[llvm] r272595 - [PM/MergeLoadStoreMotion] Convert the logic to static functions.

Daniel Berlin via llvm-commits llvm-commits at lists.llvm.org
Thu Jun 16 09:20:02 PDT 2016


(and note, you didn't explain, anywhere, why any of these changes are
necessary for the new PM, they look, at a glance, like completely
orthogonal refactorings)

On Thu, Jun 16, 2016 at 9:07 AM, Daniel Berlin <dberlin at dberlin.org> wrote:

> I don't remember seeing this for review, and you've basically taken a very
> well organized class and completely destroyed its organizational structure
> by creating a mix of class member functions and random non-class static
> functions.
>
> I don't see this as an improvement, even for the new PM.
> I also don't think we should try to take every single pass that is a class
> in LLVM and necessarily turn it into a bunch of static functions that pass
> around what was previously class state.
>
> I'm going to ask you to revert and actually post a patch for review so
> this can be actually discussed.
>
>
>
>
> On Mon, Jun 13, 2016 at 3:27 PM, Davide Italiano via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: davide
>> Date: Mon Jun 13 17:27:30 2016
>> New Revision: 272595
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=272595&view=rev
>> Log:
>> [PM/MergeLoadStoreMotion] Convert the logic to static functions.
>>
>> Pass AliasAnalyis and MemoryDepResult around. This is in preparation
>> for porting this pass to the new PM.
>>
>> Modified:
>>     llvm/trunk/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
>>
>> Modified: llvm/trunk/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp?rev=272595&r1=272594&r2=272595&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp Mon Jun 13
>> 17:27:30 2016
>> @@ -103,8 +103,7 @@ class MergedLoadStoreMotion : public Fun
>>
>>  public:
>>    static char ID; // Pass identification, replacement for typeid
>> -  MergedLoadStoreMotion()
>> -      : FunctionPass(ID), MD(nullptr), MagicCompileTimeControl(250) {
>> +  MergedLoadStoreMotion() : FunctionPass(ID), MD(nullptr) {
>>
>>  initializeMergedLoadStoreMotionPass(*PassRegistry::getPassRegistry());
>>    }
>>
>> @@ -118,43 +117,17 @@ private:
>>      AU.addPreserved<GlobalsAAWrapperPass>();
>>      AU.addPreserved<MemoryDependenceWrapperPass>();
>>    }
>> -
>> -  // Helper routines
>> -
>> -  ///
>> -  /// \brief Remove instruction from parent and update memory dependence
>> -  /// analysis.
>> -  ///
>> -  void removeInstruction(Instruction *Inst);
>> -  BasicBlock *getDiamondTail(BasicBlock *BB);
>> -  bool isDiamondHead(BasicBlock *BB);
>> -  // Routines for hoisting loads
>> -  bool isLoadHoistBarrierInRange(const Instruction &Start,
>> -                                 const Instruction &End, LoadInst *LI,
>> -                                 bool SafeToLoadUnconditionally);
>> -  LoadInst *canHoistFromBlock(BasicBlock *BB, LoadInst *LI);
>> -  void hoistInstruction(BasicBlock *BB, Instruction *HoistCand,
>> -                        Instruction *ElseInst);
>> -  bool isSafeToHoist(Instruction *I) const;
>> -  bool hoistLoad(BasicBlock *BB, LoadInst *HoistCand, LoadInst
>> *ElseInst);
>> -  bool mergeLoads(BasicBlock *BB);
>> -  // Routines for sinking stores
>> -  StoreInst *canSinkFromBlock(BasicBlock *BB, StoreInst *SI);
>> -  PHINode *getPHIOperand(BasicBlock *BB, StoreInst *S0, StoreInst *S1);
>> -  bool isStoreSinkBarrierInRange(const Instruction &Start,
>> -                                 const Instruction &End, MemoryLocation
>> Loc);
>> -  bool sinkStore(BasicBlock *BB, StoreInst *SinkCand, StoreInst
>> *ElseInst);
>> -  bool mergeStores(BasicBlock *BB);
>> -  // The mergeLoad/Store algorithms could have Size0 * Size1 complexity,
>> -  // where Size0 and Size1 are the #instructions on the two sides of
>> -  // the diamond. The constant chosen here is arbitrary. Compiler Time
>> -  // Control is enforced by the check Size0 * Size1 <
>> MagicCompileTimeControl.
