llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h - llvm-project - Git at Google

 //===----- MachOLinkGraphBuilder.h - MachO LinkGraph builder ----*- C++ -*-===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 // Generic MachO LinkGraph building code.
 //
 //===----------------------------------------------------------------------===//

 #ifndef LIB_EXECUTIONENGINE_JITLINK_MACHOLINKGRAPHBUILDER_H
 #define LIB_EXECUTIONENGINE_JITLINK_MACHOLINKGRAPHBUILDER_H

 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
 #include "llvm/Object/MachO.h"

 #include "EHFrameSupportImpl.h"
 #include "JITLinkGeneric.h"

 #include <list>

 namespace llvm {
 namespace jitlink {

 class MachOLinkGraphBuilder {
 public:
   virtual ~MachOLinkGraphBuilder();
   Expected<std::unique_ptr<LinkGraph>> buildGraph();

 protected:

   struct NormalizedSymbol {
     friend class MachOLinkGraphBuilder;

   private:
     NormalizedSymbol(Optional<StringRef> Name, uint64_t Value, uint8_t Type,
                      uint8_t Sect, uint16_t Desc, Linkage L, Scope S)
         : Name(Name), Value(Value), Type(Type), Sect(Sect), Desc(Desc), L(L),
           S(S) {
       assert((!Name || !Name->empty()) && "Name must be none or non-empty");
     }

   public:
     NormalizedSymbol(const NormalizedSymbol &) = delete;
     NormalizedSymbol &operator=(const NormalizedSymbol &) = delete;
     NormalizedSymbol(NormalizedSymbol &&) = delete;
     NormalizedSymbol &operator=(NormalizedSymbol &&) = delete;

     Optional<StringRef> Name;
     uint64_t Value = 0;
     uint8_t Type = 0;
     uint8_t Sect = 0;
     uint16_t Desc = 0;
     Linkage L = Linkage::Strong;
     Scope S = Scope::Default;
     Symbol *GraphSymbol = nullptr;
   };

   // Normalized section representation. Section and segment names are guaranteed
   // to be null-terminated, hence the extra bytes on SegName and SectName.
   class NormalizedSection {
     friend class MachOLinkGraphBuilder;

   private:
     NormalizedSection() = default;

   public:
     char SectName[17];
     char SegName[17];
     uint64_t Address = 0;
     uint64_t Size = 0;
     uint64_t Alignment = 0;
     uint32_t Flags = 0;
     const char *Data = nullptr;
     Section *GraphSection = nullptr;
     std::map<JITTargetAddress, Symbol *> CanonicalSymbols;
   };

   using SectionParserFunction = std::function<Error(NormalizedSection &S)>;

   MachOLinkGraphBuilder(const object::MachOObjectFile &Obj, Triple TT,
                         LinkGraph::GetEdgeKindNameFunction GetEdgeKindName);

   LinkGraph &getGraph() const { return *G; }

   const object::MachOObjectFile &getObject() const { return Obj; }

   void addCustomSectionParser(StringRef SectionName,
                               SectionParserFunction Parse);

   virtual Error addRelocations() = 0;

   /// Create a symbol.
   template <typename... ArgTs>
   NormalizedSymbol &createNormalizedSymbol(ArgTs &&... Args) {
     NormalizedSymbol *Sym = reinterpret_cast<NormalizedSymbol *>(
         Allocator.Allocate<NormalizedSymbol>());
     new (Sym) NormalizedSymbol(std::forward<ArgTs>(Args)...);
     return *Sym;
   }

   /// Index is zero-based (MachO section indexes are usually one-based) and
   /// assumed to be in-range. Client is responsible for checking.
   NormalizedSection &getSectionByIndex(unsigned Index) {
     auto I = IndexToSection.find(Index);
     assert(I != IndexToSection.end() && "No section recorded at index");
     return I->second;
   }

   /// Try to get the section at the given index. Will return an error if the
   /// given index is out of range, or if no section has been added for the given
   /// index.
   Expected<NormalizedSection &> findSectionByIndex(unsigned Index) {
     auto I = IndexToSection.find(Index);
     if (I == IndexToSection.end())
       return make_error<JITLinkError>("No section recorded for index " +
                                       formatv("{0:d}", Index));
     return I->second;
   }

   /// Try to get the symbol at the given index. Will return an error if the
   /// given index is out of range, or if no symbol has been added for the given
   /// index.
   Expected<NormalizedSymbol &> findSymbolByIndex(uint64_t Index) {
     auto I = IndexToSymbol.find(Index);
     if (I == IndexToSymbol.end())
       return make_error<JITLinkError>("No symbol at index " +
                                       formatv("{0:d}", Index));
     assert(I->second && "Null symbol at index");
     return *I->second;
   }

