void print(raw_ostream &OS, const Module *M = nullptr) const override;
};
+//===-------------------------------------
+/// \brief Class to defer updates to a DominatorTree.
+///
+/// Definition: Applying updates to every edge insertion and deletion is
+/// expensive and not necessary. When one needs the DominatorTree for analysis
+/// they can request a flush() to perform a larger batch update. This has the
+/// advantage of the DominatorTree inspecting the set of updates to find
+/// duplicates or unnecessary subtree updates.
+///
+/// The scope of DeferredDominance operates at a Function level.
+///
+/// It is not necessary for the user to scrub the updates for duplicates or
+/// updates that point to the same block (Delete, BB_A, BB_A). Performance
+/// can be gained if the caller attempts to batch updates before submitting
+/// to applyUpdates(ArrayRef) in cases where duplicate edge requests will
+/// occur.
+///
+/// It is required for the state of the LLVM IR to be applied *before*
+/// submitting updates. The update routines must analyze the current state
+/// between a pair of (From, To) basic blocks to determine if the update
+/// needs to be queued.
+/// Example (good):
+/// TerminatorInstructionBB->removeFromParent();
+/// DDT->deleteEdge(BB, Successor);
+/// Example (bad):
+/// DDT->deleteEdge(BB, Successor);
+/// TerminatorInstructionBB->removeFromParent();
+class DeferredDominance {
+public:
+ DeferredDominance(DominatorTree &DT_) : DT(DT_) {}
+
+ /// \brief Queues multiple updates and discards duplicates.
+ void applyUpdates(ArrayRef<DominatorTree::UpdateType> Updates);
+
+ /// \brief Helper method for a single edge insertion. It's almost always
+ /// better to batch updates and call applyUpdates to quickly remove duplicate
+ /// edges. This is best used when there is only a single insertion needed to
+ /// update Dominators.
+ void insertEdge(BasicBlock *From, BasicBlock *To);
+
+ /// \brief Helper method for a single edge deletion. It's almost always better
+ /// to batch updates and call applyUpdates to quickly remove duplicate edges.
+ /// This is best used when there is only a single deletion needed to update
+ /// Dominators.
+ void deleteEdge(BasicBlock *From, BasicBlock *To);
+
+ /// \brief Delays the deletion of a basic block until a flush() event.
+ void deleteBB(BasicBlock *DelBB);
+
+ /// \brief Returns true if DelBB is awaiting deletion at a flush() event.
+ bool pendingDeletedBB(BasicBlock *DelBB);
+
+ /// \brief Flushes all pending updates and block deletions. Returns a
+ /// correct DominatorTree reference to be used by the caller for analysis.
+ DominatorTree &flush();
+
+ /// \brief Drops all internal state and forces a (slow) recalculation of the
+ /// DominatorTree based on the current state of the LLVM IR in F. This should
+ /// only be used in corner cases such as the Entry block of F being deleted.
+ void recalculate(Function &F);
+
+ /// \brief Debug method to help view the state of pending updates.
+ LLVM_DUMP_METHOD void dump() const;
+
+private:
+ DominatorTree &DT;
+ SmallVector<DominatorTree::UpdateType, 16> PendUpdates;
+ SmallPtrSet<BasicBlock *, 8> DeletedBBs;
+
+ /// Apply an update (Kind, From, To) to the internal queued updates. The
+ /// update is only added when determined to be necessary. Checks for
+ /// self-domination, unnecessary updates, duplicate requests, and balanced
+ /// pairs of requests are all performed. Returns true if the update is
+ /// queued and false if it is discarded.
+ bool applyUpdate(DominatorTree::UpdateKind Kind, BasicBlock *From,
+ BasicBlock *To);
+
+ /// Performs all pending basic block deletions. We have to defer the deletion
+ /// of these blocks until after the DominatorTree updates are applied. The
+ /// internal workings of the DominatorTree code expect every update's From
+ /// and To blocks to exist and to be a member of the same Function.
+ bool flushDelBB();
+};
+
} // end namespace llvm
#endif // LLVM_IR_DOMINATORS_H
class BranchInst;
class CmpInst;
class Constant;
+class DeferredDominance;
class Function;
class Instruction;
class IntrinsicInst;
TargetLibraryInfo *TLI;
LazyValueInfo *LVI;
AliasAnalysis *AA;
+ DeferredDominance *DDT;
std::unique_ptr<BlockFrequencyInfo> BFI;
std::unique_ptr<BranchProbabilityInfo> BPI;
bool HasProfileData = false;
// Glue for old PM.
bool runImpl(Function &F, TargetLibraryInfo *TLI_, LazyValueInfo *LVI_,
- AliasAnalysis *AA_, bool HasProfileData_,
- std::unique_ptr<BlockFrequencyInfo> BFI_,
+ AliasAnalysis *AA_, DeferredDominance *DDT_,
+ bool HasProfileData_, std::unique_ptr<BlockFrequencyInfo> BFI_,
std::unique_ptr<BranchProbabilityInfo> BPI_);
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
class BlockFrequencyInfo;
class BranchProbabilityInfo;
+class DeferredDominance;
class DominatorTree;
class Function;
class Instruction;
class Value;
/// Delete the specified block, which must have no predecessors.
-void DeleteDeadBlock(BasicBlock *BB);
+void DeleteDeadBlock(BasicBlock *BB, DeferredDominance *DDT = nullptr);
/// We know that BB has one predecessor. If there are any single-entry PHI nodes
/// in it, fold them away. This handles the case when all entries to the PHI
/// conditions and indirectbr addresses this might make dead if
/// DeleteDeadConditions is true.
bool ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions = false,
- const TargetLibraryInfo *TLI = nullptr);
+ const TargetLibraryInfo *TLI = nullptr,
+ DeferredDominance *DDT = nullptr);
//===----------------------------------------------------------------------===//
// Local dead code elimination.
///
/// .. and delete the predecessor corresponding to the '1', this will attempt to
/// recursively fold the 'and' to 0.
-void RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred);
+void RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
+ DeferredDominance *DDT = nullptr);
/// BB is a block with one predecessor and its predecessor is known to have one
/// successor (BB!). Eliminate the edge between them, moving the instructions in
/// the predecessor into BB. This deletes the predecessor block.
-void MergeBasicBlockIntoOnlyPred(BasicBlock *BB, DominatorTree *DT = nullptr);
+void MergeBasicBlockIntoOnlyPred(BasicBlock *BB, DominatorTree *DT = nullptr,
+ DeferredDominance *DDT = nullptr);
/// BB is known to contain an unconditional branch, and contains no instructions
/// other than PHI nodes, potential debug intrinsics and the branch. If
/// possible, eliminate BB by rewriting all the predecessors to branch to the
/// successor block and return true. If we can't transform, return false.
-bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB);
+bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
+ DeferredDominance *DDT = nullptr);
/// Check for and eliminate duplicate PHI nodes in this block. This doesn't try
/// to be clever about PHI nodes which differ only in the order of the incoming
/// Insert an unreachable instruction before the specified
/// instruction, making it and the rest of the code in the block dead.
unsigned changeToUnreachable(Instruction *I, bool UseLLVMTrap,
- bool PreserveLCSSA = false);
+ bool PreserveLCSSA = false,
+ DeferredDominance *DDT = nullptr);
/// Convert the CallInst to InvokeInst with the specified unwind edge basic
/// block. This also splits the basic block where CI is located, because
///
/// \param BB Block whose terminator will be replaced. Its terminator must
/// have an unwind successor.
-void removeUnwindEdge(BasicBlock *BB);
+void removeUnwindEdge(BasicBlock *BB, DeferredDominance *DDT = nullptr);
/// Remove all blocks that can not be reached from the function's entry.
///
/// Returns true if any basic block was removed.
-bool removeUnreachableBlocks(Function &F, LazyValueInfo *LVI = nullptr);
+bool removeUnreachableBlocks(Function &F, LazyValueInfo *LVI = nullptr,
+ DeferredDominance *DDT = nullptr);
/// Combine the metadata of two instructions so that K can replace J
///
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constants.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Support/CommandLine.h"
DT.print(OS);
}
+//===----------------------------------------------------------------------===//
+// DeferredDominance Implementation
+//===----------------------------------------------------------------------===//
+//
+// The implementation details of the DeferredDominance class which allows
+// one to queue updates to a DominatorTree.
+//
+//===----------------------------------------------------------------------===//
+
+/// \brief Queues multiple updates and discards duplicates.
+void DeferredDominance::applyUpdates(
+ ArrayRef<DominatorTree::UpdateType> Updates) {
+ SmallVector<DominatorTree::UpdateType, 8> Seen;
+ for (auto U : Updates)
+ // Avoid duplicates to applyUpdate() to save on analysis.
+ if (std::none_of(Seen.begin(), Seen.end(),
+ [U](DominatorTree::UpdateType S) { return S == U; })) {
+ Seen.push_back(U);
+ applyUpdate(U.getKind(), U.getFrom(), U.getTo());
+ }
+}
+
+/// \brief Helper method for a single edge insertion. It's almost always better
+/// to batch updates and call applyUpdates to quickly remove duplicate edges.
+/// This is best used when there is only a single insertion needed to update
+/// Dominators.
+void DeferredDominance::insertEdge(BasicBlock *From, BasicBlock *To) {
+ applyUpdate(DominatorTree::Insert, From, To);
+}
+
+/// \brief Helper method for a single edge deletion. It's almost always better
+/// to batch updates and call applyUpdates to quickly remove duplicate edges.
+/// This is best used when there is only a single deletion needed to update
+/// Dominators.
+void DeferredDominance::deleteEdge(BasicBlock *From, BasicBlock *To) {
+ applyUpdate(DominatorTree::Delete, From, To);
+}
+
+/// \brief Delays the deletion of a basic block until a flush() event.
+void DeferredDominance::deleteBB(BasicBlock *DelBB) {
+ assert(DelBB && "Invalid push_back of nullptr DelBB.");
+ assert(pred_empty(DelBB) && "DelBB has one or more predecessors.");
+ // DelBB is unreachable and all its instructions are dead.
