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Imported Upstream version 5.18.0.234

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Former-commit-id: 8071ec1a8c5eaa9be24b41745add19297608001f
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Xamarin Public Jenkins (auto-signing)
2019-01-08 08:22:36 +00:00
parent f32dbaf0b2
commit 212f6bafcb
28494 changed files with 359 additions and 3867025 deletions
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external/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.h vendored
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//==- llvm/CodeGen/DwarfAccelTable.h - Dwarf Accelerator Tables --*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing dwarf accelerator tables.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFACCELTABLE_H
#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFACCELTABLE_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/CodeGen/DIE.h"
#include "llvm/CodeGen/DwarfStringPoolEntry.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include <cstddef>
#include <cstdint>
#include <vector>
// The dwarf accelerator tables are an indirect hash table optimized
// for null lookup rather than access to known data. They are output into
// an on-disk format that looks like this:
//
// .-------------.
// | HEADER |
// |-------------|
// | BUCKETS |
// |-------------|
// | HASHES |
// |-------------|
// | OFFSETS |
// |-------------|
// | DATA |
// `-------------'
//
// where the header contains a magic number, version, type of hash function,
// the number of buckets, total number of hashes, and room for a special
// struct of data and the length of that struct.
//
// The buckets contain an index (e.g. 6) into the hashes array. The hashes
// section contains all of the 32-bit hash values in contiguous memory, and
// the offsets contain the offset into the data area for the particular
// hash.
//
// For a lookup example, we could hash a function name and take it modulo the
// number of buckets giving us our bucket. From there we take the bucket value
// as an index into the hashes table and look at each successive hash as long
// as the hash value is still the same modulo result (bucket value) as earlier.
// If we have a match we look at that same entry in the offsets table and
// grab the offset in the data for our final match.
namespace llvm {
class AsmPrinter;
class DwarfDebug;
class DwarfAccelTable {
// Helper function to compute the number of buckets needed based on
// the number of unique hashes.
void ComputeBucketCount();
struct TableHeader {
uint32_t magic = MagicHash; // 'HASH' magic value to allow endian detection
uint16_t version = 1; // Version number.
uint16_t hash_function = dwarf::DW_hash_function_djb;
// The hash function enumeration that was used.
uint32_t bucket_count = 0; // The number of buckets in this hash table.
uint32_t hashes_count = 0; // The total number of unique hash values
// and hash data offsets in this table.
uint32_t header_data_len; // The bytes to skip to get to the hash
// indexes (buckets) for correct alignment.
// Also written to disk is the implementation specific header data.
static const uint32_t MagicHash = 0x48415348;
TableHeader(uint32_t data_len) : header_data_len(data_len) {}
#ifndef NDEBUG
void print(raw_ostream &OS) {
OS << "Magic: " << format("0x%x", magic) << "\n"
<< "Version: " << version << "\n"
<< "Hash Function: " << hash_function << "\n"
<< "Bucket Count: " << bucket_count << "\n"
<< "Header Data Length: " << header_data_len << "\n";
}
void dump() { print(dbgs()); }
#endif
};
public:
// The HeaderData describes the form of each set of data. In general this
// is as a list of atoms (atom_count) where each atom contains a type
// (AtomType type) of data, and an encoding form (form). In the case of
// data that is referenced via DW_FORM_ref_* the die_offset_base is
// used to describe the offset for all forms in the list of atoms.
// This also serves as a public interface of sorts.
