Package: llvm-toolchain-6.0 / 1:6.0.1-10

D42717-JumpThreading-backport-2.diff Patch series | download
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Index: llvm-toolchain-6.0-6.0.1/include/llvm/Analysis/LazyValueInfo.h
===================================================================
--- llvm-toolchain-6.0-6.0.1.orig/include/llvm/Analysis/LazyValueInfo.h
+++ llvm-toolchain-6.0-6.0.1/include/llvm/Analysis/LazyValueInfo.h
@@ -113,6 +113,13 @@ public:
   /// in LVI, so we need to pass it here as an argument.
   void printLVI(Function &F, DominatorTree &DTree, raw_ostream &OS);
 
+  /// Disables use of the DominatorTree within LVI.
+  void disableDT();
+
+  /// Enables use of the DominatorTree within LVI. Does nothing if the class
+  /// instance was initialized without a DT pointer.
+  void enableDT();
+
   // For old PM pass. Delete once LazyValueInfoWrapperPass is gone.
   void releaseMemory();
 
Index: llvm-toolchain-6.0-6.0.1/include/llvm/IR/Dominators.h
===================================================================
--- llvm-toolchain-6.0-6.0.1.orig/include/llvm/IR/Dominators.h
+++ llvm-toolchain-6.0-6.0.1/include/llvm/IR/Dominators.h
@@ -342,6 +342,9 @@ public:
   /// \brief Returns true if DelBB is awaiting deletion at a flush() event.
   bool pendingDeletedBB(BasicBlock *DelBB);
 
+  /// \brief Returns true if pending DT updates are queued for a flush() event.
+  bool pending();
+
   /// \brief Flushes all pending updates and block deletions. Returns a
   /// correct DominatorTree reference to be used by the caller for analysis.
   DominatorTree &flush();
Index: llvm-toolchain-6.0-6.0.1/lib/Analysis/LazyValueInfo.cpp
===================================================================
--- llvm-toolchain-6.0-6.0.1.orig/lib/Analysis/LazyValueInfo.cpp
+++ llvm-toolchain-6.0-6.0.1/lib/Analysis/LazyValueInfo.cpp
@@ -401,6 +401,7 @@ namespace {
     AssumptionCache *AC;  ///< A pointer to the cache of @llvm.assume calls.
     const DataLayout &DL; ///< A mandatory DataLayout
     DominatorTree *DT;    ///< An optional DT pointer.
+    DominatorTree *DisabledDT; ///< Stores DT if it's disabled.
 
   ValueLatticeElement getBlockValue(Value *Val, BasicBlock *BB);
   bool getEdgeValue(Value *V, BasicBlock *F, BasicBlock *T,
@@ -463,13 +464,30 @@ namespace {
       TheCache.eraseBlock(BB);
     }
 
+    /// Disables use of the DominatorTree within LVI.
+    void disableDT() {
+      if (DT) {
+        assert(!DisabledDT && "Both DT and DisabledDT are not nullptr!");
+        std::swap(DT, DisabledDT);
+      }
+    }
+
+    /// Enables use of the DominatorTree within LVI. Does nothing if the class
+    /// instance was initialized without a DT pointer.
+    void enableDT() {
+      if (DisabledDT) {
+        assert(!DT && "Both DT and DisabledDT are not nullptr!");
+        std::swap(DT, DisabledDT);
+      }
+    }
+
     /// This is the update interface to inform the cache that an edge from
     /// PredBB to OldSucc has been threaded to be from PredBB to NewSucc.
     void threadEdge(BasicBlock *PredBB,BasicBlock *OldSucc,BasicBlock *NewSucc);
 
     LazyValueInfoImpl(AssumptionCache *AC, const DataLayout &DL,
                        DominatorTree *DT = nullptr)
-        : AC(AC), DL(DL), DT(DT) {}
+        : AC(AC), DL(DL), DT(DT), DisabledDT(nullptr) {}
   };
 } // end anonymous namespace
 
