| //===- lib/MC/MCSectionMachO.cpp - MachO Code Section Representation ------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/MC/MCSectionMachO.h" |
| #include "llvm/MC/MCContext.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <cctype> |
| using namespace llvm; |
| |
| /// SectionTypeDescriptors - These are strings that describe the various section |
| /// types. This *must* be kept in order with and stay synchronized with the |
| /// section type list. |
| static constexpr struct { |
| StringLiteral AssemblerName, EnumName; |
| } SectionTypeDescriptors[MachO::LAST_KNOWN_SECTION_TYPE + 1] = { |
| {StringLiteral("regular"), StringLiteral("S_REGULAR")}, // 0x00 |
| {StringLiteral(""), StringLiteral("S_ZEROFILL")}, // 0x01 |
| {StringLiteral("cstring_literals"), |
| StringLiteral("S_CSTRING_LITERALS")}, // 0x02 |
| {StringLiteral("4byte_literals"), |
| StringLiteral("S_4BYTE_LITERALS")}, // 0x03 |
| {StringLiteral("8byte_literals"), |
| StringLiteral("S_8BYTE_LITERALS")}, // 0x04 |
| {StringLiteral("literal_pointers"), |
| StringLiteral("S_LITERAL_POINTERS")}, // 0x05 |
| {StringLiteral("non_lazy_symbol_pointers"), |
| StringLiteral("S_NON_LAZY_SYMBOL_POINTERS")}, // 0x06 |
| {StringLiteral("lazy_symbol_pointers"), |
| StringLiteral("S_LAZY_SYMBOL_POINTERS")}, // 0x07 |
| {StringLiteral("symbol_stubs"), StringLiteral("S_SYMBOL_STUBS")}, // 0x08 |
| {StringLiteral("mod_init_funcs"), |
| StringLiteral("S_MOD_INIT_FUNC_POINTERS")}, // 0x09 |
| {StringLiteral("mod_term_funcs"), |
| StringLiteral("S_MOD_TERM_FUNC_POINTERS")}, // 0x0A |
| {StringLiteral("coalesced"), StringLiteral("S_COALESCED")}, // 0x0B |
| {StringLiteral("") /*FIXME??*/, StringLiteral("S_GB_ZEROFILL")}, // 0x0C |
| {StringLiteral("interposing"), StringLiteral("S_INTERPOSING")}, // 0x0D |
| {StringLiteral("16byte_literals"), |
| StringLiteral("S_16BYTE_LITERALS")}, // 0x0E |
| {StringLiteral("") /*FIXME??*/, StringLiteral("S_DTRACE_DOF")}, // 0x0F |
| {StringLiteral("") /*FIXME??*/, |
| StringLiteral("S_LAZY_DYLIB_SYMBOL_POINTERS")}, // 0x10 |
| {StringLiteral("thread_local_regular"), |
| StringLiteral("S_THREAD_LOCAL_REGULAR")}, // 0x11 |
| {StringLiteral("thread_local_zerofill"), |
| StringLiteral("S_THREAD_LOCAL_ZEROFILL")}, // 0x12 |
| {StringLiteral("thread_local_variables"), |
| StringLiteral("S_THREAD_LOCAL_VARIABLES")}, // 0x13 |
| {StringLiteral("thread_local_variable_pointers"), |
| StringLiteral("S_THREAD_LOCAL_VARIABLE_POINTERS")}, // 0x14 |
| {StringLiteral("thread_local_init_function_pointers"), |
| StringLiteral("S_THREAD_LOCAL_INIT_FUNCTION_POINTERS")}, // 0x15 |
| }; |
| |
| /// SectionAttrDescriptors - This is an array of descriptors for section |
| /// attributes. Unlike the SectionTypeDescriptors, this is not directly indexed |
| /// by attribute, instead it is searched. |
| static constexpr struct { |
| unsigned AttrFlag; |
| StringLiteral AssemblerName, EnumName; |
| } SectionAttrDescriptors[] = { |
| #define ENTRY(ASMNAME, ENUM) \ |
| { MachO::ENUM, StringLiteral(ASMNAME), StringLiteral(#ENUM) }, |
| ENTRY("pure_instructions", S_ATTR_PURE_INSTRUCTIONS) |
| ENTRY("no_toc", S_ATTR_NO_TOC) |
| ENTRY("strip_static_syms", S_ATTR_STRIP_STATIC_SYMS) |
| ENTRY("no_dead_strip", S_ATTR_NO_DEAD_STRIP) |
| ENTRY("live_support", S_ATTR_LIVE_SUPPORT) |
| ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE) |
| ENTRY("debug", S_ATTR_DEBUG) |
| ENTRY("" /*FIXME*/, S_ATTR_SOME_INSTRUCTIONS) |
| ENTRY("" /*FIXME*/, S_ATTR_EXT_RELOC) |
| ENTRY("" /*FIXME*/, S_ATTR_LOC_RELOC) |
| #undef ENTRY |
