[llvm] r321825 - [JumpThreading] Preservation of DT and LVI across the pass
Brian M. Rzycki via llvm-commits
llvm-commits at lists.llvm.org
Mon Jan 8 08:29:38 PST 2018
Hello Philip,
The current implementation of LLVM's JumpThreading pass actively discards
any opportunities that span into, or out of, a loop. You can see the check
for this at the very top of JumpThreadingPass::ProcessThreadableEdges().
This is what I meant by loop boundary threading. :)
At a high-level the LLVM JT pass can only optimize a very specific three
block BB opportunity with the shape of [Prev]->[BB]->[Succ]. The rest of
the pass spends all its time attempting to produce and detect as many of
these block shapes as it can. This is quite different from GCC's JT pass
that has a clear analysis of potential threadable edge paths and then the
actual threading being done. The GCC pass also allows for several blocks on
its threaded chain.
There are quite a few real-world examples where threading into/out of a
loop is beneficial. One prominent pattern is text file parsers. These
parsers usually have nested case/switch blocks inside a while(EOF) loop and
contain token detection state. Here is one such test that illustrates this
pattern:
https://github.com/gcc-mirror/gcc/blob/master/gcc/testsuite/
gcc.dg/tree-ssa/ssa-dom-thread-8.c
When I worked with Sebastian in 2015 to extend GCC's JT parser we also
detected this pattern within GCC itself and saw a modest (couple of
percentage points) performance boost to the compiler run-time.
Hope that helps,
-Brian
On Fri, Jan 5, 2018 at 1:00 PM, Philip Reames <listmail at philipreames.com>
wrote:
> Out of curiosity, what is "loop boundary threading"? I'm unfamiliar with
> this and can find zero hits on google. :)
>
> Philip
>
> On 01/04/2018 01:57 PM, Brian M. Rzycki via llvm-commits wrote:
>
>> Author: brzycki
>> Date: Thu Jan 4 13:57:32 2018
>> New Revision: 321825
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=321825&view=rev
>> Log:
>> [JumpThreading] Preservation of DT and LVI across the pass
>>
>> Summary:
>> See D37528 for a previous (non-deferred) version of this
>> patch and its description.
>>
>> Preserves dominance in a deferred manner using a new class
>> DeferredDominance. This reduces the performance impact of
>> updating the DominatorTree at every edge insertion and
>> deletion. A user may call DDT->flush() within JumpThreading
>> for an up-to-date DT. This patch currently has one flush()
>> at the end of runImpl() to ensure DT is preserved across
>> the pass.
>>
>> LVI is also preserved to help subsequent passes such as
>> CorrelatedValuePropagation. LVI is simpler to maintain and
>> is done immediately (not deferred). The code to perfom the
>> preversation was minimally altered and was simply marked
>> as preserved for the PassManager to be informed.
>>
>> This extends the analysis available to JumpThreading for
>> future enhancements. One example is loop boundary threading.