+ while (!DelBB->empty()) {
+ Instruction &I = DelBB->back();
+ // Replace used instructions with an arbitrary value (undef).
+ if (!I.use_empty())
+ I.replaceAllUsesWith(llvm::UndefValue::get(I.getType()));
+ DelBB->getInstList().pop_back();
+ }
+ // Make sure DelBB has a valid terminator instruction. As long as DelBB is a
+ // Child of Function F it must contain valid IR.
+ new UnreachableInst(DelBB->getContext(), DelBB);
+ DeletedBBs.insert(DelBB);
+}
+
+/// \brief Returns true if DelBB is awaiting deletion at a flush() event.
+bool DeferredDominance::pendingDeletedBB(BasicBlock *DelBB) {
+ if (DeletedBBs.empty())
+ return false;
+ return DeletedBBs.count(DelBB) != 0;
+}
+
+/// \brief Flushes all pending updates and block deletions. Returns a
+/// correct DominatorTree reference to be used by the caller for analysis.
+DominatorTree &DeferredDominance::flush() {
+ // Updates to DT must happen before blocks are deleted below. Otherwise the
+ // DT traversal will encounter badref blocks and assert.
+ if (!PendUpdates.empty()) {
+ DT.applyUpdates(PendUpdates);
+ PendUpdates.clear();
+ }
+ flushDelBB();
+ return DT;
+}
+
+/// \brief Drops all internal state and forces a (slow) recalculation of the
+/// DominatorTree based on the current state of the LLVM IR in F. This should
+/// only be used in corner cases such as the Entry block of F being deleted.
+void DeferredDominance::recalculate(Function &F) {
+ // flushDelBB must be flushed before the recalculation. The state of the IR
+ // must be consistent before the DT traversal algorithm determines the
+ // actual DT.
+ if (flushDelBB() || !PendUpdates.empty()) {
+ DT.recalculate(F);
+ PendUpdates.clear();
+ }
+}
+
+/// \brief Debug method to help view the state of pending updates.
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD void DeferredDominance::dump() const {
+ raw_ostream &OS = llvm::dbgs();
+ OS << "PendUpdates:\n";
+ int I = 0;
+ for (auto U : PendUpdates) {
+ OS << " " << I << " : ";
+ ++I;
+ if (U.getKind() == DominatorTree::Insert)
+ OS << "Insert, ";
+ else
+ OS << "Delete, ";
+ BasicBlock *From = U.getFrom();
+ if (From) {
+ auto S = From->getName();
+ if (!From->hasName())
+ S = "(no name)";
+ OS << S << "(" << From << "), ";
+ } else {
+ OS << "(badref), ";
+ }
+ BasicBlock *To = U.getTo();
+ if (To) {
+ auto S = To->getName();
+ if (!To->hasName())
+ S = "(no_name)";
+ OS << S << "(" << To << ")\n";
+ } else {
+ OS << "(badref)\n";
+ }
+ }
+ OS << "DeletedBBs:\n";
+ I = 0;
+ for (auto BB : DeletedBBs) {
+ OS << " " << I << " : ";
+ ++I;
+ if (BB->hasName())
+ OS << BB->getName() << "(";
+ else
+ OS << "(no_name)(";
+ OS << BB << ")\n";
+ }
+}
+#endif
+
+/// Apply an update (Kind, From, To) to the internal queued updates. The
+/// update is only added when determined to be necessary. Checks for
+/// self-domination, unnecessary updates, duplicate requests, and balanced
+/// pairs of requests are all performed. Returns true if the update is
+/// queued and false if it is discarded.
+bool DeferredDominance::applyUpdate(DominatorTree::UpdateKind Kind,
+ BasicBlock *From, BasicBlock *To) {
+ if (From == To)
+ return false; // Cannot dominate self; discard update.
+
+ // Discard updates by inspecting the current state of successors of From.
+ // Since applyUpdate() must be called *after* the Terminator of From is
+ // altered we can determine if the update is unnecessary.
+ bool HasEdge = std::any_of(succ_begin(From), succ_end(From),
+ [To](BasicBlock *B) { return B == To; });
+ if (Kind == DominatorTree::Insert && !HasEdge)
+ return false; // Unnecessary Insert: edge does not exist in IR.
+ if (Kind == DominatorTree::Delete && HasEdge)
+ return false; // Unnecessary Delete: edge still exists in IR.
+
+ // Analyze pending updates to determine if the update is unnecessary.
+ DominatorTree::UpdateType Update = {Kind, From, To};
+ DominatorTree::UpdateType Invert = {Kind != DominatorTree::Insert
+ ? DominatorTree::Insert
+ : DominatorTree::Delete,
+ From, To};
+ for (auto I = PendUpdates.begin(), E = PendUpdates.end(); I != E; ++I) {
+ if (Update == *I)
+ return false; // Discard duplicate updates.
+ if (Invert == *I) {
+ // Update and Invert are both valid (equivalent to a no-op). Remove
+ // Invert from PendUpdates and discard the Update.
+ PendUpdates.erase(I);
+ return false;
+ }
+ }
+ PendUpdates.push_back(Update); // Save the valid update.
+ return true;
+}
+
+/// Performs all pending basic block deletions. We have to defer the deletion
+/// of these blocks until after the DominatorTree updates are applied. The
+/// internal workings of the DominatorTree code expect every update's From
+/// and To blocks to exist and to be a member of the same Function.
+bool DeferredDominance::flushDelBB() {
+ if (DeletedBBs.empty())
+ return false;
+ for (auto *BB : DeletedBBs)
+ BB->eraseFromParent();
+ DeletedBBs.clear();
+ return true;
+}
bool runOnFunction(Function &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<LazyValueInfoWrapperPass>();
AU.addPreserved<GlobalsAAWrapperPass>();
}
INITIALIZE_PASS_BEGIN(CorrelatedValuePropagation, "correlated-propagation",
"Value Propagation", false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LazyValueInfoWrapperPass)
INITIALIZE_PASS_END(CorrelatedValuePropagation, "correlated-propagation",
"Value Propagation", false, false)
bool runOnFunction(Function &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
- if (PrintLVIAfterJumpThreading)
- AU.addRequired<DominatorTreeWrapperPass>();
+ AU.addRequired<DominatorTreeWrapperPass>();
+ AU.addPreserved<DominatorTreeWrapperPass>();
AU.addRequired<AAResultsWrapperPass>();
AU.addRequired<LazyValueInfoWrapperPass>();
+ AU.addPreserved<LazyValueInfoWrapperPass>();
AU.addPreserved<GlobalsAAWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
INITIALIZE_PASS_BEGIN(JumpThreading, "jump-threading",
"Jump Threading", false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LazyValueInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
if (skipFunction(F))
return false;
auto TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ // Get DT analysis before LVI. When LVI is initialized it conditionally adds
+ // DT if it's available.
+ auto DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
auto LVI = &getAnalysis<LazyValueInfoWrapperPass>().getLVI();
auto AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
+ DeferredDominance DDT(*DT);
std::unique_ptr<BlockFrequencyInfo> BFI;
std::unique_ptr<BranchProbabilityInfo> BPI;
bool HasProfileData = F.hasProfileData();
BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));
}
- bool Changed = Impl.runImpl(F, TLI, LVI, AA, HasProfileData, std::move(BFI),
- std::move(BPI));
+ bool Changed = Impl.runImpl(F, TLI, LVI, AA, &DDT, HasProfileData,
+ std::move(BFI), std::move(BPI));
if (PrintLVIAfterJumpThreading) {
dbgs() << "LVI for function '" << F.getName() << "':\n";
- LVI->printLVI(F, getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
- dbgs());
+ LVI->printLVI(F, *DT, dbgs());
}
return Changed;
}
PreservedAnalyses JumpThreadingPass::run(Function &F,
FunctionAnalysisManager &AM) {
auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
+ // Get DT analysis before LVI. When LVI is initialized it conditionally adds
+ // DT if it's available.
+ auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &LVI = AM.getResult<LazyValueAnalysis>(F);
auto &AA = AM.getResult<AAManager>(F);
+ DeferredDominance DDT(DT);
std::unique_ptr<BlockFrequencyInfo> BFI;
std::unique_ptr<BranchProbabilityInfo> BPI;
BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));
}
- bool Changed = runImpl(F, &TLI, &LVI, &AA, HasProfileData, std::move(BFI),
- std::move(BPI));
+ bool Changed = runImpl(F, &TLI, &LVI, &AA, &DDT, HasProfileData,
+ std::move(BFI), std::move(BPI));
if (!Changed)
return PreservedAnalyses::all();
PreservedAnalyses PA;
PA.preserve<GlobalsAA>();
+ PA.preserve<DominatorTreeAnalysis>();
+ PA.preserve<LazyValueAnalysis>();
return PA;
}
bool JumpThreadingPass::runImpl(Function &F, TargetLibraryInfo *TLI_,
LazyValueInfo *LVI_, AliasAnalysis *AA_,
- bool HasProfileData_,
+ DeferredDominance *DDT_, bool HasProfileData_,
std::unique_ptr<BlockFrequencyInfo> BFI_,
std::unique_ptr<BranchProbabilityInfo> BPI_) {
DEBUG(dbgs() << "Jump threading on function '" << F.getName() << "'\n");
TLI = TLI_;
LVI = LVI_;
AA = AA_;
+ DDT = DDT_;
BFI.reset();
BPI.reset();
// When profile data is available, we need to update edge weights after
// back edges. This works for normal cases but not for unreachable blocks as
// they may have cycle with no back edge.
bool EverChanged = false;
- EverChanged |= removeUnreachableBlocks(F, LVI);
+ EverChanged |= removeUnreachableBlocks(F, LVI, DDT);
FindLoopHeaders(F);
++I;
+ // Don't thread branches over a block that's slated for deletion.
