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/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/Passes/PassBuilder.h"
  24 #include "llvm/Support/FormattedStream.h"
  25 #include "llvm/Support/TargetRegistry.h"
  26 #include "llvm/Target/TargetOptions.h"
  27 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
  28 #include "llvm/Transforms/Scalar.h"
  29 #include "llvm/Transforms/Scalar/SimplifyCFG.h"
  30 #include "llvm/Transforms/Utils/SimplifyCFGOptions.h"
  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   initializeBPFAdjustOptPass(PR);
  47   initializeBPFCheckAndAdjustIRPass(PR);
  48   initializeBPFMIPeepholePass(PR);
  49   initializeBPFMIPeepholeTruncElimPass(PR);
  50 }
  51
  52 // DataLayout: little or big endian
  53 static std::string computeDataLayout(const Triple &TT) {
  54   if (TT.getArch() == Triple::bpfeb)
  55     return "E-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
  56   else
  57     return "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
  58 }
  59
  60 static Reloc::Model getEffectiveRelocModel(Optional<Reloc::Model> RM) {
  61   return RM.getValueOr(Reloc::PIC_);
  62 }
  63
  64 BPFTargetMachine::BPFTargetMachine(const Target &T, const Triple &TT,
  65                                    StringRef CPU, StringRef FS,
  66                                    const TargetOptions &Options,
  67                                    Optional<Reloc::Model> RM,
  68                                    Optional<CodeModel::Model> CM,
  69                                    CodeGenOpt::Level OL, bool JIT)
  70     : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options,
  71                         getEffectiveRelocModel(RM),
  72                         getEffectiveCodeModel(CM, CodeModel::Small), OL),
  73       TLOF(std::make_unique<TargetLoweringObjectFileELF>()),
  74       Subtarget(TT, std::string(CPU), std::string(FS), *this) {
  75   initAsmInfo();
  76
  77   BPFMCAsmInfo *MAI =
  78       static_cast<BPFMCAsmInfo *>(const_cast<MCAsmInfo *>(AsmInfo.get()));
  79   MAI->setDwarfUsesRelocationsAcrossSections(!Subtarget.getUseDwarfRIS());
  80 }
  81
  82 namespace {
  83 // BPF Code Generator Pass Configuration Options.
  84 class BPFPassConfig : public TargetPassConfig {
  85 public:
  86   BPFPassConfig(BPFTargetMachine &TM, PassManagerBase &PM)
  87       : TargetPassConfig(TM, PM) {}
  88
  89   BPFTargetMachine &getBPFTargetMachine() const {
  90     return getTM<BPFTargetMachine>();
  91   }
  92
  93   void addIRPasses() override;
  94   bool addInstSelector() override;
  95   void addMachineSSAOptimization() override;
  96   void addPreEmitPass() override;
  97 };
  98 }
  99
 100 TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
 101   return new BPFPassConfig(*this, PM);
 102 }
 103
 104 void BPFTargetMachine::adjustPassManager(PassManagerBuilder &Builder) {
 105  Builder.addExtension(
 106       PassManagerBuilder::EP_EarlyAsPossible,
 107       [&](const PassManagerBuilder &, legacy::PassManagerBase &PM) {
 108         PM.add(createBPFAbstractMemberAccess(this));
 109         PM.add(createBPFPreserveDIType());
 110       });
 111
 112   Builder.addExtension(
 113       PassManagerBuilder::EP_Peephole,
 114       [&](const PassManagerBuilder &, legacy::PassManagerBase &PM) {
 115         PM.add(createCFGSimplificationPass(
 116             SimplifyCFGOptions().hoistCommonInsts(true)));
 117       });
 118   Builder.addExtension(
 119       PassManagerBuilder::EP_ModuleOptimizerEarly,
 120       [&](const PassManagerBuilder &, legacy::PassManagerBase &PM) {
 121         PM.add(createBPFAdjustOpt());
 122       });
 123 }
 124
 125 void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
 126   PB.registerPipelineStartEPCallback(
 127       [=](ModulePassManager &MPM, OptimizationLevel) {
 128         FunctionPassManager FPM;
 129         FPM.addPass(BPFAbstractMemberAccessPass(this));
 130         FPM.addPass(BPFPreserveDITypePass());
 131         MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
 132       });
 133   PB.registerPeepholeEPCallback([=](FunctionPassManager &FPM,
 134                                     OptimizationLevel Level) {
 135     FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(true)));
 136   });
 137   PB.registerPipelineEarlySimplificationEPCallback(
 138       [=](ModulePassManager &MPM, OptimizationLevel) {
 139         MPM.addPass(BPFAdjustOptPass());
 140       });
 141 }
 142
 143 void BPFPassConfig::addIRPasses() {
 144   addPass(createBPFCheckAndAdjustIR());
 145   TargetPassConfig::addIRPasses();
 146 }
 147
 148 TargetTransformInfo
 149 BPFTargetMachine::getTargetTransformInfo(const Function &F) {
 150   return TargetTransformInfo(BPFTTIImpl(this, F));
 151 }
 152
 153 // Install an instruction selector pass using
 154 // the ISelDag to gen BPF code.
 155 bool BPFPassConfig::addInstSelector() {
 156   addPass(createBPFISelDag(getBPFTargetMachine()));
 157
 158   return false;
 159 }
 160
 161 void BPFPassConfig::addMachineSSAOptimization() {
 162   addPass(createBPFMISimplifyPatchablePass());
 163
 164   // The default implementation must be called first as we want eBPF
 165   // Peephole ran at last.
 166   TargetPassConfig::addMachineSSAOptimization();
 167
 168   const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
 169   if (!DisableMIPeephole) {
 170     if (Subtarget->getHasAlu32())
 171       addPass(createBPFMIPeepholePass());
 172     addPass(createBPFMIPeepholeTruncElimPass());
 173   }
 174 }
 175
 176 void BPFPassConfig::addPreEmitPass() {
 177   addPass(createBPFMIPreEmitCheckingPass());
 178   if (getOptLevel() != CodeGenOpt::None)
 179     if (!DisableMIPeephole)
 180       addPass(createBPFMIPreEmitPeepholePass());
 181 }