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//===- IndirectionUtils.h - Utilities for adding indirections ---*- 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
// Contains utilities for adding indirections and breaking up modules.
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ExecutionEngine/JITSymbol.h"
#include "llvm/ExecutionEngine/Orc/Core.h"
#include "llvm/ExecutionEngine/Orc/OrcABISupport.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/Memory.h"
#include "llvm/Support/Process.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <functional>
#include <future>
#include <map>
#include <memory>
#include <system_error>
#include <utility>
#include <vector>
namespace llvm {
class Constant;
class Function;
class FunctionType;
class GlobalAlias;
class GlobalVariable;
class Module;
class PointerType;
class Triple;
class Twine;
class Value;
class MCDisassembler;
class MCInstrAnalysis;
namespace jitlink {
class LinkGraph;
class Symbol;
} // namespace jitlink
namespace orc {
/// Base class for pools of compiler re-entry trampolines.
/// These trampolines are callable addresses that save all register state
/// before calling a supplied function to return the trampoline landing
/// address, then restore all state before jumping to that address. They
/// are used by various ORC APIs to support lazy compilation
class TrampolinePool {
using NotifyLandingResolvedFunction =
unique_function<void(JITTargetAddress) const>;
using ResolveLandingFunction = unique_function<void(
JITTargetAddress TrampolineAddr,
NotifyLandingResolvedFunction OnLandingResolved) const>;
virtual ~TrampolinePool();
/// Get an available trampoline address.
/// Returns an error if no trampoline can be created.
Expected<JITTargetAddress> getTrampoline() {
std::lock_guard<std::mutex> Lock(TPMutex);
if (AvailableTrampolines.empty()) {
if (auto Err = grow())
return std::move(Err);
assert(!AvailableTrampolines.empty() && "Failed to grow trampoline pool");
auto TrampolineAddr = AvailableTrampolines.back();
return TrampolineAddr;
/// Returns the given trampoline to the pool for re-use.
void releaseTrampoline(JITTargetAddress TrampolineAddr) {
std::lock_guard<std::mutex> Lock(TPMutex);
virtual Error grow() = 0;
std::mutex TPMutex;
std::vector<JITTargetAddress> AvailableTrampolines;
/// A trampoline pool for trampolines within the current process.
template <typename ORCABI> class LocalTrampolinePool : public TrampolinePool {
/// Creates a LocalTrampolinePool with the given RunCallback function.
/// Returns an error if this function is unable to correctly allocate, write
/// and protect the resolver code block.
static Expected<std::unique_ptr<LocalTrampolinePool>>
Create(ResolveLandingFunction ResolveLanding) {
Error Err = Error::success();
auto LTP = std::unique_ptr<LocalTrampolinePool>(
new LocalTrampolinePool(std::move(ResolveLanding), Err));
if (Err)
return std::move(Err);
return std::move(LTP);
static JITTargetAddress reenter(void *TrampolinePoolPtr, void *TrampolineId) {
LocalTrampolinePool<ORCABI> *TrampolinePool =
static_cast<LocalTrampolinePool *>(TrampolinePoolPtr);
std::promise<JITTargetAddress> LandingAddressP;
auto LandingAddressF = LandingAddressP.get_future();
[&](JITTargetAddress LandingAddress) {
return LandingAddressF.get();
LocalTrampolinePool(ResolveLandingFunction ResolveLanding, Error &Err)
: ResolveLanding(std::move(ResolveLanding)) {
ErrorAsOutParameter _(&Err);
/// Try to set up the resolver block.
