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📄 AggressiveAntiDepBreaker.cpp(37.23 KB)
📄 AggressiveAntiDepBreaker.h(6.8 KB)
📄 AllocationOrder.cpp(1.96 KB)
📄 AllocationOrder.h(2.96 KB)
📄 Analysis.cpp(32.62 KB)
📁 AsmPrinter
📄 AtomicExpandPass.cpp(71.86 KB)
📄 BBSectionsPrepare.cpp(18.8 KB)
📄 BasicTargetTransformInfo.cpp(1.53 KB)
📄 BranchFolding.cpp(77.92 KB)
📄 BranchFolding.h(7.36 KB)
📄 BranchRelaxation.cpp(19.45 KB)
📄 BreakFalseDeps.cpp(9.79 KB)
📄 BuiltinGCs.cpp(4.88 KB)
📄 CFGuardLongjmp.cpp(3.73 KB)
📄 CFIInstrInserter.cpp(17.53 KB)
📄 CalcSpillWeights.cpp(10.22 KB)
📄 CallingConvLower.cpp(10.4 KB)
📄 CodeGen.cpp(5.28 KB)
📄 CodeGenPrepare.cpp(295.01 KB)
📄 CommandFlags.cpp(24.89 KB)
📄 CriticalAntiDepBreaker.cpp(27.91 KB)
📄 CriticalAntiDepBreaker.h(4.22 KB)
📄 DFAPacketizer.cpp(10.91 KB)
📄 DeadMachineInstructionElim.cpp(6.52 KB)
📄 DetectDeadLanes.cpp(20.74 KB)
📄 DwarfEHPrepare.cpp(9.01 KB)
📄 EarlyIfConversion.cpp(37.51 KB)
📄 EdgeBundles.cpp(3.21 KB)
📄 ExecutionDomainFix.cpp(14.67 KB)
📄 ExpandMemCmp.cpp(33.66 KB)
📄 ExpandPostRAPseudos.cpp(7.28 KB)
📄 ExpandReductions.cpp(7.23 KB)
📄 FEntryInserter.cpp(1.81 KB)
📄 FaultMaps.cpp(4.99 KB)
📄 FinalizeISel.cpp(2.65 KB)
📄 FixupStatepointCallerSaved.cpp(11.06 KB)
📄 FuncletLayout.cpp(2.21 KB)
📄 GCMetadata.cpp(5.1 KB)
📄 GCMetadataPrinter.cpp(748 B)
📄 GCRootLowering.cpp(11.46 KB)
📄 GCStrategy.cpp(708 B)
📁 GlobalISel
📄 GlobalMerge.cpp(24.52 KB)
📄 HardwareLoops.cpp(18.44 KB)
📄 IfConversion.cpp(89.43 KB)
📄 ImplicitNullChecks.cpp(25.14 KB)
📄 IndirectBrExpandPass.cpp(7.79 KB)
📄 InlineSpiller.cpp(58.24 KB)
📄 InterferenceCache.cpp(8.83 KB)
📄 InterferenceCache.h(7.22 KB)
📄 InterleavedAccessPass.cpp(16.59 KB)
📄 InterleavedLoadCombinePass.cpp(42.35 KB)
📄 IntrinsicLowering.cpp(17.08 KB)
📄 LLVMTargetMachine.cpp(10.25 KB)
📄 LatencyPriorityQueue.cpp(5.64 KB)
📄 LazyMachineBlockFrequencyInfo.cpp(3.36 KB)
📄 LexicalScopes.cpp(12.16 KB)
📄 LiveDebugValues.cpp(78.98 KB)
📄 LiveDebugVariables.cpp(51.79 KB)
📄 LiveDebugVariables.h(2.15 KB)
📄 LiveInterval.cpp(46.67 KB)
📄 LiveIntervalCalc.cpp(7.62 KB)
📄 LiveIntervalUnion.cpp(6.36 KB)
📄 LiveIntervals.cpp(64.59 KB)
📄 LivePhysRegs.cpp(11.08 KB)
📄 LiveRangeCalc.cpp(15.72 KB)
