diff options
Diffstat (limited to 'contrib/llvm/lib/Transforms/Scalar/ADCE.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/Scalar/ADCE.cpp | 623 |
1 files changed, 562 insertions, 61 deletions
diff --git a/contrib/llvm/lib/Transforms/Scalar/ADCE.cpp b/contrib/llvm/lib/Transforms/Scalar/ADCE.cpp index 0eed024..adc903c 100644 --- a/contrib/llvm/lib/Transforms/Scalar/ADCE.cpp +++ b/contrib/llvm/lib/Transforms/Scalar/ADCE.cpp @@ -15,14 +15,19 @@ //===----------------------------------------------------------------------===// #include "llvm/Transforms/Scalar/ADCE.h" + #include "llvm/ADT/DepthFirstIterator.h" +#include "llvm/ADT/PostOrderIterator.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/SmallVector.h" #include "llvm/ADT/Statistic.h" #include "llvm/Analysis/GlobalsModRef.h" +#include "llvm/Analysis/IteratedDominanceFrontier.h" +#include "llvm/Analysis/PostDominators.h" #include "llvm/IR/BasicBlock.h" #include "llvm/IR/CFG.h" #include "llvm/IR/DebugInfoMetadata.h" +#include "llvm/IR/IRBuilder.h" #include "llvm/IR/InstIterator.h" #include "llvm/IR/Instructions.h" #include "llvm/IR/IntrinsicInst.h" @@ -34,9 +39,372 @@ using namespace llvm; #define DEBUG_TYPE "adce" STATISTIC(NumRemoved, "Number of instructions removed"); +STATISTIC(NumBranchesRemoved, "Number of branch instructions removed"); + +// This is a tempoary option until we change the interface +// to this pass based on optimization level. +static cl::opt<bool> RemoveControlFlowFlag("adce-remove-control-flow", + cl::init(true), cl::Hidden); + +// This option enables removing of may-be-infinite loops which have no other +// effect. +static cl::opt<bool> RemoveLoops("adce-remove-loops", cl::init(false), + cl::Hidden); + +namespace { +/// Information about Instructions +struct InstInfoType { + /// True if the associated instruction is live. + bool Live = false; + /// Quick access to information for block containing associated Instruction. + struct BlockInfoType *Block = nullptr; +}; + +/// Information about basic blocks relevant to dead code elimination. +struct BlockInfoType { + /// True when this block contains a live instructions. + bool Live = false; + /// True when this block ends in an unconditional branch. + bool UnconditionalBranch = false; + /// True when this block is known to have live PHI nodes. + bool HasLivePhiNodes = false; + /// Control dependence sources need to be live for this block. + bool CFLive = false; + + /// Quick access to the LiveInfo for the terminator, + /// holds the value &InstInfo[Terminator] + InstInfoType *TerminatorLiveInfo = nullptr; + + bool terminatorIsLive() const { return TerminatorLiveInfo->Live; } + + /// Corresponding BasicBlock. + BasicBlock *BB = nullptr; + + /// Cache of BB->getTerminator(). + TerminatorInst *Terminator = nullptr; + + /// Post-order numbering of reverse control flow graph. + unsigned PostOrder; +}; + +class AggressiveDeadCodeElimination { + Function &F; + PostDominatorTree &PDT; + + /// Mapping of blocks to associated information, an element in BlockInfoVec. + DenseMap<BasicBlock *, BlockInfoType> BlockInfo; + bool isLive(BasicBlock *BB) { return BlockInfo[BB].Live; } + + /// Mapping of instructions to associated information. + DenseMap<Instruction *, InstInfoType> InstInfo; + bool isLive(Instruction *I) { return InstInfo[I].Live; } + + /// Instructions known to be live where we need to mark + /// reaching definitions as live. + SmallVector<Instruction *, 128> Worklist; + /// Debug info scopes around a live instruction. + SmallPtrSet<const Metadata *, 32> AliveScopes; + + /// Set of blocks with not known to have live terminators. + SmallPtrSet<BasicBlock *, 16> BlocksWithDeadTerminators; + + /// The set of blocks which we have determined whose control + /// dependence sources must be live and which have not had + /// those dependences analyized. + SmallPtrSet<BasicBlock *, 16> NewLiveBlocks; + + /// Set up auxiliary data structures for Instructions and BasicBlocks and + /// initialize the Worklist to the set of must-be-live Instruscions. + void