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//===-- IRExecutionUnit.h ---------------------------------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include <atomic>
#include <memory>
#include <string>
#include <vector>
#include "llvm/ExecutionEngine/SectionMemoryManager.h"
#include "llvm/IR/Module.h"
#include "lldb/Expression/IRMemoryMap.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/SymbolContext.h"
#include "lldb/Utility/DataBufferHeap.h"
#include "lldb/lldb-forward.h"
#include "lldb/lldb-private.h"
namespace llvm {
class Module;
class ExecutionEngine;
class ObjectCache;
} // namespace llvm
namespace lldb_private {
class Status;
/// \class IRExecutionUnit IRExecutionUnit.h
/// "lldb/Expression/IRExecutionUnit.h" Contains the IR and, optionally, JIT-
/// compiled code for a module.
/// This class encapsulates the compiled version of an expression, in IR form
/// (for interpretation purposes) and in raw machine code form (for execution
/// in the target).
/// This object wraps an IR module that comes from the expression parser, and
/// knows how to use the JIT to make it into executable code. It can then be
/// used as input to the IR interpreter, or the address of the executable code
/// can be passed to a thread plan to run in the target.
/// This class creates a subclass of LLVM's SectionMemoryManager, because that
/// is how the JIT emits code. Because LLDB needs to move JIT-compiled code
/// into the target process, the IRExecutionUnit knows how to copy the emitted
/// code into the target process.
class IRExecutionUnit : public std::enable_shared_from_this<IRExecutionUnit>,
public IRMemoryMap,
public ObjectFileJITDelegate {
/// Constructor
IRExecutionUnit(std::unique_ptr<llvm::LLVMContext> &context_up,
std::unique_ptr<llvm::Module> &module_up, ConstString &name,
const lldb::TargetSP &target_sp, const SymbolContext &sym_ctx,
std::vector<std::string> &cpu_features);
/// Destructor
~IRExecutionUnit() override;
ConstString GetFunctionName() { return m_name; }
llvm::Module *GetModule() { return m_module; }
llvm::Function *GetFunction() {
return ((m_module != nullptr) ? m_module->getFunction(m_name.GetStringRef())
: nullptr);
void GetRunnableInfo(Status &error, lldb::addr_t &func_addr,
lldb::addr_t &func_end);
/// Accessors for IRForTarget and other clients that may want binary data
/// placed on their behalf. The binary data is owned by the IRExecutionUnit
/// unless the client explicitly chooses to free it.
lldb::addr_t WriteNow(const uint8_t *bytes, size_t size, Status &error);
void FreeNow(lldb::addr_t allocation);
/// ObjectFileJITDelegate overrides
lldb::ByteOrder GetByteOrder() const override;
uint32_t GetAddressByteSize() const override;
void PopulateSymtab(lldb_private::ObjectFile *obj_file,
lldb_private::Symtab &symtab) override;
void PopulateSectionList(lldb_private::ObjectFile *obj_file,
lldb_private::SectionList &section_list) override;
ArchSpec GetArchitecture() override;
lldb::ModuleSP GetJITModule();
lldb::addr_t FindSymbol(ConstString name, bool &missing_weak);
void GetStaticInitializers(std::vector<lldb::addr_t> &static_initializers);
/// \class JittedFunction IRExecutionUnit.h
/// "lldb/Expression/IRExecutionUnit.h"
/// Encapsulates a single function that has been generated by the JIT.
/// Functions that have been generated by the JIT are first resident in the
/// local process, and then placed in the target process. JittedFunction
/// represents a function possibly resident in both.
struct JittedEntity {
ConstString m_name; ///< The function's name
lldb::addr_t m_local_addr; ///< The address of the function in LLDB's memory
m_remote_addr; ///< The address of the function in the target's memory
/// Constructor
/// Initializes class variabes.
/// \param[in] name
/// The name of the function.
/// \param[in] local_addr
/// The address of the function in LLDB, or LLDB_INVALID_ADDRESS if
/// it is not present in LLDB's memory.
/// \param[in] remote_addr
/// The address of the function in the target, or LLDB_INVALID_ADDRESS
/// if it is not present in the target's memory.
