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/Passes.h" 19 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h" 20 #include "llvm/CodeGen/TargetPassConfig.h" 21 #include "llvm/IR/PassManager.h" 22 #include "llvm/MC/TargetRegistry.h" 23 #include "llvm/Passes/PassBuilder.h" 24 #include "llvm/Support/FormattedStream.h" 25 #include "llvm/Target/TargetOptions.h" 26 #include "llvm/Transforms/Scalar.h" 27 #include "llvm/Transforms/Scalar/SimplifyCFG.h" 28 #include "llvm/Transforms/Utils/SimplifyCFGOptions.h" 29 #include <optional> 30 using namespace llvm; 31 32 static cl:: 33 opt<bool> DisableMIPeephole("disable-bpf-peephole", cl::Hidden, 34 cl::desc("Disable machine peepholes for BPF")); 35 36 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFTarget() { 37 // Register the target. 38 RegisterTargetMachine<BPFTargetMachine> X(getTheBPFleTarget()); 39 RegisterTargetMachine<BPFTargetMachine> Y(getTheBPFbeTarget()); 40 RegisterTargetMachine<BPFTargetMachine> Z(getTheBPFTarget()); 41 42 PassRegistry &PR = *PassRegistry::getPassRegistry(); 43 initializeBPFCheckAndAdjustIRPass(PR); 44 initializeBPFMIPeepholePass(PR); 45 initializeBPFMIPeepholeTruncElimPass(PR); 46 initializeBPFDAGToDAGISelPass(PR); 47 } 48 49 // DataLayout: little or big endian 50 static std::string computeDataLayout(const Triple &TT) { 51 if (TT.getArch() == Triple::bpfeb) 52 return "E-m:e-p:64:64-i64:64-i128:128-n32:64-S128"; 53 else 54 return "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128"; 55 } 56 57 static Reloc::Model getEffectiveRelocModel(std::optional<Reloc::Model> RM) { 58 return RM.value_or(Reloc::PIC_); 59 } 60 61 BPFTargetMachine::BPFTargetMachine(const Target &T, const Triple &TT, 62 StringRef CPU, StringRef FS, 63 const TargetOptions &Options, 64 std::optional<Reloc::Model> RM, 65 std::optional<CodeModel::Model> CM, 66 CodeGenOpt::Level OL, bool JIT) 67 : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options, 68 getEffectiveRelocModel(RM), 69 getEffectiveCodeModel(CM, CodeModel::Small), OL), 70 TLOF(std::make_unique<TargetLoweringObjectFileELF>()), 71 Subtarget(TT, std::string(CPU), std::string(FS), *this) { 72 initAsmInfo(); 73 74 BPFMCAsmInfo *MAI = 75 static_cast<BPFMCAsmInfo *>(const_cast<MCAsmInfo *>(AsmInfo.get())); 76 MAI->setDwarfUsesRelocationsAcrossSections(!Subtarget.getUseDwarfRIS()); 77 } 78 79 namespace { 80 // BPF Code Generator Pass Configuration Options. 81 class BPFPassConfig : public TargetPassConfig { 82 public: 83 BPFPassConfig(BPFTargetMachine &TM, PassManagerBase &PM) 84 : TargetPassConfig(TM, PM) {} 85 86 BPFTargetMachine &getBPFTargetMachine() const { 87 return getTM<BPFTargetMachine>(); 88 } 89 90 void addIRPasses() override; 91 bool addInstSelector() override; 92 void addMachineSSAOptimization() override; 93 void addPreEmitPass() override; 94 }; 95 } 96 97 TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) { 98 return new BPFPassConfig(*this, PM); 99 } 100 101 void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) { 102 PB.registerPipelineParsingCallback( 103 [](StringRef PassName, FunctionPassManager &FPM, 104 ArrayRef<PassBuilder::PipelineElement>) { 105 if (PassName == "bpf-ir-peephole") { 106 FPM.addPass(BPFIRPeepholePass()); 107 return true; 108 } 109 return false; 110 }); 111 PB.registerPipelineStartEPCallback( 112 [=](ModulePassManager &MPM, OptimizationLevel) { 113 FunctionPassManager FPM; 114 FPM.addPass(BPFAbstractMemberAccessPass(this)); 115 FPM.addPass(BPFPreserveDITypePass()); 116 FPM.addPass(BPFIRPeepholePass()); 117 MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM))); 118 }); 119 PB.registerPeepholeEPCallback([=](FunctionPassManager &FPM, 120 OptimizationLevel Level) { 121 FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(true))); 122 }); 123 PB.registerPipelineEarlySimplificationEPCallback( 124 [=](ModulePassManager &MPM, OptimizationLevel) { 125 MPM.addPass(BPFAdjustOptPass()); 126 }); 127 } 128 129 void BPFPassConfig::addIRPasses() { 130 addPass(createBPFCheckAndAdjustIR()); 131 TargetPassConfig::addIRPasses(); 132 } 133 134 TargetTransformInfo 135 BPFTargetMachine::getTargetTransformInfo(const Function &F) const { 136 return TargetTransformInfo(BPFTTIImpl(this, F)); 137 } 138 139 // Install an instruction selector pass using 140 // the ISelDag to gen BPF code. 141 bool BPFPassConfig::addInstSelector() { 142 addPass(createBPFISelDag(getBPFTargetMachine())); 143 144 return false; 145 } 146 147 void BPFPassConfig::addMachineSSAOptimization() { 148 addPass(createBPFMISimplifyPatchablePass()); 149 150 // The default implementation must be called first as we want eBPF 151 // Peephole ran at last. 152 TargetPassConfig::addMachineSSAOptimization(); 153 154 const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl(); 155 if (!DisableMIPeephole) { 156 if (Subtarget->getHasAlu32()) 157 addPass(createBPFMIPeepholePass()); 158 addPass(createBPFMIPeepholeTruncElimPass()); 159 } 160 } 161 162 void BPFPassConfig::addPreEmitPass() { 163 addPass(createBPFMIPreEmitCheckingPass()); 164 if (getOptLevel() != CodeGenOpt::None) 165 if (!DisableMIPeephole) 166 addPass(createBPFMIPreEmitPeepholePass()); 167 } 168