// When written to disk this will have the form:
//
// uint32_t die_offset_base
// uint32_t atom_count
// atom_count Atoms
// Make these public so that they can be used as a general interface to
// the class.
struct Atom {
uint16_t type; // enum AtomType
uint16_t form; // DWARF DW_FORM_ defines
constexpr Atom(uint16_t type, uint16_t form) : type(type), form(form) {}
#ifndef NDEBUG
void print(raw_ostream &OS) {
OS << "Type: " << dwarf::AtomTypeString(type) << "\n"
<< "Form: " << dwarf::FormEncodingString(form) << "\n";
}
void dump() { print(dbgs()); }
#endif
};
private:
struct TableHeaderData {
uint32_t die_offset_base;
SmallVector<Atom, 3> Atoms;
TableHeaderData(ArrayRef<Atom> AtomList, uint32_t offset = 0)
: die_offset_base(offset), Atoms(AtomList.begin(), AtomList.end()) {}
#ifndef NDEBUG
void print(raw_ostream &OS) {
OS << "die_offset_base: " << die_offset_base << "\n";
for (size_t i = 0; i < Atoms.size(); i++)
Atoms[i].print(OS);
}
void dump() { print(dbgs()); }
#endif
};
// The data itself consists of a str_offset, a count of the DIEs in the
// hash and the offsets to the DIEs themselves.
// On disk each data section is ended with a 0 KeyType as the end of the
// hash chain.
// On output this looks like:
// uint32_t str_offset
// uint32_t hash_data_count
// HashData[hash_data_count]
public:
struct HashDataContents {
const DIE *Die; // Offsets
char Flags; // Specific flags to output
HashDataContents(const DIE *D, char Flags) : Die(D), Flags(Flags) {}
#ifndef NDEBUG
void print(raw_ostream &OS) const {
OS << " Offset: " << Die->getOffset() << "\n"
<< " Tag: " << dwarf::TagString(Die->getTag()) << "\n"
<< " Flags: " << Flags << "\n";
}
#endif
};
private:
// String Data
struct DataArray {
DwarfStringPoolEntryRef Name;
std::vector<HashDataContents *> Values;
};
friend struct HashData;
struct HashData {
StringRef Str;
uint32_t HashValue;
MCSymbol *Sym;
DwarfAccelTable::DataArray &Data; // offsets
HashData(StringRef S, DwarfAccelTable::DataArray &Data)
: Str(S), Data(Data) {
HashValue = dwarf::djbHash(S);
}
#ifndef NDEBUG
void print(raw_ostream &OS) {
OS << "Name: " << Str << "\n";
OS << " Hash Value: " << format("0x%x", HashValue) << "\n";
OS << " Symbol: ";
if (Sym)
OS << *Sym;
else
OS << "<none>";
OS << "\n";
for (HashDataContents *C : Data.Values) {
OS << " Offset: " << C->Die->getOffset() << "\n";
OS << " Tag: " << dwarf::TagString(C->Die->getTag()) << "\n";
OS << " Flags: " << C->Flags << "\n";
}
}
void dump() { print(dbgs()); }
#endif
};
// Internal Functions
void EmitHeader(AsmPrinter *);
void EmitBuckets(AsmPrinter *);
void EmitHashes(AsmPrinter *);
void emitOffsets(AsmPrinter *, const MCSymbol *);
void EmitData(AsmPrinter *, DwarfDebug *D);
// Allocator for HashData and HashDataContents.
BumpPtrAllocator Allocator;
// Output Variables
TableHeader Header;
TableHeaderData HeaderData;
std::vector<HashData *> Data;
using StringEntries = StringMap<DataArray, BumpPtrAllocator &>;
StringEntries Entries;
// Buckets/Hashes/Offsets
using HashList = std::vector<HashData *>;
using BucketList = std::vector<HashList>;
BucketList Buckets;
HashList Hashes;
// Public Implementation
public:
DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom>);
DwarfAccelTable(const DwarfAccelTable &) = delete;
DwarfAccelTable &operator=(const DwarfAccelTable &) = delete;
void AddName(DwarfStringPoolEntryRef Name, const DIE *Die, char Flags = 0);
void FinalizeTable(AsmPrinter *, StringRef);
void emit(AsmPrinter *, const MCSymbol *, DwarfDebug *);
#ifndef NDEBUG
void print(raw_ostream &OS);
void dump() { print(dbgs()); }
#endif
};
} // end namespace llvm
#endif // LLVM_LIB_CODEGEN_ASMPRINTER_DWARFACCELTABLE_H