std::error_code EC;
ResolverBlock = sys::OwningMemoryBlock(sys::Memory::allocateMappedMemory(
ORCABI::ResolverCodeSize, nullptr,
sys::Memory::MF_READ | sys::Memory::MF_WRITE, EC));
if (EC) {
Err = errorCodeToError(EC);
ORCABI::writeResolverCode(static_cast<char *>(ResolverBlock.base()),
EC = sys::Memory::protectMappedMemory(ResolverBlock.getMemoryBlock(),
sys::Memory::MF_READ |
if (EC) {
Err = errorCodeToError(EC);
Error grow() override {
assert(AvailableTrampolines.empty() && "Growing prematurely?");
std::error_code EC;
auto TrampolineBlock =
sys::Process::getPageSizeEstimate(), nullptr,
sys::Memory::MF_READ | sys::Memory::MF_WRITE, EC));
if (EC)
return errorCodeToError(EC);
unsigned NumTrampolines =
(sys::Process::getPageSizeEstimate() - ORCABI::PointerSize) /
char *TrampolineMem = static_cast<char *>(TrampolineBlock.base());
TrampolineMem, pointerToJITTargetAddress(TrampolineMem),
pointerToJITTargetAddress(ResolverBlock.base()), NumTrampolines);
for (unsigned I = 0; I < NumTrampolines; ++I)
TrampolineMem + (I * ORCABI::TrampolineSize)));
if (auto EC = sys::Memory::protectMappedMemory(
sys::Memory::MF_READ | sys::Memory::MF_EXEC))
return errorCodeToError(EC);
return Error::success();
ResolveLandingFunction ResolveLanding;
sys::OwningMemoryBlock ResolverBlock;
std::vector<sys::OwningMemoryBlock> TrampolineBlocks;
/// Target-independent base class for compile callback management.
class JITCompileCallbackManager {
using CompileFunction = std::function<JITTargetAddress()>;
virtual ~JITCompileCallbackManager() = default;
/// Reserve a compile callback.
Expected<JITTargetAddress> getCompileCallback(CompileFunction Compile);
/// Execute the callback for the given trampoline id. Called by the JIT
/// to compile functions on demand.
JITTargetAddress executeCompileCallback(JITTargetAddress TrampolineAddr);
/// Construct a JITCompileCallbackManager.
JITCompileCallbackManager(std::unique_ptr<TrampolinePool> TP,
ExecutionSession &ES,
JITTargetAddress ErrorHandlerAddress)
: TP(std::move(TP)), ES(ES),
ErrorHandlerAddress(ErrorHandlerAddress) {}
void setTrampolinePool(std::unique_ptr<TrampolinePool> TP) {
this->TP = std::move(TP);
std::mutex CCMgrMutex;
std::unique_ptr<TrampolinePool> TP;
ExecutionSession &ES;
JITDylib &CallbacksJD;
JITTargetAddress ErrorHandlerAddress;
std::map<JITTargetAddress, SymbolStringPtr> AddrToSymbol;
size_t NextCallbackId = 0;
/// Manage compile callbacks for in-process JITs.
template <typename ORCABI>
class LocalJITCompileCallbackManager : public JITCompileCallbackManager {
/// Create a new LocalJITCompileCallbackManager.
static Expected<std::unique_ptr<LocalJITCompileCallbackManager>>
Create(ExecutionSession &ES, JITTargetAddress ErrorHandlerAddress) {
Error Err = Error::success();
auto CCMgr = std::unique_ptr<LocalJITCompileCallbackManager>(
new LocalJITCompileCallbackManager(ES, ErrorHandlerAddress, Err));
if (Err)
return std::move(Err);
return std::move(CCMgr);
/// Construct a InProcessJITCompileCallbackManager.
/// @param ErrorHandlerAddress The address of an error handler in the target
/// process to be used if a compile callback fails.
