[PM] Revert the port of MergeLoadStoreMotion to the new pass manager.

Daniel Berlin expressed some real concerns about the port and proposed
and alternative approach. I'll revert this for now while working on a
new patch, which I hope to put up for review shortly. Sorry for the churn.

llvm-svn: 272925

1 files changed, 131 insertions, 127 deletions

diff --git a/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp b/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
index 37a4bfda39b..35f2f2c9a67 100644
--- a/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
+++ b/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
@@ -72,7 +72,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/Scalar/MergedLoadStoreMotion.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/CFG.h"
@@ -97,16 +96,83 @@ using namespace llvm;
 //                         MergedLoadStoreMotion Pass
 //===----------------------------------------------------------------------===//
 
-// 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;
+namespace {
+class MergedLoadStoreMotion : public FunctionPass {
+  AliasAnalysis *AA;
+  MemoryDependenceResults *MD;
+
+public:
+  static char ID; // Pass identification, replacement for typeid
+  MergedLoadStoreMotion()
+      : FunctionPass(ID), MD(nullptr), MagicCompileTimeControl(250) {
+    initializeMergedLoadStoreMotionPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnFunction(Function &F) override;
+
+private:
+  // This transformation requires dominator postdominator info
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    AU.addRequired<AAResultsWrapperPass>();
+    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
+
+///
+/// \brief createMergedLoadStoreMotionPass - The public interface to this file.
+///
+FunctionPass *llvm::createMergedLoadStoreMotionPass() {
+  return new MergedLoadStoreMotion();
+}
+
+INITIALIZE_PASS_BEGIN(MergedLoadStoreMotion, "mldst-motion",
+                      "MergedLoadStoreMotion", false, false)
+INITIALIZE_PASS_DEPENDENCY(MemoryDependenceWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
+INITIALIZE_PASS_END(MergedLoadStoreMotion, "mldst-motion",
+                    "MergedLoadStoreMotion", false, false)
 
 ///
 /// \brief Remove instruction from parent and update memory dependence analysis.
 ///
-static void removeInstruction(Instruction *Inst, MemoryDependenceResults *MD) {
+void MergedLoadStoreMotion::removeInstruction(Instruction *Inst) {
   // Notify the memory dependence analysis.
   if (MD) {
     MD->removeInstruction(Inst);
@@ -120,9 +186,17 @@ static void removeInstruction(Instruction *Inst, MemoryDependenceResults *MD) {
 }
 
 ///
+/// \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)
 ///
-static bool isDiamondHead(BasicBlock *BB) {
+bool MergedLoadStoreMotion::isDiamondHead(BasicBlock *BB) {
   if (!BB)
     return false;
   auto *BI = dyn_cast<BranchInst>(BB->getTerminator());
@@ -146,24 +220,15 @@ static bool isDiamondHead(BasicBlock *BB) {
 }
 
 ///
-/// \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.
 ///
-static bool isLoadHoistBarrierInRange(const Instruction &Start,
-                                      const Instruction &End, LoadInst *LI,
-                                      bool SafeToLoadUnconditionally,
-                                      AliasAnalysis *AA) {
+bool MergedLoadStoreMotion::isLoadHoistBarrierInRange(
+    const Instruction &Start, const Instruction &End, LoadInst *LI,
+    bool SafeToLoadUnconditionally) {
   if (!SafeToLoadUnconditionally)
     for (const Instruction &Inst :
          make_range(Start.getIterator(), End.getIterator()))
@@ -180,8 +245,8 @@ static bool isLoadHoistBarrierInRange(const Instruction &Start,
 /// and it can be hoisted from \p BB, return that load.
 /// Otherwise return Null.
 ///
-static LoadInst *canHoistFromBlock(BasicBlock *BB1, LoadInst *Load0,
-                                   AliasAnalysis *AA) {
+LoadInst *MergedLoadStoreMotion::canHoistFromBlock(BasicBlock *BB1,
+                                                   LoadInst *Load0) {
   BasicBlock *BB0 = Load0->getParent();
   BasicBlock *Head = BB0->getSinglePredecessor();
   bool SafeToLoadUnconditionally = isSafeToLoadUnconditionally(
@@ -201,9 +266,9 @@ static LoadInst *canHoistFromBlock(BasicBlock *BB1, LoadInst *Load0,
     MemoryLocation Loc1 = MemoryLocation::get(Load1);
     if (Load0->isSameOperationAs(Load1) && AA->isMustAlias(Loc0, Loc1) &&
         !isLoadHoistBarrierInRange(BB1->front(), *Load1, Load1,
-                                   SafeToLoadUnconditionally, AA) &&
+                                   SafeToLoadUnconditionally) &&
         !isLoadHoistBarrierInRange(BB0->front(), *Load0, Load0,
-                                   SafeToLoadUnconditionally, AA)) {
+                                   SafeToLoadUnconditionally)) {
       return Load1;
     }
   }
@@ -216,9 +281,9 @@ static LoadInst *canHoistFromBlock(BasicBlock *BB1, LoadInst *Load0,
 ///
 /// BB is the head of a diamond
 ///
-static void hoistInstruction(BasicBlock *BB, Instruction *HoistCand,
-                             Instruction *ElseInst,
-                             MemoryDependenceResults *MD) {
+void MergedLoadStoreMotion::hoistInstruction(BasicBlock *BB,
+                                             Instruction *HoistCand,
+                                             Instruction *ElseInst) {
   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");
@@ -239,16 +304,16 @@ static void hoistInstruction(BasicBlock *BB, Instruction *HoistCand,
   HoistedInst->insertBefore(HoistPt);
 