@@ -1791,6 +1809,16 @@ void LazyValueInfo::printLVI(Function &F
   }
 }
 
+void LazyValueInfo::disableDT() {
+  if (PImpl)
+    getImpl(PImpl, AC, DL, DT).disableDT();
+}
+
+void LazyValueInfo::enableDT() {
+  if (PImpl)
+    getImpl(PImpl, AC, DL, DT).enableDT();
+}
+
 // Print the LVI for the function arguments at the start of each basic block.
 void LazyValueInfoAnnotatedWriter::emitBasicBlockStartAnnot(
     const BasicBlock *BB, formatted_raw_ostream &OS) {
Index: llvm-toolchain-6.0-6.0.1/lib/IR/Dominators.cpp
===================================================================
--- llvm-toolchain-6.0-6.0.1.orig/lib/IR/Dominators.cpp
+++ llvm-toolchain-6.0-6.0.1/lib/IR/Dominators.cpp
@@ -453,6 +453,9 @@ bool DeferredDominance::pendingDeletedBB
   return DeletedBBs.count(DelBB) != 0;
 }
 
+/// \brief Returns true if pending DT updates are queued for a flush() event.
+bool DeferredDominance::pending() { return !PendUpdates.empty(); }
+
 /// \brief Flushes all pending updates and block deletions. Returns a
 /// correct DominatorTree reference to be used by the caller for analysis.
 DominatorTree &DeferredDominance::flush() {
Index: llvm-toolchain-6.0-6.0.1/lib/Transforms/Scalar/JumpThreading.cpp
===================================================================
--- llvm-toolchain-6.0-6.0.1.orig/lib/Transforms/Scalar/JumpThreading.cpp
+++ llvm-toolchain-6.0-6.0.1/lib/Transforms/Scalar/JumpThreading.cpp
@@ -425,6 +425,7 @@ bool JumpThreadingPass::runImpl(Function
 
   LoopHeaders.clear();
   DDT->flush();
+  LVI->enableDT();
   return EverChanged;
 }
 
@@ -617,6 +618,10 @@ bool JumpThreadingPass::ComputeValueKnow
     // "X < 4" and "X < 3" is known true but "X < 4" itself is not available.
     // Perhaps getConstantOnEdge should be smart enough to do this?
 
+    if (DDT->pending())
+      LVI->disableDT();
+    else
+      LVI->enableDT();
     for (BasicBlock *P : predecessors(BB)) {
       // If the value is known by LazyValueInfo to be a constant in a
       // predecessor, use that information to try to thread this block.
@@ -630,6 +635,10 @@ bool JumpThreadingPass::ComputeValueKnow
 
   /// If I is a PHI node, then we know the incoming values for any constants.
   if (PHINode *PN = dyn_cast<PHINode>(I)) {
+    if (DDT->pending())
+      LVI->disableDT();
+    else
+      LVI->enableDT();
     for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
       Value *InVal = PN->getIncomingValue(i);
       if (Constant *KC = getKnownConstant(InVal, Preference)) {
@@ -759,6 +768,10 @@ bool JumpThreadingPass::ComputeValueKnow
       const DataLayout &DL = PN->getModule()->getDataLayout();
       // We can do this simplification if any comparisons fold to true or false.
       // See if any do.
+      if (DDT->pending())
+        LVI->disableDT();
+      else
+        LVI->enableDT();
       for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
         BasicBlock *PredBB = PN->getIncomingBlock(i);
         Value *LHS = PN->getIncomingValue(i);
@@ -792,6 +805,10 @@ bool JumpThreadingPass::ComputeValueKnow
 
       if (!isa<Instruction>(CmpLHS) ||
           cast<Instruction>(CmpLHS)->getParent() != BB) {
+        if (DDT->pending())
+          LVI->disableDT();
+        else
+          LVI->enableDT();
         for (BasicBlock *P : predecessors(BB)) {
           // If the value is known by LazyValueInfo to be a constant in a
           // predecessor, use that information to try to thread this block.
@@ -820,6 +837,10 @@ bool JumpThreadingPass::ComputeValueKnow
             match(CmpLHS, m_Add(m_Value(AddLHS), m_ConstantInt(AddConst)))) {
           if (!isa<Instruction>(AddLHS) ||
               cast<Instruction>(AddLHS)->getParent() != BB) {
+            if (DDT->pending())
+              LVI->disableDT();
+            else
+              LVI->enableDT();
             for (BasicBlock *P : predecessors(BB)) {
               // If the value is known by LazyValueInfo to be a ConstantRange in
               // a predecessor, use that information to try to thread this
@@ -901,6 +922,10 @@ bool JumpThreadingPass::ComputeValueKnow
   }
 
