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