📄 LiveRangeEdit.cpp(17.03 KB)
📄 LiveRangeShrink.cpp(8.69 KB)
📄 LiveRangeUtils.h(2.12 KB)
📄 LiveRegMatrix.cpp(7.47 KB)
📄 LiveRegUnits.cpp(4.72 KB)
📄 LiveStacks.cpp(2.95 KB)
📄 LiveVariables.cpp(30.26 KB)
📄 LocalStackSlotAllocation.cpp(17.26 KB)
📄 LoopTraversal.cpp(2.89 KB)
📄 LowLevelType.cpp(1.93 KB)
📄 LowerEmuTLS.cpp(5.66 KB)
📄 MBFIWrapper.cpp(1.57 KB)
📄 MIRCanonicalizerPass.cpp(12.46 KB)
📄 MIRNamerPass.cpp(2.16 KB)
📁 MIRParser
📄 MIRPrinter.cpp(32.67 KB)
📄 MIRPrintingPass.cpp(1.99 KB)
📄 MIRVRegNamerUtils.cpp(6.04 KB)
📄 MIRVRegNamerUtils.h(3.25 KB)
📄 MachineBasicBlock.cpp(50.47 KB)
📄 MachineBlockFrequencyInfo.cpp(10.13 KB)
📄 MachineBlockPlacement.cpp(137.61 KB)
📄 MachineBranchProbabilityInfo.cpp(3.5 KB)
📄 MachineCSE.cpp(31.82 KB)
📄 MachineCombiner.cpp(28.13 KB)
📄 MachineCopyPropagation.cpp(29.21 KB)
📄 MachineDebugify.cpp(6.47 KB)
📄 MachineDominanceFrontier.cpp(1.83 KB)
📄 MachineDominators.cpp(4.86 KB)
📄 MachineFrameInfo.cpp(9.77 KB)
📄 MachineFunction.cpp(42.97 KB)
📄 MachineFunctionPass.cpp(4.78 KB)
📄 MachineFunctionPrinterPass.cpp(2.3 KB)
📄 MachineInstr.cpp(76.39 KB)
📄 MachineInstrBundle.cpp(11.49 KB)
📄 MachineLICM.cpp(57.05 KB)
📄 MachineLoopInfo.cpp(4.98 KB)
📄 MachineLoopUtils.cpp(5.16 KB)
📄 MachineModuleInfo.cpp(9.9 KB)
📄 MachineModuleInfoImpls.cpp(1.5 KB)
📄 MachineOperand.cpp(39.6 KB)
📄 MachineOptimizationRemarkEmitter.cpp(3.29 KB)
📄 MachineOutliner.cpp(42.13 KB)
📄 MachinePipeliner.cpp(111.33 KB)
📄 MachinePostDominators.cpp(2.42 KB)
📄 MachineRegionInfo.cpp(4.75 KB)
📄 MachineRegisterInfo.cpp(22.97 KB)
📄 MachineSSAUpdater.cpp(12.99 KB)
📄 MachineScheduler.cpp(136.89 KB)
📄 MachineSink.cpp(51.94 KB)
📄 MachineSizeOpts.cpp(8.76 KB)
📄 MachineStripDebug.cpp(3.76 KB)
📄 MachineTraceMetrics.cpp(49.58 KB)
📄 MachineVerifier.cpp(107.98 KB)
📄 MacroFusion.cpp(7.55 KB)
📄 ModuloSchedule.cpp(85.09 KB)
📄 NonRelocatableStringpool.cpp(1.65 KB)
📄 OptimizePHIs.cpp(6.7 KB)
📄 PHIElimination.cpp(27.73 KB)
📄 PHIEliminationUtils.cpp(2.56 KB)
📄 PHIEliminationUtils.h(972 B)
📄 ParallelCG.cpp(3.71 KB)
📄 PatchableFunction.cpp(3.44 KB)
📄 PeepholeOptimizer.cpp(78.41 KB)
📄 PostRAHazardRecognizer.cpp(3.5 KB)
📄 PostRASchedulerList.cpp(24.31 KB)