>> -  const int MagicCompileTimeControl;
>>  };
>>
>>  char MergedLoadStoreMotion::ID = 0;
>>  } // anonymous namespace
>>
>> +// The mergeLoad/Store algorithms could have Size0 * Size1 complexity,
>> +// where Size0 and Size1 are the #instructions on the two sides of
>> +// the diamond. The constant chosen here is arbitrary. Compiler Time
>> +// Control is enforced by the check Size0 * Size1 <
>> MagicCompileTimeControl.
>> +const int MagicCompileTimeControl = 250;
>> +
>>  ///
>>  /// \brief createMergedLoadStoreMotionPass - The public interface to
>> this file.
>>  ///
>> @@ -173,7 +146,7 @@ INITIALIZE_PASS_END(MergedLoadStoreMotio
>>  ///
>>  /// \brief Remove instruction from parent and update memory dependence
>> analysis.
>>  ///
>> -void MergedLoadStoreMotion::removeInstruction(Instruction *Inst) {
>> +static void removeInstruction(Instruction *Inst, MemoryDependenceResults
>> *MD) {
>>    // Notify the memory dependence analysis.
>>    if (MD) {
>>      MD->removeInstruction(Inst);
>> @@ -187,17 +160,9 @@ void MergedLoadStoreMotion::removeInstru
>>  }
>>
>>  ///
>> -/// \brief Return tail block of a diamond.
>> -///
>> -BasicBlock *MergedLoadStoreMotion::getDiamondTail(BasicBlock *BB) {
>> -  assert(isDiamondHead(BB) && "Basic block is not head of a diamond");
>> -  return BB->getTerminator()->getSuccessor(0)->getSingleSuccessor();
>> -}
>> -
>> -///
>>  /// \brief True when BB is the head of a diamond (hammock)
>>  ///
>> -bool MergedLoadStoreMotion::isDiamondHead(BasicBlock *BB) {
>> +static bool isDiamondHead(BasicBlock *BB) {
>>    if (!BB)
>>      return false;
>>    auto *BI = dyn_cast<BranchInst>(BB->getTerminator());
>> @@ -221,15 +186,24 @@ bool MergedLoadStoreMotion::isDiamondHea
>>  }
>>
>>  ///
>> +/// \brief Return tail block of a diamond.
>> +///
>> +static BasicBlock *getDiamondTail(BasicBlock *BB) {
>> +  assert(isDiamondHead(BB) && "Basic block is not head of a diamond");
>> +  return BB->getTerminator()->getSuccessor(0)->getSingleSuccessor();
>> +}
>> +
>> +///
>>  /// \brief True when instruction is a hoist barrier for a load
>>  ///
>>  /// Whenever an instruction could possibly modify the value
>>  /// being loaded or protect against the load from happening
>>  /// it is considered a hoist barrier.
>>  ///
>> -bool MergedLoadStoreMotion::isLoadHoistBarrierInRange(
>> -    const Instruction &Start, const Instruction &End, LoadInst *LI,
>> -    bool SafeToLoadUnconditionally) {
>> +static bool isLoadHoistBarrierInRange(const Instruction &Start,
>> +                                      const Instruction &End, LoadInst
>> *LI,
>> +                                      bool SafeToLoadUnconditionally,
>> +                                      AliasAnalysis *AA) {
>>    if (!SafeToLoadUnconditionally)
>>      for (const Instruction &Inst :
>>           make_range(Start.getIterator(), End.getIterator()))
>> @@ -246,8 +220,8 @@ bool MergedLoadStoreMotion::isLoadHoistB
>>  /// and it can be hoisted from \p BB, return that load.
>>  /// Otherwise return Null.
