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//===------ JITLinkGeneric.h - Generic JIT linker utilities -----*- 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 JITLinker utilities. E.g. graph pruning, eh-frame parsing.
//
//===----------------------------------------------------------------------===//
#ifndef LIB_EXECUTIONENGINE_JITLINK_JITLINKGENERIC_H
#define LIB_EXECUTIONENGINE_JITLINK_JITLINKGENERIC_H
#include "llvm/ADT/DenseSet.h"
#include "llvm/ExecutionEngine/JITLink/JITLink.h"
#define DEBUG_TYPE "jitlink"
namespace llvm {
namespace jitlink {
/// Base class for a JIT linker.
///
/// A JITLinkerBase instance links one object file into an ongoing JIT
/// session. Symbol resolution and finalization operations are pluggable,
/// and called using continuation passing (passing a continuation for the
/// remaining linker work) to allow them to be performed asynchronously.
class JITLinkerBase {
public:
JITLinkerBase(std::unique_ptr<JITLinkContext> Ctx,
std::unique_ptr<LinkGraph> G, PassConfiguration Passes)
: Ctx(std::move(Ctx)), G(std::move(G)), Passes(std::move(Passes)) {
assert(this->Ctx && "Ctx can not be null");
assert(this->G && "G can not be null");
}
virtual ~JITLinkerBase();
protected:
using InFlightAlloc = JITLinkMemoryManager::InFlightAlloc;
using AllocResult = Expected<std::unique_ptr<InFlightAlloc>>;
using FinalizeResult = Expected<JITLinkMemoryManager::FinalizedAlloc>;
// Returns the PassConfiguration for this instance. This can be used by
// JITLinkerBase implementations to add late passes that reference their
// own data structures (e.g. for ELF implementations to locate / construct
// a GOT start symbol prior to fixup).
PassConfiguration &getPassConfig() { return Passes; }
// Phase 1:
// 1.1: Run pre-prune passes
// 1.2: Prune graph
// 1.3: Run post-prune passes
// 1.4: Allocate memory.
void linkPhase1(std::unique_ptr<JITLinkerBase> Self);
// Phase 2:
// 2.2: Run post-allocation passes
// 2.3: Notify context of final assigned symbol addresses
// 2.4: Identify external symbols and make an async call to resolve
void linkPhase2(std::unique_ptr<JITLinkerBase> Self, AllocResult AR);
// Phase 3:
// 3.1: Apply resolution results
// 3.2: Run pre-fixup passes
// 3.3: Fix up block contents
// 3.4: Run post-fixup passes
// 3.5: Make an async call to transfer and finalize memory.
void linkPhase3(std::unique_ptr<JITLinkerBase> Self,
Expected<AsyncLookupResult> LookupResult);
// Phase 4:
// 4.1: Call OnFinalized callback, handing off allocation.
void linkPhase4(std::unique_ptr<JITLinkerBase> Self, FinalizeResult FR);
private:
// Run all passes in the given pass list, bailing out immediately if any pass
// returns an error.
Error runPasses(LinkGraphPassList &Passes);
// Copy block contents and apply relocations.
// Implemented in JITLinker.
virtual Error fixUpBlocks(LinkGraph &G) const = 0;
JITLinkContext::LookupMap getExternalSymbolNames() const;
void applyLookupResult(AsyncLookupResult LR);
void abandonAllocAndBailOut(std::unique_ptr<JITLinkerBase> Self, Error Err);
std::unique_ptr<JITLinkContext> Ctx;
std::unique_ptr<LinkGraph> G;
PassConfiguration Passes;
std::unique_ptr<InFlightAlloc> Alloc;
};
template <typename LinkerImpl> class JITLinker : public JITLinkerBase {
public:
using JITLinkerBase::JITLinkerBase;
/// Link constructs a LinkerImpl instance and calls linkPhase1.
/// Link should be called with the constructor arguments for LinkerImpl, which
/// will be forwarded to the constructor.
template <typename... ArgTs> static void link(ArgTs &&... Args) {
auto L = std::make_unique<LinkerImpl>(std::forward<ArgTs>(Args)...);
// Ownership of the linker is passed into the linker's doLink function to
// allow it to be passed on to async continuations.
//
// FIXME: Remove LTmp once we have c++17.
// C++17 sequencing rules guarantee that function name expressions are
// sequenced before arguments, so L->linkPhase1(std::move(L), ...) will be
// well formed.
auto <mp = *L;
LTmp.linkPhase1(std::move(L));
}
private:
const LinkerImpl &impl() const {
return static_cast<const LinkerImpl &>(*this);
}
Error fixUpBlocks(LinkGraph &G) const override {
LLVM_DEBUG(dbgs() << "Fixing up blocks:\n");
for (auto *B : G.blocks()) {
LLVM_DEBUG(dbgs() << " " << *B << ":\n");
// Copy Block data and apply fixups.
LLVM_DEBUG(dbgs() << " Applying fixups.\n");
assert((!B->isZeroFill() || B->edges_size() == 0) &&
"Edges in zero-fill block?");
for (auto &E : B->edges()) {
// Skip non-relocation edges.
if (!E.isRelocation())
continue;
// Dispatch to LinkerImpl for fixup.
if (auto Err = impl().applyFixup(G, *B, E))
return Err;
}
}
return Error::success();
}
};
/// Removes dead symbols/blocks/addressables.
///
/// Finds the set of symbols and addressables reachable from any symbol
/// initially marked live. All symbols/addressables not marked live at the end
/// of this process are removed.
void prune(LinkGraph &G);
} // end namespace jitlink
} // end namespace llvm
#undef DEBUG_TYPE // "jitlink"
#endif // LIB_EXECUTIONENGINE_JITLINK_JITLINKGENERIC_H
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