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📄 AMDGPUEmitPrintf.cpp(8.57 KB)
📄 ASanStackFrameLayout.cpp(5.75 KB)
📄 AddDiscriminators.cpp(10.78 KB)
📄 AssumeBundleBuilder.cpp(21.46 KB)
📄 BasicBlockUtils.cpp(51.81 KB)
📄 BreakCriticalEdges.cpp(19.03 KB)
📄 BuildLibCalls.cpp(43.9 KB)
📄 BypassSlowDivision.cpp(17.95 KB)
📄 CallGraphUpdater.cpp(5.76 KB)
📄 CallPromotionUtils.cpp(22.18 KB)
📄 CanonicalizeAliases.cpp(3.18 KB)
📄 CanonicalizeFreezeInLoops.cpp(7.93 KB)
📄 CloneFunction.cpp(34.49 KB)
📄 CloneModule.cpp(7.93 KB)
📄 CodeExtractor.cpp(65.69 KB)
📄 CodeMoverUtils.cpp(15.82 KB)
📄 CtorUtils.cpp(5.1 KB)
📄 Debugify.cpp(17.78 KB)
📄 DemoteRegToStack.cpp(6.1 KB)
📄 EntryExitInstrumenter.cpp(5.83 KB)
📄 EscapeEnumerator.cpp(2.96 KB)
📄 Evaluator.cpp(27.98 KB)
📄 FixIrreducible.cpp(12.68 KB)
📄 FlattenCFG.cpp(16.99 KB)
📄 FunctionComparator.cpp(34.36 KB)
📄 FunctionImportUtils.cpp(13.8 KB)
📄 GlobalStatus.cpp(7.23 KB)
📄 GuardUtils.cpp(4.76 KB)
📄 ImportedFunctionsInliningStatistics.cpp(7.67 KB)
📄 InjectTLIMappings.cpp(6.62 KB)
📄 InlineFunction.cpp(103.28 KB)
📄 InstructionNamer.cpp(1.98 KB)
📄 IntegerDivision.cpp(26.17 KB)
📄 LCSSA.cpp(18.72 KB)
📄 LibCallsShrinkWrap.cpp(18.68 KB)
📄 Local.cpp(114.96 KB)
📄 LoopRotationUtils.cpp(29.47 KB)
📄 LoopSimplify.cpp(36.13 KB)
📄 LoopUnroll.cpp(38.07 KB)
📄 LoopUnrollAndJam.cpp(37.71 KB)
📄 LoopUnrollPeel.cpp(31.88 KB)
📄 LoopUnrollRuntime.cpp(40.17 KB)
📄 LoopUtils.cpp(65.03 KB)
📄 LoopVersioning.cpp(12.42 KB)
📄 LowerInvoke.cpp(3.3 KB)
📄 LowerMemIntrinsics.cpp(20.41 KB)
📄 LowerSwitch.cpp(23.46 KB)
📄 Mem2Reg.cpp(3.71 KB)
📄 MetaRenamer.cpp(5.29 KB)
📄 MisExpect.cpp(6.97 KB)
📄 ModuleUtils.cpp(10.99 KB)
📄 NameAnonGlobals.cpp(3.33 KB)
📄 PredicateInfo.cpp(36.79 KB)
📄 PromoteMemoryToRegister.cpp(37.26 KB)
📄 SSAUpdater.cpp(16.72 KB)
📄 SSAUpdaterBulk.cpp(7.46 KB)
📄 SanitizerStats.cpp(4.08 KB)
📄 ScalarEvolutionExpander.cpp(101.25 KB)
📄 SimplifyCFG.cpp(238.13 KB)
📄 SimplifyIndVar.cpp(34.53 KB)
📄 SimplifyLibCalls.cpp(122.25 KB)
📄 SizeOpts.cpp(5.08 KB)
📄 SplitModule.cpp(9.67 KB)
📄 StripGCRelocates.cpp(2.86 KB)
📄 StripNonLineTableDebugInfo.cpp(1.4 KB)
📄 SymbolRewriter.cpp(18.82 KB)
📄 UnifyFunctionExitNodes.cpp(4.42 KB)
📄 UnifyLoopExits.cpp(8.16 KB)
📄 UniqueInternalLinkageNames.cpp(2.91 KB)
📄 Utils.cpp(2.53 KB)
📄 VNCoercion.cpp(25.89 KB)
📄 ValueMapper.cpp(38.06 KB)

Editing: CtorUtils.cpp

//===- CtorUtils.cpp - Helpers for working with global_ctors ----*- C++ -*-===//
//
// 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 defines functions that are used to process llvm.global_ctors.
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Utils/CtorUtils.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"

#define DEBUG_TYPE "ctor_utils"

using namespace llvm;