📄 PreISelIntrinsicLowering.cpp(7.91 KB)
📄 ProcessImplicitDefs.cpp(5.4 KB)
📄 PrologEpilogInserter.cpp(50.45 KB)
📄 PseudoSourceValue.cpp(4.71 KB)
📄 RDFGraph.cpp(58.39 KB)
📄 RDFLiveness.cpp(40.7 KB)
📄 RDFRegisters.cpp(11.29 KB)
📄 ReachingDefAnalysis.cpp(21.74 KB)
📄 RegAllocBase.cpp(6.31 KB)
📄 RegAllocBase.h(4.63 KB)
📄 RegAllocBasic.cpp(11.33 KB)
📄 RegAllocFast.cpp(45.78 KB)
📄 RegAllocGreedy.cpp(123.32 KB)
📄 RegAllocPBQP.cpp(33.14 KB)
📄 RegUsageInfoCollector.cpp(7.39 KB)
📄 RegUsageInfoPropagate.cpp(5.07 KB)
📄 RegisterClassInfo.cpp(6.62 KB)
📄 RegisterCoalescer.cpp(151.71 KB)
📄 RegisterCoalescer.h(4.04 KB)
📄 RegisterPressure.cpp(48.86 KB)
📄 RegisterScavenging.cpp(27.48 KB)
📄 RegisterUsageInfo.cpp(3.18 KB)
📄 RenameIndependentSubregs.cpp(14.79 KB)
📄 ResetMachineFunctionPass.cpp(3.48 KB)
📄 SafeStack.cpp(34.12 KB)
📄 SafeStackLayout.cpp(5.3 KB)
📄 SafeStackLayout.h(2.41 KB)
📄 ScalarizeMaskedMemIntrin.cpp(31.46 KB)
📄 ScheduleDAG.cpp(21.34 KB)
📄 ScheduleDAGInstrs.cpp(54.59 KB)
📄 ScheduleDAGPrinter.cpp(3.21 KB)
📄 ScoreboardHazardRecognizer.cpp(7.96 KB)
📁 SelectionDAG
📄 ShadowStackGCLowering.cpp(14.16 KB)
📄 ShrinkWrap.cpp(23.03 KB)
📄 SjLjEHPrepare.cpp(18.93 KB)
📄 SlotIndexes.cpp(9.35 KB)
📄 SpillPlacement.cpp(12.58 KB)
📄 SpillPlacement.h(6.67 KB)
📄 SplitKit.cpp(66.39 KB)
📄 SplitKit.h(23.7 KB)
📄 StackColoring.cpp(49.03 KB)
📄 StackMapLivenessAnalysis.cpp(6.16 KB)
📄 StackMaps.cpp(19.74 KB)
📄 StackProtector.cpp(22.94 KB)
📄 StackSlotColoring.cpp(17.12 KB)
📄 SwiftErrorValueTracking.cpp(11.37 KB)
📄 SwitchLoweringUtils.cpp(18.33 KB)
📄 TailDuplication.cpp(3.32 KB)
📄 TailDuplicator.cpp(38.29 KB)
📄 TargetFrameLoweringImpl.cpp(6.24 KB)
📄 TargetInstrInfo.cpp(51.1 KB)
📄 TargetLoweringBase.cpp(82.53 KB)
📄 TargetLoweringObjectFileImpl.cpp(80.52 KB)
📄 TargetOptionsImpl.cpp(2 KB)
📄 TargetPassConfig.cpp(48.89 KB)
📄 TargetRegisterInfo.cpp(19.15 KB)
📄 TargetSchedule.cpp(13.16 KB)
📄 TargetSubtargetInfo.cpp(1.89 KB)
📄 TwoAddressInstructionPass.cpp(62.08 KB)
📄 TypePromotion.cpp(32.46 KB)
📄 UnreachableBlockElim.cpp(7.48 KB)
📄 ValueTypes.cpp(19.87 KB)
📄 VirtRegMap.cpp(21.4 KB)
📄 WasmEHPrepare.cpp(17.48 KB)
📄 WinEHPrepare.cpp(51.16 KB)
📄 XRayInstrumentation.cpp(9.66 KB)