   /// Returns the symbol with the highest address not greater than the search
   /// address, or null if no such symbol exists.
   Symbol *getSymbolByAddress(NormalizedSection &NSec,
                              JITTargetAddress Address) {
     auto I = NSec.CanonicalSymbols.upper_bound(Address);
     if (I == NSec.CanonicalSymbols.begin())
       return nullptr;
     return std::prev(I)->second;
   }

   /// Returns the symbol with the highest address not greater than the search
   /// address, or an error if no such symbol exists.
   Expected<Symbol &> findSymbolByAddress(NormalizedSection &NSec,
                                          JITTargetAddress Address) {
     auto *Sym = getSymbolByAddress(NSec, Address);
     if (Sym)
       if (Address <= Sym->getAddress() + Sym->getSize())
         return *Sym;
     return make_error<JITLinkError>("No symbol covering address " +
                                     formatv("{0:x16}", Address));
   }

   static Linkage getLinkage(uint16_t Desc);
   static Scope getScope(StringRef Name, uint8_t Type);
   static bool isAltEntry(const NormalizedSymbol &NSym);

   static bool isDebugSection(const NormalizedSection &NSec);
   static bool isZeroFillSection(const NormalizedSection &NSec);

   MachO::relocation_info
   getRelocationInfo(const object::relocation_iterator RelItr) {
     MachO::any_relocation_info ARI =
         getObject().getRelocation(RelItr->getRawDataRefImpl());
     MachO::relocation_info RI;
     RI.r_address = ARI.r_word0;
     RI.r_symbolnum = ARI.r_word1 & 0xffffff;
     RI.r_pcrel = (ARI.r_word1 >> 24) & 1;
     RI.r_length = (ARI.r_word1 >> 25) & 3;
     RI.r_extern = (ARI.r_word1 >> 27) & 1;
     RI.r_type = (ARI.r_word1 >> 28);
     return RI;
   }

 private:
   static unsigned getPointerSize(const object::MachOObjectFile &Obj);
   static support::endianness getEndianness(const object::MachOObjectFile &Obj);

   void setCanonicalSymbol(NormalizedSection &NSec, Symbol &Sym) {
     auto *&CanonicalSymEntry = NSec.CanonicalSymbols[Sym.getAddress()];
     // There should be no symbol at this address, or, if there is,
     // it should be a zero-sized symbol from an empty section (which
     // we can safely override).
     assert((!CanonicalSymEntry || CanonicalSymEntry->getSize() == 0) &&
            "Duplicate canonical symbol at address");
     CanonicalSymEntry = &Sym;
   }

   Section &getCommonSection();
   void addSectionStartSymAndBlock(unsigned SecIndex, Section &GraphSec,
                                   uint64_t Address, const char *Data,
                                   uint64_t Size, uint32_t Alignment,
                                   bool IsLive);

   Error createNormalizedSections();
   Error createNormalizedSymbols();

   /// Create graph blocks and symbols for externals, absolutes, commons and
   /// all defined symbols in sections without custom parsers.
   Error graphifyRegularSymbols();

   /// Create and return a graph symbol for the given normalized symbol.
   ///
   /// NSym's GraphSymbol member will be updated to point at the newly created
   /// symbol.
   Symbol &createStandardGraphSymbol(NormalizedSymbol &Sym, Block &B,
                                     size_t Size, bool IsText,
                                     bool IsNoDeadStrip, bool IsCanonical);

   /// Create graph blocks and symbols for all sections.
   Error graphifySectionsWithCustomParsers();

   /// Graphify cstring section.
   Error graphifyCStringSection(NormalizedSection &NSec,
                                std::vector<NormalizedSymbol *> NSyms);

   // Put the BumpPtrAllocator first so that we don't free any of the underlying
   // memory until the Symbol/Addressable destructors have been run.
   BumpPtrAllocator Allocator;

   const object::MachOObjectFile &Obj;
   std::unique_ptr<LinkGraph> G;

   DenseMap<unsigned, NormalizedSection> IndexToSection;
   Section *CommonSection = nullptr;

   DenseMap<uint32_t, NormalizedSymbol *> IndexToSymbol;
   StringMap<SectionParserFunction> CustomSectionParserFunctions;
 };

 /// A pass to split up __LD,__compact_unwind sections.
 class CompactUnwindSplitter {
 public:
   CompactUnwindSplitter(StringRef CompactUnwindSectionName)
       : CompactUnwindSectionName(CompactUnwindSectionName) {}
   Error operator()(LinkGraph &G);

 private:
   StringRef CompactUnwindSectionName;
 };

 } // end namespace jitlink
 } // end namespace llvm

 #endif // LIB_EXECUTIONENGINE_JITLINK_MACHOLINKGRAPHBUILDER_H
	//===----- MachOLinkGraphBuilder.h - MachO LinkGraph builder ----- C++ --===//
	//
	// 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
	//
	//===----------------------------------------------------------------------===//
	//
	// Generic MachO LinkGraph building code.
	//
	//===----------------------------------------------------------------------===//