>>
>> Reviewers: dberlin, kuhar, sebpop
>>
>> Reviewed By: kuhar, sebpop
>>
>> Subscribers: hiraditya, llvm-commits
>>
>> Differential Revision: https://reviews.llvm.org/D40146
>>
>> Added:
>> llvm/trunk/test/Transforms/JumpThreading/ddt-crash.ll
>> llvm/trunk/test/Transforms/JumpThreading/lvi-tristate.ll
>> Modified:
>> llvm/trunk/include/llvm/IR/Dominators.h
>> llvm/trunk/include/llvm/Transforms/Scalar/JumpThreading.h
>> llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
>> llvm/trunk/include/llvm/Transforms/Utils/Local.h
>> llvm/trunk/lib/IR/Dominators.cpp
>> llvm/trunk/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
>> llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
>> llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
>> llvm/trunk/lib/Transforms/Utils/Local.cpp
>> llvm/trunk/test/Analysis/LazyValueAnalysis/lvi-after-jumpth
>> reading.ll
>>
>> Modified: llvm/trunk/include/llvm/IR/Dominators.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/
>> IR/Dominators.h?rev=321825&r1=321824&r2=321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/include/llvm/IR/Dominators.h (original)
>> +++ llvm/trunk/include/llvm/IR/Dominators.h Thu Jan 4 13:57:32 2018
>> @@ -290,6 +290,90 @@ public:
>> 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
>>
>> Modified: llvm/trunk/include/llvm/Transforms/Scalar/JumpThreading.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/
>> Transforms/Scalar/JumpThreading.h?rev=321825&r1=321824&r2=
>> 321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/include/llvm/Transforms/Scalar/JumpThreading.h (original)
>> +++ llvm/trunk/include/llvm/Transforms/Scalar/JumpThreading.h Thu Jan 4
>> 13:57:32 2018
>> @@ -34,6 +34,7 @@ class BinaryOperator;
>> class BranchInst;
>> class CmpInst;
>> class Constant;
>> +class DeferredDominance;
>> class Function;
>> class Instruction;
>> class IntrinsicInst;
>> @@ -77,6 +78,7 @@ class JumpThreadingPass : public PassInf
>> TargetLibraryInfo *TLI;
>> LazyValueInfo *LVI;
>> AliasAnalysis *AA;
>> + DeferredDominance *DDT;
>> std::unique_ptr<BlockFrequencyInfo> BFI;
>> std::unique_ptr<BranchProbabilityInfo> BPI;
>> bool HasProfileData = false;
>> @@ -107,8 +109,8 @@ public:
>> // 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);
>>
>> Modified: llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/
>> Transforms/Utils/BasicBlockUtils.h?rev=321825&r1=321824&r2=
>> 321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h (original)
>> +++ llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h Thu Jan
>> 4 13:57:32 2018
>> @@ -27,6 +27,7 @@ namespace llvm {
>> class BlockFrequencyInfo;
>> class BranchProbabilityInfo;
>> +class DeferredDominance;
>> class DominatorTree;
>> class Function;
>> class Instruction;
>> @@ -38,7 +39,7 @@ class TargetLibraryInfo;
>> 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
>>
>> Modified: llvm/trunk/include/llvm/Transforms/Utils/Local.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/
>> Transforms/Utils/Local.h?rev=321825&r1=321824&r2=321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/include/llvm/Transforms/Utils/Local.h (original)
>> +++ llvm/trunk/include/llvm/Transforms/Utils/Local.h Thu Jan 4 13:57:32
>> 2018
>> @@ -117,7 +117,8 @@ struct SimplifyCFGOptions {
>> /// 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.
>> @@ -171,18 +172,21 @@ bool SimplifyInstructionsInBlock(BasicBl
>> ///
>> /// .. 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
>> @@ -382,7 +386,8 @@ unsigned removeAllNonTerminatorAndEHPadI
>> /// 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
>> @@ -397,12 +402,13 @@ BasicBlock *changeToInvokeAndSplitBasicB
>> ///
>> /// \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
>> ///
>>
>> Modified: llvm/trunk/lib/IR/Dominators.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Domina
>> tors.cpp?rev=321825&r1=321824&r2=321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/lib/IR/Dominators.cpp (original)
>> +++ llvm/trunk/lib/IR/Dominators.cpp Thu Jan 4 13:57:32 2018
>> @@ -18,6 +18,7 @@
>> #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"
>> @@ -389,3 +390,190 @@ void DominatorTreeWrapperPass::print(raw
>> 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;
>> +}
>>
>> Modified: llvm/trunk/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transform
