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Add a new ObjectLinkingLayer plugin `DebugObjectManagerPlugin` and infrastructure to handle creation of `DebugObject`s as well as their registration in OrcTargetProcess. The current implementation only covers ELF on x86-64, but the infrastructure is not limited to that. The journey starts with a new `LinkGraph` / `JITLinkContext` pair being created for a `MaterializationResponsibility` in ORC's `ObjectLinkingLayer`. It sends a `notifyMaterializing()` notification, which is forwarded to all registered plugins. The `DebugObjectManagerPlugin` aims to create a `DebugObject` form the provided target triple and object buffer. (Future implementations might create `DebugObject`s from a `LinkGraph` in other ways.) On success it will track it as the pending `DebugObject` for the `MaterializationResponsibility`. This patch only implements the `ELFDebugObject` for `x86-64` targets. It follows the RuntimeDyld approach for debug object setup: it captures a copy of the input object, parses all section headers and prepares to patch their load-address fields with their final addresses in target memory. It instructs the plugin to report the section load-addresses once they are available. The plugin overrides `modifyPassConfig()` and installs a JITLink post-allocation pass to capture them. Once JITLink emitted the finalized executable, the plugin emits and registers the `DebugObject`. For emission it requests a new `JITLinkMemoryManager::Allocation` with a single read-only segment, copies the object with patched section load-addresses over to working memory and triggers finalization to target memory. For registration, it notifies the `DebugObjectRegistrar` provided in the constructor and stores the previously pending`DebugObject` as registered for the corresponding MaterializationResponsibility. The `DebugObjectRegistrar` registers the `DebugObject` with the target process. `llvm-jitlink` uses the `TPCDebugObjectRegistrar`, which calls `llvm_orc_registerJITLoaderGDBWrapper()` in the target process via `TargetProcessControl` to emit a `jit_code_entry` compatible with the GDB JIT interface [1]. So far the implementation only supports registration and no removal. It appears to me that it wouldn't raise any new design questions, so I left this as an addition for the near future. [1] https://sourceware.org/gdb/current/onlinedocs/gdb/JIT-Interface.html Reviewed By: lhames Differential Revision: https://reviews.llvm.org/D97335
63 lines
2.2 KiB
C++
63 lines
2.2 KiB
C++
//===----- TPCDebugObjectRegistrar.cpp - TPC-based debug registration -----===//
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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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#include "llvm/ExecutionEngine/Orc/TPCDebugObjectRegistrar.h"
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#include "llvm/ExecutionEngine/Orc/Core.h"
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#include "llvm/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.h"
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#include "llvm/Support/BinaryStreamWriter.h"
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namespace llvm {
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namespace orc {
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// Counterpart for readDebugObjectInfo() in TargetProcess/JITLoaderGDB.cpp
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static std::vector<uint8_t>
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writeDebugObjectInfo(sys::MemoryBlock TargetMemBlock) {
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auto DebugObjAddr = pointerToJITTargetAddress(TargetMemBlock.base());
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uint64_t DebugObjSize = TargetMemBlock.allocatedSize();
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std::vector<uint8_t> ArgBuffer;
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ArgBuffer.resize(sizeof(decltype(DebugObjAddr)) +
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sizeof(decltype(DebugObjSize)));
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BinaryStreamWriter ArgWriter(ArgBuffer, support::endianness::big);
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cantFail(ArgWriter.writeInteger(DebugObjAddr));
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cantFail(ArgWriter.writeInteger(DebugObjSize));
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return ArgBuffer;
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}
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Expected<std::unique_ptr<TPCDebugObjectRegistrar>>
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createJITLoaderGDBRegistrar(TargetProcessControl &TPC) {
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auto ProcessHandle = TPC.loadDylib(nullptr);
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if (!ProcessHandle)
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return ProcessHandle.takeError();
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SymbolStringPtr RegisterFn =
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TPC.getTargetTriple().isOSBinFormatMachO()
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? TPC.intern("_llvm_orc_registerJITLoaderGDBWrapper")
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: TPC.intern("llvm_orc_registerJITLoaderGDBWrapper");
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SymbolLookupSet RegistrationSymbols;
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RegistrationSymbols.add(RegisterFn);
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auto Result = TPC.lookupSymbols({{*ProcessHandle, RegistrationSymbols}});
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if (!Result)
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return Result.takeError();
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assert(Result->size() == 1 && "Unexpected number of dylibs in result");
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assert((*Result)[0].size() == 1 &&
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"Unexpected number of addresses in result");
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return std::make_unique<TPCDebugObjectRegistrar>(TPC, (*Result)[0][0],
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&writeDebugObjectInfo);
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}
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} // namespace orc
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} // namespace llvm
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