4f0325873f
For Darwin/arm64 (including Apple Silicon Macs) this will enable exception
handling and stack unwinding in JIT'd code.
Darwin supports two unwind-info formats: DWARF eh-frames and compact-unwind. On
Darwin/x86-64 compilers usually produce both by default, and ORC supported
exceptions and unwinding via eh-frames (same as on Linux), discarding the
redundant compact-unwind info. On Darwin/arm64 compilers typically default to
producing compact-unwind only, with DWARF eh-frames as a fallback for functions
that can't be described in compact-unwind. Since ORC did not previously support
the compact-unwind format and eh-frames were not present ORC was unable to
handle exceptions or unwinding by default in Darwin/arm64 JIT'd code.
This patch enables support for the compact-unwind-info format, and contains
three major moving parts:
(1) The JITLink CompactUnwindManager class is responsible for transforming the
__compact_unwind records produced by the linker into the __unwind_info
tables that libunwind parses during unwinding. To enable this the
CompactUnwindManager class provides three JITLink passes: The
prepareForPrune pass that splits the __compact_unwind section into
single-record blocks, allowing unused records to be dead-stripped; the
processAndReserveUnwindInfo pass that reserves space for the final
__unwind_info section, and the writeUnwindInfo pass that writes the
__unwind_info section.
(2) The OrcTargetProcess UnwindInfoManager class maintains a table of
registered JIT'd __unwind_info and __eh_frame sections, and handles
requests from libunwind for unwind info sections (by registering a callback
with libunwind's __unw_add_find_dynamic_unwind_sections function).
(3) The Orc UnwindInfoRegistrationPlugin, which scans LinkGraphs for
__unwind_info and __eh_frame sections to register with the
UnwindInfoManager.
This commit adds the CompactUnwindManager passes to the default JITLink
pipelines for Darwin/arm64 and Darwin/x86-64, and UnwindInfoManager intances to
the SelfExecutorProcessControl class (when built for apple platforms) and the
llvm-jitlink-executor tool.
The LLJIT class will now create an UnwindInfoRegistrationPlugin when targeting
a process running on Darwin if it detects that an UnwindInfoManager is
available to handle the registrations.
The ORC runtime macho_platform class already supported libunwind callbacks, so
out-of-process execution and unwinding support will work when loading the ORC
runtime.
The llvm-jitlink tool will only support compact-unwind when the orc-runtime is
loaded, as the UnwindInfoRegistrationPlugin requires access to an IR compiler
to load a helper module and llvm-jitlink does not provide an IR compiler.
97 lines
2.9 KiB
C++
97 lines
2.9 KiB
C++
//===------ CompileUtils.cpp - Utilities for compiling IR in the JIT ------===//
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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/CompileUtils.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ExecutionEngine/ObjectCache.h"
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#include "llvm/IR/LegacyPassManager.h"
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#include "llvm/IR/Module.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/Object/ObjectFile.h"
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#include "llvm/Support/Error.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/SmallVectorMemoryBuffer.h"
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#include "llvm/Target/TargetMachine.h"
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namespace llvm {
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namespace orc {
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IRSymbolMapper::ManglingOptions
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irManglingOptionsFromTargetOptions(const TargetOptions &Opts) {
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IRSymbolMapper::ManglingOptions MO;
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MO.EmulatedTLS = Opts.EmulatedTLS;
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return MO;
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}
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/// Compile a Module to an ObjectFile.
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Expected<SimpleCompiler::CompileResult> SimpleCompiler::operator()(Module &M) {
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if (M.getDataLayout().isDefault())
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M.setDataLayout(TM.createDataLayout());
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CompileResult CachedObject = tryToLoadFromObjectCache(M);
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if (CachedObject)
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return std::move(CachedObject);
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SmallVector<char, 0> ObjBufferSV;
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{
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raw_svector_ostream ObjStream(ObjBufferSV);
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legacy::PassManager PM;
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MCContext *Ctx;
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if (TM.addPassesToEmitMC(PM, Ctx, ObjStream))
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return make_error<StringError>("Target does not support MC emission",
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inconvertibleErrorCode());
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PM.run(M);
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}
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auto ObjBuffer = std::make_unique<SmallVectorMemoryBuffer>(
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std::move(ObjBufferSV), M.getModuleIdentifier() + "-jitted-objectbuffer",
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/*RequiresNullTerminator=*/false);
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auto Obj = object::ObjectFile::createObjectFile(ObjBuffer->getMemBufferRef());
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if (!Obj)
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return Obj.takeError();
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notifyObjectCompiled(M, *ObjBuffer);
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return std::move(ObjBuffer);
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}
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SimpleCompiler::CompileResult
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SimpleCompiler::tryToLoadFromObjectCache(const Module &M) {
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if (!ObjCache)
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return CompileResult();
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return ObjCache->getObject(&M);
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}
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void SimpleCompiler::notifyObjectCompiled(const Module &M,
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const MemoryBuffer &ObjBuffer) {
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if (ObjCache)
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ObjCache->notifyObjectCompiled(&M, ObjBuffer.getMemBufferRef());
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}
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ConcurrentIRCompiler::ConcurrentIRCompiler(JITTargetMachineBuilder JTMB,
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ObjectCache *ObjCache)
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: IRCompiler(irManglingOptionsFromTargetOptions(JTMB.getOptions())),
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JTMB(std::move(JTMB)), ObjCache(ObjCache) {}
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Expected<std::unique_ptr<MemoryBuffer>>
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ConcurrentIRCompiler::operator()(Module &M) {
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auto TM = cantFail(JTMB.createTargetMachine());
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SimpleCompiler C(*TM, ObjCache);
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return C(M);
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}
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} // end namespace orc
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} // end namespace llvm
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