>> s/Scalar/CorrelatedValuePropagation.cpp?rev=321825&r1=
>> 321824&r2=321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
>> (original)
>> +++ llvm/trunk/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp Thu
>> Jan 4 13:57:32 2018
>> @@ -77,6 +77,7 @@ namespace {
>> bool runOnFunction(Function &F) override;
>> void getAnalysisUsage(AnalysisUsage &AU) const override {
>> + AU.addRequired<DominatorTreeWrapperPass>();
>> AU.addRequired<LazyValueInfoWrapperPass>();
>> AU.addPreserved<GlobalsAAWrapperPass>();
>> }
>> @@ -88,6 +89,7 @@ char CorrelatedValuePropagation::ID = 0;
>> 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)
>>
>> Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transform
>> s/Scalar/JumpThreading.cpp?rev=321825&r1=321824&r2=321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Thu Jan 4
>> 13:57:32 2018
>> @@ -131,10 +131,11 @@ namespace {
>> 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>();
>> }
>> @@ -148,6 +149,7 @@ char JumpThreading::ID = 0;
>> 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)
>> @@ -278,8 +280,12 @@ bool JumpThreading::runOnFunction(Functi
>> 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();
>> @@ -289,12 +295,11 @@ bool JumpThreading::runOnFunction(Functi
>> 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<DominatorTreeWrapp
>> erPass>().getDomTree(),
>> - dbgs());
>> + LVI->printLVI(F, *DT, dbgs());
>> }
>> return Changed;
>> }
>> @@ -302,8 +307,12 @@ bool JumpThreading::runOnFunction(Functi
>> 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;
>> @@ -313,25 +322,28 @@ PreservedAnalyses JumpThreadingPass::run
>> 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
>> @@ -353,7 +365,7 @@ bool JumpThreadingPass::runImpl(Function
>> // 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);
>> @@ -368,6 +380,10 @@ bool JumpThreadingPass::runImpl(Function
>> ++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) &&
>> @@ -376,7 +392,7 @@ bool JumpThreadingPass::runImpl(Function
>> << "' with terminator: " << *BB->getTerminator() << '\n');
>> LoopHeaders.erase(BB);
>> LVI->eraseBlock(BB);
>> - DeleteDeadBlock(BB);
>> + DeleteDeadBlock(BB, DDT);
>> Changed = true;
>> continue;
>> }
>> @@ -400,7 +416,7 @@ bool JumpThreadingPass::runImpl(Function
>> // 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;
>> }
>> }
>> @@ -408,6 +424,7 @@ bool JumpThreadingPass::runImpl(Function
>> } while (Changed);
>> LoopHeaders.clear();
>> + DDT->flush();
>> return EverChanged;
>> }
>> @@ -931,8 +948,8 @@ static bool hasAddressTakenAndUsed(Basic
>> 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
>> @@ -948,7 +965,7 @@ bool JumpThreadingPass::ProcessBlock(Bas
>> 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
>> @@ -1031,18 +1048,23 @@ bool JumpThreadingPass::ProcessBlock(Bas
>> // 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;
>> }
>> @@ -1053,7 +1075,7 @@ bool JumpThreadingPass::ProcessBlock(Bas
>> DEBUG(dbgs() << " In block '" << BB->getName()
>> << "' folding terminator: " << *BB->getTerminator() << '\n');
>> ++NumFolds;
>> - ConstantFoldTerminator(BB, true);
>> + ConstantFoldTerminator(BB, true, nullptr, DDT);
>> return true;
>> }
>> @@ -1086,7 +1108,8 @@ bool JumpThreadingPass::ProcessBlock(Bas
>> 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())
>> @@ -1104,6 +1127,7 @@ bool JumpThreadingPass::ProcessBlock(Bas
>> ConstantInt::getFalse(CondCmp->getType());
>> ReplaceFoldableUses(CondCmp, CI);
>> }
>> + DDT->deleteEdge(BB, ToRemoveSucc);
>> return true;
>> }
>> @@ -1182,9 +1206,12 @@ bool JumpThreadingPass::ProcessImpliedCo
>> 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;
>> @@ -1591,17 +1618,22 @@ bool JumpThreadingPass::ProcessThreadabl
>> 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.
>> @@ -1964,6 +1996,10 @@ bool JumpThreadingPass::ThreadEdge(Basic
>> 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.
>> @@ -1983,20 +2019,42 @@ bool JumpThreadingPass::ThreadEdge(Basic
>> 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) {
>> @@ -2140,6 +2198,7 @@ bool JumpThreadingPass::DuplicateCondBra
>> }
>> // 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];
>> @@ -2148,6 +2207,7 @@ bool JumpThreadingPass::DuplicateCondBra
>> << " 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.
