1//===-- BPFTargetMachine.cpp - Define TargetMachine for BPF ---------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// Implements the info about BPF target spec.
10//
11//===----------------------------------------------------------------------===//
12
13#include "BPFTargetMachine.h"
14#include "BPF.h"
15#include "MCTargetDesc/BPFMCAsmInfo.h"
16#include "TargetInfo/BPFTargetInfo.h"
17#include "llvm/CodeGen/Passes.h"
18#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
19#include "llvm/CodeGen/TargetPassConfig.h"
20#include "llvm/IR/LegacyPassManager.h"
21#include "llvm/Support/FormattedStream.h"
22#include "llvm/Support/TargetRegistry.h"
23#include "llvm/Target/TargetOptions.h"
24using namespace llvm;
25
26static cl::
27opt<bool> DisableMIPeephole("disable-bpf-peephole", cl::Hidden,
28                            cl::desc("Disable machine peepholes for BPF"));
29
30extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFTarget() {
31  // Register the target.
32  RegisterTargetMachine<BPFTargetMachine> X(getTheBPFleTarget());
33  RegisterTargetMachine<BPFTargetMachine> Y(getTheBPFbeTarget());
34  RegisterTargetMachine<BPFTargetMachine> Z(getTheBPFTarget());
35
36  PassRegistry &PR = *PassRegistry::getPassRegistry();
37  initializeBPFAbstractMemberAccessPass(PR);
38  initializeBPFPreserveDITypePass(PR);
39  initializeBPFMIPeepholePass(PR);
40  initializeBPFMIPeepholeTruncElimPass(PR);
41}
42
43// DataLayout: little or big endian
44static std::string computeDataLayout(const Triple &TT) {
45  if (TT.getArch() == Triple::bpfeb)
46    return "E-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
47  else
48    return "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
49}
50
51static Reloc::Model getEffectiveRelocModel(Optional<Reloc::Model> RM) {
52  if (!RM.hasValue())
53    return Reloc::PIC_;
54  return *RM;
55}
56
57BPFTargetMachine::BPFTargetMachine(const Target &T, const Triple &TT,
58                                   StringRef CPU, StringRef FS,
59                                   const TargetOptions &Options,
60                                   Optional<Reloc::Model> RM,
61                                   Optional<CodeModel::Model> CM,
62                                   CodeGenOpt::Level OL, bool JIT)
63    : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options,
64                        getEffectiveRelocModel(RM),
65                        getEffectiveCodeModel(CM, CodeModel::Small), OL),
66      TLOF(std::make_unique<TargetLoweringObjectFileELF>()),
67      Subtarget(TT, std::string(CPU), std::string(FS), *this) {
68  initAsmInfo();
69
70  BPFMCAsmInfo *MAI =
71      static_cast<BPFMCAsmInfo *>(const_cast<MCAsmInfo *>(AsmInfo.get()));
72  MAI->setDwarfUsesRelocationsAcrossSections(!Subtarget.getUseDwarfRIS());
73}
74
75namespace {
76// BPF Code Generator Pass Configuration Options.
77class BPFPassConfig : public TargetPassConfig {
78public:
79  BPFPassConfig(BPFTargetMachine &TM, PassManagerBase &PM)
80      : TargetPassConfig(TM, PM) {}
81
82  BPFTargetMachine &getBPFTargetMachine() const {
83    return getTM<BPFTargetMachine>();
84  }
85
86  void addIRPasses() override;
87  bool addInstSelector() override;
88  void addMachineSSAOptimization() override;
89  void addPreEmitPass() override;
90};
91}
92
93TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
94  return new BPFPassConfig(*this, PM);
95}
96
97void BPFPassConfig::addIRPasses() {
98
99  addPass(createBPFAbstractMemberAccess(&getBPFTargetMachine()));
100  addPass(createBPFPreserveDIType());
101
102  TargetPassConfig::addIRPasses();
103}
104
105// Install an instruction selector pass using
106// the ISelDag to gen BPF code.
107bool BPFPassConfig::addInstSelector() {
108  addPass(createBPFISelDag(getBPFTargetMachine()));
109
110  return false;
111}
112
113void BPFPassConfig::addMachineSSAOptimization() {
114  addPass(createBPFMISimplifyPatchablePass());
115
116  // The default implementation must be called first as we want eBPF
117  // Peephole ran at last.
118  TargetPassConfig::addMachineSSAOptimization();
119
120  const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
121  if (!DisableMIPeephole) {
122    if (Subtarget->getHasAlu32())
123      addPass(createBPFMIPeepholePass());
124    addPass(createBPFMIPeepholeTruncElimPass());
125  }
126}
127
128void BPFPassConfig::addPreEmitPass() {
129  addPass(createBPFMIPreEmitCheckingPass());
130  if (getOptLevel() != CodeGenOpt::None)
131    if (!DisableMIPeephole)
132      addPass(createBPFMIPreEmitPeepholePass());
133}
134