| { 0, StringLiteral("none"), StringLiteral("") }, // used if section has no attributes but has a stub size |
| }; |
| |
| MCSectionMachO::MCSectionMachO(StringRef Segment, StringRef Section, |
| unsigned TAA, unsigned reserved2, SectionKind K, |
| MCSymbol *Begin) |
| : MCSection(SV_MachO, K, Begin), TypeAndAttributes(TAA), |
| Reserved2(reserved2) { |
| assert(Segment.size() <= 16 && Section.size() <= 16 && |
| "Segment or section string too long"); |
| for (unsigned i = 0; i != 16; ++i) { |
| if (i < Segment.size()) |
| SegmentName[i] = Segment[i]; |
| else |
| SegmentName[i] = 0; |
| |
| if (i < Section.size()) |
| SectionName[i] = Section[i]; |
| else |
| SectionName[i] = 0; |
| } |
| } |
| |
| void MCSectionMachO::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T, |
| raw_ostream &OS, |
| const MCExpr *Subsection) const { |
| OS << "\t.section\t" << getSegmentName() << ',' << getSectionName(); |
| |
| // Get the section type and attributes. |
| unsigned TAA = getTypeAndAttributes(); |
| if (TAA == 0) { |
| OS << '\n'; |
| return; |
| } |
| |
| MachO::SectionType SectionType = getType(); |
| assert(SectionType <= MachO::LAST_KNOWN_SECTION_TYPE && |
| "Invalid SectionType specified!"); |
| |
| if (!SectionTypeDescriptors[SectionType].AssemblerName.empty()) { |
| OS << ','; |
| OS << SectionTypeDescriptors[SectionType].AssemblerName; |
| } else { |
| // If we have no name for the attribute, stop here. |
| OS << '\n'; |
| return; |
| } |
| |
| // If we don't have any attributes, we're done. |
| unsigned SectionAttrs = TAA & MachO::SECTION_ATTRIBUTES; |
| if (SectionAttrs == 0) { |
| // If we have a S_SYMBOL_STUBS size specified, print it along with 'none' as |
| // the attribute specifier. |
| if (Reserved2 != 0) |
| OS << ",none," << Reserved2; |
| OS << '\n'; |
| return; |
| } |
| |
| // Check each attribute to see if we have it. |
| char Separator = ','; |
| for (unsigned i = 0; |
| SectionAttrs != 0 && SectionAttrDescriptors[i].AttrFlag; |
| ++i) { |
| // Check to see if we have this attribute. |
| if ((SectionAttrDescriptors[i].AttrFlag & SectionAttrs) == 0) |
| continue; |
| |
| // Yep, clear it and print it. |
| SectionAttrs &= ~SectionAttrDescriptors[i].AttrFlag; |
| |
| OS << Separator; |
| if (!SectionAttrDescriptors[i].AssemblerName.empty()) |
| OS << SectionAttrDescriptors[i].AssemblerName; |
| else |
| OS << "<<" << SectionAttrDescriptors[i].EnumName << ">>"; |
| Separator = '+'; |
| } |
| |
| assert(SectionAttrs == 0 && "Unknown section attributes!"); |
| |
| // If we have a S_SYMBOL_STUBS size specified, print it. |
| if (Reserved2 != 0) |
| OS << ',' << Reserved2; |
| OS << '\n'; |
| } |
| |
| bool MCSectionMachO::UseCodeAlign() const { |
| return hasAttribute(MachO::S_ATTR_PURE_INSTRUCTIONS); |
| } |
| |
| bool MCSectionMachO::isVirtualSection() const { |
| return (getType() == MachO::S_ZEROFILL || |
| getType() == MachO::S_GB_ZEROFILL || |
| getType() == MachO::S_THREAD_LOCAL_ZEROFILL); |
| } |
| |
| /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec". |
| /// This is a string that can appear after a .section directive in a mach-o |
| /// flavored .s file. If successful, this fills in the specified Out |
| /// parameters and returns an empty string. When an invalid section |
| /// specifier is present, this returns a string indicating the problem. |
| std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec, // In. |
| StringRef &Segment, // Out. |
| StringRef &Section, // Out. |
| unsigned &TAA, // Out. |
| bool &TAAParsed, // Out. |
| unsigned &StubSize) { // Out. |
