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 "BPFTargetTransformInfo.h"
16#include "MCTargetDesc/BPFMCAsmInfo.h"
17#include "TargetInfo/BPFTargetInfo.h"
18#include "llvm/CodeGen/GlobalISel/IRTranslator.h"
19#include "llvm/CodeGen/GlobalISel/InstructionSelect.h"
20#include "llvm/CodeGen/GlobalISel/Legalizer.h"
21#include "llvm/CodeGen/GlobalISel/RegBankSelect.h"
22#include "llvm/CodeGen/Passes.h"
23#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
24#include "llvm/CodeGen/TargetPassConfig.h"
25#include "llvm/IR/PassManager.h"
26#include "llvm/InitializePasses.h"
27#include "llvm/MC/TargetRegistry.h"
28#include "llvm/Passes/PassBuilder.h"
29#include "llvm/Support/Compiler.h"
30#include "llvm/Target/TargetOptions.h"
31#include "llvm/Transforms/Scalar.h"
32#include "llvm/Transforms/Scalar/SimplifyCFG.h"
33#include "llvm/Transforms/Utils/SimplifyCFGOptions.h"
34#include <optional>
35using namespace llvm;
36
37static cl::
38opt<bool> DisableMIPeephole("disable-bpf-peephole", cl::Hidden,
39 cl::desc("Disable machine peepholes for BPF"));
40
41static cl::opt<bool>
42 DisableCheckUnreachable("bpf-disable-trap-unreachable", cl::Hidden,
43 cl::desc("Disable Trap Unreachable for BPF"));
44
45extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFTarget() {
46 // Register the target.
47 RegisterTargetMachine<BPFTargetMachine> X(getTheBPFleTarget());
48 RegisterTargetMachine<BPFTargetMachine> Y(getTheBPFbeTarget());
49 RegisterTargetMachine<BPFTargetMachine> Z(getTheBPFTarget());
50
51 PassRegistry &PR = *PassRegistry::getPassRegistry();
52 initializeGlobalISel(PR);
53 initializeBPFAsmPrinterPass(PR);
54 initializeBPFCheckAndAdjustIRPass(PR);
55 initializeBPFMIPeepholePass(PR);
56 initializeBPFMIPreEmitPeepholePass(PR);
57 initializeBPFDAGToDAGISelLegacyPass(PR);
58 initializeBPFMISimplifyPatchablePass(PR);
59 initializeBPFMIPreEmitCheckingPass(PR);
60}
61
62// DataLayout: little or big endian
63static std::string computeDataLayout(const Triple &TT) {
64 if (TT.getArch() == Triple::bpfeb)
65 return "E-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
66 else
67 return "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
68}
69
70static Reloc::Model getEffectiveRelocModel(std::optional<Reloc::Model> RM) {
71 return RM.value_or(u: Reloc::PIC_);
72}
73
74BPFTargetMachine::BPFTargetMachine(const Target &T, const Triple &TT,
75 StringRef CPU, StringRef FS,
76 const TargetOptions &Options,
77 std::optional<Reloc::Model> RM,
78 std::optional<CodeModel::Model> CM,
79 CodeGenOptLevel OL, bool JIT)
80 : CodeGenTargetMachineImpl(T, computeDataLayout(TT), TT, CPU, FS, Options,
81 getEffectiveRelocModel(RM),
82 getEffectiveCodeModel(CM, Default: CodeModel::Small), OL),
83 TLOF(std::make_unique<TargetLoweringObjectFileELF>()),
84 Subtarget(TT, std::string(CPU), std::string(FS), *this) {
85 if (!DisableCheckUnreachable) {
86 this->Options.TrapUnreachable = true;
87 this->Options.NoTrapAfterNoreturn = true;
88 }
89
90 initAsmInfo();
91
92 BPFMCAsmInfo *MAI =
93 static_cast<BPFMCAsmInfo *>(const_cast<MCAsmInfo *>(AsmInfo.get()));
94 MAI->setDwarfUsesRelocationsAcrossSections(!Subtarget.getUseDwarfRIS());
95}
96
97namespace {
98// BPF Code Generator Pass Configuration Options.