+ if (DDT->pendingDeletedBB(BB))
+ continue;
+
// If the block is trivially dead, zap it. This eliminates the successor
// edges which simplifies the CFG.
if (pred_empty(BB) &&
<< "' with terminator: " << *BB->getTerminator() << '\n');
LoopHeaders.erase(BB);
LVI->eraseBlock(BB);
- DeleteDeadBlock(BB);
+ DeleteDeadBlock(BB, DDT);
Changed = true;
continue;
}
// awesome, but it allows us to use AssertingVH to prevent nasty
// dangling pointer issues within LazyValueInfo.
LVI->eraseBlock(BB);
- if (TryToSimplifyUncondBranchFromEmptyBlock(BB))
+ if (TryToSimplifyUncondBranchFromEmptyBlock(BB, DDT))
Changed = true;
}
}
} while (Changed);
LoopHeaders.clear();
+ DDT->flush();
return EverChanged;
}
bool JumpThreadingPass::ProcessBlock(BasicBlock *BB) {
// If the block is trivially dead, just return and let the caller nuke it.
// This simplifies other transformations.
- if (pred_empty(BB) &&
- BB != &BB->getParent()->getEntryBlock())
+ if (DDT->pendingDeletedBB(BB) ||
+ (pred_empty(BB) && BB != &BB->getParent()->getEntryBlock()))
return false;
// If this block has a single predecessor, and if that pred has a single
LoopHeaders.insert(BB);
LVI->eraseBlock(SinglePred);
- MergeBasicBlockIntoOnlyPred(BB);
+ MergeBasicBlockIntoOnlyPred(BB, nullptr, DDT);
// Now that BB is merged into SinglePred (i.e. SinglePred Code followed by
// BB code within one basic block `BB`), we need to invalidate the LVI
// successors to branch to. Let GetBestDestForJumpOnUndef decide.
if (isa<UndefValue>(Condition)) {
unsigned BestSucc = GetBestDestForJumpOnUndef(BB);
+ std::vector<DominatorTree::UpdateType> Updates;
// Fold the branch/switch.
TerminatorInst *BBTerm = BB->getTerminator();
+ Updates.reserve(BBTerm->getNumSuccessors());
for (unsigned i = 0, e = BBTerm->getNumSuccessors(); i != e; ++i) {
if (i == BestSucc) continue;
- BBTerm->getSuccessor(i)->removePredecessor(BB, true);
+ BasicBlock *Succ = BBTerm->getSuccessor(i);
+ Succ->removePredecessor(BB, true);
+ Updates.push_back({DominatorTree::Delete, BB, Succ});
}
DEBUG(dbgs() << " In block '" << BB->getName()
<< "' folding undef terminator: " << *BBTerm << '\n');
BranchInst::Create(BBTerm->getSuccessor(BestSucc), BBTerm);
BBTerm->eraseFromParent();
+ DDT->applyUpdates(Updates);
return true;
}
DEBUG(dbgs() << " In block '" << BB->getName()
<< "' folding terminator: " << *BB->getTerminator() << '\n');
++NumFolds;
- ConstantFoldTerminator(BB, true);
+ ConstantFoldTerminator(BB, true, nullptr, DDT);
return true;
}
if (Ret != LazyValueInfo::Unknown) {
unsigned ToRemove = Ret == LazyValueInfo::True ? 1 : 0;
unsigned ToKeep = Ret == LazyValueInfo::True ? 0 : 1;
- CondBr->getSuccessor(ToRemove)->removePredecessor(BB, true);
+ BasicBlock *ToRemoveSucc = CondBr->getSuccessor(ToRemove);
+ ToRemoveSucc->removePredecessor(BB, true);
BranchInst::Create(CondBr->getSuccessor(ToKeep), CondBr);
CondBr->eraseFromParent();
if (CondCmp->use_empty())
ConstantInt::getFalse(CondCmp->getType());
ReplaceFoldableUses(CondCmp, CI);
}
+ DDT->deleteEdge(BB, ToRemoveSucc);
return true;
}
Optional<bool> Implication =
isImpliedCondition(PBI->getCondition(), Cond, DL, CondIsTrue);
if (Implication) {
- BI->getSuccessor(*Implication ? 1 : 0)->removePredecessor(BB);
- BranchInst::Create(BI->getSuccessor(*Implication ? 0 : 1), BI);
+ BasicBlock *KeepSucc = BI->getSuccessor(*Implication ? 0 : 1);
+ BasicBlock *RemoveSucc = BI->getSuccessor(*Implication ? 1 : 0);
+ RemoveSucc->removePredecessor(BB);
+ BranchInst::Create(KeepSucc, BI);
BI->eraseFromParent();
+ DDT->deleteEdge(BB, RemoveSucc);
return true;
}
CurrentBB = CurrentPred;
if (PredWithKnownDest ==
(size_t)std::distance(pred_begin(BB), pred_end(BB))) {
bool SeenFirstBranchToOnlyDest = false;
+ std::vector <DominatorTree::UpdateType> Updates;
+ Updates.reserve(BB->getTerminator()->getNumSuccessors() - 1);
for (BasicBlock *SuccBB : successors(BB)) {
- if (SuccBB == OnlyDest && !SeenFirstBranchToOnlyDest)
+ if (SuccBB == OnlyDest && !SeenFirstBranchToOnlyDest) {
SeenFirstBranchToOnlyDest = true; // Don't modify the first branch.
- else
+ } else {
SuccBB->removePredecessor(BB, true); // This is unreachable successor.
+ Updates.push_back({DominatorTree::Delete, BB, SuccBB});
+ }
}
// Finally update the terminator.
TerminatorInst *Term = BB->getTerminator();
BranchInst::Create(OnlyDest, Term);
Term->eraseFromParent();
+ DDT->applyUpdates(Updates);
// If the condition is now dead due to the removal of the old terminator,
// erase it.
PredTerm->setSuccessor(i, NewBB);
}
+ DDT->applyUpdates({{DominatorTree::Insert, NewBB, SuccBB},
+ {DominatorTree::Insert, PredBB, NewBB},
+ {DominatorTree::Delete, PredBB, BB}});
+
// At this point, the IR is fully up to date and consistent. Do a quick scan
// over the new instructions and zap any that are constants or dead. This
// frequently happens because of phi translation.
BasicBlock *JumpThreadingPass::SplitBlockPreds(BasicBlock *BB,
ArrayRef<BasicBlock *> Preds,
const char *Suffix) {
+ SmallVector<BasicBlock *, 2> NewBBs;
+
// Collect the frequencies of all predecessors of BB, which will be used to
- // update the edge weight on BB->SuccBB.
- BlockFrequency PredBBFreq(0);
+ // update the edge weight of the result of splitting predecessors.
+ DenseMap<BasicBlock *, BlockFrequency> FreqMap;
if (HasProfileData)
for (auto Pred : Preds)
- PredBBFreq += BFI->getBlockFreq(Pred) * BPI->getEdgeProbability(Pred, BB);
+ FreqMap.insert(std::make_pair(
+ Pred, BFI->getBlockFreq(Pred) * BPI->getEdgeProbability(Pred, BB)));
+
+ // In the case when BB is a LandingPad block we create 2 new predecessors
+ // instead of just one.
+ if (BB->isLandingPad()) {
+ std::string NewName = std::string(Suffix) + ".split-lp";
+ SplitLandingPadPredecessors(BB, Preds, Suffix, NewName.c_str(), NewBBs);
+ } else {
+ NewBBs.push_back(SplitBlockPredecessors(BB, Preds, Suffix));
+ }
- BasicBlock *PredBB = SplitBlockPredecessors(BB, Preds, Suffix);
+ std::vector<DominatorTree::UpdateType> Updates;
+ Updates.reserve((2 * Preds.size()) + NewBBs.size());
+ for (auto NewBB : NewBBs) {
+ BlockFrequency NewBBFreq(0);
+ Updates.push_back({DominatorTree::Insert, NewBB, BB});
+ for (auto Pred : predecessors(NewBB)) {
+ Updates.push_back({DominatorTree::Delete, Pred, BB});
+ Updates.push_back({DominatorTree::Insert, Pred, NewBB});
+ if (HasProfileData) // Update frequencies between Pred -> NewBB.
+ NewBBFreq += FreqMap.lookup(Pred);
+ }
+ if (HasProfileData) // Apply the summed frequency to NewBB.
+ BFI->setBlockFreq(NewBB, NewBBFreq.getFrequency());
+ }
- // Set the block frequency of the newly created PredBB, which is the sum of
- // frequencies of Preds.
- if (HasProfileData)
- BFI->setBlockFreq(PredBB, PredBBFreq.getFrequency());
- return PredBB;
+ DDT->applyUpdates(Updates);
+ return NewBBs[0];
}
bool JumpThreadingPass::doesBlockHaveProfileData(BasicBlock *BB) {
}
// And finally, do it! Start by factoring the predecessors if needed.
+ std::vector<DominatorTree::UpdateType> Updates;
BasicBlock *PredBB;
if (PredBBs.size() == 1)
PredBB = PredBBs[0];
<< " common predecessors.\n");
PredBB = SplitBlockPreds(BB, PredBBs, ".thr_comm");
}
+ Updates.push_back({DominatorTree::Delete, PredBB, BB});
// Okay, we decided to do this! Clone all the instructions in BB onto the end
// of PredBB.
BranchInst *OldPredBranch = dyn_cast<BranchInst>(PredBB->getTerminator());
if (!OldPredBranch || !OldPredBranch->isUnconditional()) {
- PredBB = SplitEdge(PredBB, BB);
+ BasicBlock *OldPredBB = PredBB;
+ PredBB = SplitEdge(OldPredBB, BB);
+ Updates.push_back({DominatorTree::Insert, OldPredBB, PredBB});
+ Updates.push_back({DominatorTree::Insert, PredBB, BB});
+ Updates.push_back({DominatorTree::Delete, OldPredBB, BB});
OldPredBranch = cast<BranchInst>(PredBB->getTerminator());
}
// Otherwise, insert the new instruction into the block.