| TAAParsed = false; |
| |
| SmallVector<StringRef, 5> SplitSpec; |
| Spec.split(SplitSpec, ','); |
| // Remove leading and trailing whitespace. |
| auto GetEmptyOrTrim = [&SplitSpec](size_t Idx) -> StringRef { |
| return SplitSpec.size() > Idx ? SplitSpec[Idx].trim() : StringRef(); |
| }; |
| Segment = GetEmptyOrTrim(0); |
| Section = GetEmptyOrTrim(1); |
| StringRef SectionType = GetEmptyOrTrim(2); |
| StringRef Attrs = GetEmptyOrTrim(3); |
| StringRef StubSizeStr = GetEmptyOrTrim(4); |
| |
| // Verify that the segment is present and not too long. |
| if (Segment.empty() || Segment.size() > 16) |
| return "mach-o section specifier requires a segment whose length is " |
| "between 1 and 16 characters"; |
| |
| // Verify that the section is present and not too long. |
| if (Section.empty()) |
| return "mach-o section specifier requires a segment and section " |
| "separated by a comma"; |
| |
| if (Section.size() > 16) |
| return "mach-o section specifier requires a section whose length is " |
| "between 1 and 16 characters"; |
| |
| // If there is no comma after the section, we're done. |
| TAA = 0; |
| StubSize = 0; |
| if (SectionType.empty()) |
| return ""; |
| |
| // Figure out which section type it is. |
| auto TypeDescriptor = std::find_if( |
| std::begin(SectionTypeDescriptors), std::end(SectionTypeDescriptors), |
| [&](decltype(*SectionTypeDescriptors) &Descriptor) { |
| return SectionType == Descriptor.AssemblerName; |
| }); |
| |
| // If we didn't find the section type, reject it. |
| if (TypeDescriptor == std::end(SectionTypeDescriptors)) |
| return "mach-o section specifier uses an unknown section type"; |
| |
| // Remember the TypeID. |
| TAA = TypeDescriptor - std::begin(SectionTypeDescriptors); |
| TAAParsed = true; |
| |
| // If we have no comma after the section type, there are no attributes. |
| if (Attrs.empty()) { |
| // S_SYMBOL_STUBS always require a symbol stub size specifier. |
| if (TAA == MachO::S_SYMBOL_STUBS) |
| return "mach-o section specifier of type 'symbol_stubs' requires a size " |
| "specifier"; |
| return ""; |
| } |
| |
| // The attribute list is a '+' separated list of attributes. |
| SmallVector<StringRef, 1> SectionAttrs; |
| Attrs.split(SectionAttrs, '+', /*MaxSplit=*/-1, /*KeepEmpty=*/false); |
| |
| for (StringRef &SectionAttr : SectionAttrs) { |
| auto AttrDescriptorI = std::find_if( |
| std::begin(SectionAttrDescriptors), std::end(SectionAttrDescriptors), |
| [&](decltype(*SectionAttrDescriptors) &Descriptor) { |
| return SectionAttr.trim() == Descriptor.AssemblerName; |
| }); |
| if (AttrDescriptorI == std::end(SectionAttrDescriptors)) |
| return "mach-o section specifier has invalid attribute"; |
| |
| TAA |= AttrDescriptorI->AttrFlag; |
| } |
| |
| // Okay, we've parsed the section attributes, see if we have a stub size spec. |
| if (StubSizeStr.empty()) { |
| // S_SYMBOL_STUBS always require a symbol stub size specifier. |
| if (TAA == MachO::S_SYMBOL_STUBS) |
| return "mach-o section specifier of type 'symbol_stubs' requires a size " |
| "specifier"; |
| return ""; |
| } |
| |
| // If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS. |
| if ((TAA & MachO::SECTION_TYPE) != MachO::S_SYMBOL_STUBS) |
| return "mach-o section specifier cannot have a stub size specified because " |
| "it does not have type 'symbol_stubs'"; |
| |
| // Convert the stub size from a string to an integer. |
| if (StubSizeStr.getAsInteger(0, StubSize)) |
| return "mach-o section specifier has a malformed stub size"; |
| |
| return ""; |
| } |