LocalJITCompileCallbackManager(ExecutionSession &ES,
JITTargetAddress ErrorHandlerAddress,
Error &Err)
: JITCompileCallbackManager(nullptr, ES, ErrorHandlerAddress) {
using NotifyLandingResolvedFunction =
ErrorAsOutParameter _(&Err);
auto TP = LocalTrampolinePool<ORCABI>::Create(
[this](JITTargetAddress TrampolineAddr,
NotifyLandingResolvedFunction NotifyLandingResolved) {
if (!TP) {
Err = TP.takeError();
/// Base class for managing collections of named indirect stubs.
class IndirectStubsManager {
/// Map type for initializing the manager. See init.
using StubInitsMap = StringMap<std::pair<JITTargetAddress, JITSymbolFlags>>;
virtual ~IndirectStubsManager() = default;
/// Create a single stub with the given name, target address and flags.
virtual Error createStub(StringRef StubName, JITTargetAddress StubAddr,
JITSymbolFlags StubFlags) = 0;
/// Create StubInits.size() stubs with the given names, target
/// addresses, and flags.
virtual Error createStubs(const StubInitsMap &StubInits) = 0;
/// Find the stub with the given name. If ExportedStubsOnly is true,
/// this will only return a result if the stub's flags indicate that it
/// is exported.
virtual JITEvaluatedSymbol findStub(StringRef Name, bool ExportedStubsOnly) = 0;
/// Find the implementation-pointer for the stub.
virtual JITEvaluatedSymbol findPointer(StringRef Name) = 0;
/// Change the value of the implementation pointer for the stub.
virtual Error updatePointer(StringRef Name, JITTargetAddress NewAddr) = 0;
virtual void anchor();
template <typename ORCABI> class LocalIndirectStubsInfo {
LocalIndirectStubsInfo(unsigned NumStubs, sys::OwningMemoryBlock StubsMem)
: NumStubs(NumStubs), StubsMem(std::move(StubsMem)) {}
static Expected<LocalIndirectStubsInfo> create(unsigned MinStubs,
unsigned PageSize) {
auto ISAS = getIndirectStubsBlockSizes<ORCABI>(MinStubs, PageSize);
assert((ISAS.StubBytes % PageSize == 0) &&
"StubBytes is not a page size multiple");
uint64_t PointerAlloc = alignTo(ISAS.PointerBytes, PageSize);
// Allocate memory for stubs and pointers in one call.
std::error_code EC;
auto StubsAndPtrsMem =
ISAS.StubBytes + PointerAlloc, nullptr,
sys::Memory::MF_READ | sys::Memory::MF_WRITE, EC));
if (EC)
return errorCodeToError(EC);
sys::MemoryBlock StubsBlock(StubsAndPtrsMem.base(), ISAS.StubBytes);
auto StubsBlockMem = static_cast<char *>(StubsAndPtrsMem.base());
auto PtrBlockAddress =
pointerToJITTargetAddress(StubsBlockMem) + ISAS.StubBytes;
PtrBlockAddress, ISAS.NumStubs);
if (auto EC = sys::Memory::protectMappedMemory(
StubsBlock, sys::Memory::MF_READ | sys::Memory::MF_EXEC))
return errorCodeToError(EC);
return LocalIndirectStubsInfo(ISAS.NumStubs, std::move(StubsAndPtrsMem));
unsigned getNumStubs() const { return NumStubs; }
void *getStub(unsigned Idx) const {
return static_cast<char *>(StubsMem.base()) + Idx * ORCABI::StubSize;
void **getPtr(unsigned Idx) const {
char *PtrsBase =
static_cast<char *>(StubsMem.base()) + NumStubs * ORCABI::StubSize;
return reinterpret_cast<void **>(PtrsBase) + Idx;
unsigned NumStubs = 0;
sys::OwningMemoryBlock StubsMem;
/// IndirectStubsManager implementation for the host architecture, e.g.
/// OrcX86_64. (See OrcArchitectureSupport.h).