New->setName(BI->getName());
PredBB->getInstList().insert(OldPredBranch->getIterator(), New);
+ // Update Dominance from simplified New instruction operands.
+ for (unsigned i = 0, e = New->getNumOperands(); i != e; ++i)
+ if (BasicBlock *SuccBB = dyn_cast<BasicBlock>(New->getOperand(i)))
+ Updates.push_back({DominatorTree::Insert, PredBB, SuccBB});
}
}
// Remove the unconditional branch at the end of the PredBB block.
OldPredBranch->eraseFromParent();
+ DDT->applyUpdates(Updates);
++NumDupes;
return true;
// The select is now dead.
SI->eraseFromParent();
+ DDT->applyUpdates({{DominatorTree::Insert, NewBB, BB},
+ {DominatorTree::Insert, Pred, NewBB}});
// Update any other PHI nodes in BB.
for (BasicBlock::iterator BI = BB->begin();
PHINode *Phi = dyn_cast<PHINode>(BI); ++BI)
// Expand the select.
TerminatorInst *Term =
SplitBlockAndInsertIfThen(SI->getCondition(), SI, false);
+ BasicBlock *SplitBB = SI->getParent();
+ BasicBlock *NewBB = Term->getParent();
PHINode *NewPN = PHINode::Create(SI->getType(), 2, "", SI);
NewPN->addIncoming(SI->getTrueValue(), Term->getParent());
NewPN->addIncoming(SI->getFalseValue(), BB);
SI->replaceAllUsesWith(NewPN);
SI->eraseFromParent();
+ // NewBB and SplitBB are newly created blocks which require insertion.
+ std::vector<DominatorTree::UpdateType> Updates;
+ Updates.reserve((2 * SplitBB->getTerminator()->getNumSuccessors()) + 3);
+ Updates.push_back({DominatorTree::Insert, BB, SplitBB});
+ Updates.push_back({DominatorTree::Insert, BB, NewBB});
+ Updates.push_back({DominatorTree::Insert, NewBB, SplitBB});
+ // BB's successors were moved to SplitBB, update DDT accordingly.
+ for (auto *Succ : successors(SplitBB)) {
+ Updates.push_back({DominatorTree::Delete, BB, Succ});
+ Updates.push_back({DominatorTree::Insert, SplitBB, Succ});
+ }
+ DDT->applyUpdates(Updates);
return true;
}
return false;
if (!TrueDestIsSafe && !FalseDestIsSafe)
return false;
- BasicBlock *UnguardedBlock = TrueDestIsSafe ? TrueDest : FalseDest;
- BasicBlock *GuardedBlock = FalseDestIsSafe ? TrueDest : FalseDest;
+ BasicBlock *PredUnguardedBlock = TrueDestIsSafe ? TrueDest : FalseDest;
+ BasicBlock *PredGuardedBlock = FalseDestIsSafe ? TrueDest : FalseDest;
ValueToValueMapTy UnguardedMapping, GuardedMapping;
Instruction *AfterGuard = Guard->getNextNode();
return false;
// Duplicate all instructions before the guard and the guard itself to the
// branch where implication is not proved.
- GuardedBlock = DuplicateInstructionsInSplitBetween(
- BB, GuardedBlock, AfterGuard, GuardedMapping);
+ BasicBlock *GuardedBlock = DuplicateInstructionsInSplitBetween(
+ BB, PredGuardedBlock, AfterGuard, GuardedMapping);
assert(GuardedBlock && "Could not create the guarded block?");
// Duplicate all instructions before the guard in the unguarded branch.
// Since we have successfully duplicated the guarded block and this block
// has fewer instructions, we expect it to succeed.
- UnguardedBlock = DuplicateInstructionsInSplitBetween(BB, UnguardedBlock,
- Guard, UnguardedMapping);
+ BasicBlock *UnguardedBlock = DuplicateInstructionsInSplitBetween(
+ BB, PredUnguardedBlock, Guard, UnguardedMapping);
assert(UnguardedBlock && "Could not create the unguarded block?");
DEBUG(dbgs() << "Moved guard " << *Guard << " to block "
<< GuardedBlock->getName() << "\n");
-
+ // DuplicateInstructionsInSplitBetween inserts a new block "BB.split" between
+ // PredBB and BB. We need to perform two inserts and one delete for each of
+ // the above calls to update Dominators.
+ DDT->applyUpdates(
+ {// Guarded block split.
+ {DominatorTree::Delete, PredGuardedBlock, BB},
+ {DominatorTree::Insert, PredGuardedBlock, GuardedBlock},
+ {DominatorTree::Insert, GuardedBlock, BB},
+ // Unguarded block split.
+ {DominatorTree::Delete, PredUnguardedBlock, BB},
+ {DominatorTree::Insert, PredUnguardedBlock, UnguardedBlock},
+ {DominatorTree::Insert, UnguardedBlock, BB}});
// Some instructions before the guard may still have uses. For them, we need
// to create Phi nodes merging their copies in both guarded and unguarded
// branches. Those instructions that have no uses can be just removed.
using namespace llvm;
-void llvm::DeleteDeadBlock(BasicBlock *BB) {
+void llvm::DeleteDeadBlock(BasicBlock *BB, DeferredDominance *DDT) {
assert((pred_begin(BB) == pred_end(BB) ||
// Can delete self loop.
BB->getSinglePredecessor() == BB) && "Block is not dead!");
TerminatorInst *BBTerm = BB->getTerminator();
+ std::vector<DominatorTree::UpdateType> Updates;
// Loop through all of our successors and make sure they know that one
// of their predecessors is going away.
- for (BasicBlock *Succ : BBTerm->successors())
+ if (DDT)
+ Updates.reserve(BBTerm->getNumSuccessors());
+ for (BasicBlock *Succ : BBTerm->successors()) {
Succ->removePredecessor(BB);
+ if (DDT)
+ Updates.push_back({DominatorTree::Delete, BB, Succ});
+ }
// Zap all the instructions in the block.
while (!BB->empty()) {
BB->getInstList().pop_back();
}
- // Zap the block!
- BB->eraseFromParent();
+ if (DDT) {
+ DDT->applyUpdates(Updates);
+ DDT->deleteBB(BB); // Deferred deletion of BB.
+ } else {
+ BB->eraseFromParent(); // Zap the block!
+ }
}
void llvm::FoldSingleEntryPHINodes(BasicBlock *BB,
/// conditions and indirectbr addresses this might make dead if
/// DeleteDeadConditions is true.
bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
- const TargetLibraryInfo *TLI) {
+ const TargetLibraryInfo *TLI,
+ DeferredDominance *DDT) {
TerminatorInst *T = BB->getTerminator();
IRBuilder<> Builder(T);
// Replace the conditional branch with an unconditional one.
Builder.CreateBr(Destination);
BI->eraseFromParent();
+ if (DDT)
+ DDT->deleteEdge(BB, OldDest);
return true;
}
createBranchWeights(Weights));
}
// Remove this entry.
- DefaultDest->removePredecessor(SI->getParent());
+ BasicBlock *ParentBB = SI->getParent();
+ DefaultDest->removePredecessor(ParentBB);
i = SI->removeCase(i);
e = SI->case_end();
+ if (DDT)
+ DDT->deleteEdge(ParentBB, DefaultDest);
continue;
}
// Insert the new branch.
Builder.CreateBr(TheOnlyDest);
BasicBlock *BB = SI->getParent();
+ std::vector <DominatorTree::UpdateType> Updates;
+ if (DDT)
+ Updates.reserve(SI->getNumSuccessors() - 1);
// Remove entries from PHI nodes which we no longer branch to...
for (BasicBlock *Succ : SI->successors()) {
// Found case matching a constant operand?
- if (Succ == TheOnlyDest)
+ if (Succ == TheOnlyDest) {
TheOnlyDest = nullptr; // Don't modify the first branch to TheOnlyDest
- else
+ } else {
Succ->removePredecessor(BB);
+ if (DDT)
+ Updates.push_back({DominatorTree::Delete, BB, Succ});
+ }
}
// Delete the old switch.
SI->eraseFromParent();
if (DeleteDeadConditions)
RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
+ if (DDT)
+ DDT->applyUpdates(Updates);
return true;
}
if (auto *BA =
dyn_cast<BlockAddress>(IBI->getAddress()->stripPointerCasts())) {
BasicBlock *TheOnlyDest = BA->getBasicBlock();
+ std::vector <DominatorTree::UpdateType> Updates;
+ if (DDT)
+ Updates.reserve(IBI->getNumDestinations() - 1);
+
// Insert the new branch.
Builder.CreateBr(TheOnlyDest);
for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) {
- if (IBI->getDestination(i) == TheOnlyDest)
+ if (IBI->getDestination(i) == TheOnlyDest) {
TheOnlyDest = nullptr;
- else
- IBI->getDestination(i)->removePredecessor(IBI->getParent());
+ } else {
+ BasicBlock *ParentBB = IBI->getParent();
+ BasicBlock *DestBB = IBI->getDestination(i);
+ DestBB->removePredecessor(ParentBB);
+ if (DDT)
+ Updates.push_back({DominatorTree::Delete, ParentBB, DestBB});
+ }
}
Value *Address = IBI->getAddress();
IBI->eraseFromParent();
new UnreachableInst(BB->getContext(), BB);
}
+ if (DDT)
+ DDT->applyUpdates(Updates);
return true;
}
}
///
/// .. and delete the predecessor corresponding to the '1', this will attempt to
/// recursively fold the and to 0.
-void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred) {
+void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
+ DeferredDominance *DDT) {
// This only adjusts blocks with PHI nodes.
if (!isa<PHINode>(BB->begin()))
return;
// of the block.
if (PhiIt != OldPhiIt) PhiIt = &BB->front();
}
+ if (DDT)
+ DDT->deleteEdge(Pred, BB);
}
/// MergeBasicBlockIntoOnlyPred - DestBB is a block with one predecessor and its
/// predecessor is known to have one successor (DestBB!). Eliminate the edge
/// between them, moving the instructions in the predecessor into DestBB and
/// deleting the predecessor block.