/// Given a specified llvm.global_ctors list, remove the listed elements.
static void removeGlobalCtors(GlobalVariable *GCL, const BitVector &CtorsToRemove) {
  // Filter out the initializer elements to remove.
  ConstantArray *OldCA = cast<ConstantArray>(GCL->getInitializer());
  SmallVector<Constant *, 10> CAList;
  for (unsigned I = 0, E = OldCA->getNumOperands(); I < E; ++I)
    if (!CtorsToRemove.test(I))
      CAList.push_back(OldCA->getOperand(I));

// Create the new array initializer.
  ArrayType *ATy =
      ArrayType::get(OldCA->getType()->getElementType(), CAList.size());
  Constant *CA = ConstantArray::get(ATy, CAList);

// If we didn't change the number of elements, don't create a new GV.
  if (CA->getType() == OldCA->getType()) {
    GCL->setInitializer(CA);
    return;
  }

// Create the new global and insert it next to the existing list.
  GlobalVariable *NGV =
      new GlobalVariable(CA->getType(), GCL->isConstant(), GCL->getLinkage(),
                         CA, "", GCL->getThreadLocalMode());
  GCL->getParent()->getGlobalList().insert(GCL->getIterator(), NGV);
  NGV->takeName(GCL);

// Nuke the old list, replacing any uses with the new one.
  if (!GCL->use_empty()) {
    Constant *V = NGV;
    if (V->getType() != GCL->getType())
      V = ConstantExpr::getBitCast(V, GCL->getType());
    GCL->replaceAllUsesWith(V);
  }
  GCL->eraseFromParent();
}

/// Given a llvm.global_ctors list that we can understand,
/// return a list of the functions and null terminator as a vector.
static std::vector<Function *> parseGlobalCtors(GlobalVariable *GV) {
  if (GV->getInitializer()->isNullValue())
    return std::vector<Function *>();
  ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
  std::vector<Function *> Result;
  Result.reserve(CA->getNumOperands());
  for (auto &V : CA->operands()) {
    ConstantStruct *CS = cast<ConstantStruct>(V);
    Result.push_back(dyn_cast<Function>(CS->getOperand(1)));
  }
  return Result;
}

/// Find the llvm.global_ctors list, verifying that all initializers have an
/// init priority of 65535.
static GlobalVariable *findGlobalCtors(Module &M) {
  GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
  if (!GV)
    return nullptr;

// Verify that the initializer is simple enough for us to handle. We are
  // only allowed to optimize the initializer if it is unique.
  if (!GV->hasUniqueInitializer())
    return nullptr;

if (isa<ConstantAggregateZero>(GV->getInitializer()))
    return GV;
  ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());

for (auto &V : CA->operands()) {
    if (isa<ConstantAggregateZero>(V))
      continue;
    ConstantStruct *CS = cast<ConstantStruct>(V);
    if (isa<ConstantPointerNull>(CS->getOperand(1)))
      continue;

// Must have a function or null ptr.
    if (!isa<Function>(CS->getOperand(1)))
      return nullptr;

// Init priority must be standard.
    ConstantInt *CI = cast<ConstantInt>(CS->getOperand(0));
    if (CI->getZExtValue() != 65535)
      return nullptr;
  }

return GV;
}

/// Call "ShouldRemove" for every entry in M's global_ctor list and remove the
/// entries for which it returns true.  Return true if anything changed.
bool llvm::optimizeGlobalCtorsList(
    Module &M, function_ref<bool(Function *)> ShouldRemove) {
  GlobalVariable *GlobalCtors = findGlobalCtors(M);
  if (!GlobalCtors)
    return false;

std::vector<Function *> Ctors = parseGlobalCtors(GlobalCtors);
  if (Ctors.empty())
    return false;

bool MadeChange = false;

// Loop over global ctors, optimizing them when we can.
  unsigned NumCtors = Ctors.size();
  BitVector CtorsToRemove(NumCtors);
  for (unsigned i = 0; i != Ctors.size() && NumCtors > 0; ++i) {
    Function *F = Ctors[i];
    // Found a null terminator in the middle of the list, prune off the rest of
    // the list.
    if (!F)
      continue;

LLVM_DEBUG(dbgs() << "Optimizing Global Constructor: " << *F << "\n");

// We cannot simplify external ctor functions.
    if (F->empty())
      continue;

// If we can evaluate the ctor at compile time, do.
    if (ShouldRemove(F)) {
      Ctors[i] = nullptr;
      CtorsToRemove.set(i);
      NumCtors--;
      MadeChange = true;
      continue;
    }
  }

if (!MadeChange)
    return false;

removeGlobalCtors(GlobalCtors, CtorsToRemove);
  return true;
}

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Editing: CtorUtils.cpp

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