SECTION_TYPE+1; ++TypeID) 228 if (SectionTypeDescriptors[TypeID].AssemblerName && 229 SectionType == SectionTypeDescriptors[TypeID].AssemblerName) 230 break; 231 232 // If we didn't find the section type, reject it. 233 if (TypeID > MCSectionMachO::LAST_KNOWN_SECTION_TYPE) 234 return "mach-o section specifier uses an unknown section type"; 235 236 // Remember the TypeID. 237 TAA = TypeID; 238 239 // If we have no comma after the section type, there are no attributes. 240 if (Comma.second.empty()) { 241 // S_SYMBOL_STUBS always require a symbol stub size specifier. 242 if (TAA == MCSectionMachO::S_SYMBOL_STUBS) 243 return "mach-o section specifier of type 'symbol_stubs' requires a size " 244 "specifier"; 245 return ""; 246 } 247 248 // Otherwise, we do have some attributes. Split off the size specifier if 249 // present. 250 Comma = Comma.second.split(','); 251 StringRef Attrs = Comma.first; 252 253 // The attribute list is a '+' separated list of attributes. 254 std::pair<StringRef, StringRef> Plus = Attrs.split('+'); 255 256 while (1) { 257 StringRef Attr = Plus.first; 258 StripSpaces(Attr); 259 260 // Look up the attribute. 261 for (unsigned i = 0; ; ++i) { 262 if (SectionAttrDescriptors[i].AttrFlag == AttrFlagEnd) 263 return "mach-o section specifier has invalid attribute"; 264 265 if (SectionAttrDescriptors[i].AssemblerName && 266 Attr == SectionAttrDescriptors[i].AssemblerName) { 267 TAA |= SectionAttrDescriptors[i].AttrFlag; 268 break; 269 } 270 } 271 272 if (Plus.second.empty()) break; 273 Plus = Plus.second.split('+'); 274 }; 275 276 // Okay, we've parsed the section attributes, see if we have a stub size spec. 277 if (Comma.second.empty()) { 278 // S_SYMBOL_STUBS always require a symbol stub size specifier. 279 if (TAA == MCSectionMachO::S_SYMBOL_STUBS) 280 return "mach-o section specifier of type 'symbol_stubs' requires a size " 281 "specifier"; 282 return ""; 283 } 284 285 // If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS. 286 if ((TAA & MCSectionMachO::SECTION_TYPE) != MCSectionMachO::S_SYMBOL_STUBS) 287 return "mach-o section specifier cannot have a stub size specified because " 288 "it does not have type 'symbol_stubs'"; 289 290 // Okay, if we do, it must be a number. 291 StringRef StubSizeStr = Comma.second; 292 StripSpaces(StubSizeStr); 293 294 // Convert the stub size from a string to an integer. 295 if (StubSizeStr.getAsInteger(0, StubSize)) 296 return "mach-o section specifier has a malformed stub size"; 297 298 return ""; 299} 300