-void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT) {
+void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT,
+ DeferredDominance *DDT) {
+ assert(!(DT && DDT) && "Cannot call with both DT and DDT.");
+
// If BB has single-entry PHI nodes, fold them.
while (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
Value *NewVal = PN->getIncomingValue(0);
BasicBlock *PredBB = DestBB->getSinglePredecessor();
assert(PredBB && "Block doesn't have a single predecessor!");
+ bool ReplaceEntryBB = false;
+ if (PredBB == &DestBB->getParent()->getEntryBlock())
+ ReplaceEntryBB = true;
+
+ // Deferred DT update: Collect all the edges that enter PredBB. These
+ // dominator edges will be redirected to DestBB.
+ std::vector <DominatorTree::UpdateType> Updates;
+ if (DDT && !ReplaceEntryBB) {
+ Updates.reserve(1 +
+ (2 * std::distance(pred_begin(PredBB), pred_end(PredBB))));
+ Updates.push_back({DominatorTree::Delete, PredBB, DestBB});
+ for (auto I = pred_begin(PredBB), E = pred_end(PredBB); I != E; ++I) {
+ Updates.push_back({DominatorTree::Delete, *I, PredBB});
+ // This predecessor of PredBB may already have DestBB as a successor.
+ if (llvm::find(successors(*I), DestBB) == succ_end(*I))
+ Updates.push_back({DominatorTree::Insert, *I, DestBB});
+ }
+ }
+
// Zap anything that took the address of DestBB. Not doing this will give the
// address an invalid value.
if (DestBB->hasAddressTaken()) {
// If the PredBB is the entry block of the function, move DestBB up to
// become the entry block after we erase PredBB.
- if (PredBB == &DestBB->getParent()->getEntryBlock())
+ if (ReplaceEntryBB)
DestBB->moveAfter(PredBB);
if (DT) {
DT->eraseNode(PredBB);
}
}
- // Nuke BB.
- PredBB->eraseFromParent();
+
+ if (DDT) {
+ DDT->deleteBB(PredBB); // Deferred deletion of BB.
+ if (ReplaceEntryBB)
+ // The entry block was removed and there is no external interface for the
+ // dominator tree to be notified of this change. In this corner-case we
+ // recalculate the entire tree.
+ DDT->recalculate(*(DestBB->getParent()));
+ else
+ DDT->applyUpdates(Updates);
+ } else {
+ PredBB->eraseFromParent(); // Nuke BB.
+ }
}
/// CanMergeValues - Return true if we can choose one of these values to use
/// potential side-effect free intrinsics and the branch. If possible,
/// eliminate BB by rewriting all the predecessors to branch to the successor
/// block and return true. If we can't transform, return false.
-bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB) {
+bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
+ DeferredDominance *DDT) {
assert(BB != &BB->getParent()->getEntryBlock() &&
"TryToSimplifyUncondBranchFromEmptyBlock called on entry block!");
DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB);
+ std::vector<DominatorTree::UpdateType> Updates;
+ if (DDT) {
+ Updates.reserve(1 + (2 * std::distance(pred_begin(BB), pred_end(BB))));
+ Updates.push_back({DominatorTree::Delete, BB, Succ});
+ // All predecessors of BB will be moved to Succ.
+ for (auto I = pred_begin(BB), E = pred_end(BB); I != E; ++I) {
+ Updates.push_back({DominatorTree::Delete, *I, BB});
+ // This predecessor of BB may already have Succ as a successor.
+ if (llvm::find(successors(*I), Succ) == succ_end(*I))
+ Updates.push_back({DominatorTree::Insert, *I, Succ});
+ }
+ }
+
if (isa<PHINode>(Succ->begin())) {
// If there is more than one pred of succ, and there are PHI nodes in
// the successor, then we need to add incoming edges for the PHI nodes
// Everything that jumped to BB now goes to Succ.
BB->replaceAllUsesWith(Succ);
if (!Succ->hasName()) Succ->takeName(BB);
- BB->eraseFromParent(); // Delete the old basic block.
+
+ if (DDT) {
+ DDT->deleteBB(BB); // Deferred deletion of the old basic block.
+ DDT->applyUpdates(Updates);
+ } else {
+ BB->eraseFromParent(); // Delete the old basic block.
+ }
return true;
}
}
unsigned llvm::changeToUnreachable(Instruction *I, bool UseLLVMTrap,
- bool PreserveLCSSA) {
+ bool PreserveLCSSA, DeferredDominance *DDT) {
BasicBlock *BB = I->getParent();
+ std::vector <DominatorTree::UpdateType> Updates;
+
// Loop over all of the successors, removing BB's entry from any PHI
// nodes.
- for (BasicBlock *Successor : successors(BB))
+ if (DDT)
+ Updates.reserve(BB->getTerminator()->getNumSuccessors());
+ for (BasicBlock *Successor : successors(BB)) {
Successor->removePredecessor(BB, PreserveLCSSA);
-
+ if (DDT)
+ Updates.push_back({DominatorTree::Delete, BB, Successor});
+ }
// Insert a call to llvm.trap right before this. This turns the undefined
// behavior into a hard fail instead of falling through into random code.
if (UseLLVMTrap) {
BB->getInstList().erase(BBI++);
++NumInstrsRemoved;
}
+ if (DDT)
+ DDT->applyUpdates(Updates);
return NumInstrsRemoved;
}
/// changeToCall - Convert the specified invoke into a normal call.
-static void changeToCall(InvokeInst *II) {
+static void changeToCall(InvokeInst *II, DeferredDominance *DDT = nullptr) {
SmallVector<Value*, 8> Args(II->arg_begin(), II->arg_end());
SmallVector<OperandBundleDef, 1> OpBundles;
II->getOperandBundlesAsDefs(OpBundles);
II->replaceAllUsesWith(NewCall);
// Follow the call by a branch to the normal destination.
- BranchInst::Create(II->getNormalDest(), II);
+ BasicBlock *NormalDestBB = II->getNormalDest();
+ BranchInst::Create(NormalDestBB, II);
// Update PHI nodes in the unwind destination
- II->getUnwindDest()->removePredecessor(II->getParent());
+ BasicBlock *BB = II->getParent();
+ BasicBlock *UnwindDestBB = II->getUnwindDest();
+ UnwindDestBB->removePredecessor(BB);
II->eraseFromParent();
+ if (DDT)
+ DDT->deleteEdge(BB, UnwindDestBB);
}
BasicBlock *llvm::changeToInvokeAndSplitBasicBlock(CallInst *CI,
}
static bool markAliveBlocks(Function &F,
- SmallPtrSetImpl<BasicBlock*> &Reachable) {
+ SmallPtrSetImpl<BasicBlock*> &Reachable,
+ DeferredDominance *DDT = nullptr) {
SmallVector<BasicBlock*, 128> Worklist;
BasicBlock *BB = &F.front();
Worklist.push_back(BB);
if (II->getIntrinsicID() == Intrinsic::assume) {
if (match(II->getArgOperand(0), m_CombineOr(m_Zero(), m_Undef()))) {
// Don't insert a call to llvm.trap right before the unreachable.
- changeToUnreachable(II, false);
+ changeToUnreachable(II, false, false, DDT);
Changed = true;
break;
}
// still be useful for widening.
if (match(II->getArgOperand(0), m_Zero()))
if (!isa<UnreachableInst>(II->getNextNode())) {
- changeToUnreachable(II->getNextNode(), /*UseLLVMTrap=*/ false);
+ changeToUnreachable(II->getNextNode(), /*UseLLVMTrap=*/false,
+ false, DDT);
Changed = true;
break;
}
if (auto *CI = dyn_cast<CallInst>(&I)) {
Value *Callee = CI->getCalledValue();
if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
- changeToUnreachable(CI, /*UseLLVMTrap=*/false);
+ changeToUnreachable(CI, /*UseLLVMTrap=*/false, false, DDT);
Changed = true;
break;
}
// though.
if (!isa<UnreachableInst>(CI->getNextNode())) {
// Don't insert a call to llvm.trap right before the unreachable.
- changeToUnreachable(CI->getNextNode(), false);
+ changeToUnreachable(CI->getNextNode(), false, false, DDT);
Changed = true;
}
break;
if (isa<UndefValue>(Ptr) ||
(isa<ConstantPointerNull>(Ptr) &&
SI->getPointerAddressSpace() == 0)) {
- changeToUnreachable(SI, true);
+ changeToUnreachable(SI, true, false, DDT);
Changed = true;
break;
}
// Turn invokes that call 'nounwind' functions into ordinary calls.
Value *Callee = II->getCalledValue();
if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
- changeToUnreachable(II, true);
+ changeToUnreachable(II, true, false, DDT);
Changed = true;
} else if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(&F)) {
if (II->use_empty() && II->onlyReadsMemory()) {
// jump to the normal destination branch.
- BranchInst::Create(II->getNormalDest(), II);
- II->getUnwindDest()->removePredecessor(II->getParent());
+ BasicBlock *NormalDestBB = II->getNormalDest();
+ BasicBlock *UnwindDestBB = II->getUnwindDest();
+ BranchInst::Create(NormalDestBB, II);
+ UnwindDestBB->removePredecessor(II->getParent());
II->eraseFromParent();
+ if (DDT)
+ DDT->deleteEdge(BB, UnwindDestBB);
} else
- changeToCall(II);
+ changeToCall(II, DDT);
Changed = true;
}
} else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Terminator)) {
}
}
- Changed |= ConstantFoldTerminator(BB, true);
+ Changed |= ConstantFoldTerminator(BB, true, nullptr, DDT);
for (BasicBlock *Successor : successors(BB))
if (Reachable.insert(Successor).second)
Worklist.push_back(Successor);
return Changed;
}
-void llvm::removeUnwindEdge(BasicBlock *BB) {
+void llvm::removeUnwindEdge(BasicBlock *BB, DeferredDominance *DDT) {
TerminatorInst *TI = BB->getTerminator();
if (auto *II = dyn_cast<InvokeInst>(TI)) {
- changeToCall(II);
+ changeToCall(II, DDT);
return;
}
UnwindDest->removePredecessor(BB);
TI->replaceAllUsesWith(NewTI);
TI->eraseFromParent();
+ if (DDT)
+ DDT->deleteEdge(BB, UnwindDest);
}
/// removeUnreachableBlocks - Remove blocks that are not reachable, even
/// if they are in a dead cycle. Return true if a change was made, false
/// otherwise. If `LVI` is passed, this function preserves LazyValueInfo
/// after modifying the CFG.
-bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI) {
+bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI,
+ DeferredDominance *DDT) {
SmallPtrSet<BasicBlock*, 16> Reachable;
- bool Changed = markAliveBlocks(F, Reachable);
+ bool Changed = markAliveBlocks(F, Reachable, DDT);
// If there are unreachable blocks in the CFG...
if (Reachable.size() == F.size())
NumRemoved += F.size()-Reachable.size();
// Loop over all of the basic blocks that are not reachable, dropping all of
- // their internal references...
- for (Function::iterator BB = ++F.begin(), E = F.end(); BB != E; ++BB) {
- if (Reachable.count(&*BB))
+ // their internal references. Update DDT and LVI if available.
+ std::vector <DominatorTree::UpdateType> Updates;
+ for (Function::iterator I = ++F.begin(), E = F.end(); I != E; ++I) {
+ auto *BB = &*I;
+ if (Reachable.count(BB))
continue;
-
- for (BasicBlock *Successor : successors(&*BB))
+ for (BasicBlock *Successor : successors(BB)) {
if (Reachable.count(Successor))
- Successor->removePredecessor(&*BB);
+ Successor->removePredecessor(BB);
+ if (DDT)
+ Updates.push_back({DominatorTree::Delete, BB, Successor});
+ }
if (LVI)
- LVI->eraseBlock(&*BB);
+ LVI->eraseBlock(BB);
BB->dropAllReferences();
}
- for (Function::iterator I = ++F.begin(); I != F.end();)
- if (!Reachable.count(&*I))
- I = F.getBasicBlockList().erase(I);
- else
+ for (Function::iterator I = ++F.begin(); I != F.end();) {
+ auto *BB = &*I;
+ if (Reachable.count(BB)) {
+ ++I;
+ continue;
+ }
+ if (DDT) {
+ DDT->deleteBB(BB); // deferred deletion of BB.
++I;
+ } else {
+ I = F.getBasicBlockList().erase(I);
+ }
+ }
+ if (DDT)
+ DDT->applyUpdates(Updates);
return true;
}
; CHECK-NEXT: ; LatticeVal for: 'i32 %a' is: overdefined
; CHECK-NEXT: ; LatticeVal for: 'i32 %length' is: overdefined
; CHECK-NEXT: ; LatticeVal for: ' %iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]' in BB: '%backedge' is: constantrange<0, 400>
+; CHECK-NEXT: ; LatticeVal for: ' %iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]' in BB: '%exit' is: constantrange<399, 400>
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]
; CHECK-NEXT: ; LatticeVal for: ' %iv.next = add nsw i32 %iv, 1' in BB: '%backedge' is: constantrange<1, 401>
+; CHECK-NEXT: ; LatticeVal for: ' %iv.next = add nsw i32 %iv, 1' in BB: '%exit' is: constantrange<400, 401>
; CHECK-NEXT: %iv.next = add nsw i32 %iv, 1
; CHECK-NEXT: ; LatticeVal for: ' %cont = icmp slt i32 %iv.next, 400' in BB: '%backedge' is: overdefined
+; CHECK-NEXT: ; LatticeVal for: ' %cont = icmp slt i32 %iv.next, 400' in BB: '%exit' is: constantrange<0, -1>
; CHECK-NEXT: %cont = icmp slt i32 %iv.next, 400
; CHECK-NOT: loop
loop:
--- /dev/null
+; RUN: opt < %s -jump-threading -disable-output
+
+%struct.ham = type { i8, i8, i16, i32 }
+%struct.zot = type { i32 (...)** }
+%struct.quux.0 = type { %struct.wombat }
+%struct.wombat = type { %struct.zot }
+
+@global = external global %struct.ham*, align 8
+@global.1 = external constant i8*
+
+declare i32 @wombat.2()
+
+define void @blam() {
+bb:
+ %tmp = load i32, i32* undef
+ %tmp1 = icmp eq i32 %tmp, 0
+ br i1 %tmp1, label %bb11, label %bb2
+
+bb2:
+ %tmp3 = tail call i32 @wombat.2()
+ switch i32 %tmp3, label %bb4 [
+ i32 0, label %bb5
+ i32 1, label %bb7
+ i32 2, label %bb7
+ i32 3, label %bb11
+ ]
+
+bb4:
+ br label %bb7
+
+bb5:
+ %tmp6 = tail call i32 @wombat.2()
+ br label %bb7
+
+bb7:
+ %tmp8 = phi i32 [ 0, %bb5 ], [ 1, %bb4 ], [ 2, %bb2 ], [ 2, %bb2 ]
+ %tmp9 = icmp eq i32 %tmp8, 0
+ br i1 %tmp9, label %bb11, label %bb10
+
+bb10:
+ ret void
+
+bb11:
+ ret void
+}
+
+define void @spam(%struct.ham* %arg) {
+bb:
+ %tmp = load i8, i8* undef, align 8
+ switch i8 %tmp, label %bb11 [
+ i8 1, label %bb11
+ i8 2, label %bb11
+ i8 3, label %bb1
+ i8 4, label %bb1
+ ]
+
+bb1:
+ br label %bb2
+
+bb2:
+ %tmp3 = phi i32 [ 0, %bb1 ], [ %tmp3, %bb8 ]
+ br label %bb4
+
+bb4:
+ %tmp5 = load i8, i8* undef, align 8
+ switch i8 %tmp5, label %bb11 [
+ i8 0, label %bb11
+ i8 1, label %bb10
+ i8 2, label %bb10
+ i8 3, label %bb6
+ i8 4, label %bb6
+ ]
+
+bb6:
+ br label %bb7
+
+bb7:
+ br i1 undef, label %bb8, label %bb10
+
+bb8:
+ %tmp9 = icmp eq %struct.ham* undef, %arg
+ br i1 %tmp9, label %bb10, label %bb2
+
+bb10:
+ switch i32 %tmp3, label %bb4 [
+ i32 0, label %bb14
+ i32 1, label %bb11
+ i32 2, label %bb12
+ ]
+
+bb11:
+ unreachable
+
+bb12:
+ %tmp13 = load %struct.ham*, %struct.ham** undef
+ br label %bb14
+
+bb14:
+ %tmp15 = phi %struct.ham* [ %tmp13, %bb12 ], [ null, %bb10 ]
+ br label %bb16
+
+bb16:
+ %tmp17 = load i8, i8* undef, align 8
+ switch i8 %tmp17, label %bb11 [
+ i8 0, label %bb11
+ i8 11, label %bb18
+ i8 12, label %bb18
+ ]
+
+bb18:
+ br label %bb19
+
+bb19:
+ br label %bb20
+
+bb20:
+ %tmp21 = load %struct.ham*, %struct.ham** undef
+ switch i8 undef, label %bb22 [
+ i8 0, label %bb4
+ i8 11, label %bb10
+ i8 12, label %bb10
+ ]
+
+bb22:
+ br label %bb23
+
+bb23:
+ %tmp24 = icmp eq %struct.ham* %tmp21, null
+ br i1 %tmp24, label %bb35, label %bb25
+
+bb25:
+ %tmp26 = icmp eq %struct.ham* %tmp15, null
+ br i1 %tmp26, label %bb34, label %bb27
+
+bb27:
+ %tmp28 = load %struct.ham*, %struct.ham** undef
+ %tmp29 = icmp eq %struct.ham* %tmp28, %tmp21
+ br i1 %tmp29, label %bb35, label %bb30
+
+bb30:
+ br label %bb31
+
+bb31:
+ %tmp32 = load i8, i8* undef, align 8
+ %tmp33 = icmp eq i8 %tmp32, 0
+ br i1 %tmp33, label %bb31, label %bb34
+
+bb34:
+ br label %bb35
+
+bb35:
+ %tmp36 = phi i1 [ true, %bb34 ], [ false, %bb23 ], [ true, %bb27 ]
+ br label %bb37
+
+bb37:
+ %tmp38 = icmp eq %struct.ham* %tmp15, null
+ br i1 %tmp38, label %bb39, label %bb41
+
+bb39:
+ %tmp40 = load %struct.ham*, %struct.ham** @global
+ br label %bb41
+
+bb41:
+ %tmp42 = select i1 %tmp36, %struct.ham* undef, %struct.ham* undef
+ ret void
+}
+
+declare i32 @foo(...)