Editing: IndirectBrExpandPass.cpp

//===- IndirectBrExpandPass.cpp - Expand indirectbr to switch -------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
///
/// Implements an expansion pass to turn `indirectbr` instructions in the IR
/// into `switch` instructions. This works by enumerating the basic blocks in
/// a dense range of integers, replacing each `blockaddr` constant with the
/// corresponding integer constant, and then building a switch that maps from
/// the integers to the actual blocks. All of the indirectbr instructions in the
/// function are redirected to this common switch.
///
/// While this is generically useful if a target is unable to codegen
/// `indirectbr` natively, it is primarily useful when there is some desire to
/// get the builtin non-jump-table lowering of a switch even when the input
/// source contained an explicit indirect branch construct.
///
/// Note that it doesn't make any sense to enable this pass unless a target also
/// disables jump-table lowering of switches. Doing that is likely to pessimize
/// the code.
///
//===----------------------------------------------------------------------===//

#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Sequence.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"

using namespace llvm;

#define DEBUG_TYPE "indirectbr-expand"

namespace {

class IndirectBrExpandPass : public FunctionPass {
  const TargetLowering *TLI = nullptr;

public:
  static char ID; // Pass identification, replacement for typeid

IndirectBrExpandPass() : FunctionPass(ID) {
    initializeIndirectBrExpandPassPass(*PassRegistry::getPassRegistry());
  }

bool runOnFunction(Function &F) override;
};

} // end anonymous namespace

char IndirectBrExpandPass::ID = 0;

INITIALIZE_PASS(IndirectBrExpandPass, DEBUG_TYPE,
                "Expand indirectbr instructions", false, false)

FunctionPass *llvm::createIndirectBrExpandPass() {
  return new IndirectBrExpandPass();
}

bool IndirectBrExpandPass::runOnFunction(Function &F) {
  auto &DL = F.getParent()->getDataLayout();
  auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();
  if (!TPC)
    return false;

auto &TM = TPC->getTM<TargetMachine>();
  auto &STI = *TM.getSubtargetImpl(F);
  if (!STI.enableIndirectBrExpand())
    return false;
  TLI = STI.getTargetLowering();

SmallVector<IndirectBrInst *, 1> IndirectBrs;

// Set of all potential successors for indirectbr instructions.
  SmallPtrSet<BasicBlock *, 4> IndirectBrSuccs;

// Build a list of indirectbrs that we want to rewrite.
  for (BasicBlock &BB : F)
    if (auto *IBr = dyn_cast<IndirectBrInst>(BB.getTerminator())) {
      // Handle the degenerate case of no successors by replacing the indirectbr
      // with unreachable as there is no successor available.
      if (IBr->getNumSuccessors() == 0) {
        (void)new UnreachableInst(F.getContext(), IBr);
        IBr->eraseFromParent();
        continue;
      }

IndirectBrs.push_back(IBr);
      for (BasicBlock *SuccBB : IBr->successors())
        IndirectBrSuccs.insert(SuccBB);
    }

if (IndirectBrs.empty())
    return false;

