mirror of
https://github.com/ClickHouse/ClickHouse.git
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292 lines
9.3 KiB
C++
292 lines
9.3 KiB
C++
#pragma once
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#if defined(__ELF__) && !defined(__FreeBSD__)
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/*
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* Copyright 2012-present Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/** This file was edited for ClickHouse.
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*/
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#include <string>
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#include <string_view>
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#include <variant>
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namespace DB
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{
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class Elf;
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/**
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* DWARF record parser.
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*
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* We only implement enough DWARF functionality to convert from PC address
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* to file and line number information.
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*
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* This means (although they're not part of the public API of this class), we
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* can parse Debug Information Entries (DIEs), abbreviations, attributes (of
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* all forms), and we can interpret bytecode for the line number VM.
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*
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* We can interpret DWARF records of version 2, 3, or 4, although we don't
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* actually support many of the version 4 features (such as VLIW, multiple
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* operations per instruction)
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*
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* Note that the DWARF record parser does not allocate heap memory at all.
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* This is on purpose: you can use the parser from
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* memory-constrained situations (such as an exception handler for
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* std::out_of_memory) If it weren't for this requirement, some things would
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* be much simpler: the Path class would be unnecessary and would be replaced
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* with a std::string; the list of file names in the line number VM would be
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* kept as a vector of strings instead of re-executing the program to look for
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* DW_LNE_define_file instructions, etc.
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*/
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class Dwarf final
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{
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// Note that Dwarf uses (and returns) std::string_view a lot.
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// The std::string_view point within sections in the ELF file, and so will
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// be live for as long as the passed-in Elf is live.
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public:
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/** Create a DWARF parser around an ELF file. */
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explicit Dwarf(const Elf & elf);
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/**
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* Represent a file path a s collection of three parts (base directory,
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* subdirectory, and file).
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*/
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class Path
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{
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public:
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Path() {}
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Path(std::string_view baseDir, std::string_view subDir, std::string_view file);
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std::string_view baseDir() const { return baseDir_; }
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std::string_view subDir() const { return subDir_; }
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std::string_view file() const { return file_; }
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size_t size() const;
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/**
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* Copy the Path to a buffer of size bufSize.
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*
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* toBuffer behaves like snprintf: It will always null-terminate the
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* buffer (so it will copy at most bufSize-1 bytes), and it will return
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* the number of bytes that would have been written if there had been
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* enough room, so, if toBuffer returns a value >= bufSize, the output
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* was truncated.
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*/
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size_t toBuffer(char * buf, size_t bufSize) const;
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void toString(std::string & dest) const;
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std::string toString() const
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{
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std::string s;
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toString(s);
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return s;
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}
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// TODO(tudorb): Implement operator==, operator!=; not as easy as it
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// seems as the same path can be represented in multiple ways
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private:
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std::string_view baseDir_;
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std::string_view subDir_;
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std::string_view file_;
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};
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enum class LocationInfoMode
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{
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// Don't resolve location info.
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DISABLED,
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// Perform CU lookup using .debug_aranges (might be incomplete).
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FAST,
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// Scan all CU in .debug_info (slow!) on .debug_aranges lookup failure.
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FULL,
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};
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struct LocationInfo
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{
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bool hasMainFile = false;
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Path mainFile;
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bool hasFileAndLine = false;
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Path file;
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uint64_t line = 0;
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};
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/** Find the file and line number information corresponding to address.
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* The address must be physical - offset in object file without offset in virtual memory where the object is loaded.
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*/
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bool findAddress(uintptr_t address, LocationInfo & info, LocationInfoMode mode) const;
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private:
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static bool findDebugInfoOffset(uintptr_t address, std::string_view aranges, uint64_t & offset);
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void init();
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bool findLocation(uintptr_t address, std::string_view & infoEntry, LocationInfo & info) const;
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const Elf * elf_;
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// DWARF section made up of chunks, each prefixed with a length header.
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// The length indicates whether the chunk is DWARF-32 or DWARF-64, which
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// guides interpretation of "section offset" records.
