Revert r246244 and r246243

These two commits cause clang/llvm bootstrap to hang.

llvm-svn: 246279

3 files changed, 13 insertions, 117 deletions

diff --git a/llvm/lib/IR/Dominators.cpp b/llvm/lib/IR/Dominators.cpp
index d94e31d4875..775bd92f2ed 100644
--- a/llvm/lib/IR/Dominators.cpp
+++ b/llvm/lib/IR/Dominators.cpp
@@ -147,8 +147,7 @@ bool DominatorTree::dominates(const BasicBlockEdge &BBE,
   // Assert that we have a single edge. We could handle them by simply
   // returning false, but since isSingleEdge is linear on the number of
   // edges, the callers can normally handle them more efficiently.
-  assert(BBE.isSingleEdge() &&
-         "This function is not efficient in handling multiple edges");
+  assert(BBE.isSingleEdge());
 
   // If the BB the edge ends in doesn't dominate the use BB, then the
   // edge also doesn't.
@@ -198,8 +197,7 @@ bool DominatorTree::dominates(const BasicBlockEdge &BBE, const Use &U) const {
   // Assert that we have a single edge. We could handle them by simply
   // returning false, but since isSingleEdge is linear on the number of
   // edges, the callers can normally handle them more efficiently.
-  assert(BBE.isSingleEdge() &&
-         "This function is not efficient in handling multiple edges");
+  assert(BBE.isSingleEdge());
 
   Instruction *UserInst = cast<Instruction>(U.getUser());
   // A PHI in the end of the edge is dominated by it.
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 092cb69f17c..d898b1796b6 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -608,10 +608,6 @@ namespace {
     DenseMap<uint32_t, LeaderTableEntry> LeaderTable;
     BumpPtrAllocator TableAllocator;
 
-    // Block-local map of equivalent values to their leader, does not
-    // propagate to any successors. Entries added mid-block are applied
-    // to the remaining instructions in the block.
-    SmallMapVector<llvm::Value *, llvm::Constant *, 4> ReplaceWithConstMap;
     SmallVector<Instruction*, 8> InstrsToErase;
 
     typedef SmallVector<NonLocalDepResult, 64> LoadDepVect;
@@ -703,7 +699,6 @@ namespace {
     // Helper functions of redundant load elimination 
     bool processLoad(LoadInst *L);
     bool processNonLocalLoad(LoadInst *L);
-    bool processAssumeIntrinsic(IntrinsicInst *II);
     void AnalyzeLoadAvailability(LoadInst *LI, LoadDepVect &Deps, 
                                  AvailValInBlkVect &ValuesPerBlock,
                                  UnavailBlkVect &UnavailableBlocks);
@@ -724,9 +719,7 @@ namespace {
     void verifyRemoved(const Instruction *I) const;
     bool splitCriticalEdges();
     BasicBlock *splitCriticalEdges(BasicBlock *Pred, BasicBlock *Succ);
-    bool replaceOperandsWithConsts(Instruction *I) const;
-    bool propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root,
-                           bool DominatesByEdge);
+    bool propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root);
     bool processFoldableCondBr(BranchInst *BI);
     void addDeadBlock(BasicBlock *BB);
     void assignValNumForDeadCode();
@@ -1767,46 +1760,6 @@ bool GVN::processNonLocalLoad(LoadInst *LI) {
   return PerformLoadPRE(LI, ValuesPerBlock, UnavailableBlocks);
 }
 