JittedEntity(const char *name,
lldb::addr_t local_addr = LLDB_INVALID_ADDRESS,
lldb::addr_t remote_addr = LLDB_INVALID_ADDRESS)
: m_name(name), m_local_addr(local_addr), m_remote_addr(remote_addr) {}
struct JittedFunction : JittedEntity {
bool m_external;
JittedFunction(const char *name, bool external,
lldb::addr_t local_addr = LLDB_INVALID_ADDRESS,
lldb::addr_t remote_addr = LLDB_INVALID_ADDRESS)
: JittedEntity(name, local_addr, remote_addr), m_external(external) {}
struct JittedGlobalVariable : JittedEntity {
JittedGlobalVariable(const char *name,
lldb::addr_t local_addr = LLDB_INVALID_ADDRESS,
lldb::addr_t remote_addr = LLDB_INVALID_ADDRESS)
: JittedEntity(name, local_addr, remote_addr) {}
const std::vector<JittedFunction> &GetJittedFunctions() {
return m_jitted_functions;
const std::vector<JittedGlobalVariable> &GetJittedGlobalVariables() {
return m_jitted_global_variables;
/// Look up the object in m_address_map that contains a given address, find
/// where it was copied to, and return the remote address at the same offset
/// into the copied entity
/// \param[in] local_address
/// The address in the debugger.
/// \return
/// The address in the target process.
lldb::addr_t GetRemoteAddressForLocal(lldb::addr_t local_address);
typedef std::pair<lldb::addr_t, uintptr_t> AddrRange;
/// Look up the object in m_address_map that contains a given address, find
/// where it was copied to, and return its address range in the target
/// process
/// \param[in] local_address
/// The address in the debugger.
/// \return
/// The range of the containing object in the target process.
AddrRange GetRemoteRangeForLocal(lldb::addr_t local_address);
/// Commit all allocations to the process and record where they were stored.
/// \param[in] process_sp
/// The process to allocate memory in.
/// \return
/// True <=> all allocations were performed successfully.
/// This method will attempt to free allocated memory if the
/// operation fails.
bool CommitAllocations(lldb::ProcessSP &process_sp);
/// Report all committed allocations to the execution engine.
/// \param[in] engine
/// The execution engine to notify.
void ReportAllocations(llvm::ExecutionEngine &engine);
/// Write the contents of all allocations to the process.
/// \param[in] process_sp
/// The process containing the allocations.
/// \return
/// True <=> all allocations were performed successfully.
bool WriteData(lldb::ProcessSP &process_sp);
Status DisassembleFunction(Stream &stream, lldb::ProcessSP &process_sp);
void CollectCandidateCNames(std::vector<ConstString> &C_names,
ConstString name);
void CollectCandidateCPlusPlusNames(std::vector<ConstString> &CPP_names,
const std::vector<ConstString> &C_names,
const SymbolContext &sc);
lldb::addr_t FindInSymbols(const std::vector<ConstString> &names,
const lldb_private::SymbolContext &sc,
bool &symbol_was_missing_weak);
lldb::addr_t FindInRuntimes(const std::vector<ConstString> &names,
const lldb_private::SymbolContext &sc);
lldb::addr_t FindInUserDefinedSymbols(const std::vector<ConstString> &names,
const lldb_private::SymbolContext &sc);
void ReportSymbolLookupError(ConstString name);
class MemoryManager : public llvm::SectionMemoryManager {
MemoryManager(IRExecutionUnit &parent);
~MemoryManager() override;
/// Allocate space for executable code, and add it to the m_spaceBlocks
/// map
/// \param[in] Size
/// The size of the area.
/// \param[in] Alignment
/// The required alignment of the area.
/// \param[in] SectionID
/// A unique identifier for the section.
/// \return
/// Allocated space.
uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
unsigned SectionID,
llvm::StringRef SectionName) override;
/// Allocate space for data, and add it to the m_spaceBlocks map
/// \param[in] Size
/// The size of the area.
/// \param[in] Alignment
/// The required alignment of the area.
/// \param[in] SectionID
/// A unique identifier for the section.
/// \param[in] IsReadOnly
/// Flag indicating the section is read-only.