   HoistCand->replaceAllUsesWith(HoistedInst);
-  removeInstruction(HoistCand, MD);
+  removeInstruction(HoistCand);
   // Replace the else block instruction.
   ElseInst->replaceAllUsesWith(HoistedInst);
-  removeInstruction(ElseInst, MD);
+  removeInstruction(ElseInst);
 }
 
 ///
 /// \brief Return true if no operand of \p I is defined in I's parent block
 ///
-static bool isSafeToHoist(Instruction *I) {
+bool MergedLoadStoreMotion::isSafeToHoist(Instruction *I) const {
   BasicBlock *Parent = I->getParent();
   for (Use &U : I->operands())
     if (auto *Instr = dyn_cast<Instruction>(&U))
@@ -260,8 +325,8 @@ static bool isSafeToHoist(Instruction *I) {
 ///
 /// \brief Merge two equivalent loads and GEPs and hoist into diamond head
 ///
-static bool hoistLoad(BasicBlock *BB, LoadInst *L0, LoadInst *L1,
-                      MemoryDependenceResults *MD) {
+bool MergedLoadStoreMotion::hoistLoad(BasicBlock *BB, LoadInst *L0,
+                                      LoadInst *L1) {
   // Only one definition?
   auto *A0 = dyn_cast<Instruction>(L0->getPointerOperand());
   auto *A1 = dyn_cast<Instruction>(L1->getPointerOperand());
@@ -272,8 +337,8 @@ static bool hoistLoad(BasicBlock *BB, LoadInst *L0, LoadInst *L1,
     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, MD);
-    hoistInstruction(BB, L0, L1, MD);
+    hoistInstruction(BB, A0, A1);
+    hoistInstruction(BB, L0, L1);
     return true;
   }
   return false;
@@ -285,8 +350,7 @@ static bool hoistLoad(BasicBlock *BB, LoadInst *L0, LoadInst *L1,
 /// Starting from a diamond head block, iterate over the instructions in one
 /// successor block and try to match a load in the second successor.
 ///
-static bool mergeLoads(BasicBlock *BB, AliasAnalysis *AA,
-                       MemoryDependenceResults *MD) {
+bool MergedLoadStoreMotion::mergeLoads(BasicBlock *BB) {
   bool MergedLoads = false;
   assert(isDiamondHead(BB));
   BranchInst *BI = cast<BranchInst>(BB->getTerminator());
@@ -308,8 +372,8 @@ static bool mergeLoads(BasicBlock *BB, AliasAnalysis *AA,
     ++NLoads;
     if (NLoads * Size1 >= MagicCompileTimeControl)
       break;
-    if (LoadInst *L1 = canHoistFromBlock(Succ1, L0, AA)) {
-      bool Res = hoistLoad(BB, L0, L1, MD);
+    if (LoadInst *L1 = canHoistFromBlock(Succ1, L0)) {
+      bool Res = hoistLoad(BB, L0, L1);
       MergedLoads |= Res;
       // Don't attempt to hoist above loads that had not been hoisted.
       if (!Res)
@@ -327,9 +391,9 @@ static bool mergeLoads(BasicBlock *BB, AliasAnalysis *AA,
 /// value being stored or protect against the store from
 /// happening it is considered a sink barrier.
 ///
-static bool isStoreSinkBarrierInRange(const Instruction &Start,
-                                      const Instruction &End,
-                                      MemoryLocation Loc, AliasAnalysis *AA) {
+bool MergedLoadStoreMotion::isStoreSinkBarrierInRange(const Instruction &Start,
+                                                      const Instruction &End,
+                                                      MemoryLocation Loc) {
   for (const Instruction &Inst :
        make_range(Start.getIterator(), End.getIterator()))
     if (Inst.mayThrow())
@@ -342,8 +406,8 @@ static bool isStoreSinkBarrierInRange(const Instruction &Start,
 ///
 /// \return The store in \p  when it is safe to sink. Otherwise return Null.
 ///
