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//===-- InMemoryAssembler.cpp -----------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "InMemoryAssembler.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/ExecutionEngine/ExecutionEngine.h"
#include "llvm/ExecutionEngine/MCJIT.h"
#include "llvm/ExecutionEngine/SectionMemoryManager.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/MC/MCFixup.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/Object/Binary.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/PassInfo.h"
#include "llvm/PassRegistry.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
namespace exegesis {
static constexpr const char ModuleID[] = "ExegesisInfoTest";
static constexpr const char FunctionID[] = "foo";
// Small utility function to add named passes.
static bool addPass(llvm::PassManagerBase &PM, llvm::StringRef PassName,
llvm::TargetPassConfig &TPC) {
const llvm::PassRegistry *PR = llvm::PassRegistry::getPassRegistry();
const llvm::PassInfo *PI = PR->getPassInfo(PassName);
if (!PI) {
llvm::errs() << " run-pass " << PassName << " is not registered.\n";
return true;
}
if (!PI->getNormalCtor()) {
llvm::errs() << " cannot create pass: " << PI->getPassName() << "\n";
return true;
}
llvm::Pass *P = PI->getNormalCtor()();
std::string Banner = std::string("After ") + std::string(P->getPassName());
PM.add(P);
TPC.printAndVerify(Banner);
return false;
}
// Creates a void MachineFunction with no argument.
static llvm::MachineFunction &
createVoidVoidMachineFunction(llvm::StringRef FunctionID, llvm::Module *Module,
llvm::MachineModuleInfo *MMI) {
llvm::Type *const ReturnType = llvm::Type::getInt32Ty(Module->getContext());
llvm::FunctionType *FunctionType = llvm::FunctionType::get(ReturnType, false);
llvm::Function *const F = llvm::Function::Create(
FunctionType, llvm::GlobalValue::InternalLinkage, FunctionID, Module);
// Making sure we can create a MachineFunction out of this Function even if it
// contains no IR.
F->setIsMaterializable(true);
return MMI->getOrCreateMachineFunction(*F);
}
static llvm::object::OwningBinary<llvm::object::ObjectFile>
assemble(llvm::Module *Module, std::unique_ptr<llvm::MachineModuleInfo> MMI,
llvm::LLVMTargetMachine *LLVMTM) {
llvm::legacy::PassManager PM;
llvm::MCContext &Context = MMI->getContext();
llvm::TargetLibraryInfoImpl TLII(llvm::Triple(Module->getTargetTriple()));
PM.add(new llvm::TargetLibraryInfoWrapperPass(TLII));
llvm::TargetPassConfig *TPC = LLVMTM->createPassConfig(PM);
PM.add(TPC);
PM.add(MMI.release());
TPC->printAndVerify("MachineFunctionGenerator::assemble");
// Adding the following passes:
// - machineverifier: checks that the MachineFunction is well formed.
// - prologepilog: saves and restore callee saved registers.
for (const char *PassName : {"machineverifier", "prologepilog"})
if (addPass(PM, PassName, *TPC))
llvm::report_fatal_error("Unable to add a mandatory pass");
TPC->setInitialized();
llvm::SmallVector<char, 4096> AsmBuffer;
llvm::raw_svector_ostream AsmStream(AsmBuffer);
// AsmPrinter is responsible for generating the assembly into AsmBuffer.
if (LLVMTM->addAsmPrinter(PM, AsmStream, llvm::TargetMachine::CGFT_ObjectFile,
Context))
llvm::report_fatal_error("Cannot add AsmPrinter passes");
PM.run(*Module); // Run all the passes
// Storing the generated assembly into a MemoryBuffer that owns the memory.
std::unique_ptr<llvm::MemoryBuffer> Buffer =
llvm::MemoryBuffer::getMemBufferCopy(AsmStream.str());
// Create the ObjectFile from the MemoryBuffer.
std::unique_ptr<llvm::object::ObjectFile> Obj = llvm::cantFail(
llvm::object::ObjectFile::createObjectFile(Buffer->getMemBufferRef()));
// Returning both the MemoryBuffer and the ObjectFile.