>> @@ -2160,7 +2220,11 @@ bool JumpThreadingPass::DuplicateCondBra
>> BranchInst *OldPredBranch = dyn_cast<BranchInst>(PredBB->g
>> etTerminator());
>> 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());
>> }
>> @@ -2202,6 +2266,10 @@ bool JumpThreadingPass::DuplicateCondBra
>> // 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->getO
>> perand(i)))
>> + Updates.push_back({DominatorTree::Insert, PredBB, SuccBB});
>> }
>> }
>> @@ -2257,6 +2325,7 @@ bool JumpThreadingPass::DuplicateCondBra
>> // Remove the unconditional branch at the end of the PredBB block.
>> OldPredBranch->eraseFromParent();
>> + DDT->applyUpdates(Updates);
>> ++NumDupes;
>> return true;
>> @@ -2329,6 +2398,8 @@ bool JumpThreadingPass::TryToUnfoldSelec
>> // 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)
>> @@ -2407,11 +2478,25 @@ bool JumpThreadingPass::TryToUnfoldSelec
>> // 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;
>> @@ -2498,8 +2583,8 @@ bool JumpThreadingPass::ThreadGuard(Basi
>> 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();
>> @@ -2508,18 +2593,29 @@ bool JumpThreadingPass::ThreadGuard(Basi
>> 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.
>>
>> Modified: llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transform
>> s/Utils/BasicBlockUtils.cpp?rev=321825&r1=321824&r2=321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp Thu Jan 4
>> 13:57:32 2018
>> @@ -45,16 +45,22 @@
>> 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()) {
>> @@ -69,8 +75,12 @@ void llvm::DeleteDeadBlock(BasicBlock *B
>> 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,
>>
>> Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transform
>> s/Utils/Local.cpp?rev=321825&r1=321824&r2=321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Utils/Local.cpp Thu Jan 4 13:57:32 2018
>> @@ -100,7 +100,8 @@ STATISTIC(NumRemoved, "Number of unreach
>> /// 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);
>> @@ -123,6 +124,8 @@ bool llvm::ConstantFoldTerminator(BasicB
>> // Replace the conditional branch with an unconditional one.
>> Builder.CreateBr(Destination);
>> BI->eraseFromParent();
>> + if (DDT)
>> + DDT->deleteEdge(BB, OldDest);
>> return true;
>> }
>> @@ -193,9 +196,12 @@ bool llvm::ConstantFoldTerminator(BasicB
>> 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;
>> }
>> @@ -221,14 +227,20 @@ bool llvm::ConstantFoldTerminator(BasicB
>> // 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.
>> @@ -236,6 +248,8 @@ bool llvm::ConstantFoldTerminator(BasicB
>> SI->eraseFromParent();
>> if (DeleteDeadConditions)
>> RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
>> + if (DDT)
>> + DDT->applyUpdates(Updates);
>> return true;
>> }
>> @@ -281,14 +295,23 @@ bool llvm::ConstantFoldTerminator(BasicB
>> 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();
>> @@ -303,6 +326,8 @@ bool llvm::ConstantFoldTerminator(BasicB
>> new UnreachableInst(BB->getContext(), BB);
>> }
>> + if (DDT)
>> + DDT->applyUpdates(Updates);
>> return true;
>> }
>> }
>> @@ -579,7 +604,8 @@ bool llvm::SimplifyInstructionsInBlock(B
>> ///
>> /// .. 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;
>> @@ -602,13 +628,18 @@ void llvm::RemovePredecessorAndSimplify(
>> // 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);
>> @@ -621,6 +652,23 @@ void llvm::MergeBasicBlockIntoOnlyPred(B
>> 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((2 * std::distance(pred_begin(PredBB),
>> pred_end(PredBB))) +
>> + 1);
>> + 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});
>> + 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()) {
>> @@ -641,7 +689,7 @@ void llvm::MergeBasicBlockIntoOnlyPred(B
>> // 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) {
>> @@ -653,8 +701,19 @@ void llvm::MergeBasicBlockIntoOnlyPred(B
>> 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
>> @@ -861,7 +920,8 @@ static void redirectValuesFromPredecesso
>> /// 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!");