-bool GVN::processAssumeIntrinsic(IntrinsicInst *IntrinsicI) {
-  assert(IntrinsicI->getIntrinsicID() == Intrinsic::assume &&
-         "This function can only be called with llvm.assume intrinsic");
-  Value *V = IntrinsicI->getArgOperand(0);
-  Constant *True = ConstantInt::getTrue(V->getContext());
-  bool Changed = false;
-  for (BasicBlock *Successor : successors(IntrinsicI->getParent())) {
-    BasicBlockEdge Edge(IntrinsicI->getParent(), Successor);
-
-    // This property is only true in dominated successors, propagateEquality
-    // will check dominance for us.
-    Changed |= propagateEquality(V, True, Edge, false);
-  }
-  // We can replace assume value with true, which covers cases like this:
-  // call void @llvm.assume(i1 %cmp)
-  // br i1 %cmp, label %bb1, label %bb2 ; will change %cmp to true
-  ReplaceWithConstMap[V] = True;
-
-  // If one of *cmp *eq operand is const, adding it to map will cover this:
-  // %cmp = fcmp oeq float 3.000000e+00, %0 ; const on lhs could happen
-  // call void @llvm.assume(i1 %cmp)
-  // ret float %0 ; will change it to ret float 3.000000e+00
-  if (auto *CmpI = dyn_cast<CmpInst>(V)) {
-    if (CmpI->getPredicate() == CmpInst::Predicate::ICMP_EQ ||
-        CmpI->getPredicate() == CmpInst::Predicate::FCMP_OEQ ||
-        (CmpI->getPredicate() == CmpInst::Predicate::FCMP_UEQ &&
-         CmpI->getFastMathFlags().noNaNs())) {
-      Value *CmpLHS = CmpI->getOperand(0);
-      Value *CmpRHS = CmpI->getOperand(1);
-      if (isa<Constant>(CmpLHS))
-        std::swap(CmpLHS, CmpRHS);
-      auto *RHSConst = dyn_cast<Constant>(CmpRHS);
-
-      // If only one operand is constant.
-      if (RHSConst != nullptr && !isa<Constant>(CmpLHS))
-        ReplaceWithConstMap[CmpLHS] = RHSConst;
-    }
-  }
-  return Changed;
-}
 
 static void patchReplacementInstruction(Instruction *I, Value *Repl) {
   // Patch the replacement so that it is not more restrictive than the value
@@ -2079,27 +2032,11 @@ static bool isOnlyReachableViaThisEdge(const BasicBlockEdge &E,
   return Pred != nullptr;
 }
 
-// Tries to replace instruction with const, using information from
-// ReplaceWithConstMap.
-bool GVN::replaceOperandsWithConsts(Instruction *Instr) const {
-  bool Changed = false;
-  for (unsigned OpNum = 0; OpNum < Instr->getNumOperands(); ++OpNum) {
-    Value *Operand = Instr->getOperand(OpNum);
-    auto it = ReplaceWithConstMap.find(Operand);
-    if (it != ReplaceWithConstMap.end()) {
-      Instr->setOperand(OpNum, it->second);
-      Changed = true;
-    }
-  }
-  return Changed;
-}
-
 /// The given values are known to be equal in every block
 /// dominated by 'Root'.  Exploit this, for example by replacing 'LHS' with
 /// 'RHS' everywhere in the scope.  Returns whether a change was made.
-/// If DominatesByEdge is false, then it means that it is dominated by Root.End.
-bool GVN::propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root,
-                            bool DominatesByEdge) {
+bool GVN::propagateEquality(Value *LHS, Value *RHS,
+                            const BasicBlockEdge &Root) {
   SmallVector<std::pair<Value*, Value*>, 4> Worklist;
   Worklist.push_back(std::make_pair(LHS, RHS));
   bool Changed = false;
@@ -2111,13 +2048,11 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root,
     std::pair<Value*, Value*> Item = Worklist.pop_back_val();
     LHS = Item.first; RHS = Item.second;
 
-    if (LHS == RHS)
-      continue;
+    if (LHS == RHS) continue;
     assert(LHS->getType() == RHS->getType() && "Equality but unequal types!");
 
     // Don't try to propagate equalities between constants.
-    if (isa<Constant>(LHS) && isa<Constant>(RHS))
-      continue;
+    if (isa<Constant>(LHS) && isa<Constant>(RHS)) continue;
 