initialize(); + /// Return true for operations which are always treated as live. + bool isAlwaysLive(Instruction &I); + /// Return true for instrumentation instructions for value profiling. + bool isInstrumentsConstant(Instruction &I); + + /// Propagate liveness to reaching definitions. + void markLiveInstructions(); + /// Mark an instruction as live. + void markLive(Instruction *I); + /// Mark a block as live. + void markLive(BlockInfoType &BB); + void markLive(BasicBlock *BB) { markLive(BlockInfo[BB]); } + + /// Mark terminators of control predecessors of a PHI node live. + void markPhiLive(PHINode *PN); + + /// Record the Debug Scopes which surround live debug information. + void collectLiveScopes(const DILocalScope &LS); + void collectLiveScopes(const DILocation &DL); + + /// Analyze dead branches to find those whose branches are the sources + /// of control dependences impacting a live block. Those branches are + /// marked live. + void markLiveBranchesFromControlDependences(); + + /// Remove instructions not marked live, return if any any instruction + /// was removed. + bool removeDeadInstructions(); + + /// Identify connected sections of the control flow grap which have + /// dead terminators and rewrite the control flow graph to remove them. + void updateDeadRegions(); + + /// Set the BlockInfo::PostOrder field based on a post-order + /// numbering of the reverse control flow graph. + void computeReversePostOrder(); + + /// Make the terminator of this block an unconditional branch to \p Target. + void makeUnconditional(BasicBlock *BB, BasicBlock *Target); + +public: + AggressiveDeadCodeElimination(Function &F, PostDominatorTree &PDT) + : F(F), PDT(PDT) {} + bool performDeadCodeElimination(); +}; +} + +bool AggressiveDeadCodeElimination::performDeadCodeElimination() { + initialize(); + markLiveInstructions(); + return removeDeadInstructions(); +} + +static bool isUnconditionalBranch(TerminatorInst *Term) { + auto *BR = dyn_cast<BranchInst>(Term); + return BR && BR->isUnconditional(); +} + +void AggressiveDeadCodeElimination::initialize() { + + auto NumBlocks = F.size(); + + // We will have an entry in the map for each block so we grow the + // structure to twice that size to keep the load factor low in the hash table. + BlockInfo.reserve(NumBlocks); + size_t NumInsts = 0; + + // Iterate over blocks and initialize BlockInfoVec entries, count + // instructions to size the InstInfo hash table. + for (auto &BB : F) { + NumInsts += BB.size(); + auto &Info = BlockInfo[&BB]; + Info.BB = &BB; + Info.Terminator = BB.getTerminator(); + Info.UnconditionalBranch = isUnconditionalBranch(Info.Terminator); + } + + // Initialize instruction map and set pointers to block info. + InstInfo.reserve(NumInsts); + for (auto &BBInfo : BlockInfo) + for (Instruction &I : *BBInfo.second.BB) + InstInfo[&I].Block = &BBInfo.second; + + // Since BlockInfoVec holds pointers into InstInfo and vice-versa, we may not + // add any more elements to either after this point. + for (auto &BBInfo : BlockInfo) + BBInfo.second.TerminatorLiveInfo = &InstInfo[BBInfo.second.Terminator]; + + // Collect the set of "root" instructions that are known live. + for (Instruction &I : instructions(F)) + if (isAlwaysLive(I)) + markLive(&I); + + if (!RemoveControlFlowFlag) + return; + + if (!RemoveLoops) { + // This stores state for the depth-first iterator. In addition + // to recording which nodes have been visited we also record whether + // a node is currently on the "stack" of active ancestors of the current + // node. + typedef DenseMap<BasicBlock *, bool> StatusMap ; + class DFState : public StatusMap { + public: + std::pair<StatusMap::iterator, bool> insert(BasicBlock *BB) { + return StatusMap::insert(std::make_pair(BB, true)); + } + + // Invoked after we have visited all children of a node. + void completed(BasicBlock *BB) { (*this)[BB] = false; } + + // Return true if \p BB is currently on the active stack + // of ancestors. + bool onStack(BasicBlock *BB) { + auto Iter = find(BB); + return Iter != end() && Iter->second; + } + } State; + + State.reserve(F.size()); + // Iterate over blocks in depth-first pre-order and + // treat all edges to a block already seen as loop back edges + // and mark the branch live it if there is a back edge. + for (auto *BB: depth_first_ext(&F.getEntryBlock(), State)) { + TerminatorInst *Term = BB->getTerminator(); + if (isLive(Term)) + continue; + + for (auto *Succ : successors(BB)) + if (State.onStack(Succ)) { + // back edge.... + markLive(Term); + break; + } + } + } + + // Mark blocks live if there is no path from the block to the + // return of the function or a successor for which this is true. + // This protects IDFCalculator which cannot handle such blocks. + for (auto &BBInfoPair : BlockInfo) { + auto &BBInfo = BBInfoPair.second; + if (BBInfo.terminatorIsLive()) + continue; + auto *BB = BBInfo.BB; + if (!PDT.getNode(BB)) { + markLive(BBInfo.Terminator); + continue; + } + for (auto *Succ : successors(BB)) + if (!PDT.getNode(Succ)) { + markLive(BBInfo.Terminator); + break; + } + } + + // Mark blocks live if there is no path from the block to the + // return of the function or a successor for which this is true. + // This protects IDFCalculator which cannot handle such blocks. + for (auto &BBInfoPair : BlockInfo) { + auto &BBInfo = BBInfoPair.second; + if (BBInfo.terminatorIsLive()) + continue; + auto *BB = BBInfo.BB; + if (!PDT.getNode(BB)) { + DEBUG(dbgs() << "Not post-dominated by return: " << BB->getName() + << '\n';); + markLive(BBInfo.Terminator); + continue; + } + for (auto *Succ : successors(BB)) + if (!PDT.getNode(Succ)) { + DEBUG(dbgs() << "Successor not post-dominated by return: " + << BB->getName() << '\n';); + markLive(BBInfo.Terminator); + break; + } + } + + // Treat the entry block as always live + auto *BB = &F.getEntryBlock(); + auto &EntryInfo = BlockInfo[BB]; + EntryInfo.Live = true; + if (EntryInfo.UnconditionalBranch) + markLive(EntryInfo.Terminator); + + // Build initial collection of blocks with dead terminators + for (auto &BBInfo : BlockInfo) + if (!BBInfo.second.terminatorIsLive()) + BlocksWithDeadTerminators.insert(BBInfo.second.BB); +} + +bool AggressiveDeadCodeElimination::isAlwaysLive(Instruction &I) { + // TODO -- use llvm::isInstructionTriviallyDead + if (I.isEHPad() || I.mayHaveSideEffects()) { + // Skip any value profile instrumentation calls if they are + // instrumenting constants. + if (isInstrumentsConstant(I)) + return false; + return true; + } + if (!isa<TerminatorInst>(I)) + return false; + if (RemoveControlFlowFlag && (isa<BranchInst>(I) || isa<SwitchInst>(I))) + return false; + return true; +} + +// Check if this instruction is a runtime call for value profiling and +// if it's instrumenting a constant. +bool AggressiveDeadCodeElimination::isInstrumentsConstant(Instruction &I) { + // TODO -- move this test into llvm::isInstructionTriviallyDead + if (CallInst *CI = dyn_cast<CallInst>(&I)) + if (Function *Callee = CI->getCalledFunction()) + if (Callee->getName().equals(getInstrProfValueProfFuncName())) + if (isa<Constant>(CI->getArgOperand(0))) + return true; + return false; +} + +void AggressiveDeadCodeElimination::markLiveInstructions() { + + // Propagate liveness backwards to operands. + do { + // Worklist holds newly discovered live instructions + // where we need to mark the inputs as live. + while (!Worklist.empty()) { + Instruction *LiveInst = Worklist.pop_back_val(); + DEBUG(dbgs() << "work live: "; LiveInst->dump();); + + for (Use &OI : LiveInst->operands()) + if (Instruction *Inst = dyn_cast<Instruction>(OI)) + markLive(Inst); + + if (auto *PN = dyn_cast<PHINode>(LiveInst)) + markPhiLive(PN); + } -static void collectLiveScopes(const DILocalScope &LS, - SmallPtrSetImpl<const Metadata *> &AliveScopes) { + // After data flow liveness has been identified, examine which branch + // decisions are required to determine live instructions are executed. + markLiveBranchesFromControlDependences(); + + } while (!Worklist.empty()); +} + +void AggressiveDeadCodeElimination::markLive(Instruction *I) { + + auto &Info = InstInfo[I]; + if (Info.Live) + return; + + DEBUG(dbgs() << "mark live: "; I->dump()); + Info.Live = true; + Worklist.push_back(I); + + // Collect the live debug info scopes attached to this instruction. + if (const DILocation *DL = I->getDebugLoc()) + collectLiveScopes(*DL); + + // Mark the containing block live + auto &BBInfo = *Info.Block; + if (BBInfo.Terminator == I) { + BlocksWithDeadTerminators.erase(BBInfo.BB); + // For live terminators, mark destination blocks + // live to preserve this control flow edges. + if (!BBInfo.UnconditionalBranch) + for (auto *BB : successors(I->getParent())) + markLive(BB); + } + markLive(BBInfo); +} + +void AggressiveDeadCodeElimination::markLive(BlockInfoType &BBInfo) { + if (BBInfo.Live) + return; + DEBUG(dbgs() << "mark block live: " << BBInfo.BB->getName() << '\n'); + BBInfo.Live = true; + if (!BBInfo.CFLive) { + BBInfo.CFLive = true; + NewLiveBlocks.insert(BBInfo.BB); + } + + // Mark unconditional branches at the end of live + // blocks as live since there is no work to do for them later + if (BBInfo.UnconditionalBranch) + markLive(BBInfo.Terminator); +} + +void AggressiveDeadCodeElimination::collectLiveScopes(const DILocalScope &LS) { if (!AliveScopes.insert(&LS).second) return; @@ -44,75 +412,115 @@ static void collectLiveScopes(const DILocalScope &LS, return; // Tail-recurse through the scope chain. - collectLiveScopes(cast<DILocalScope>(*LS.getScope()), AliveScopes); + collectLiveScopes(cast<DILocalScope>(*LS.getScope())); } -static void collectLiveScopes(const DILocation &DL, - SmallPtrSetImpl<const Metadata *> &AliveScopes) { +void AggressiveDeadCodeElimination::collectLiveScopes(const DILocation &DL) { // Even though DILocations are not scopes, shove them into AliveScopes so we // don't revisit them. if (!AliveScopes.insert(&DL).second) return; // Collect live scopes from the scope chain. - collectLiveScopes(*DL.getScope(), AliveScopes); + collectLiveScopes(*DL.getScope()); // Tail-recurse through the inlined-at chain. if (const DILocation *IA = DL.getInlinedAt()) - collectLiveScopes(*IA, AliveScopes); + collectLiveScopes(*IA); } -// Check if this instruction is a runtime call for value profiling and -// if it's instrumenting a constant. -static bool isInstrumentsConstant(Instruction &I) { - if (CallInst *CI = dyn_cast<CallInst>(&I)) - if (Function *Callee = CI->getCalledFunction()) - if (Callee->getName().equals(getInstrProfValueProfFuncName())) - if (isa<Constant>(CI->getArgOperand(0))) - return true; - return false; +void AggressiveDeadCodeElimination::markPhiLive(PHINode *PN) { + auto &Info = BlockInfo[PN->getParent()]; + // Only need to check this once per block. + if (Info.HasLivePhiNodes) + return; + Info.HasLivePhiNodes = true; + + // If a predecessor block is not live, mark it as control-flow live + // which will trigger marking live branches upon which + // that block is control dependent. + for (auto *PredBB : predecessors(Info.BB)) { + auto &Info = BlockInfo[PredBB]; + if (!Info.CFLive) { + Info.CFLive = true; + NewLiveBlocks.insert(PredBB); + } + } } -static bool aggressiveDCE(Function& F) { - SmallPtrSet<Instruction*, 32> Alive; - SmallVector<Instruction*, 128> Worklist; +void AggressiveDeadCodeElimination::markLiveBranchesFromControlDependences() { - // Collect the set of "root" instructions that are known live. - for (Instruction &I : instructions(F)) { - if (isa<TerminatorInst>(I) || I.isEHPad() || I.mayHaveSideEffects()) { - // Skip any value profile instrumentation calls if they are - // instrumenting constants. - if (isInstrumentsConstant(I)) - continue; - Alive.insert(&I); - Worklist.push_back(&I); - } + if (BlocksWithDeadTerminators.empty()) + return; + + DEBUG({ + dbgs() << "new live blocks:\n"; + for (auto *BB : NewLiveBlocks) + dbgs() << "\t" << BB->getName() << '\n'; + dbgs() << "dead terminator blocks:\n"; + for (auto *BB : BlocksWithDeadTerminators) + dbgs() << "\t" << BB->getName() << '\n'; + }); + + // The dominance frontier of a live block X in the reverse + // control graph