99class BPFPassConfig : public TargetPassConfig {
100public:
101 BPFPassConfig(BPFTargetMachine &TM, PassManagerBase &PM)
102 : TargetPassConfig(TM, PM) {}
103
104 BPFTargetMachine &getBPFTargetMachine() const {
105 return getTM<BPFTargetMachine>();
106 }
107
108 void addIRPasses() override;
109 bool addInstSelector() override;
110 void addMachineSSAOptimization() override;
111 void addPreEmitPass() override;
112
113 bool addIRTranslator() override;
114 bool addLegalizeMachineIR() override;
115 bool addRegBankSelect() override;
116 bool addGlobalInstructionSelect() override;
117};
118}
119
120TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
121 return new BPFPassConfig(*this, PM);
122}
123
124static Expected<bool> parseBPFPreserveStaticOffsetOptions(StringRef Params) {
125 return PassBuilder::parseSinglePassOption(Params, OptionName: "allow-partial",
126 PassName: "BPFPreserveStaticOffsetPass");
127}
128
129void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
130#define GET_PASS_REGISTRY "BPFPassRegistry.def"
131#include "llvm/Passes/TargetPassRegistry.inc"
132
133 PB.registerPipelineStartEPCallback(
134 C: [=](ModulePassManager &MPM, OptimizationLevel) {
135 FunctionPassManager FPM;
136 FPM.addPass(Pass: BPFPreserveStaticOffsetPass(true));
137 FPM.addPass(Pass: BPFAbstractMemberAccessPass(this));
138 FPM.addPass(Pass: BPFPreserveDITypePass());
139 FPM.addPass(Pass: BPFIRPeepholePass());
140 MPM.addPass(Pass: createModuleToFunctionPassAdaptor(Pass: std::move(FPM)));
141 });
142 PB.registerPeepholeEPCallback(C: [=](FunctionPassManager &FPM,
143 OptimizationLevel Level) {
144 FPM.addPass(Pass: SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(B: true)));
145 FPM.addPass(Pass: BPFASpaceCastSimplifyPass());
146 });
147 PB.registerScalarOptimizerLateEPCallback(
148 C: [=](FunctionPassManager &FPM, OptimizationLevel Level) {
149 // Run this after loop unrolling but before
150 // SimplifyCFGPass(... .sinkCommonInsts(true))
151 FPM.addPass(Pass: BPFPreserveStaticOffsetPass(false));
152 });
153 PB.registerPipelineEarlySimplificationEPCallback(
154 C: [=](ModulePassManager &MPM, OptimizationLevel, ThinOrFullLTOPhase) {
155 MPM.addPass(Pass: BPFAdjustOptPass());
156 });
157}
158
159void BPFPassConfig::addIRPasses() {
160 addPass(P: createAtomicExpandLegacyPass());
161 addPass(P: createBPFCheckAndAdjustIR());
162
163 TargetPassConfig::addIRPasses();
164}
165
166TargetTransformInfo
167BPFTargetMachine::getTargetTransformInfo(const Function &F) const {
168 return TargetTransformInfo(std::make_unique<BPFTTIImpl>(args: this, args: F));
169}
170
171// Install an instruction selector pass using
172// the ISelDag to gen BPF code.
173bool BPFPassConfig::addInstSelector() {
174 addPass(P: createBPFISelDag(TM&: getBPFTargetMachine()));
175
176 return false;
177}
178
179void BPFPassConfig::addMachineSSAOptimization() {
180 addPass(P: createBPFMISimplifyPatchablePass());
181
182 // The default implementation must be called first as we want eBPF
183 // Peephole ran at last.
184 TargetPassConfig::addMachineSSAOptimization();
185
186 const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
187 if (!DisableMIPeephole) {
188 if (Subtarget->getHasAlu32())
189 addPass(P: createBPFMIPeepholePass());
190 }
191}
192
193void BPFPassConfig::addPreEmitPass() {
194 addPass(P: createBPFMIPreEmitCheckingPass());
195 if (getOptLevel() != CodeGenOptLevel::None)
196 if (!DisableMIPeephole)
197 addPass(P: createBPFMIPreEmitPeepholePass());
198}
199
200bool BPFPassConfig::addIRTranslator() {
201 addPass(P: new IRTranslator());
202 return false;
203}
204
205bool BPFPassConfig::addLegalizeMachineIR() {
206 addPass(P: new Legalizer());
207 return false;
208}
209
210bool BPFPassConfig::addRegBankSelect() {
211 addPass(P: new RegBankSelect());
212 return false;
213}
214
215bool BPFPassConfig::addGlobalInstructionSelect() {
216 addPass(P: new InstructionSelect(getOptLevel()));
217 return false;
218}
219