llvm/lib/Target/BPF/BPFTargetMachine.cpp

   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/FormattedStream.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 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFTarget() {
  42   // Register the target.
  43   RegisterTargetMachine<BPFTargetMachine> X(getTheBPFleTarget());
  44   RegisterTargetMachine<BPFTargetMachine> Y(getTheBPFbeTarget());
  45   RegisterTargetMachine<BPFTargetMachine> Z(getTheBPFTarget());
  46
  47   PassRegistry &PR = *PassRegistry::getPassRegistry();
  48   initializeGlobalISel(PR);
  49   initializeBPFCheckAndAdjustIRPass(PR);
  50   initializeBPFMIPeepholePass(PR);
  51   initializeBPFDAGToDAGISelLegacyPass(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                                    CodeGenOptLevel 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   bool addIRTranslator() override;
 101   bool addLegalizeMachineIR() override;
 102   bool addRegBankSelect() override;
 103   bool addGlobalInstructionSelect() override;
 104 };
 105 }
 106
 107 TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
 108   return new BPFPassConfig(*this, PM);
 109 }
 110
 111 static Expected<bool> parseBPFPreserveStaticOffsetOptions(StringRef Params) {
 112   return PassBuilder::parseSinglePassOption(Params, "allow-partial",
 113                                             "BPFPreserveStaticOffsetPass");
 114 }
 115
 116 void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
 117 #define GET_PASS_REGISTRY "BPFPassRegistry.def"
 118 #include "llvm/Passes/TargetPassRegistry.inc"
 119
 120   PB.registerPipelineStartEPCallback(
 121       [=](ModulePassManager &MPM, OptimizationLevel) {
 122         FunctionPassManager FPM;
 123         FPM.addPass(BPFPreserveStaticOffsetPass(true));
 124         FPM.addPass(BPFAbstractMemberAccessPass(this));
 125         FPM.addPass(BPFPreserveDITypePass());
 126         FPM.addPass(BPFIRPeepholePass());
 127         MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
 128       });
 129   PB.registerPeepholeEPCallback([=](FunctionPassManager &FPM,
 130                                     OptimizationLevel Level) {
 131     FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(true)));
 132     FPM.addPass(BPFASpaceCastSimplifyPass());
 133   });
 134   PB.registerScalarOptimizerLateEPCallback(
 135       [=](FunctionPassManager &FPM, OptimizationLevel Level) {
 136         // Run this after loop unrolling but before
 137         // SimplifyCFGPass(... .sinkCommonInsts(true))
 138         FPM.addPass(BPFPreserveStaticOffsetPass(false));
 139       });
 140   PB.registerPipelineEarlySimplificationEPCallback(
 141       [=](ModulePassManager &MPM, OptimizationLevel) {
 142         MPM.addPass(BPFAdjustOptPass());
 143       });
 144 }
 145
 146 void BPFPassConfig::addIRPasses() {
 147   addPass(createAtomicExpandLegacyPass());
 148   addPass(createBPFCheckAndAdjustIR());
 149
 150   TargetPassConfig::addIRPasses();
 151 }
 152
 153 TargetTransformInfo
 154 BPFTargetMachine::getTargetTransformInfo(const Function &F) const {
 155   return TargetTransformInfo(BPFTTIImpl(this, F));
 156 }
 157
 158 // Install an instruction selector pass using
 159 // the ISelDag to gen BPF code.
 160 bool BPFPassConfig::addInstSelector() {
 161   addPass(createBPFISelDag(getBPFTargetMachine()));
 162
 163   return false;
 164 }
 165
 166 void BPFPassConfig::addMachineSSAOptimization() {
 167   addPass(createBPFMISimplifyPatchablePass());
 168
 169   // The default implementation must be called first as we want eBPF
 170   // Peephole ran at last.
 171   TargetPassConfig::addMachineSSAOptimization();
 172
 173   const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
 174   if (!DisableMIPeephole) {
 175     if (Subtarget->getHasAlu32())
 176       addPass(createBPFMIPeepholePass());
 177   }
 178 }
 179
 180 void BPFPassConfig::addPreEmitPass() {
 181   addPass(createBPFMIPreEmitCheckingPass());
 182   if (getOptLevel() != CodeGenOptLevel::None)
 183     if (!DisableMIPeephole)
 184       addPass(createBPFMIPreEmitPeepholePass());
 185 }
 186
 187 bool BPFPassConfig::addIRTranslator() {
 188   addPass(new IRTranslator());
 189   return false;
 190 }
 191
 192 bool BPFPassConfig::addLegalizeMachineIR() {
 193   addPass(new Legalizer());
 194   return false;
 195 }
 196
 197 bool BPFPassConfig::addRegBankSelect() {
 198   addPass(new RegBankSelect());
 199   return false;
 200 }
 201
 202 bool BPFPassConfig::addGlobalInstructionSelect() {
 203   addPass(new InstructionSelect(getOptLevel()));
 204   return false;
 205 }