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//===-- BPFTargetMachine.cpp - Define TargetMachine for BPF ---------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Implements the info about BPF target spec.
//
//===----------------------------------------------------------------------===//
#include "BPFTargetMachine.h"
#include "BPF.h"
#include "BPFTargetTransformInfo.h"
#include "MCTargetDesc/BPFMCAsmInfo.h"
#include "TargetInfo/BPFTargetInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/PassManager.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Scalar/SimplifyCFG.h"
#include "llvm/Transforms/Utils/SimplifyCFGOptions.h"
#include <optional>
using namespace llvm;
static cl::
opt<bool> DisableMIPeephole("disable-bpf-peephole", cl::Hidden,
cl::desc("Disable machine peepholes for BPF"));
extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFTarget() {
// Register the target.
RegisterTargetMachine<BPFTargetMachine> X(getTheBPFleTarget());
RegisterTargetMachine<BPFTargetMachine> Y(getTheBPFbeTarget());
RegisterTargetMachine<BPFTargetMachine> Z(getTheBPFTarget());
PassRegistry &PR = *PassRegistry::getPassRegistry();
initializeBPFCheckAndAdjustIRPass(PR);
initializeBPFMIPeepholePass(PR);
initializeBPFDAGToDAGISelPass(PR);
}
// DataLayout: little or big endian
static std::string computeDataLayout(const Triple &TT) {
if (TT.getArch() == Triple::bpfeb)
return "E-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
else
return "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
}
static Reloc::Model getEffectiveRelocModel(std::optional<Reloc::Model> RM) {
return RM.value_or(Reloc::PIC_);
}
BPFTargetMachine::BPFTargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
std::optional<Reloc::Model> RM,
std::optional<CodeModel::Model> CM,
CodeGenOptLevel OL, bool JIT)
: LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options,
getEffectiveRelocModel(RM),
getEffectiveCodeModel(CM, CodeModel::Small), OL),
TLOF(std::make_unique<TargetLoweringObjectFileELF>()),
Subtarget(TT, std::string(CPU), std::string(FS), *this) {
initAsmInfo();
BPFMCAsmInfo *MAI =
static_cast<BPFMCAsmInfo *>(const_cast<MCAsmInfo *>(AsmInfo.get()));
MAI->setDwarfUsesRelocationsAcrossSections(!Subtarget.getUseDwarfRIS());
}
namespace {
// BPF Code Generator Pass Configuration Options.
class BPFPassConfig : public TargetPassConfig {
public:
BPFPassConfig(BPFTargetMachine &TM, PassManagerBase &PM)
: TargetPassConfig(TM, PM) {}
BPFTargetMachine &getBPFTargetMachine() const {
return getTM<BPFTargetMachine>();
}
void addIRPasses() override;
bool addInstSelector() override;
void addMachineSSAOptimization() override;
void addPreEmitPass() override;
};
}
TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
return new BPFPassConfig(*this, PM);
}
void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
PB.registerPipelineParsingCallback(
[](StringRef PassName, FunctionPassManager &FPM,
ArrayRef<PassBuilder::PipelineElement>) {
if (PassName == "bpf-ir-peephole") {
FPM.addPass(BPFIRPeepholePass());
return true;
}
return false;
});
PB.registerPipelineStartEPCallback(
[=](ModulePassManager &MPM, OptimizationLevel) {
FunctionPassManager FPM;
FPM.addPass(BPFAbstractMemberAccessPass(this));
FPM.addPass(BPFPreserveDITypePass());
FPM.addPass(BPFIRPeepholePass());
MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
});
PB.registerPeepholeEPCallback([=](FunctionPassManager &FPM,
OptimizationLevel Level) {
FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(true)));
});
PB.registerPipelineEarlySimplificationEPCallback(
[=](ModulePassManager &MPM, OptimizationLevel) {
MPM.addPass(BPFAdjustOptPass());
});
}
void BPFPassConfig::addIRPasses() {
addPass(createBPFCheckAndAdjustIR());
TargetPassConfig::addIRPasses();
}
TargetTransformInfo
BPFTargetMachine::getTargetTransformInfo(const Function &F) const {
return TargetTransformInfo(BPFTTIImpl(this, F));
}
// Install an instruction selector pass using
// the ISelDag to gen BPF code.
bool BPFPassConfig::addInstSelector() {
addPass(createBPFISelDag(getBPFTargetMachine()));
return false;
}
void BPFPassConfig::addMachineSSAOptimization() {
addPass(createBPFMISimplifyPatchablePass());
// The default implementation must be called first as we want eBPF
// Peephole ran at last.
TargetPassConfig::addMachineSSAOptimization();
const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
if (!DisableMIPeephole) {
if (Subtarget->getHasAlu32())
addPass(createBPFMIPeepholePass());
}
}
void BPFPassConfig::addPreEmitPass() {
addPass(createBPFMIPreEmitCheckingPass());
if (getOptLevel() != CodeGenOptLevel::None)
if (!DisableMIPeephole)
addPass(createBPFMIPreEmitPeepholePass());
}