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> 35 using namespace llvm; 36 37 static cl:: 38 opt<bool> DisableMIPeephole("disable-bpf-peephole", cl::Hidden, 39 cl::desc("Disable machine peepholes for BPF")); 40 41 static cl::opt<bool> 42 DisableCheckUnreachable("bpf-disable-trap-unreachable", cl::Hidden, 43 cl::desc("Disable Trap Unreachable for BPF")); 44 45 extern "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 63 static 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 70 static Reloc::Model getEffectiveRelocModel(std::optional<Reloc::Model> RM) { 71 return RM.value_or(Reloc::PIC_); 72 } 73 74 BPFTargetMachine::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, 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 97 namespace { 98 // BPF Code Generator Pass Configuration Options. 99 class BPFPassConfig : public TargetPassConfig { 100 public: 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 } 119 120 TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) { 121 return new BPFPassConfig(*this, PM); 122 } 123 124 static Expected<bool> parseBPFPreserveStaticOffsetOptions(StringRef Params) { 125 return PassBuilder::parseSinglePassOption(Params, "allow-partial", 126 "BPFPreserveStaticOffsetPass"); 127 } 128 129 void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) { 130 #define GET_PASS_REGISTRY "BPFPassRegistry.def" 131 #include "llvm/Passes/TargetPassRegistry.inc" 132 133 PB.registerPipelineStartEPCallback( 134 [=](ModulePassManager &MPM, OptimizationLevel) { 135 FunctionPassManager FPM; 136 FPM.addPass(BPFPreserveStaticOffsetPass(true)); 137 FPM.addPass(BPFAbstractMemberAccessPass(this)); 138 FPM.addPass(BPFPreserveDITypePass()); 139 FPM.addPass(BPFIRPeepholePass()); 140 MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM))); 141 }); 142 PB.registerPeepholeEPCallback([=](FunctionPassManager &FPM, 143 OptimizationLevel Level) { 144 FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(true))); 145 FPM.addPass(BPFASpaceCastSimplifyPass()); 146 }); 147 PB.registerScalarOptimizerLateEPCallback( 148 [=](FunctionPassManager &FPM, OptimizationLevel Level) { 149 // Run this after loop unrolling but before 150 // SimplifyCFGPass(... .sinkCommonInsts(true)) 151 FPM.addPass(BPFPreserveStaticOffsetPass(false)); 152 }); 153 PB.registerPipelineEarlySimplificationEPCallback( 154 [=](ModulePassManager &MPM, OptimizationLevel, ThinOrFullLTOPhase) { 155 MPM.addPass(BPFAdjustOptPass()); 156 }); 157 } 158 159 void BPFPassConfig::addIRPasses() { 160 addPass(createAtomicExpandLegacyPass()); 161 addPass(createBPFCheckAndAdjustIR()); 162 163 TargetPassConfig::addIRPasses(); 164 } 165 166 TargetTransformInfo 167 BPFTargetMachine::getTargetTransformInfo(const Function &F) const { 168 return TargetTransformInfo(std::make_unique<BPFTTIImpl>(this, F)); 169 } 170 171 // Install an instruction selector pass using 172 // the ISelDag to gen BPF code. 173 bool BPFPassConfig::addInstSelector() { 174 addPass(createBPFISelDag(getBPFTargetMachine())); 175 176 return false; 177 } 178 179 void BPFPassConfig::addMachineSSAOptimization() { 180 addPass(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(createBPFMIPeepholePass()); 190 } 191 } 192 193 void BPFPassConfig::addPreEmitPass() { 194 addPass(createBPFMIPreEmitCheckingPass()); 195 if (getOptLevel() != CodeGenOptLevel::None) 196 if (!DisableMIPeephole) 197 addPass(createBPFMIPreEmitPeepholePass()); 198 } 199 200 bool BPFPassConfig::addIRTranslator() { 201 addPass(new IRTranslator()); 202 return false; 203 } 204 205 bool BPFPassConfig::addLegalizeMachineIR() { 206 addPass(new Legalizer()); 207 return false; 208 } 209 210 bool BPFPassConfig::addRegBankSelect() { 211 addPass(new RegBankSelect()); 212 return false; 213 } 214 215 bool BPFPassConfig::addGlobalInstructionSelect() { 216 addPass(new InstructionSelect(getOptLevel())); 217 return false; 218 } 219