/// \return
/// Allocated space.
uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
unsigned SectionID,
llvm::StringRef SectionName,
bool IsReadOnly) override;
/// Called when object loading is complete and section page permissions
/// can be applied. Currently unimplemented for LLDB.
/// \param[out] ErrMsg
/// The error that prevented the page protection from succeeding.
/// \return
/// True in case of failure, false in case of success.
bool finalizeMemory(std::string *ErrMsg) override {
// TODO: Ensure that the instruction cache is flushed because
// relocations are updated by dy-load. See:
// sys::Memory::InvalidateInstructionCache
// llvm::SectionMemoryManager
return false;
// Ignore any EHFrame registration.
void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
size_t Size) override {}
void deregisterEHFrames() override {}
uint64_t getSymbolAddress(const std::string &Name) override;
// Find the address of the symbol Name. If Name is a missing weak symbol
// then missing_weak will be true.
uint64_t GetSymbolAddressAndPresence(const std::string &Name,
bool &missing_weak);
llvm::JITSymbol findSymbol(const std::string &Name) override;
void *getPointerToNamedFunction(const std::string &Name,
bool AbortOnFailure = true) override;
std::unique_ptr<SectionMemoryManager> m_default_mm_up; ///< The memory
/// allocator to use
/// in actually
/// creating space.
/// All calls are
/// passed through to
/// it.
IRExecutionUnit &m_parent; ///< The execution unit this is a proxy for.
static const unsigned eSectionIDInvalid = (unsigned)-1;
enum class AllocationKind { Stub, Code, Data, Global, Bytes };
static lldb::SectionType
GetSectionTypeFromSectionName(const llvm::StringRef &name,
AllocationKind alloc_kind);
/// Encapsulates a single allocation request made by the JIT.
/// Allocations made by the JIT are first queued up and then applied in bulk
/// to the underlying process.
struct AllocationRecord {
std::string m_name;
lldb::addr_t m_process_address;
uintptr_t m_host_address;
uint32_t m_permissions;
lldb::SectionType m_sect_type;
size_t m_size;
unsigned m_alignment;
unsigned m_section_id;
AllocationRecord(uintptr_t host_address, uint32_t permissions,
lldb::SectionType sect_type, size_t size,
unsigned alignment, unsigned section_id, const char *name)
: m_name(), m_process_address(LLDB_INVALID_ADDRESS),
m_host_address(host_address), m_permissions(permissions),
m_sect_type(sect_type), m_size(size), m_alignment(alignment),
m_section_id(section_id) {
if (name && name[0])
m_name = name;
void dump(Log *log);
bool CommitOneAllocation(lldb::ProcessSP &process_sp, Status &error,
AllocationRecord &record);
typedef std::vector<AllocationRecord> RecordVector;
RecordVector m_records;
std::unique_ptr<llvm::LLVMContext> m_context_up;
std::unique_ptr<llvm::ExecutionEngine> m_execution_engine_up;
std::unique_ptr<llvm::ObjectCache> m_object_cache_up;
m_module_up; ///< Holder for the module until it's been handed off
llvm::Module *m_module; ///< Owned by the execution engine
std::vector<std::string> m_cpu_features;
std::vector<JittedFunction> m_jitted_functions; ///< A vector of all functions
///that have been JITted into
///machine code
std::vector<JittedGlobalVariable> m_jitted_global_variables; ///< A vector of
///all functions
///that have been
///JITted into
///machine code
const ConstString m_name;
SymbolContext m_sym_ctx; ///< Used for symbol lookups
std::vector<ConstString> m_failed_lookups;
std::atomic<bool> m_did_jit;
lldb::addr_t m_function_load_addr;
lldb::addr_t m_function_end_load_addr;
bool m_strip_underscore = true; ///< True for platforms where global symbols
/// have a _ prefix
bool m_reported_allocations; ///< True after allocations have been reported.
///It is possible that
///< sections will be allocated when this is true, in which case they weren't
///< depended on by any function. (Top-level code defining a variable, but
///< defining no functions using that variable, would do this.) If this
///< is true, any allocations need to be committed immediately -- no
///< opportunity for relocation.
} // namespace lldb_private