is the set of blocks upon which X is control + // dependent. The following sequence computes the set of blocks + // which currently have dead terminators that are control + // dependence sources of a block which is in NewLiveBlocks. + + SmallVector<BasicBlock *, 32> IDFBlocks; + ReverseIDFCalculator IDFs(PDT); + IDFs.setDefiningBlocks(NewLiveBlocks); + IDFs.setLiveInBlocks(BlocksWithDeadTerminators); + IDFs.calculate(IDFBlocks); + NewLiveBlocks.clear(); + + // Dead terminators which control live blocks are now marked live. + for (auto *BB : IDFBlocks) { + DEBUG(dbgs() << "live control in: " << BB->getName() << '\n'); + markLive(BB->getTerminator()); } +} - // Propagate liveness backwards to operands. Keep track of live debug info - // scopes. - SmallPtrSet<const Metadata *, 32> AliveScopes; - while (!Worklist.empty()) { - Instruction *Curr = Worklist.pop_back_val(); +//===----------------------------------------------------------------------===// +// +// Routines to update the CFG and SSA information before removing dead code. +// +//===----------------------------------------------------------------------===// +bool AggressiveDeadCodeElimination::removeDeadInstructions() { - // Collect the live debug info scopes attached to this instruction. - if (const DILocation *DL = Curr->getDebugLoc()) - collectLiveScopes(*DL, AliveScopes); + // Updates control and dataflow around dead blocks + updateDeadRegions(); - for (Use &OI : Curr->operands()) { - if (Instruction *Inst = dyn_cast<Instruction>(OI)) - if (Alive.insert(Inst).second) - Worklist.push_back(Inst); + DEBUG({ + for (Instruction &I : instructions(F)) { + // Check if the instruction is alive. + if (isLive(&I)) + continue; + + if (auto *DII = dyn_cast<DbgInfoIntrinsic>(&I)) { + // Check if the scope of this variable location is alive. + if (AliveScopes.count(DII->getDebugLoc()->getScope())) + continue; + + // If intrinsic is pointing at a live SSA value, there may be an + // earlier optimization bug: if we know the location of the variable, + // why isn't the scope of the location alive? + if (Value *V = DII->getVariableLocation()) + if (Instruction *II = dyn_cast<Instruction>(V)) + if (isLive(II)) + dbgs() << "Dropping debug info for " << *DII << "\n"; + } } - } + }); // The inverse of the live set is the dead set. These are those instructions - // which have no side effects and do not influence the control flow or return + // that have no side effects and do not influence the control flow or return // value of the function, and may therefore be deleted safely. // NOTE: We reuse the Worklist vector here for memory efficiency. for (Instruction &I : instructions(F)) { // Check if the instruction is alive. - if (Alive.count(&I)) + if (isLive(&I)) continue; if (auto *DII = dyn_cast<DbgInfoIntrinsic>(&I)) { @@ -121,15 +529,6 @@ static bool aggressiveDCE(Function& F) { continue; // Fallthrough and drop the intrinsic. - DEBUG({ - // If intrinsic is pointing at a live SSA value, there may be an - // earlier optimization bug: if we know the location of the variable, - // why isn't the scope of the location alive? - if (Value *V = DII->getVariableLocation()) - if (Instruction *II = dyn_cast<Instruction>(V)) - if (Alive.count(II)) - dbgs() << "Dropping debug info for " << *DII << "\n"; - }); } // Prepare to delete. @@ -145,8 +544,104 @@ static bool aggressiveDCE(Function& F) { return !Worklist.empty(); } -PreservedAnalyses ADCEPass::run(Function &F, FunctionAnalysisManager &) { - if (!aggressiveDCE(F)) +// A dead region is the set of dead blocks with a common live post-dominator. +void AggressiveDeadCodeElimination::updateDeadRegions() { + + DEBUG({ + dbgs() << "final dead terminator blocks: " << '\n'; + for (auto *BB : BlocksWithDeadTerminators) + dbgs() << '\t' << BB->getName() + << (BlockInfo[BB].Live ? " LIVE\n" : "\n"); + }); + + // Don't compute the post ordering unless we needed it. + bool HavePostOrder = false; + + for (auto *BB : BlocksWithDeadTerminators) { + auto &Info = BlockInfo[BB]; + if (Info.UnconditionalBranch) { + InstInfo[Info.Terminator].Live = true; + continue; + } + + if (!HavePostOrder) { + computeReversePostOrder(); + HavePostOrder = true; + } + + // Add an unconditional branch to the successor closest to the + // end of the function which insures a path to the exit for each + // live edge. + BlockInfoType *PreferredSucc = nullptr; + for (auto *Succ : successors(BB)) { + auto *Info = &BlockInfo[Succ]; + if (!PreferredSucc || PreferredSucc->PostOrder < Info->PostOrder) + PreferredSucc = Info; + } + assert((PreferredSucc && PreferredSucc->PostOrder > 0) && + "Failed to find safe successor for dead branc"); + bool First = true; + for (auto *Succ : successors(BB)) { + if (!First || Succ != PreferredSucc->BB) + Succ->removePredecessor(BB); + else + First = false; + } + makeUnconditional(BB, PreferredSucc->BB); + NumBranchesRemoved += 1; + } +} + +// reverse top-sort order +void AggressiveDeadCodeElimination::computeReversePostOrder() { + + // This provides a post-order numbering of the reverse conrtol flow graph + // Note that it is incomplete in the presence of infinite loops but we don't + // need numbers blocks which don't reach the end of the functions since + // all branches in those blocks are forced live. + + // For each block without successors, extend the DFS from the bloack + // backward through the graph + SmallPtrSet<BasicBlock*, 16> Visited; + unsigned PostOrder = 0; + for (auto &BB : F) { + if (succ_begin(&BB) != succ_end(&BB)) + continue; + for (BasicBlock *Block : inverse_post_order_ext(&BB,Visited)) + BlockInfo[Block].PostOrder = PostOrder++; + } +} + +void AggressiveDeadCodeElimination::makeUnconditional(BasicBlock *BB, + BasicBlock *Target) { + TerminatorInst *PredTerm = BB->getTerminator(); + // Collect the live debug info scopes attached to this instruction. + if (const DILocation *DL = PredTerm->getDebugLoc()) + collectLiveScopes(*DL); + + // Just mark live an existing unconditional branch + if (isUnconditionalBranch(PredTerm)) { + PredTerm->setSuccessor(0, Target); + InstInfo[PredTerm].Live = true; + return; + } + DEBUG(dbgs() << "making unconditional " << BB->getName() << '\n'); + NumBranchesRemoved += 1; + IRBuilder<> Builder(PredTerm); + auto *NewTerm = Builder.CreateBr(Target); + InstInfo[NewTerm].Live = true; + if (const DILocation *DL = PredTerm->getDebugLoc()) + NewTerm->setDebugLoc(DL); +} + +//===----------------------------------------------------------------------===// +// +// Pass Manager integration code +// +//===----------------------------------------------------------------------===// +PreservedAnalyses ADCEPass::run(Function &F, FunctionAnalysisManager &FAM) { + auto &PDT = FAM.getResult<PostDominatorTreeAnalysis>(F); + if (!AggressiveDeadCodeElimination(F, PDT).performDeadCodeElimination()) return PreservedAnalyses::all(); // FIXME: This should also 'preserve the CFG'. @@ -162,21 +657,27 @@ struct ADCELegacyPass : public FunctionPass { initializeADCELegacyPassPass(*PassRegistry::getPassRegistry()); } - bool runOnFunction(Function& F) override { + bool runOnFunction(Function &F) override { if (skipFunction(F)) return false; - return aggressiveDCE(F); + auto &PDT = getAnalysis<PostDominatorTreeWrapperPass>().getPostDomTree(); + return AggressiveDeadCodeElimination(F, PDT).performDeadCodeElimination(); } - void getAnalysisUsage(AnalysisUsage& AU) const override { - AU.setPreservesCFG(); + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.addRequired<PostDominatorTreeWrapperPass>(); + if (!RemoveControlFlowFlag) + AU.setPreservesCFG(); AU.addPreserved<GlobalsAAWrapperPass>(); } }; } char ADCELegacyPass::ID = 0; -INITIALIZE_PASS(ADCELegacyPass, "adce", "Aggressive Dead Code Elimination", - false, false) +INITIALIZE_PASS_BEGIN(ADCELegacyPass, "adce", + "Aggressive Dead Code Elimination", false, false) +INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass) +INITIALIZE_PASS_END(ADCELegacyPass, "adce", "Aggressive Dead Code Elimination", + false, false) FunctionPass *llvm::createAggressiveDCEPass() { return new ADCELegacyPass(); } |