template <typename TargetT>
class LocalIndirectStubsManager : public IndirectStubsManager {
Error createStub(StringRef StubName, JITTargetAddress StubAddr,
JITSymbolFlags StubFlags) override {
std::lock_guard<std::mutex> Lock(StubsMutex);
if (auto Err = reserveStubs(1))
return Err;
createStubInternal(StubName, StubAddr, StubFlags);
return Error::success();
Error createStubs(const StubInitsMap &StubInits) override {
std::lock_guard<std::mutex> Lock(StubsMutex);
if (auto Err = reserveStubs(StubInits.size()))
return Err;
for (auto &Entry : StubInits)
createStubInternal(Entry.first(), Entry.second.first,
return Error::success();
JITEvaluatedSymbol findStub(StringRef Name, bool ExportedStubsOnly) override {
std::lock_guard<std::mutex> Lock(StubsMutex);
auto I = StubIndexes.find(Name);
if (I == StubIndexes.end())
return nullptr;
auto Key = I->second.first;
void *StubAddr = IndirectStubsInfos[Key.first].getStub(Key.second);
assert(StubAddr && "Missing stub address");
auto StubTargetAddr =
auto StubSymbol = JITEvaluatedSymbol(StubTargetAddr, I->second.second);
if (ExportedStubsOnly && !StubSymbol.getFlags().isExported())
return nullptr;
return StubSymbol;
JITEvaluatedSymbol findPointer(StringRef Name) override {
std::lock_guard<std::mutex> Lock(StubsMutex);
auto I = StubIndexes.find(Name);
if (I == StubIndexes.end())
return nullptr;
auto Key = I->second.first;
void *PtrAddr = IndirectStubsInfos[Key.first].getPtr(Key.second);
assert(PtrAddr && "Missing pointer address");
auto PtrTargetAddr =
return JITEvaluatedSymbol(PtrTargetAddr, I->second.second);
Error updatePointer(StringRef Name, JITTargetAddress NewAddr) override {
using AtomicIntPtr = std::atomic<uintptr_t>;
std::lock_guard<std::mutex> Lock(StubsMutex);
auto I = StubIndexes.find(Name);
assert(I != StubIndexes.end() && "No stub pointer for symbol");
auto Key = I->second.first;
AtomicIntPtr *AtomicStubPtr = reinterpret_cast<AtomicIntPtr *>(
*AtomicStubPtr = static_cast<uintptr_t>(NewAddr);
return Error::success();
Error reserveStubs(unsigned NumStubs) {
if (NumStubs <= FreeStubs.size())
return Error::success();
unsigned NewStubsRequired = NumStubs - FreeStubs.size();
unsigned NewBlockId = IndirectStubsInfos.size();
auto ISI =
LocalIndirectStubsInfo<TargetT>::create(NewStubsRequired, PageSize);
if (!ISI)
return ISI.takeError();
for (unsigned I = 0; I < ISI->getNumStubs(); ++I)
FreeStubs.push_back(std::make_pair(NewBlockId, I));
return Error::success();
void createStubInternal(StringRef StubName, JITTargetAddress InitAddr,
JITSymbolFlags StubFlags) {
auto Key = FreeStubs.back();
*IndirectStubsInfos[Key.first].getPtr(Key.second) =
jitTargetAddressToPointer<void *>(InitAddr);
StubIndexes[StubName] = std::make_pair(Key, StubFlags);
unsigned PageSize = sys::Process::getPageSizeEstimate();
std::mutex StubsMutex;
std::vector<LocalIndirectStubsInfo<TargetT>> IndirectStubsInfos;
using StubKey = std::pair<uint16_t, uint16_t>;
std::vector<StubKey> FreeStubs;
StringMap<std::pair<StubKey, JITSymbolFlags>> StubIndexes;
/// Create a local compile callback manager.
/// The given target triple will determine the ABI, and the given
/// ErrorHandlerAddress will be used by the resulting compile callback
/// manager if a compile callback fails.
createLocalCompileCallbackManager(const Triple &T, ExecutionSession &ES,
JITTargetAddress ErrorHandlerAddress);
/// Create a local indriect stubs manager builder.
/// The given target triple will determine the ABI.
createLocalIndirectStubsManagerBuilder(const Triple &T);
/// Build a function pointer of FunctionType with the given constant
/// address.
/// Usage example: Turn a trampoline address into a function pointer constant
/// for use in a stub.
Constant *createIRTypedAddress(FunctionType &FT, JITTargetAddress Addr);
/// Create a function pointer with the given type, name, and initializer
/// in the given Module.