   // If all else fails, see if LVI can figure out a constant value for us.
+  if (DDT->pending())
+    LVI->disableDT();
+  else
+    LVI->enableDT();
   Constant *CI = LVI->getConstant(V, BB, CxtI);
   if (Constant *KC = getKnownConstant(CI, Preference)) {
     for (BasicBlock *Pred : predecessors(BB))
@@ -1102,6 +1127,10 @@ bool JumpThreadingPass::ProcessBlock(Bas
       // threading is concerned.
       assert(CondBr->isConditional() && "Threading on unconditional terminator");
 
+      if (DDT->pending())
+        LVI->disableDT();
+      else
+        LVI->enableDT();
       LazyValueInfo::Tristate Ret =
         LVI->getPredicateAt(CondCmp->getPredicate(), CondCmp->getOperand(0),
                             CondConst, CondBr);
@@ -1914,6 +1943,10 @@ bool JumpThreadingPass::ThreadEdge(Basic
         << ", across block:\n    "
         << *BB << "\n");
 
+  if (DDT->pending())
+    LVI->disableDT();
+  else
+    LVI->enableDT();
   LVI->threadEdge(PredBB, BB, SuccBB);
 
   // We are going to have to map operands from the original BB block to the new
@@ -2383,6 +2416,10 @@ bool JumpThreadingPass::TryToUnfoldSelec
     // Now check if one of the select values would allow us to constant fold the
     // terminator in BB. We don't do the transform if both sides fold, those
     // cases will be threaded in any case.
+    if (DDT->pending())
+      LVI->disableDT();
+    else
+      LVI->enableDT();
     LazyValueInfo::Tristate LHSFolds =
         LVI->getPredicateOnEdge(CondCmp->getPredicate(), SI->getOperand(1),
                                 CondRHS, Pred, BB, CondCmp);
Index: llvm-toolchain-6.0-6.0.1/test/Transforms/JumpThreading/pr36133.ll
===================================================================
--- /dev/null
+++ llvm-toolchain-6.0-6.0.1/test/Transforms/JumpThreading/pr36133.ll
@@ -0,0 +1,44 @@
+; RUN: opt -jump-threading -S < %s | FileCheck %s
+@global = external global i8*, align 8
+
+define i32 @foo(i32 %arg) {
+; CHECK-LABEL: @foo
+; CHECK-LABEL: bb:
+; CHECK: icmp eq
+; CHECK-NEXT: br i1 %tmp1, label %bb7, label %bb7
+bb:
+  %tmp = load i8*, i8** @global, align 8
+  %tmp1 = icmp eq i8* %tmp, null
+  br i1 %tmp1, label %bb3, label %bb2
+
+; CHECK-NOT: bb2:
+bb2:
+  br label %bb3
+
+; CHECK-NOT: bb3:
+bb3:
+  %tmp4 = phi i8 [ 1, %bb2 ], [ 0, %bb ]
+  %tmp5 = icmp eq i8 %tmp4, 0
+  br i1 %tmp5, label %bb7, label %bb6
+
+; CHECK-NOT: bb6:
+bb6:
+  br label %bb7
+
+; CHECK-LABEL: bb7:
+bb7:
+  %tmp8 = icmp eq i32 %arg, -1
+  br i1 %tmp8, label %bb9, label %bb10
+
+; CHECK-LABEL: bb9:
+bb9:
+  ret i32 0
+
+; CHECK-LABEL: bb10:
+bb10:
+  %tmp11 = icmp sgt i32 %arg, -1
+  call void @llvm.assume(i1 %tmp11)
+  ret i32 1
+}
+
+declare void @llvm.assume(i1)