+
+define void @zot() align 2 personality i8* bitcast (i32 (...)* @foo to i8*) {
+bb:
+ invoke void @bar()
+ to label %bb1 unwind label %bb3
+
+bb1:
+ invoke void @bar()
+ to label %bb2 unwind label %bb4
+
+bb2:
+ invoke void @bar()
+ to label %bb6 unwind label %bb17
+
+bb3:
+ %tmp = landingpad { i8*, i32 }
+ catch i8* bitcast (i8** @global.1 to i8*)
+ catch i8* null
+ unreachable
+
+bb4:
+ %tmp5 = landingpad { i8*, i32 }
+ catch i8* bitcast (i8** @global.1 to i8*)
+ catch i8* null
+ unreachable
+
+bb6:
+ invoke void @bar()
+ to label %bb7 unwind label %bb19
+
+bb7:
+ invoke void @bar()
+ to label %bb10 unwind label %bb8
+
+bb8:
+ %tmp9 = landingpad { i8*, i32 }
+ cleanup
+ catch i8* bitcast (i8** @global.1 to i8*)
+ catch i8* null
+ unreachable
+
+bb10:
+ %tmp11 = load i32 (%struct.zot*)*, i32 (%struct.zot*)** undef, align 8
+ %tmp12 = invoke i32 %tmp11(%struct.zot* nonnull undef)
+ to label %bb13 unwind label %bb21
+
+bb13:
+ invoke void @bar()
+ to label %bb14 unwind label %bb23
+
+bb14:
+ %tmp15 = load i32 (%struct.zot*)*, i32 (%struct.zot*)** undef, align 8
+ %tmp16 = invoke i32 %tmp15(%struct.zot* nonnull undef)
+ to label %bb26 unwind label %bb23
+
+bb17:
+ %tmp18 = landingpad { i8*, i32 }
+ catch i8* bitcast (i8** @global.1 to i8*)
+ catch i8* null
+ unreachable
+
+bb19:
+ %tmp20 = landingpad { i8*, i32 }
+ catch i8* bitcast (i8** @global.1 to i8*)
+ catch i8* null
+ unreachable
+
+bb21:
+ %tmp22 = landingpad { i8*, i32 }
+ catch i8* bitcast (i8** @global.1 to i8*)
+ catch i8* null
+ unreachable
+
+bb23:
+ %tmp24 = phi %struct.quux.0* [ null, %bb26 ], [ null, %bb14 ], [ undef, %bb13 ]
+ %tmp25 = landingpad { i8*, i32 }
+ catch i8* bitcast (i8** @global.1 to i8*)
+ catch i8* null
+ br label %bb30
+
+bb26:
+ %tmp27 = load i32 (%struct.zot*)*, i32 (%struct.zot*)** undef, align 8
+ %tmp28 = invoke i32 %tmp27(%struct.zot* nonnull undef)
+ to label %bb29 unwind label %bb23
+
+bb29:
+ unreachable
+
+bb30:
+ %tmp31 = icmp eq %struct.quux.0* %tmp24, null
+ br i1 %tmp31, label %bb32, label %bb29
+
+bb32:
+ unreachable
+}
+
+declare void @bar()
--- /dev/null
+; RUN: opt < %s -jump-threading -disable-output
+
+%struct.aaa = type { i8 }
+
+define void @chrome(%struct.aaa* noalias sret %arg) local_unnamed_addr #0 align 2 personality i8* bitcast (i32 (...)* @chrome2 to i8*) {
+bb:
+ %tmp = load i32, i32* undef, align 4
+ %tmp1 = icmp eq i32 %tmp, 0
+ br i1 %tmp1, label %bb2, label %bb13
+
+bb2:
+ %tmp3 = getelementptr inbounds %struct.aaa, %struct.aaa* %arg, i64 0, i32 0
+ %tmp4 = load i8, i8* %tmp3, align 1
+ %tmp5 = icmp eq i8 %tmp4, 0
+ br i1 %tmp5, label %bb6, label %bb7
+
+bb6:
+ store i8 0, i8* %tmp3, align 1
+ br label %bb7
+
+bb7:
+ %tmp8 = load i8, i8* %tmp3, align 1
+ %tmp9 = icmp ne i8 %tmp8, 0
+ %tmp10 = select i1 %tmp9, i1 true, i1 false
+ br i1 %tmp10, label %bb12, label %bb11
+
+bb11:
+ br label %bb12
+
+bb12:
+ br i1 %tmp9, label %bb14, label %bb13
+
+bb13:
+ unreachable
+
+bb14:
+ ret void
+}
+
+declare i32 @chrome2(...)
--- /dev/null
+; RUN: opt -jump-threading -simplifycfg -S < %s | FileCheck %s
+; CHECK-NOT: bb6:
+; CHECK-NOT: bb7:
+; CHECK-NOT: bb8:
+; CHECK-NOT: bb11:
+; CHECK-NOT: bb12:
+; CHECK: bb:
+; CHECK: bb2:
+; CHECK: bb4:
+; CHECK: bb10:
+; CHECK: bb13:
+declare void @ham()
+
+define void @hoge() {
+bb:
+ %tmp = and i32 undef, 1073741823
+ %tmp1 = icmp eq i32 %tmp, 2
+ br i1 %tmp1, label %bb12, label %bb2
+
+bb2:
+ %tmp3 = icmp eq i32 %tmp, 3
+ br i1 %tmp3, label %bb13, label %bb4
+
+bb4:
+ %tmp5 = icmp eq i32 %tmp, 5
+ br i1 %tmp5, label %bb6, label %bb7
+
+bb6:
+ tail call void @ham()
+ br label %bb7
+
+bb7:
+ br i1 %tmp3, label %bb13, label %bb8
+
+bb8:
+ %tmp9 = icmp eq i32 %tmp, 4
+ br i1 %tmp9, label %bb13, label %bb10
+
+bb10:
+ br i1 %tmp9, label %bb11, label %bb13
+
+bb11:
+ br label %bb13
+
+bb12:
+ br label %bb2
+
+bb13:
+ ret void
+}
ConstantsTest.cpp
DebugInfoTest.cpp
DebugTypeODRUniquingTest.cpp
+ DeferredDominanceTest.cpp
DominatorTreeTest.cpp
DominatorTreeBatchUpdatesTest.cpp
FunctionTest.cpp
--- /dev/null
+//===- llvm/unittests/IR/DeferredDominanceTest.cpp - DDT unit tests -------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/AsmParser/Parser.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/SourceMgr.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+static std::unique_ptr<Module> makeLLVMModule(LLVMContext &Context,
+ StringRef ModuleStr) {
+ SMDiagnostic Err;
+ std::unique_ptr<Module> M = parseAssemblyString(ModuleStr, Err, Context);
+ assert(M && "Bad LLVM IR?");
+ return M;
+}
+
+TEST(DeferredDominance, BasicOperations) {
+ StringRef FuncName = "f";
+ StringRef ModuleString =
+ "define i32 @f(i32 %i, i32 *%p) {\n"
+ " bb0:\n"
+ " store i32 %i, i32 *%p\n"
+ " switch i32 %i, label %bb1 [\n"
+ " i32 0, label %bb2\n"
+ " i32 1, label %bb2\n"
+ " i32 2, label %bb3\n"
+ " ]\n"
+ " bb1:\n"
+ " ret i32 1\n"
+ " bb2:\n"
+ " ret i32 2\n"
+ " bb3:\n"
+ " ret i32 3\n"
+ "}\n";
+ // Make the module.
+ LLVMContext Context;
+ std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
+ Function *F = M->getFunction(FuncName);
+ ASSERT_NE(F, nullptr) << "Couldn't get function " << FuncName << ".";
+
+ // Make the DDT.
+ DominatorTree DT(*F);
+ DeferredDominance DDT(DT);
+ ASSERT_TRUE(DDT.flush().verify());
+
+ Function::iterator FI = F->begin();
+ BasicBlock *BB0 = &*FI++;
+ BasicBlock *BB1 = &*FI++;
+ BasicBlock *BB2 = &*FI++;
+ BasicBlock *BB3 = &*FI++;
+
+ // Test discards of invalid self-domination updates. These use the single
+ // short-hand interface but are still queued inside DDT.
+ DDT.deleteEdge(BB0, BB0);
+ DDT.insertEdge(BB1, BB1);
+
+ // Delete edge bb0 -> bb3 and push the update twice to verify duplicate
+ // entries are discarded.
+ std::vector<DominatorTree::UpdateType> Updates;
+ Updates.reserve(4);
+ Updates.push_back({DominatorTree::Delete, BB0, BB3});
+ Updates.push_back({DominatorTree::Delete, BB0, BB3});
+
+ // Unnecessary Insert: no edge bb1 -> bb2 after change to bb0.
+ Updates.push_back({DominatorTree::Insert, BB1, BB2});
+ // Unnecessary Delete: edge exists bb0 -> bb1 after change to bb0.
+ Updates.push_back({DominatorTree::Delete, BB0, BB1});
+
+ // CFG Change: remove edge bb0 -> bb3 and one duplicate edge bb0 -> bb2.
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 4u);
+ BB0->getTerminator()->eraseFromParent();
+ BranchInst::Create(BB1, BB2, ConstantInt::getTrue(F->getContext()), BB0);
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 2u);
+
+ // Deletion of a BasicBlock is an immediate event. We remove all uses to the
+ // contained Instructions and change the Terminator to "unreachable" when
+ // queued for deletion. Its parent is still F until DDT.flush() is called. We
+ // don't defer this action because it can cause problems for other transforms
+ // or analysis as it's part of the actual CFG. We only defer updates to the
+ // DominatorTree. This code will crash if it is placed before the
+ // BranchInst::Create() call above.
+ ASSERT_FALSE(isa<UnreachableInst>(BB3->getTerminator()));
+ EXPECT_FALSE(DDT.pendingDeletedBB(BB3));
+ DDT.deleteBB(BB3);
+ EXPECT_TRUE(DDT.pendingDeletedBB(BB3));
+ ASSERT_TRUE(isa<UnreachableInst>(BB3->getTerminator()));
+ EXPECT_EQ(BB3->getParent(), F);
+
+ // Verify. Updates to DDT must be applied *after* all changes to the CFG
+ // (including block deletion).
+ DDT.applyUpdates(Updates);
+ ASSERT_TRUE(DDT.flush().verify());
+}
+
+TEST(DeferredDominance, PairedUpdate) {
+ StringRef FuncName = "f";
+ StringRef ModuleString =
+ "define i32 @f(i32 %i, i32 *%p) {\n"
+ " bb0:\n"
+ " store i32 %i, i32 *%p\n"
+ " switch i32 %i, label %bb1 [\n"
+ " i32 0, label %bb2\n"
+ " i32 1, label %bb2\n"
+ " ]\n"
+ " bb1:\n"
+ " ret i32 1\n"
+ " bb2:\n"
+ " ret i32 2\n"
+ "}\n";
+ // Make the module.
