llvm-mirror/lib/MC/MCSectionMachO.cpp
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

282 lines
11 KiB
C++

//===- 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 "";
}