>>  ///
>> -LoadInst *MergedLoadStoreMotion::canHoistFromBlock(BasicBlock *BB1,
>> -                                                   LoadInst *Load0) {
>> +static LoadInst *canHoistFromBlock(BasicBlock *BB1, LoadInst *Load0,
>> +                                   AliasAnalysis *AA) {
>>    BasicBlock *BB0 = Load0->getParent();
>>    BasicBlock *Head = BB0->getSinglePredecessor();
>>    bool SafeToLoadUnconditionally = isSafeToLoadUnconditionally(
>> @@ -267,9 +241,9 @@ LoadInst *MergedLoadStoreMotion::canHois
>>      MemoryLocation Loc1 = MemoryLocation::get(Load1);
>>      if (AA->isMustAlias(Loc0, Loc1) && Load0->isSameOperationAs(Load1) &&
>>          !isLoadHoistBarrierInRange(BB1->front(), *Load1, Load1,
>> -                                   SafeToLoadUnconditionally) &&
>> +                                   SafeToLoadUnconditionally, AA) &&
>>          !isLoadHoistBarrierInRange(BB0->front(), *Load0, Load0,
>> -                                   SafeToLoadUnconditionally)) {
>> +                                   SafeToLoadUnconditionally, AA)) {
>>        return Load1;
>>      }
>>    }
>> @@ -282,9 +256,9 @@ LoadInst *MergedLoadStoreMotion::canHois
>>  ///
>>  /// BB is the head of a diamond
>>  ///
>> -void MergedLoadStoreMotion::hoistInstruction(BasicBlock *BB,
>> -                                             Instruction *HoistCand,
>> -                                             Instruction *ElseInst) {
>> +static void hoistInstruction(BasicBlock *BB, Instruction *HoistCand,
>> +                             Instruction *ElseInst,
>> +                             MemoryDependenceResults *MD) {
>>    DEBUG(dbgs() << " Hoist Instruction into BB \n"; BB->dump();
>>          dbgs() << "Instruction Left\n"; HoistCand->dump(); dbgs() <<
>> "\n";
>>          dbgs() << "Instruction Right\n"; ElseInst->dump(); dbgs() <<
>> "\n");
>> @@ -305,16 +279,16 @@ void MergedLoadStoreMotion::hoistInstruc
>>    HoistedInst->insertBefore(HoistPt);
>>
>>    HoistCand->replaceAllUsesWith(HoistedInst);
>> -  removeInstruction(HoistCand);
>> +  removeInstruction(HoistCand, MD);
>>    // Replace the else block instruction.
>>    ElseInst->replaceAllUsesWith(HoistedInst);
>> -  removeInstruction(ElseInst);
>> +  removeInstruction(ElseInst, MD);
>>  }
>>
>>  ///
>>  /// \brief Return true if no operand of \p I is defined in I's parent
>> block
>>  ///
>> -bool MergedLoadStoreMotion::isSafeToHoist(Instruction *I) const {
>> +static bool isSafeToHoist(Instruction *I) {
>>    BasicBlock *Parent = I->getParent();
>>    for (Use &U : I->operands())
>>      if (auto *Instr = dyn_cast<Instruction>(&U))
>> @@ -326,8 +300,8 @@ bool MergedLoadStoreMotion::isSafeToHois
>>  ///
>>  /// \brief Merge two equivalent loads and GEPs and hoist into diamond
>> head
>>  ///
>> -bool MergedLoadStoreMotion::hoistLoad(BasicBlock *BB, LoadInst *L0,
>> -                                      LoadInst *L1) {
>> +static bool hoistLoad(BasicBlock *BB, LoadInst *L0, LoadInst *L1,
>> +                      MemoryDependenceResults *MD) {
>>    // Only one definition?
>>    auto *A0 = dyn_cast<Instruction>(L0->getPointerOperand());
>>    auto *A1 = dyn_cast<Instruction>(L1->getPointerOperand());
>> @@ -338,8 +312,8 @@ bool MergedLoadStoreMotion::hoistLoad(Ba
>>      DEBUG(dbgs() << "Hoist Instruction into BB \n"; BB->dump();
>>            dbgs() << "Instruction Left\n"; L0->dump(); dbgs() << "\n";
>>            dbgs() << "Instruction Right\n"; L1->dump(); dbgs() << "\n");
>> -    hoistInstruction(BB, A0, A1);
>> -    hoistInstruction(BB, L0, L1);
>> +    hoistInstruction(BB, A0, A1, MD);
>> +    hoistInstruction(BB, L0, L1, MD);
>>      return true;
>>    }
>>    return false;
>> @@ -351,7 +325,8 @@ bool MergedLoadStoreMotion::hoistLoad(Ba
>>  /// Starting from a diamond head block, iterate over the instructions in
>> one
>>  /// successor block and try to match a load in the second successor.
