//===- lib/MC/MCSectionMachO.cpp - MachO Code Section Representation ------===//

//

//                     The LLVM Compiler Infrastructure

//

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

//

//===----------------------------------------------------------------------===//

#include "llvm/MC/MCSectionMachO.h"

#include "llvm/MC/MCContext.h"

#include "llvm/Support/raw_ostream.h"

#include <cctype>

using namespace llvm_ks;

/// 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 const struct {

  const char *AssemblerName, *EnumName;

} SectionTypeDescriptors[MachO::LAST_KNOWN_SECTION_TYPE+1] = {

  { "regular",                  "S_REGULAR" },                    // 0x00

  { nullptr,                    "S_ZEROFILL" },                   // 0x01

  { "cstring_literals",         "S_CSTRING_LITERALS" },           // 0x02

  { "4byte_literals",           "S_4BYTE_LITERALS" },             // 0x03

  { "8byte_literals",           "S_8BYTE_LITERALS" },             // 0x04

  { "literal_pointers",         "S_LITERAL_POINTERS" },           // 0x05

  { "non_lazy_symbol_pointers", "S_NON_LAZY_SYMBOL_POINTERS" },   // 0x06

  { "lazy_symbol_pointers",     "S_LAZY_SYMBOL_POINTERS" },       // 0x07

  { "symbol_stubs",             "S_SYMBOL_STUBS" },               // 0x08

  { "mod_init_funcs",           "S_MOD_INIT_FUNC_POINTERS" },     // 0x09

  { "mod_term_funcs",           "S_MOD_TERM_FUNC_POINTERS" },     // 0x0A

  { "coalesced",                "S_COALESCED" },                  // 0x0B

  { nullptr, /*FIXME??*/        "S_GB_ZEROFILL" },                // 0x0C

  { "interposing",              "S_INTERPOSING" },                // 0x0D

  { "16byte_literals",          "S_16BYTE_LITERALS" },            // 0x0E

  { nullptr, /*FIXME??*/        "S_DTRACE_DOF" },                 // 0x0F

  { nullptr, /*FIXME??*/        "S_LAZY_DYLIB_SYMBOL_POINTERS" }, // 0x10

  { "thread_local_regular",     "S_THREAD_LOCAL_REGULAR" },       // 0x11

  { "thread_local_zerofill",    "S_THREAD_LOCAL_ZEROFILL" },      // 0x12

  { "thread_local_variables",   "S_THREAD_LOCAL_VARIABLES" },     // 0x13

  { "thread_local_variable_pointers",

    "S_THREAD_LOCAL_VARIABLE_POINTERS" },                         // 0x14

  { "thread_local_init_function_pointers",

    "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 const struct {

  unsigned AttrFlag;

  const char *AssemblerName, *EnumName;

} SectionAttrDescriptors[] = {

#define ENTRY(ASMNAME, ENUM) \

  { MachO::ENUM, ASMNAME, #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(nullptr /*FIXME*/,     S_ATTR_SOME_INSTRUCTIONS)

ENTRY(nullptr /*FIXME*/,     S_ATTR_EXT_RELOC)

ENTRY(nullptr /*FIXME*/,     S_ATTR_LOC_RELOC)

#undef ENTRY

  { 0, "none", nullptr }, // 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,

                                          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) {

    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)

      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 Descriptor.AssemblerName &&

               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 Descriptor.AssemblerName &&

                 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 "";

}