+ LLVMContext Context;
+ std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
+ Function *F = M->getFunction(FuncName);
+ ASSERT_NE(F, nullptr) << "Couldn't get function " << FuncName << ".";
+
+ // Make the DDT.
+ DominatorTree DT(*F);
+ DeferredDominance DDT(DT);
+ ASSERT_TRUE(DDT.flush().verify());
+
+ Function::iterator FI = F->begin();
+ BasicBlock *BB0 = &*FI++;
+ BasicBlock *BB1 = &*FI++;
+ BasicBlock *BB2 = &*FI++;
+
+ // CFG Change: only edge from bb0 is bb0 -> bb1.
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 3u);
+ BB0->getTerminator()->eraseFromParent();
+ BranchInst::Create(BB1, BB0);
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
+
+ // Must be done after the CFG change. The applyUpdate() routine analyzes the
+ // current state of the CFG.
+ DDT.deleteEdge(BB0, BB2);
+
+ // CFG Change: bb0 now has bb0 -> bb1 and bb0 -> bb2.
+ // With this change no dominance has been altered from the original IR. DT
+ // doesn't care if the type of TerminatorInstruction changed, only if the
+ // unique edges have.
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
+ BB0->getTerminator()->eraseFromParent();
+ BranchInst::Create(BB1, BB2, ConstantInt::getTrue(F->getContext()), BB0);
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 2u);
+
+ // Must be done after the CFG change. The applyUpdate() routine analyzes the
+ // current state of the CFG. This DDT update pairs with the previous one and
+ // is cancelled out before ever applying updates to DT.
+ DDT.insertEdge(BB0, BB2);
+
+ // Test the empty DeletedBB list.
+ EXPECT_FALSE(DDT.pendingDeletedBB(BB0));
+ EXPECT_FALSE(DDT.pendingDeletedBB(BB1));
+ EXPECT_FALSE(DDT.pendingDeletedBB(BB2));
+
+ // The DT has no changes, this flush() simply returns a reference to the
+ // internal DT calculated at the beginning of this test.
+ ASSERT_TRUE(DDT.flush().verify());
+}
+
+TEST(DeferredDominance, ReplaceEntryBB) {
+ StringRef FuncName = "f";
+ StringRef ModuleString =
+ "define i32 @f() {\n"
+ "bb0:\n"
+ " br label %bb1\n"
+ " bb1:\n"
+ " ret i32 1\n"
+ "}\n";
+ // Make the module.
+ LLVMContext Context;
+ std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
+ Function *F = M->getFunction(FuncName);
+ ASSERT_NE(F, nullptr) << "Couldn't get function " << FuncName << ".";
+
+ // Make the DDT.
+ DominatorTree DT(*F);
+ DeferredDominance DDT(DT);
+ ASSERT_TRUE(DDT.flush().verify());
+
+ Function::iterator FI = F->begin();
+ BasicBlock *BB0 = &*FI++;
+ BasicBlock *BB1 = &*FI++;
+
+ // Add a block as the new function entry BB. We also link it to BB0.
+ BasicBlock *NewEntry =
+ BasicBlock::Create(F->getContext(), "new_entry", F, BB0);
+ BranchInst::Create(BB0, NewEntry);
+ EXPECT_EQ(F->begin()->getName(), NewEntry->getName());
+ EXPECT_TRUE(&F->getEntryBlock() == NewEntry);
+
+ // Insert the new edge between new_eentry -> bb0. Without this the
+ // recalculate() call below will not actually recalculate the DT as there
+ // are no changes pending and no blocks deleted.
+ DDT.insertEdge(NewEntry, BB0);
+
+ // Changing the Entry BB requires a full recalulation.
+ DDT.recalculate(*F);
+ ASSERT_TRUE(DDT.flush().verify());
+
+ // CFG Change: remove new_edge -> bb0 and redirect to new_edge -> bb1.
+ EXPECT_EQ(NewEntry->getTerminator()->getNumSuccessors(), 1u);
+ NewEntry->getTerminator()->eraseFromParent();
+ BranchInst::Create(BB1, NewEntry);
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
+
+ // Update the DDT. At this point bb0 now has no predecessors but is still a
+ // Child of F.
+ DDT.applyUpdates({{DominatorTree::Delete, NewEntry, BB0},
+ {DominatorTree::Insert, NewEntry, BB1}});
+ ASSERT_TRUE(DDT.flush().verify());
+
+ // Now remove bb0 from F.
+ ASSERT_FALSE(isa<UnreachableInst>(BB0->getTerminator()));
+ EXPECT_FALSE(DDT.pendingDeletedBB(BB0));
+ DDT.deleteBB(BB0);
+ EXPECT_TRUE(DDT.pendingDeletedBB(BB0));
+ ASSERT_TRUE(isa<UnreachableInst>(BB0->getTerminator()));
+ EXPECT_EQ(BB0->getParent(), F);
+
+ // Perform a full recalculation of the DDT. It is not necessary here but we
+ // do this to test the case when there are no pending DT updates but there are
+ // pending deleted BBs.
+ DDT.recalculate(*F);
+ ASSERT_TRUE(DDT.flush().verify());
+}
+
+TEST(DeferredDominance, InheritedPreds) {
+ StringRef FuncName = "f";
+ StringRef ModuleString =
+ "define i32 @f(i32 %i, i32 *%p) {\n"
+ " bb0:\n"
+ " store i32 %i, i32 *%p\n"
+ " switch i32 %i, label %bb1 [\n"
+ " i32 2, label %bb2\n"
+ " i32 3, label %bb3\n"
+ " ]\n"
+ " bb1:\n"
+ " br label %bb3\n"
+ " bb2:\n"
+ " br label %bb3\n"
+ " bb3:\n"
+ " ret i32 3\n"
+ "}\n";
+ // Make the module.
+ LLVMContext Context;
+ std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
+ Function *F = M->getFunction(FuncName);
+ ASSERT_NE(F, nullptr) << "Couldn't get function " << FuncName << ".";
+
+ // Make the DDT.
+ DominatorTree DT(*F);
+ DeferredDominance DDT(DT);
+ ASSERT_TRUE(DDT.flush().verify());
+
+ Function::iterator FI = F->begin();
+ BasicBlock *BB0 = &*FI++;
+ BasicBlock *BB1 = &*FI++;
+ BasicBlock *BB2 = &*FI++;
+ BasicBlock *BB3 = &*FI++;
+
+ // There are several CFG locations where we have:
+ //
+ // pred1..predN
+ // | |
+ // +> curr <+ converted into: pred1..predN curr
+ // | | |
+ // v +> succ <+
+ // succ
+ //
+ // There is a specific shape of this we have to be careful of:
+ //
+ // pred1..predN
+ // || |
+ // |+> curr <+ converted into: pred1..predN curr
+ // | | | |
+ // | v +> succ <+
+ // +-> succ
+ //
+ // While the final CFG form is functionally identical the updates to
+ // DDT are not. In the first case we must have DDT.insertEdge(Pred1, Succ)
+ // while in the latter case we must *NOT* have DDT.insertEdge(Pred1, Succ).
+
+ // CFG Change: bb0 now only has bb0 -> bb1 and bb0 -> bb3. We are preparing to
+ // remove bb2.
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 3u);
+ BB0->getTerminator()->eraseFromParent();
+ BranchInst::Create(BB1, BB3, ConstantInt::getTrue(F->getContext()), BB0);
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 2u);
+
+ // Remove bb2 from F. This has to happen before the call to applyUpdates() for
+ // DDT to detect there is no longer an edge between bb2 -> bb3. The deleteBB()
+ // method converts bb2's TI into "unreachable".
+ ASSERT_FALSE(isa<UnreachableInst>(BB2->getTerminator()));
+ EXPECT_FALSE(DDT.pendingDeletedBB(BB2));
+ DDT.deleteBB(BB2);
+ EXPECT_TRUE(DDT.pendingDeletedBB(BB2));
+ ASSERT_TRUE(isa<UnreachableInst>(BB2->getTerminator()));
+ EXPECT_EQ(BB2->getParent(), F);
+
+ // Queue up the DDT updates.
+ std::vector<DominatorTree::UpdateType> Updates;
+ Updates.reserve(4);
+ Updates.push_back({DominatorTree::Delete, BB0, BB2});
+ Updates.push_back({DominatorTree::Delete, BB2, BB3});
+
+ // Handle the specific shape case next.
+ // CFG Change: bb0 now only branches to bb3. We are preparing to remove bb1.
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 2u);
+ BB0->getTerminator()->eraseFromParent();
+ BranchInst::Create(BB3, BB0);
+ EXPECT_EQ(BB0->getTerminator()->getNumSuccessors(), 1u);
+
+ // Remove bb1 from F. This has to happen before the call to applyUpdates() for
+ // DDT to detect there is no longer an edge between bb1 -> bb3. The deleteBB()
+ // method converts bb1's TI into "unreachable".
+ ASSERT_FALSE(isa<UnreachableInst>(BB1->getTerminator()));
+ EXPECT_FALSE(DDT.pendingDeletedBB(BB1));
+ DDT.deleteBB(BB1);
+ EXPECT_TRUE(DDT.pendingDeletedBB(BB1));
+ ASSERT_TRUE(isa<UnreachableInst>(BB1->getTerminator()));
+ EXPECT_EQ(BB1->getParent(), F);
+
+ // Update the DDT. In this case we don't call DDT.insertEdge(BB0, BB3) because
+ // the edge previously existed at the start of this test when DT was first
+ // created.
+ Updates.push_back({DominatorTree::Delete, BB0, BB1});
+ Updates.push_back({DominatorTree::Delete, BB1, BB3});
+
+ // Verify everything.
+ DDT.applyUpdates(Updates);
+ ASSERT_TRUE(DDT.flush().verify());
+}
projects / llvm-toolchain-6.0.git / commitdiff