     // Prefer a constant on the right-hand side, or an Argument if no constants.
     if (isa<Constant>(LHS) || (isa<Argument>(LHS) && !isa<Constant>(RHS)))
@@ -2156,11 +2091,7 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root,
     // LHS always has at least one use that is not dominated by Root, this will
     // never do anything if LHS has only one use.
     if (!LHS->hasOneUse()) {
-      unsigned NumReplacements =
-          DominatesByEdge
-              ? replaceDominatedUsesWith(LHS, RHS, *DT, Root)
-              : replaceDominatedUsesWith(LHS, RHS, *DT, Root.getEnd());
-
+      unsigned NumReplacements = replaceDominatedUsesWith(LHS, RHS, *DT, Root);
       Changed |= NumReplacements > 0;
       NumGVNEqProp += NumReplacements;
     }
@@ -2232,10 +2163,7 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root,
         Value *NotCmp = findLeader(Root.getEnd(), Num);
         if (NotCmp && isa<Instruction>(NotCmp)) {
           unsigned NumReplacements =
-              DominatesByEdge
-                  ? replaceDominatedUsesWith(NotCmp, NotVal, *DT, Root)
-                  : replaceDominatedUsesWith(NotCmp, NotVal, *DT,
-                                             Root.getEnd());
+            replaceDominatedUsesWith(NotCmp, NotVal, *DT, Root);
           Changed |= NumReplacements > 0;
           NumGVNEqProp += NumReplacements;
         }
@@ -2275,10 +2203,6 @@ bool GVN::processInstruction(Instruction *I) {
     return true;
   }
 
-  if (IntrinsicInst *IntrinsicI = dyn_cast<IntrinsicInst>(I))
-    if (IntrinsicI->getIntrinsicID() == Intrinsic::assume)
-      return processAssumeIntrinsic(IntrinsicI);
-
   if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
     if (processLoad(LI))
       return true;
@@ -2309,11 +2233,11 @@ bool GVN::processInstruction(Instruction *I) {
 
     Value *TrueVal = ConstantInt::getTrue(TrueSucc->getContext());
     BasicBlockEdge TrueE(Parent, TrueSucc);
-    Changed |= propagateEquality(BranchCond, TrueVal, TrueE, true);
+    Changed |= propagateEquality(BranchCond, TrueVal, TrueE);
 
     Value *FalseVal = ConstantInt::getFalse(FalseSucc->getContext());
     BasicBlockEdge FalseE(Parent, FalseSucc);
-    Changed |= propagateEquality(BranchCond, FalseVal, FalseE, true);
+    Changed |= propagateEquality(BranchCond, FalseVal, FalseE);
 
     return Changed;
   }
@@ -2335,7 +2259,7 @@ bool GVN::processInstruction(Instruction *I) {
       // If there is only a single edge, propagate the case value into it.
       if (SwitchEdges.lookup(Dst) == 1) {
         BasicBlockEdge E(Parent, Dst);
-        Changed |= propagateEquality(SwitchCond, i.getCaseValue(), E, true);
+        Changed |= propagateEquality(SwitchCond, i.getCaseValue(), E);
       }
     }
     return Changed;
@@ -2343,8 +2267,7 @@ bool GVN::processInstruction(Instruction *I) {
 
   // Instructions with void type don't return a value, so there's
   // no point in trying to find redundancies in them.
-  if (I->getType()->isVoidTy())
-    return false;
+  if (I->getType()->isVoidTy()) return false;
 
   uint32_t NextNum = VN.getNextUnusedValueNumber();
   unsigned Num = VN.lookup_or_add(I);
@@ -2451,15 +2374,10 @@ bool GVN::processBlock(BasicBlock *BB) {
   if (DeadBlocks.count(BB))
     return false;
 
-  // Clearing map before every BB because it can be used only for single BB.
-  ReplaceWithConstMap.clear();
   bool ChangedFunction = false;
 
   for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
        BI != BE;) {
-    if (!ReplaceWithConstMap.empty())
-      ChangedFunction |= replaceOperandsWithConsts(BI);
-
     ChangedFunction |= processInstruction(BI);
     if (InstrsToErase.empty()) {
       ++BI;
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 364651bda3c..8c29ed50b45 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1349,23 +1349,3 @@ unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
   }
   return Count;
 }
-
-unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
-                                        DominatorTree &DT,
-                                        const BasicBlock *BB) {
-  assert(From->getType() == To->getType());
-
-  unsigned Count = 0;
-  for (Value::use_iterator UI = From->use_begin(), UE = From->use_end();
-       UI != UE;) {
-    Use &U = *UI++;
-    auto *I = cast<Instruction>(U.getUser());
-    if (DT.dominates(BB, I->getParent())) {
-      U.set(To);
-      DEBUG(dbgs() << "Replace dominated use of '" << From->getName() << "' as "
-                   << *To << " in " << *U << "\n");
-      ++Count;
-    }
-  }
-  return Count;
-}