>>  ///
>> -bool MergedLoadStoreMotion::mergeLoads(BasicBlock *BB) {
>> +static bool mergeLoads(BasicBlock *BB, AliasAnalysis *AA,
>> +                       MemoryDependenceResults *MD) {
>>    bool MergedLoads = false;
>>    assert(isDiamondHead(BB));
>>    BranchInst *BI = cast<BranchInst>(BB->getTerminator());
>> @@ -373,8 +348,8 @@ bool MergedLoadStoreMotion::mergeLoads(B
>>      ++NLoads;
>>      if (NLoads * Size1 >= MagicCompileTimeControl)
>>        break;
>> -    if (LoadInst *L1 = canHoistFromBlock(Succ1, L0)) {
>> -      bool Res = hoistLoad(BB, L0, L1);
>> +    if (LoadInst *L1 = canHoistFromBlock(Succ1, L0, AA)) {
>> +      bool Res = hoistLoad(BB, L0, L1, MD);
>>        MergedLoads |= Res;
>>        // Don't attempt to hoist above loads that had not been hoisted.
>>        if (!Res)
>> @@ -392,9 +367,9 @@ bool MergedLoadStoreMotion::mergeLoads(B
>>  /// value being stored or protect against the store from
>>  /// happening it is considered a sink barrier.
>>  ///
>> -bool MergedLoadStoreMotion::isStoreSinkBarrierInRange(const Instruction
>> &Start,
>> -                                                      const Instruction
>> &End,
>> -                                                      MemoryLocation
>> Loc) {
>> +static bool isStoreSinkBarrierInRange(const Instruction &Start,
>> +                                      const Instruction &End,
>> +                                      MemoryLocation Loc, AliasAnalysis
>> *AA) {
>>    for (const Instruction &Inst :
>>         make_range(Start.getIterator(), End.getIterator()))
>>      if (Inst.mayThrow())
>> @@ -407,8 +382,8 @@ bool MergedLoadStoreMotion::isStoreSinkB
>>  ///
>>  /// \return The store in \p  when it is safe to sink. Otherwise return
>> Null.
>>  ///
>> -StoreInst *MergedLoadStoreMotion::canSinkFromBlock(BasicBlock *BB1,
>> -                                                   StoreInst *Store0) {
>> +static StoreInst *canSinkFromBlock(BasicBlock *BB1, StoreInst *Store0,
>> +                                   AliasAnalysis *AA) {
>>    DEBUG(dbgs() << "can Sink? : "; Store0->dump(); dbgs() << "\n");
>>    BasicBlock *BB0 = Store0->getParent();
>>    for (BasicBlock::reverse_iterator RBI = BB1->rbegin(), RBE =
>> BB1->rend();
>> @@ -422,8 +397,10 @@ StoreInst *MergedLoadStoreMotion::canSin
>>      MemoryLocation Loc0 = MemoryLocation::get(Store0);
>>      MemoryLocation Loc1 = MemoryLocation::get(Store1);
>>      if (AA->isMustAlias(Loc0, Loc1) && Store0->isSameOperationAs(Store1)
>> &&
>> -        !isStoreSinkBarrierInRange(*Store1->getNextNode(), BB1->back(),
>> Loc1) &&
>> -        !isStoreSinkBarrierInRange(*Store0->getNextNode(), BB0->back(),
>> Loc0)) {
>> +        !isStoreSinkBarrierInRange(*Store1->getNextNode(), BB1->back(),
>> Loc1,
>> +                                   AA) &&
>> +        !isStoreSinkBarrierInRange(*Store0->getNextNode(), BB0->back(),
>> Loc0,
>> +                                   AA)) {
>>        return Store1;
>>      }
>>    }
>> @@ -433,8 +410,8 @@ StoreInst *MergedLoadStoreMotion::canSin
>>  ///
>>  /// \brief Create a PHI node in BB for the operands of S0 and S1
>>  ///
>> -PHINode *MergedLoadStoreMotion::getPHIOperand(BasicBlock *BB, StoreInst
>> *S0,
>> -                                              StoreInst *S1) {
>> +static PHINode *getPHIOperand(BasicBlock *BB, StoreInst *S0, StoreInst
>> *S1,
>> +                              MemoryDependenceResults *MD) {
>>    // Create a phi if the values mismatch.
