4e920e58e6
In the Atom model the symbols, content and relocations of a relocatable object file are represented as a graph of atoms, where each Atom represents a contiguous block of content with a single name (or no name at all if the content is anonymous), and where edges between Atoms represent relocations. If more than one symbol is associated with a contiguous block of content then the content is broken into multiple atoms and layout constraints (represented by edges) are introduced to ensure that the content remains effectively contiguous. These layout constraints must be kept in mind when examining the content associated with a symbol (it may be spread over multiple atoms) or when applying certain relocation types (e.g. MachO subtractors). This patch replaces the Atom model in JITLink with a blocks-and-symbols model. The blocks-and-symbols model represents relocatable object files as bipartite graphs, with one set of nodes representing contiguous content (Blocks) and another representing named or anonymous locations (Symbols) within a Block. Relocations are represented as edges from Blocks to Symbols. This scheme removes layout constraints (simplifying handling of MachO alt-entry symbols, and hopefully ELF sections at some point in the future) and simplifies some relocation logic. llvm-svn: 373689
79 lines
2.8 KiB
C++
79 lines
2.8 KiB
C++
//===------- EHFrameSupportImpl.h - JITLink eh-frame utils ------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// EHFrame registration support for JITLink.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_EXECUTIONENGINE_JITLINK_EHFRAMESUPPORTIMPL_H
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#define LLVM_LIB_EXECUTIONENGINE_JITLINK_EHFRAMESUPPORTIMPL_H
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#include "llvm/ExecutionEngine/JITLink/EHFrameSupport.h"
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#include "llvm/ExecutionEngine/JITLink/JITLink.h"
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#include "llvm/Support/BinaryStreamReader.h"
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namespace llvm {
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namespace jitlink {
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/// A generic binary parser for eh-frame sections.
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///
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/// Adds blocks and symbols representing CIE and FDE entries to a JITLink graph.
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///
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/// This parser assumes that the user has already verified that the EH-frame's
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/// address range does not overlap any other section/symbol, so that generated
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/// CIE/FDE records do not overlap other sections/symbols.
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class EHFrameBinaryParser {
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public:
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EHFrameBinaryParser(JITTargetAddress EHFrameAddress, StringRef EHFrameContent,
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unsigned PointerSize, support::endianness Endianness);
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virtual ~EHFrameBinaryParser() {}
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Error addToGraph();
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private:
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virtual void anchor();
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virtual Symbol *getSymbolAtAddress(JITTargetAddress Addr) = 0;
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virtual Symbol &createCIERecord(JITTargetAddress RecordAddr,
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StringRef RecordContent) = 0;
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virtual Expected<Symbol &>
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createFDERecord(JITTargetAddress RecordAddr, StringRef RecordContent,
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Symbol &CIE, size_t CIEOffset, Symbol &Func,
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size_t FuncOffset, Symbol *LSDA, size_t LSDAOffset) = 0;
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struct AugmentationInfo {
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bool AugmentationDataPresent = false;
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bool EHDataFieldPresent = false;
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uint8_t Fields[4] = {0x0, 0x0, 0x0, 0x0};
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};
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Expected<AugmentationInfo> parseAugmentationString();
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Expected<JITTargetAddress> readAbsolutePointer();
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Error processCIE(size_t RecordOffset, size_t RecordLength);
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Error processFDE(size_t RecordOffset, size_t RecordLength,
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JITTargetAddress CIEPointerOffset, uint32_t CIEPointer);
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struct CIEInformation {
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CIEInformation() = default;
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CIEInformation(Symbol &CIESymbol) : CIESymbol(&CIESymbol) {}
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Symbol *CIESymbol = nullptr;
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bool FDEsHaveLSDAField = false;
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};
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JITTargetAddress EHFrameAddress;
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StringRef EHFrameContent;
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unsigned PointerSize;
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BinaryStreamReader EHFrameReader;
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DenseMap<JITTargetAddress, CIEInformation> CIEInfos;
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};
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} // end namespace jitlink
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} // end namespace llvm
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#endif // LLVM_LIB_EXECUTIONENGINE_JITLINK_EHFRAMESUPPORTIMPL_H
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