	#ifndef LIB_EXECUTIONENGINE_JITLINK_MACHOLINKGRAPHBUILDER_H
	#define LIB_EXECUTIONENGINE_JITLINK_MACHOLINKGRAPHBUILDER_H

	#include "llvm/ADT/DenseMap.h"
	#include "llvm/ADT/StringMap.h"
	#include "llvm/ExecutionEngine/JITLink/JITLink.h"
	#include "llvm/Object/MachO.h"

	#include "EHFrameSupportImpl.h"
	#include "JITLinkGeneric.h"

	#include <list>

	namespace llvm {
	namespace jitlink {

	class MachOLinkGraphBuilder {
	public:
	virtual ~MachOLinkGraphBuilder();
	Expected<std::unique_ptr<LinkGraph>> buildGraph();

	protected:

	struct NormalizedSymbol {
	friend class MachOLinkGraphBuilder;

	private:
	NormalizedSymbol(Optional<StringRef> Name, uint64_t Value, uint8_t Type,
	uint8_t Sect, uint16_t Desc, Linkage L, Scope S)
	: Name(Name), Value(Value), Type(Type), Sect(Sect), Desc(Desc), L(L),
	S(S) {
	assert((!Name \|\| !Name->empty()) && "Name must be none or non-empty");
	}

	public:
	NormalizedSymbol(const NormalizedSymbol &) = delete;
	NormalizedSymbol &operator=(const NormalizedSymbol &) = delete;
	NormalizedSymbol(NormalizedSymbol &&) = delete;
	NormalizedSymbol &operator=(NormalizedSymbol &&) = delete;

	Optional<StringRef> Name;
	uint64_t Value = 0;
	uint8_t Type = 0;
	uint8_t Sect = 0;
	uint16_t Desc = 0;
	Linkage L = Linkage::Strong;
	Scope S = Scope::Default;
	Symbol *GraphSymbol = nullptr;
	};

	// Normalized section representation. Section and segment names are guaranteed
	// to be null-terminated, hence the extra bytes on SegName and SectName.
	class NormalizedSection {
	friend class MachOLinkGraphBuilder;

	private:
	NormalizedSection() = default;

	public:
	char SectName[17];
	char SegName[17];
	uint64_t Address = 0;
	uint64_t Size = 0;
	uint64_t Alignment = 0;
	uint32_t Flags = 0;
	const char *Data = nullptr;
	Section *GraphSection = nullptr;
	std::map<JITTargetAddress, Symbol *> CanonicalSymbols;
	};

	using SectionParserFunction = std::function<Error(NormalizedSection &S)>;

	MachOLinkGraphBuilder(const object::MachOObjectFile &Obj, Triple TT,
	LinkGraph::GetEdgeKindNameFunction GetEdgeKindName);

	LinkGraph &getGraph() const { return *G; }

	const object::MachOObjectFile &getObject() const { return Obj; }

	void addCustomSectionParser(StringRef SectionName,
	SectionParserFunction Parse);

	virtual Error addRelocations() = 0;

	/// Create a symbol.
	template <typename... ArgTs>
	NormalizedSymbol &createNormalizedSymbol(ArgTs &&... Args) {
	NormalizedSymbol Sym = reinterpret_cast<NormalizedSymbol >(
	Allocator.Allocate<NormalizedSymbol>());
	new (Sym) NormalizedSymbol(std::forward<ArgTs>(Args)...);
	return *Sym;
	}

	/// Index is zero-based (MachO section indexes are usually one-based) and
	/// assumed to be in-range. Client is responsible for checking.
	NormalizedSection &getSectionByIndex(unsigned Index) {
	auto I = IndexToSection.find(Index);
	assert(I != IndexToSection.end() && "No section recorded at index");
	return I->second;
	}

	/// Try to get the section at the given index. Will return an error if the
	/// given index is out of range, or if no section has been added for the given
	/// index.
	Expected<NormalizedSection &> findSectionByIndex(unsigned Index) {
	auto I = IndexToSection.find(Index);
	if (I == IndexToSection.end())
	return make_error<JITLinkError>("No section recorded for index " +
	formatv("{0:d}", Index));
	return I->second;
	}

	/// Try to get the symbol at the given index. Will return an error if the
	/// given index is out of range, or if no symbol has been added for the given
	/// index.
	Expected<NormalizedSymbol &> findSymbolByIndex(uint64_t Index) {
	auto I = IndexToSymbol.find(Index);
	if (I == IndexToSymbol.end())
	return make_error<JITLinkError>("No symbol at index " +
	formatv("{0:d}", Index));
	assert(I->second && "Null symbol at index");
	return *I->second;
	}