// If we need to replace any indirectbrs we need to establish integer
  // constants that will correspond to each of the basic blocks in the function
  // whose address escapes. We do that here and rewrite all the blockaddress
  // constants to just be those integer constants cast to a pointer type.
  SmallVector<BasicBlock *, 4> BBs;

for (BasicBlock &BB : F) {
    // Skip blocks that aren't successors to an indirectbr we're going to
    // rewrite.
    if (!IndirectBrSuccs.count(&BB))
      continue;

auto IsBlockAddressUse = [&](const Use &U) {
      return isa<BlockAddress>(U.getUser());
    };
    auto BlockAddressUseIt = llvm::find_if(BB.uses(), IsBlockAddressUse);
    if (BlockAddressUseIt == BB.use_end())
      continue;

assert(std::find_if(std::next(BlockAddressUseIt), BB.use_end(),
                        IsBlockAddressUse) == BB.use_end() &&
           "There should only ever be a single blockaddress use because it is "
           "a constant and should be uniqued.");

auto *BA = cast<BlockAddress>(BlockAddressUseIt->getUser());

// Skip if the constant was formed but ended up not being used (due to DCE
    // or whatever).
    if (!BA->isConstantUsed())
      continue;

// Compute the index we want to use for this basic block. We can't use zero
    // because null can be compared with block addresses.
    int BBIndex = BBs.size() + 1;
    BBs.push_back(&BB);

auto *ITy = cast<IntegerType>(DL.getIntPtrType(BA->getType()));
    ConstantInt *BBIndexC = ConstantInt::get(ITy, BBIndex);

// Now rewrite the blockaddress to an integer constant based on the index.
    // FIXME: This part doesn't properly recognize other uses of blockaddress
    // expressions, for instance, where they are used to pass labels to
    // asm-goto. This part of the pass needs a rework.
    BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(BBIndexC, BA->getType()));
  }

if (BBs.empty()) {
    // There are no blocks whose address is taken, so any indirectbr instruction
    // cannot get a valid input and we can replace all of them with unreachable.
    for (auto *IBr : IndirectBrs) {
      (void)new UnreachableInst(F.getContext(), IBr);
      IBr->eraseFromParent();
    }
    return true;
  }

BasicBlock *SwitchBB;
  Value *SwitchValue;

// Compute a common integer type across all the indirectbr instructions.
  IntegerType *CommonITy = nullptr;
  for (auto *IBr : IndirectBrs) {
    auto *ITy =
        cast<IntegerType>(DL.getIntPtrType(IBr->getAddress()->getType()));
    if (!CommonITy || ITy->getBitWidth() > CommonITy->getBitWidth())
      CommonITy = ITy;
  }

auto GetSwitchValue = [DL, CommonITy](IndirectBrInst *IBr) {
    return CastInst::CreatePointerCast(
        IBr->getAddress(), CommonITy,
        Twine(IBr->getAddress()->getName()) + ".switch_cast", IBr);
  };

if (IndirectBrs.size() == 1) {
    // If we only have one indirectbr, we can just directly replace it within
    // its block.
    SwitchBB = IndirectBrs[0]->getParent();
    SwitchValue = GetSwitchValue(IndirectBrs[0]);
    IndirectBrs[0]->eraseFromParent();
  } else {
    // Otherwise we need to create a new block to hold the switch across BBs,
    // jump to that block instead of each indirectbr, and phi together the
    // values for the switch.
    SwitchBB = BasicBlock::Create(F.getContext(), "switch_bb", &F);
    auto *SwitchPN = PHINode::Create(CommonITy, IndirectBrs.size(),
                                     "switch_value_phi", SwitchBB);
    SwitchValue = SwitchPN;

// Now replace the indirectbr instructions with direct branches to the
    // switch block and fill out the PHI operands.
    for (auto *IBr : IndirectBrs) {
      SwitchPN->addIncoming(GetSwitchValue(IBr), IBr->getParent());
      BranchInst::Create(SwitchBB, IBr);
      IBr->eraseFromParent();
    }
  }

// Now build the switch in the block. The block will have no terminator
  // already.
  auto *SI = SwitchInst::Create(SwitchValue, BBs[0], BBs.size(), SwitchBB);

// Add a case for each block.
  for (int i : llvm::seq<int>(1, BBs.size()))
    SI->addCase(ConstantInt::get(CommonITy, i + 1), BBs[i]);

return true;
}

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Editing: IndirectBrExpandPass.cpp

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