>> @@ -902,6 +962,17 @@ bool llvm::TryToSimplifyUncondBranchFrom
>> DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB);
>> + std::vector<DominatorTree::UpdateType> Updates;
>> + if (DDT) {
>> + Updates.reserve((2 * std::distance(pred_begin(BB), pred_end(BB))) +
>> 1);
>> + 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});
>> + 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
>> @@ -946,7 +1017,13 @@ bool llvm::TryToSimplifyUncondBranchFrom
>> // 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;
>> }
>> @@ -1448,13 +1525,19 @@ unsigned llvm::removeAllNonTerminatorAnd
>> }
>> 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) {
>> @@ -1474,11 +1557,13 @@ unsigned llvm::changeToUnreachable(Instr
>> 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);
>> @@ -1491,11 +1576,16 @@ static void changeToCall(InvokeInst *II)
>> 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,
>> @@ -1536,7 +1626,8 @@ BasicBlock *llvm::changeToInvokeAndSplit
>> }
>> 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);
>> @@ -1556,7 +1647,7 @@ static bool markAliveBlocks(Function &F,
>> 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;
>> }
>> @@ -1573,7 +1664,8 @@ static bool markAliveBlocks(Function &F,
>> // 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;
>> }
>> @@ -1583,7 +1675,7 @@ static bool markAliveBlocks(Function &F,
>> 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;
>> }
>> @@ -1593,7 +1685,7 @@ static bool markAliveBlocks(Function &F,
>> // 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;
>> @@ -1612,7 +1704,7 @@ static bool markAliveBlocks(Function &F,
>> if (isa<UndefValue>(Ptr) ||
>> (isa<ConstantPointerNull>(Ptr) &&
>> SI->getPointerAddressSpace() == 0)) {
>> - changeToUnreachable(SI, true);
>> + changeToUnreachable(SI, true, false, DDT);
>> Changed = true;
>> break;
>> }
>> @@ -1624,16 +1716,20 @@ static bool markAliveBlocks(Function &F,
>> // 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))
>> {
>> @@ -1679,7 +1775,7 @@ static bool markAliveBlocks(Function &F,
>> }
>> }
>> - Changed |= ConstantFoldTerminator(BB, true);
>> + Changed |= ConstantFoldTerminator(BB, true, nullptr, DDT);
>> for (BasicBlock *Successor : successors(BB))
>> if (Reachable.insert(Successor).second)
>> Worklist.push_back(Successor);
>> @@ -1687,11 +1783,11 @@ static bool markAliveBlocks(Function &F,
>> 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;
>> }
>> @@ -1719,15 +1815,18 @@ void llvm::removeUnwindEdge(BasicBlock *
>> 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())
>> @@ -1737,25 +1836,39 @@ bool llvm::removeUnreachableBlocks(Funct
>> 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;
>> }
>>
>> Modified: llvm/trunk/test/Analysis/LazyValueAnalysis/lvi-after-jumpthr
>> eading.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis
>> /LazyValueAnalysis/lvi-after-jumpthreading.ll?rev=321825&
>> r1=321824&r2=321825&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/test/Analysis/LazyValueAnalysis/lvi-after-jumpthreading.ll
>> (original)
>> +++ llvm/trunk/test/Analysis/LazyValueAnalysis/lvi-after-jumpthreading.ll
>> Thu Jan 4 13:57:32 2018
>> @@ -19,10 +19,13 @@ entry:
>> ; 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:
>>
>> Added: llvm/trunk/test/Transforms/JumpThreading/ddt-crash.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transfor
>> ms/JumpThreading/ddt-crash.ll?rev=321825&view=auto
>> ============================================================
>> ==================
>> --- llvm/trunk/test/Transforms/JumpThreading/ddt-crash.ll (added)
>> +++ llvm/trunk/test/Transforms/JumpThreading/ddt-crash.ll Thu Jan 4
>> 13:57:32 2018
>> @@ -0,0 +1,265 @@
>> +; 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 }
>> +
>> + at global = external global %struct.ham*, align 8
>> + at 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
>
>
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