	/// Returns the symbol with the highest address not greater than the search
	/// address, or null if no such symbol exists.
	Symbol *getSymbolByAddress(NormalizedSection &NSec,
	JITTargetAddress Address) {
	auto I = NSec.CanonicalSymbols.upper_bound(Address);
	if (I == NSec.CanonicalSymbols.begin())
	return nullptr;
	return std::prev(I)->second;
	}

	/// Returns the symbol with the highest address not greater than the search
	/// address, or an error if no such symbol exists.
	Expected<Symbol &> findSymbolByAddress(NormalizedSection &NSec,
	JITTargetAddress Address) {
	auto *Sym = getSymbolByAddress(NSec, Address);
	if (Sym)
	if (Address <= Sym->getAddress() + Sym->getSize())
	return *Sym;
	return make_error<JITLinkError>("No symbol covering address " +
	formatv("{0:x16}", Address));
	}

	static Linkage getLinkage(uint16_t Desc);
	static Scope getScope(StringRef Name, uint8_t Type);
	static bool isAltEntry(const NormalizedSymbol &NSym);

	static bool isDebugSection(const NormalizedSection &NSec);
	static bool isZeroFillSection(const NormalizedSection &NSec);

	MachO::relocation_info
	getRelocationInfo(const object::relocation_iterator RelItr) {
	MachO::any_relocation_info ARI =
	getObject().getRelocation(RelItr->getRawDataRefImpl());
	MachO::relocation_info RI;
	RI.r_address = ARI.r_word0;
	RI.r_symbolnum = ARI.r_word1 & 0xffffff;
	RI.r_pcrel = (ARI.r_word1 >> 24) & 1;
	RI.r_length = (ARI.r_word1 >> 25) & 3;
	RI.r_extern = (ARI.r_word1 >> 27) & 1;
	RI.r_type = (ARI.r_word1 >> 28);
	return RI;
	}

	private:
	static unsigned getPointerSize(const object::MachOObjectFile &Obj);
	static support::endianness getEndianness(const object::MachOObjectFile &Obj);

	void setCanonicalSymbol(NormalizedSection &NSec, Symbol &Sym) {
	auto *&CanonicalSymEntry = NSec.CanonicalSymbols[Sym.getAddress()];
	// There should be no symbol at this address, or, if there is,
	// it should be a zero-sized symbol from an empty section (which
	// we can safely override).
	assert((!CanonicalSymEntry \|\| CanonicalSymEntry->getSize() == 0) &&
	"Duplicate canonical symbol at address");
	CanonicalSymEntry = &Sym;
	}

	Section &getCommonSection();
	void addSectionStartSymAndBlock(unsigned SecIndex, Section &GraphSec,
	uint64_t Address, const char *Data,
	uint64_t Size, uint32_t Alignment,
	bool IsLive);

	Error createNormalizedSections();
	Error createNormalizedSymbols();

	/// Create graph blocks and symbols for externals, absolutes, commons and
	/// all defined symbols in sections without custom parsers.
	Error graphifyRegularSymbols();

	/// Create and return a graph symbol for the given normalized symbol.
	///
	/// NSym's GraphSymbol member will be updated to point at the newly created
	/// symbol.
	Symbol &createStandardGraphSymbol(NormalizedSymbol &Sym, Block &B,
	size_t Size, bool IsText,
	bool IsNoDeadStrip, bool IsCanonical);

	/// Create graph blocks and symbols for all sections.
	Error graphifySectionsWithCustomParsers();

	/// Graphify cstring section.
	Error graphifyCStringSection(NormalizedSection &NSec,
	std::vector<NormalizedSymbol *> NSyms);

	// Put the BumpPtrAllocator first so that we don't free any of the underlying
	// memory until the Symbol/Addressable destructors have been run.
	BumpPtrAllocator Allocator;

	const object::MachOObjectFile &Obj;
	std::unique_ptr<LinkGraph> G;

	DenseMap<unsigned, NormalizedSection> IndexToSection;
	Section *CommonSection = nullptr;

	DenseMap<uint32_t, NormalizedSymbol *> IndexToSymbol;
	StringMap<SectionParserFunction> CustomSectionParserFunctions;
	};

	/// A pass to split up __LD,__compact_unwind sections.
	class CompactUnwindSplitter {
	public:
	CompactUnwindSplitter(StringRef CompactUnwindSectionName)
	: CompactUnwindSectionName(CompactUnwindSectionName) {}
	Error operator()(LinkGraph &G);

	private:
	StringRef CompactUnwindSectionName;
	};

	} // end namespace jitlink
	} // end namespace llvm

	#endif // LIB_EXECUTIONENGINE_JITLINK_MACHOLINKGRAPHBUILDER_H