GlobalVariable *createImplPointer(PointerType &PT, Module &M, const Twine &Name,
Constant *Initializer);
/// Turn a function declaration into a stub function that makes an
/// indirect call using the given function pointer.
void makeStub(Function &F, Value &ImplPointer);
/// Promotes private symbols to global hidden, and renames to prevent clashes
/// with other promoted symbols. The same SymbolPromoter instance should be
/// used for all symbols to be added to a single JITDylib.
class SymbolLinkagePromoter {
/// Promote symbols in the given module. Returns the set of global values
/// that have been renamed/promoted.
std::vector<GlobalValue *> operator()(Module &M);
unsigned NextId = 0;
/// Clone a function declaration into a new module.
/// This function can be used as the first step towards creating a callback
/// stub (see makeStub), or moving a function body (see moveFunctionBody).
/// If the VMap argument is non-null, a mapping will be added between F and
/// the new declaration, and between each of F's arguments and the new
/// declaration's arguments. This map can then be passed in to moveFunction to
/// move the function body if required. Note: When moving functions between
/// modules with these utilities, all decls should be cloned (and added to a
/// single VMap) before any bodies are moved. This will ensure that references
/// between functions all refer to the versions in the new module.
Function *cloneFunctionDecl(Module &Dst, const Function &F,
ValueToValueMapTy *VMap = nullptr);
/// Move the body of function 'F' to a cloned function declaration in a
/// different module (See related cloneFunctionDecl).
/// If the target function declaration is not supplied via the NewF parameter
/// then it will be looked up via the VMap.
/// This will delete the body of function 'F' from its original parent module,
/// but leave its declaration.
void moveFunctionBody(Function &OrigF, ValueToValueMapTy &VMap,
ValueMaterializer *Materializer = nullptr,
Function *NewF = nullptr);
/// Clone a global variable declaration into a new module.
GlobalVariable *cloneGlobalVariableDecl(Module &Dst, const GlobalVariable &GV,
ValueToValueMapTy *VMap = nullptr);
/// Move global variable GV from its parent module to cloned global
/// declaration in a different module.
/// If the target global declaration is not supplied via the NewGV parameter
/// then it will be looked up via the VMap.
/// This will delete the initializer of GV from its original parent module,
/// but leave its declaration.
void moveGlobalVariableInitializer(GlobalVariable &OrigGV,
ValueToValueMapTy &VMap,
ValueMaterializer *Materializer = nullptr,
GlobalVariable *NewGV = nullptr);
/// Clone a global alias declaration into a new module.
GlobalAlias *cloneGlobalAliasDecl(Module &Dst, const GlobalAlias &OrigA,
ValueToValueMapTy &VMap);
/// Clone module flags metadata into the destination module.
void cloneModuleFlagsMetadata(Module &Dst, const Module &Src,
ValueToValueMapTy &VMap);
/// Introduce relocations to \p Sym in its own definition if there are any
/// pointers formed via PC-relative address that do not already have a
/// relocation.
/// This is useful when introducing indirection via a stub function at link time
/// without compiler support. If a function pointer is formed without a
/// relocation, e.g. in the definition of \c foo
/// \code
/// _foo:
/// leaq -7(%rip), rax # form pointer to _foo without relocation
/// _bar:
/// leaq (%rip), %rax # uses X86_64_RELOC_SIGNED to '_foo'
/// \endcode
/// the pointer to \c _foo computed by \c _foo and \c _bar may differ if we
/// introduce a stub for _foo. If the pointer is used as a key, this may be
/// observable to the program. This pass will attempt to introduce the missing
/// "self-relocation" on the leaq instruction.
/// This is based on disassembly and should be considered "best effort". It may
/// silently fail to add relocations.
Error addFunctionPointerRelocationsToCurrentSymbol(jitlink::Symbol &Sym,
jitlink::LinkGraph &G,
MCDisassembler &Disassembler,
MCInstrAnalysis &MIA);
} // end namespace orc
} // end namespace llvm