return llvm::object::OwningBinary<llvm::object::ObjectFile>(
std::move(Obj), std::move(Buffer));
}
static void fillMachineFunction(llvm::MachineFunction &MF,
llvm::ArrayRef<llvm::MCInst> Instructions) {
llvm::MachineBasicBlock *MBB = MF.CreateMachineBasicBlock();
MF.push_back(MBB);
const llvm::MCInstrInfo *MCII = MF.getTarget().getMCInstrInfo();
llvm::DebugLoc DL;
for (const llvm::MCInst &Inst : Instructions) {
const unsigned Opcode = Inst.getOpcode();
const llvm::MCInstrDesc &MCID = MCII->get(Opcode);
llvm::MachineInstrBuilder Builder = llvm::BuildMI(MBB, DL, MCID);
for (unsigned OpIndex = 0, E = Inst.getNumOperands(); OpIndex < E;
++OpIndex) {
const llvm::MCOperand &Op = Inst.getOperand(OpIndex);
if (Op.isReg()) {
const bool IsDef = OpIndex < MCID.getNumDefs();
unsigned Flags = 0;
const llvm::MCOperandInfo &OpInfo = MCID.operands().begin()[OpIndex];
if (IsDef && !OpInfo.isOptionalDef())
Flags |= llvm::RegState::Define;
Builder.addReg(Op.getReg(), Flags);
} else if (Op.isImm()) {
Builder.addImm(Op.getImm());
} else {
llvm_unreachable("Not yet implemented");
}
}
}
// Adding the Return Opcode.
const llvm::TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
llvm::BuildMI(MBB, DL, TII->get(TII->getReturnOpcode()));
}
namespace {
// Implementation of this class relies on the fact that a single object with a
// single function will be loaded into memory.
class TrackingSectionMemoryManager : public llvm::SectionMemoryManager {
public:
explicit TrackingSectionMemoryManager(uintptr_t *CodeSize)
: CodeSize(CodeSize) {}
uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
unsigned SectionID,
llvm::StringRef SectionName) override {
*CodeSize = Size;
return llvm::SectionMemoryManager::allocateCodeSection(
Size, Alignment, SectionID, SectionName);
}
private:
uintptr_t *const CodeSize = nullptr;
};
} // namespace
JitFunctionContext::JitFunctionContext(
std::unique_ptr<llvm::LLVMTargetMachine> TheTM)
: Context(llvm::make_unique<llvm::LLVMContext>()), TM(std::move(TheTM)),
MMI(llvm::make_unique<llvm::MachineModuleInfo>(TM.get())),
Module(llvm::make_unique<llvm::Module>(ModuleID, *Context)) {
Module->setDataLayout(TM->createDataLayout());
MF = &createVoidVoidMachineFunction(FunctionID, Module.get(), MMI.get());
// We need to instruct the passes that we're done with SSA and virtual
// registers.
auto &Properties = MF->getProperties();
Properties.set(llvm::MachineFunctionProperties::Property::NoVRegs);
Properties.reset(llvm::MachineFunctionProperties::Property::IsSSA);
Properties.reset(llvm::MachineFunctionProperties::Property::TracksLiveness);
// prologue/epilogue pass needs the reserved registers to be frozen, this is
// usually done by the SelectionDAGISel pass.
MF->getRegInfo().freezeReservedRegs(*MF);
// Saving reserved registers for client.
ReservedRegs = MF->getSubtarget().getRegisterInfo()->getReservedRegs(*MF);
}
JitFunction::JitFunction(JitFunctionContext &&Context,
llvm::ArrayRef<llvm::MCInst> Instructions)
: FunctionContext(std::move(Context)) {
fillMachineFunction(*FunctionContext.MF, Instructions);
// We create the pass manager, run the passes and returns the produced
// ObjectFile.
llvm::object::OwningBinary<llvm::object::ObjectFile> ObjHolder =
assemble(FunctionContext.Module.get(), std::move(FunctionContext.MMI),
FunctionContext.TM.get());
assert(ObjHolder.getBinary() && "cannot create object file");
// Initializing the execution engine.
// We need to use the JIT EngineKind to be able to add an object file.
LLVMLinkInMCJIT();
uintptr_t CodeSize = 0;
std::string Error;
ExecEngine.reset(
llvm::EngineBuilder(std::move(FunctionContext.Module))
.setErrorStr(&Error)
.setMCPU(FunctionContext.TM->getTargetCPU())
.setEngineKind(llvm::EngineKind::JIT)
.setMCJITMemoryManager(
llvm::make_unique<TrackingSectionMemoryManager>(&CodeSize))
.create(FunctionContext.TM.release()));
if (!ExecEngine)
llvm::report_fatal_error(Error);
// Adding the generated object file containing the assembled function.
// The ExecutionEngine makes sure the object file is copied into an
// executable page.
ExecEngine->addObjectFile(ObjHolder.takeBinary().first);
// Setting function
FunctionBytes =
llvm::StringRef(reinterpret_cast<const char *>(
ExecEngine->getFunctionAddress(FunctionID)),
CodeSize);
}
} // namespace exegesis
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