-static StoreInst *canSinkFromBlock(BasicBlock *BB1, StoreInst *Store0,
-                                   AliasAnalysis *AA) {
+StoreInst *MergedLoadStoreMotion::canSinkFromBlock(BasicBlock *BB1,
+                                                   StoreInst *Store0) {
   DEBUG(dbgs() << "can Sink? : "; Store0->dump(); dbgs() << "\n");
   BasicBlock *BB0 = Store0->getParent();
   for (BasicBlock::reverse_iterator RBI = BB1->rbegin(), RBE = BB1->rend();
@@ -357,10 +421,8 @@ static StoreInst *canSinkFromBlock(BasicBlock *BB1, StoreInst *Store0,
     MemoryLocation Loc0 = MemoryLocation::get(Store0);
     MemoryLocation Loc1 = MemoryLocation::get(Store1);
     if (AA->isMustAlias(Loc0, Loc1) && Store0->isSameOperationAs(Store1) &&
-        !isStoreSinkBarrierInRange(*Store1->getNextNode(), BB1->back(), Loc1,
-                                   AA) &&
-        !isStoreSinkBarrierInRange(*Store0->getNextNode(), BB0->back(), Loc0,
-                                   AA)) {
+        !isStoreSinkBarrierInRange(*Store1->getNextNode(), BB1->back(), Loc1) &&
+        !isStoreSinkBarrierInRange(*Store0->getNextNode(), BB0->back(), Loc0)) {
       return Store1;
     }
   }
@@ -370,8 +432,8 @@ static StoreInst *canSinkFromBlock(BasicBlock *BB1, StoreInst *Store0,
 ///
 /// \brief Create a PHI node in BB for the operands of S0 and S1
 ///
-static PHINode *getPHIOperand(BasicBlock *BB, StoreInst *S0, StoreInst *S1,
-                              MemoryDependenceResults *MD) {
+PHINode *MergedLoadStoreMotion::getPHIOperand(BasicBlock *BB, StoreInst *S0,
+                                              StoreInst *S1) {
   // Create a phi if the values mismatch.
   Value *Opd1 = S0->getValueOperand();
   Value *Opd2 = S1->getValueOperand();
@@ -392,8 +454,8 @@ static PHINode *getPHIOperand(BasicBlock *BB, StoreInst *S0, StoreInst *S1,
 ///
 /// Also sinks GEP instruction computing the store address
 ///
-static bool sinkStore(BasicBlock *BB, StoreInst *S0, StoreInst *S1,
-                      MemoryDependenceResults *MD) {
+bool MergedLoadStoreMotion::sinkStore(BasicBlock *BB, StoreInst *S0,
+                                      StoreInst *S1) {
   // Only one definition?
   auto *A0 = dyn_cast<Instruction>(S0->getPointerOperand());
   auto *A1 = dyn_cast<Instruction>(S1->getPointerOperand());
@@ -419,14 +481,14 @@ static bool sinkStore(BasicBlock *BB, StoreInst *S0, StoreInst *S1,
     assert(S1->getParent() == A1->getParent());
 
     // New PHI operand? Use it.
-    if (PHINode *NewPN = getPHIOperand(BB, S0, S1, MD))
+    if (PHINode *NewPN = getPHIOperand(BB, S0, S1))
       SNew->setOperand(0, NewPN);
-    removeInstruction(S0, MD);
-    removeInstruction(S1, MD);
+    removeInstruction(S0);
+    removeInstruction(S1);
     A0->replaceAllUsesWith(ANew);
-    removeInstruction(A0, MD);
+    removeInstruction(A0);
     A1->replaceAllUsesWith(ANew);
-    removeInstruction(A1, MD);
+    removeInstruction(A1);
     return true;
   }
   return false;
@@ -438,8 +500,7 @@ static bool sinkStore(BasicBlock *BB, StoreInst *S0, StoreInst *S1,
 /// Starting from a diamond tail block, iterate over the instructions in one
 /// predecessor block and try to match a store in the second predecessor.
 ///
-static bool mergeStores(BasicBlock *T, AliasAnalysis *AA,
-                        MemoryDependenceResults *MD) {
+bool MergedLoadStoreMotion::mergeStores(BasicBlock *T) {
 
