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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: XRayInstrumentation.cpp

//===- XRayInstrumentation.cpp - Adds XRay instrumentation to functions. --===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements a MachineFunctionPass that inserts the appropriate
// XRay instrumentation instructions. We look for XRay-specific attributes
// on the function to determine whether we should insert the replacement
// operations.
//
//===---------------------------------------------------------------------===//

#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/Function.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Target/TargetMachine.h"

using namespace llvm;

namespace {

struct InstrumentationOptions {
  // Whether to emit PATCHABLE_TAIL_CALL.
  bool HandleTailcall;

// Whether to emit PATCHABLE_RET/PATCHABLE_FUNCTION_EXIT for all forms of
  // return, e.g. conditional return.
  bool HandleAllReturns;
};

struct XRayInstrumentation : public MachineFunctionPass {
  static char ID;

XRayInstrumentation() : MachineFunctionPass(ID) {
    initializeXRayInstrumentationPass(*PassRegistry::getPassRegistry());
  }

void getAnalysisUsage(AnalysisUsage &AU) const override {
    AU.setPreservesCFG();
    AU.addPreserved<MachineLoopInfo>();
    AU.addPreserved<MachineDominatorTree>();
    MachineFunctionPass::getAnalysisUsage(AU);
  }

bool runOnMachineFunction(MachineFunction &MF) override;

private:
  // Replace the original RET instruction with the exit sled code ("patchable
  //   ret" pseudo-instruction), so that at runtime XRay can replace the sled
  //   with a code jumping to XRay trampoline, which calls the tracing handler
  //   and, in the end, issues the RET instruction.
  // This is the approach to go on CPUs which have a single RET instruction,
  //   like x86/x86_64.
  void replaceRetWithPatchableRet(MachineFunction &MF,
                                  const TargetInstrInfo *TII,
                                  InstrumentationOptions);

// Prepend the original return instruction with the exit sled code ("patchable
  //   function exit" pseudo-instruction), preserving the original return
  //   instruction just after the exit sled code.
  // This is the approach to go on CPUs which have multiple options for the
  //   return instruction, like ARM. For such CPUs we can't just jump into the
  //   XRay trampoline and issue a single return instruction there. We rather
  //   have to call the trampoline and return from it to the original return
  //   instruction of the function being instrumented.
  void prependRetWithPatchableExit(MachineFunction &MF,
                                   const TargetInstrInfo *TII,
                                   InstrumentationOptions);
};

} // end anonymous namespace

void XRayInstrumentation::replaceRetWithPatchableRet(
    MachineFunction &MF, const TargetInstrInfo *TII,
    InstrumentationOptions op) {
  // We look for *all* terminators and returns, then replace those with
  // PATCHABLE_RET instructions.
  SmallVector<MachineInstr *, 4> Terminators;
  for (auto &MBB : MF) {
    for (auto &T : MBB.terminators()) {
      unsigned Opc = 0;
      if (T.isReturn() &&
          (op.HandleAllReturns || T.getOpcode() == TII->getReturnOpcode())) {
        // Replace return instructions with:
        //   PATCHABLE_RET <Opcode>, <Operand>...
        Opc = TargetOpcode::PATCHABLE_RET;
      }
      if (TII->isTailCall(T) && op.HandleTailcall) {
        // Treat the tail call as a return instruction, which has a
        // different-looking sled than the normal return case.
        Opc = TargetOpcode::PATCHABLE_TAIL_CALL;
      }
      if (Opc != 0) {
        auto MIB = BuildMI(MBB, T, T.getDebugLoc(), TII->get(Opc))
                       .addImm(T.getOpcode());
        for (auto &MO : T.operands())
          MIB.add(MO);
        Terminators.push_back(&T);
        if (T.shouldUpdateCallSiteInfo())
          MF.eraseCallSiteInfo(&T);
      }
    }
  }

for (auto &I : Terminators)
    I->eraseFromParent();
}

void XRayInstrumentation::prependRetWithPatchableExit(
    MachineFunction &MF, const TargetInstrInfo *TII,
    InstrumentationOptions op) {
  for (auto &MBB : MF)
    for (auto &T : MBB.terminators()) {
      unsigned Opc = 0;
      if (T.isReturn() &&
          (op.HandleAllReturns || T.getOpcode() == TII->getReturnOpcode())) {
        Opc = TargetOpcode::PATCHABLE_FUNCTION_EXIT;
      }
      if (TII->isTailCall(T) && op.HandleTailcall) {
        Opc = TargetOpcode::PATCHABLE_TAIL_CALL;
      }
      if (Opc != 0) {
        // Prepend the return instruction with PATCHABLE_FUNCTION_EXIT or
        //   PATCHABLE_TAIL_CALL .
        BuildMI(MBB, T, T.getDebugLoc(), TII->get(Opc));
      }
    }
}