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// (yes, DWARF-32 and DWARF-64 sections may coexist in the same file)
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class Section
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{
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public:
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Section() : is64Bit_(false) {}
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explicit Section(std::string_view d);
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// Return next chunk, if any; the 4- or 12-byte length was already
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// parsed and isn't part of the chunk.
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bool next(std::string_view & chunk);
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// Is the current chunk 64 bit?
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bool is64Bit() const { return is64Bit_; }
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private:
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// Yes, 32- and 64- bit sections may coexist. Yikes!
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bool is64Bit_;
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std::string_view data_;
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};
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// Abbreviation for a Debugging Information Entry.
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struct DIEAbbreviation
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{
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uint64_t code;
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uint64_t tag;
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bool hasChildren;
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struct Attribute
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{
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uint64_t name;
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uint64_t form;
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};
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std::string_view attributes;
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};
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// Interpreter for the line number bytecode VM
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class LineNumberVM
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{
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public:
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LineNumberVM(std::string_view data, std::string_view compilationDirectory);
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bool findAddress(uintptr_t target, Path & file, uint64_t & line);
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private:
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void init();
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void reset();
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// Execute until we commit one new row to the line number matrix
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bool next(std::string_view & program);
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enum StepResult
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{
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CONTINUE, // Continue feeding opcodes
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COMMIT, // Commit new <address, file, line> tuple
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END, // End of sequence
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};
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// Execute one opcode
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StepResult step(std::string_view & program);
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struct FileName
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{
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std::string_view relativeName;
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// 0 = current compilation directory
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// otherwise, 1-based index in the list of include directories
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uint64_t directoryIndex;
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};
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// Read one FileName object, remove_prefix program
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static bool readFileName(std::string_view & program, FileName & fn);
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// Get file name at given index; may be in the initial table
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// (fileNames_) or defined using DW_LNE_define_file (and we reexecute
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// enough of the program to find it, if so)
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FileName getFileName(uint64_t index) const;
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// Get include directory at given index
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std::string_view getIncludeDirectory(uint64_t index) const;
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// Execute opcodes until finding a DW_LNE_define_file and return true;
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// return file at the end.
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bool nextDefineFile(std::string_view & program, FileName & fn) const;
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// Initialization
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bool is64Bit_;
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std::string_view data_;
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std::string_view compilationDirectory_;
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// Header
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uint16_t version_;
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uint8_t minLength_;
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bool defaultIsStmt_;
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int8_t lineBase_;
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uint8_t lineRange_;
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uint8_t opcodeBase_;
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const uint8_t * standardOpcodeLengths_;
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std::string_view includeDirectories_;
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size_t includeDirectoryCount_;
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std::string_view fileNames_;
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size_t fileNameCount_;
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// State machine registers
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uint64_t address_;
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uint64_t file_;
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uint64_t line_;
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uint64_t column_;
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bool isStmt_;
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bool basicBlock_;
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bool endSequence_;
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bool prologueEnd_;
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bool epilogueBegin_;
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uint64_t isa_;
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uint64_t discriminator_;
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};
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// Read an abbreviation from a std::string_view, return true if at end; remove_prefix section
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static bool readAbbreviation(std::string_view & section, DIEAbbreviation & abbr);
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// Get abbreviation corresponding to a code, in the chunk starting at
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// offset in the .debug_abbrev section
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DIEAbbreviation getAbbreviation(uint64_t code, uint64_t offset) const;
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// Read one attribute <name, form> pair, remove_prefix sp; returns <0, 0> at end.
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static DIEAbbreviation::Attribute readAttribute(std::string_view & sp);
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// Read one attribute value, remove_prefix sp
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typedef std::variant<uint64_t, std::string_view> AttributeValue;
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AttributeValue readAttributeValue(std::string_view & sp, uint64_t form, bool is64Bit) const;
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// Get an ELF section by name, return true if found
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bool getSection(const char * name, std::string_view * section) const;
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// Get a string from the .debug_str section
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std::string_view getStringFromStringSection(uint64_t offset) const;
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std::string_view info_; // .debug_info
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std::string_view abbrev_; // .debug_abbrev
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std::string_view aranges_; // .debug_aranges
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std::string_view line_; // .debug_line
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std::string_view strings_; // .debug_str
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};
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}
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#endif
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