   bool MergedStores = false;
   assert(T && "Footer of a diamond cannot be empty");
@@ -474,8 +535,8 @@ static bool mergeStores(BasicBlock *T, AliasAnalysis *AA,
     ++NStores;
     if (NStores * Size1 >= MagicCompileTimeControl)
       break;
-    if (StoreInst *S1 = canSinkFromBlock(Pred1, S0, AA)) {
-      bool Res = sinkStore(T, S0, S1, MD);
+    if (StoreInst *S1 = canSinkFromBlock(Pred1, S0)) {
+      bool Res = sinkStore(T, S0, S1);
       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
@@ -494,8 +555,14 @@ static bool mergeStores(BasicBlock *T, AliasAnalysis *AA,
 ///
 /// \brief Run the transformation for each function
 ///
-static bool runMergedLoadStoreMotion(Function &F, AliasAnalysis *AA,
-                                     MemoryDependenceResults *MD) {
+bool MergedLoadStoreMotion::runOnFunction(Function &F) {
+  if (skipFunction(F))
+    return false;
+
+  auto *MDWP = getAnalysisIfAvailable<MemoryDependenceWrapperPass>();
+  MD = MDWP ? &MDWP->getMemDep() : nullptr;
+  AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
+
   bool Changed = false;
   DEBUG(dbgs() << "Instruction Merger\n");
 
@@ -507,72 +574,9 @@ static bool runMergedLoadStoreMotion(Function &F, AliasAnalysis *AA,
     // Hoist equivalent loads and sink stores
     // outside diamonds when possible
     if (isDiamondHead(BB)) {
-      Changed |= mergeLoads(BB, AA, MD);
-      Changed |= mergeStores(getDiamondTail(BB), AA, MD);
+      Changed |= mergeLoads(BB);
+      Changed |= mergeStores(getDiamondTail(BB));
     }
   }
   return Changed;
 }
-
-PreservedAnalyses
-MergedLoadStoreMotionPass::run(Function &F, AnalysisManager<Function> &AM) {
-  auto &AA = AM.getResult<AAManager>(F);
-  auto *MD = AM.getCachedResult<MemoryDependenceAnalysis>(F);
-  if (!runMergedLoadStoreMotion(F, &AA, MD))
-    return PreservedAnalyses::all();
-  // FIXME: This pass should also 'preserve the CFG'.
-  // The new pass manager has currently no way to do it.
-  PreservedAnalyses PA;
-  PA.preserve<GlobalsAA>();
-  PA.preserve<MemoryDependenceAnalysis>();
-  return PA;
-}
-
-namespace {
-class MergedLoadStoreMotionLegacyPass : public FunctionPass {
-  AliasAnalysis *AA;
-  MemoryDependenceResults *MD;
-
-public:
-  static char ID; // Pass identification, replacement for typeid
-  MergedLoadStoreMotionLegacyPass() : FunctionPass(ID), MD(nullptr) {
-    initializeMergedLoadStoreMotionLegacyPassPass(
-        *PassRegistry::getPassRegistry());
-  }
-
-  bool runOnFunction(Function &F) override {
-    if (skipFunction(F))
-      return false;
-
-    AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
-    auto *MDWP = getAnalysisIfAvailable<MemoryDependenceWrapperPass>();
-    MD = MDWP ? &MDWP->getMemDep() : nullptr;
-    return runMergedLoadStoreMotion(F, AA, MD);
-  }
-
-private:
-  // This transformation requires dominator postdominator info
-  void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.setPreservesCFG();
-    AU.addRequired<AAResultsWrapperPass>();
-    AU.addPreserved<GlobalsAAWrapperPass>();
-    AU.addPreserved<MemoryDependenceWrapperPass>();
-  }
-};
-
-char MergedLoadStoreMotionLegacyPass::ID = 0;
-} // anonymous namespace
-
-///
-/// \brief createMergedLoadStoreMotionPass - The public interface to this file.
-///
-FunctionPass *llvm::createMergedLoadStoreMotionPass() {
-  return new MergedLoadStoreMotionLegacyPass();
-}
-
-INITIALIZE_PASS_BEGIN(MergedLoadStoreMotionLegacyPass, "mldst-motion",
-                      "MergedLoadStoreMotion", false, false)
-INITIALIZE_PASS_DEPENDENCY(MemoryDependenceWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
-INITIALIZE_PASS_END(MergedLoadStoreMotionLegacyPass, "mldst-motion",
-                    "MergedLoadStoreMotion", false, false)