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llvm-project/llvm/lib/MC/MCSectionMachO.cpp

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//===- 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, Section, 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;
}
}
void MCSectionMachO::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
raw_ostream &OS,
const MCExpr *Subsection) const {
OS << "\t.section\t" << getSegmentName() << ',' << getName();
// 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 "";
}
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