bool XRayInstrumentation::runOnMachineFunction(MachineFunction &MF) {
  auto &F = MF.getFunction();
  auto InstrAttr = F.getFnAttribute("function-instrument");
  bool AlwaysInstrument = !InstrAttr.hasAttribute(Attribute::None) &&
                          InstrAttr.isStringAttribute() &&
                          InstrAttr.getValueAsString() == "xray-always";
  auto ThresholdAttr = F.getFnAttribute("xray-instruction-threshold");
  auto IgnoreLoopsAttr = F.getFnAttribute("xray-ignore-loops");
  unsigned int XRayThreshold = 0;
  if (!AlwaysInstrument) {
    if (ThresholdAttr.hasAttribute(Attribute::None) ||
        !ThresholdAttr.isStringAttribute())
      return false; // XRay threshold attribute not found.
    if (ThresholdAttr.getValueAsString().getAsInteger(10, XRayThreshold))
      return false; // Invalid value for threshold.

bool IgnoreLoops = !IgnoreLoopsAttr.hasAttribute(Attribute::None);

// Count the number of MachineInstr`s in MachineFunction
    int64_t MICount = 0;
    for (const auto &MBB : MF)
      MICount += MBB.size();

bool TooFewInstrs = MICount < XRayThreshold;

if (!IgnoreLoops) {
      // Get MachineDominatorTree or compute it on the fly if it's unavailable
      auto *MDT = getAnalysisIfAvailable<MachineDominatorTree>();
      MachineDominatorTree ComputedMDT;
      if (!MDT) {
        ComputedMDT.getBase().recalculate(MF);
        MDT = &ComputedMDT;
      }

// Get MachineLoopInfo or compute it on the fly if it's unavailable
      auto *MLI = getAnalysisIfAvailable<MachineLoopInfo>();
      MachineLoopInfo ComputedMLI;
      if (!MLI) {
        ComputedMLI.getBase().analyze(MDT->getBase());
        MLI = &ComputedMLI;
      }

// Check if we have a loop.
      // FIXME: Maybe make this smarter, and see whether the loops are dependent
      // on inputs or side-effects?
      if (MLI->empty() && TooFewInstrs)
        return false; // Function is too small and has no loops.
    } else if (TooFewInstrs) {
      // Function is too small
      return false;
    }
  }

// We look for the first non-empty MachineBasicBlock, so that we can insert
  // the function instrumentation in the appropriate place.
  auto MBI = llvm::find_if(
      MF, [&](const MachineBasicBlock &MBB) { return !MBB.empty(); });
  if (MBI == MF.end())
    return false; // The function is empty.

auto *TII = MF.getSubtarget().getInstrInfo();
  auto &FirstMBB = *MBI;
  auto &FirstMI = *FirstMBB.begin();

if (!MF.getSubtarget().isXRaySupported()) {
    FirstMI.emitError("An attempt to perform XRay instrumentation for an"
                      " unsupported target.");
    return false;
  }

if (!F.hasFnAttribute("xray-skip-entry")) {
    // First, insert an PATCHABLE_FUNCTION_ENTER as the first instruction of the
    // MachineFunction.
    BuildMI(FirstMBB, FirstMI, FirstMI.getDebugLoc(),
            TII->get(TargetOpcode::PATCHABLE_FUNCTION_ENTER));
  }

if (!F.hasFnAttribute("xray-skip-exit")) {
    switch (MF.getTarget().getTargetTriple().getArch()) {
    case Triple::ArchType::arm:
    case Triple::ArchType::thumb:
    case Triple::ArchType::aarch64:
    case Triple::ArchType::mips:
    case Triple::ArchType::mipsel:
    case Triple::ArchType::mips64:
    case Triple::ArchType::mips64el: {
      // For the architectures which don't have a single return instruction
      InstrumentationOptions op;
      op.HandleTailcall = false;
      op.HandleAllReturns = true;
      prependRetWithPatchableExit(MF, TII, op);
      break;
    }
    case Triple::ArchType::ppc64le: {
      // PPC has conditional returns. Turn them into branch and plain returns.
      InstrumentationOptions op;
      op.HandleTailcall = false;
      op.HandleAllReturns = true;
      replaceRetWithPatchableRet(MF, TII, op);
      break;
    }
    default: {
      // For the architectures that have a single return instruction (such as
      //   RETQ on x86_64).
      InstrumentationOptions op;
      op.HandleTailcall = true;
      op.HandleAllReturns = false;
      replaceRetWithPatchableRet(MF, TII, op);
      break;
    }
    }
  }
  return true;
}

char XRayInstrumentation::ID = 0;
char &llvm::XRayInstrumentationID = XRayInstrumentation::ID;
INITIALIZE_PASS_BEGIN(XRayInstrumentation, "xray-instrumentation",
                      "Insert XRay ops", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
INITIALIZE_PASS_END(XRayInstrumentation, "xray-instrumentation",
                    "Insert XRay ops", false, false)

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