>>    Value *Opd1 = S0->getValueOperand();
>>    Value *Opd2 = S1->getValueOperand();
>> @@ -455,8 +432,8 @@ PHINode *MergedLoadStoreMotion::getPHIOp
>>  ///
>>  /// Also sinks GEP instruction computing the store address
>>  ///
>> -bool MergedLoadStoreMotion::sinkStore(BasicBlock *BB, StoreInst *S0,
>> -                                      StoreInst *S1) {
>> +static bool sinkStore(BasicBlock *BB, StoreInst *S0, StoreInst *S1,
>> +                      MemoryDependenceResults *MD) {
>>    // Only one definition?
>>    auto *A0 = dyn_cast<Instruction>(S0->getPointerOperand());
>>    auto *A1 = dyn_cast<Instruction>(S1->getPointerOperand());
>> @@ -482,14 +459,14 @@ bool MergedLoadStoreMotion::sinkStore(Ba
>>      assert(S1->getParent() == A1->getParent());
>>
>>      // New PHI operand? Use it.
>> -    if (PHINode *NewPN = getPHIOperand(BB, S0, S1))
>> +    if (PHINode *NewPN = getPHIOperand(BB, S0, S1, MD))
>>        SNew->setOperand(0, NewPN);
>> -    removeInstruction(S0);
>> -    removeInstruction(S1);
>> +    removeInstruction(S0, MD);
>> +    removeInstruction(S1, MD);
>>      A0->replaceAllUsesWith(ANew);
>> -    removeInstruction(A0);
>> +    removeInstruction(A0, MD);
>>      A1->replaceAllUsesWith(ANew);
>> -    removeInstruction(A1);
>> +    removeInstruction(A1, MD);
>>      return true;
>>    }
>>    return false;
>> @@ -501,7 +478,8 @@ bool MergedLoadStoreMotion::sinkStore(Ba
>>  /// Starting from a diamond tail block, iterate over the instructions in
>> one
>>  /// predecessor block and try to match a store in the second predecessor.
>>  ///
>> -bool MergedLoadStoreMotion::mergeStores(BasicBlock *T) {
>> +static bool mergeStores(BasicBlock *T, AliasAnalysis *AA,
>> +                        MemoryDependenceResults *MD) {
>>
>>    bool MergedStores = false;
>>    assert(T && "Footer of a diamond cannot be empty");
>> @@ -536,8 +514,8 @@ bool MergedLoadStoreMotion::mergeStores(
>>      ++NStores;
>>      if (NStores * Size1 >= MagicCompileTimeControl)
>>        break;
>> -    if (StoreInst *S1 = canSinkFromBlock(Pred1, S0)) {
>> -      bool Res = sinkStore(T, S0, S1);
>> +    if (StoreInst *S1 = canSinkFromBlock(Pred1, S0, AA)) {
>> +      bool Res = sinkStore(T, S0, S1, MD);
>>        MergedStores |= Res;
>>        // Don't attempt to sink below stores that had to stick around
>>        // But after removal of a store and some of its feeding
>> @@ -575,8 +553,8 @@ bool MergedLoadStoreMotion::runOnFunctio
>>      // Hoist equivalent loads and sink stores
>>      // outside diamonds when possible
>>      if (isDiamondHead(BB)) {
>> -      Changed |= mergeLoads(BB);
>> -      Changed |= mergeStores(getDiamondTail(BB));
>> +      Changed |= mergeLoads(BB, AA, MD);
>> +      Changed |= mergeStores(getDiamondTail(BB), AA, MD);
>>      }
>>    }
>>    return Changed;
>>
>>
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