Upgrade our copy of clang and llvm to 3.5.1 release. This is a bugfix

only release, no new features have been added.

Please note that this version requires C++11 support to build; see
UPDATING for more information.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.5.1/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.5.1/tools/clang/docs/ReleaseNotes.html>

MFC after:	1 month
X-MFC-With:	276479

3 files changed, 66 insertions, 36 deletions

diff --git a/contrib/llvm/lib/Analysis/AliasSetTracker.cpp b/contrib/llvm/lib/Analysis/AliasSetTracker.cpp
index a45fe23..75b6be0 100644
--- a/contrib/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/contrib/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -55,10 +55,13 @@ void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
       AliasTy = MayAlias;
   }
 
+  bool ASHadUnknownInsts = !AS.UnknownInsts.empty();
   if (UnknownInsts.empty()) {            // Merge call sites...
-    if (!AS.UnknownInsts.empty())
+    if (ASHadUnknownInsts) {
       std::swap(UnknownInsts, AS.UnknownInsts);
-  } else if (!AS.UnknownInsts.empty()) {
+      addRef();
+    }
+  } else if (ASHadUnknownInsts) {
     UnknownInsts.insert(UnknownInsts.end(), AS.UnknownInsts.begin(), AS.UnknownInsts.end());
     AS.UnknownInsts.clear();
   }
@@ -76,6 +79,8 @@ void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
     AS.PtrListEnd = &AS.PtrList;
     assert(*AS.PtrListEnd == nullptr && "End of list is not null?");
   }
+  if (ASHadUnknownInsts)
+    AS.dropRef(AST);
 }
 
 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
@@ -123,6 +128,8 @@ void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
 }
 
 void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
+  if (UnknownInsts.empty())
+    addRef();
   UnknownInsts.push_back(I);
 
   if (!I->mayWriteToMemory()) {
@@ -218,13 +225,14 @@ AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
                                                   uint64_t Size,
                                                   const MDNode *TBAAInfo) {
   AliasSet *FoundSet = nullptr;
-  for (iterator I = begin(), E = end(); I != E; ++I) {
-    if (I->Forward || !I->aliasesPointer(Ptr, Size, TBAAInfo, AA)) continue;
+  for (iterator I = begin(), E = end(); I != E;) {
+    iterator Cur = I++;
+    if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, TBAAInfo, AA)) continue;
     
     if (!FoundSet) {      // If this is the first alias set ptr can go into.
-      FoundSet = I;       // Remember it.
+      FoundSet = Cur;     // Remember it.
     } else {              // Otherwise, we must merge the sets.
-      FoundSet->mergeSetIn(*I, *this);     // Merge in contents.
+      FoundSet->mergeSetIn(*Cur, *this);     // Merge in contents.
     }
   }
 
@@ -246,14 +254,14 @@ bool AliasSetTracker::containsPointer(Value *Ptr, uint64_t Size,
 
 AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
   AliasSet *FoundSet = nullptr;
-  for (iterator I = begin(), E = end(); I != E; ++I) {
-    if (I->Forward || !I->aliasesUnknownInst(Inst, AA))
+  for (iterator I = begin(), E = end(); I != E;) {
+    iterator Cur = I++;
+    if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
       continue;
-    
     if (!FoundSet)            // If this is the first alias set ptr can go into.
-      FoundSet = I;           // Remember it.
-    else if (!I->Forward)     // Otherwise, we must merge the sets.
-      FoundSet->mergeSetIn(*I, *this);     // Merge in contents.
+      FoundSet = Cur;         // Remember it.
+    else if (!Cur->Forward)   // Otherwise, we must merge the sets.
+      FoundSet->mergeSetIn(*Cur, *this);     // Merge in contents.
   }
   return FoundSet;
 }
@@ -393,6 +401,8 @@ void AliasSetTracker::add(const AliasSetTracker &AST) {
 /// tracker.
 void AliasSetTracker::remove(AliasSet &AS) {
   // Drop all call sites.
+  if (!AS.UnknownInsts.empty())
+    AS.dropRef(*this);
   AS.UnknownInsts.clear();
   
   // Clear the alias set.
@@ -489,10 +499,10 @@ void AliasSetTracker::deleteValue(Value *PtrVal) {
   if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
     if (Inst->mayReadOrWriteMemory()) {
       // Scan all the alias sets to see if this call site is contained.
-      for (iterator I = begin(), E = end(); I != E; ++I) {
-        if (I->Forward) continue;
-        
-        I->removeUnknownInst(Inst);
+      for (iterator I = begin(), E = end(); I != E;) {
+        iterator Cur = I++;
+        if (!Cur->Forward)
+          Cur->removeUnknownInst(*this, Inst);
       }
     }
   }
diff --git a/contrib/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp b/contrib/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp
index 3203c37..723332d 100644
--- a/contrib/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp
+++ b/contrib/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp
@@ -14,7 +14,7 @@
 #include "llvm/Analysis/BlockFrequencyInfoImpl.h"
 #include "llvm/ADT/SCCIterator.h"
 #include "llvm/Support/raw_ostream.h"
-#include <deque>
+#include <numeric>
 
 using namespace llvm;
 using namespace llvm::bfi_detail;
@@ -123,8 +123,12 @@ static void combineWeight(Weight &W, const Weight &OtherW) {
   }
   assert(W.Type == OtherW.Type);
   assert(W.TargetNode == OtherW.TargetNode);
-  assert(W.Amount < W.Amount + OtherW.Amount && "Unexpected overflow");
-  W.Amount += OtherW.Amount;
+  assert(OtherW.Amount && "Expected non-zero weight");
+  if (W.Amount > W.Amount + OtherW.Amount)
+    // Saturate on overflow.
+    W.Amount = UINT64_MAX;
+  else
+    W.Amount += OtherW.Amount;
 }
 static void combineWeightsBySorting(WeightList &Weights) {
   // Sort so edges to the same node are adjacent.
@@ -207,11 +211,19 @@ void Distribution::normalize() {
     Shift = 33 - countLeadingZeros(Total);
 
   // Early exit if nothing needs to be scaled.
-  if (!Shift)
+  if (!Shift) {
+    // If we didn't overflow then combineWeights() shouldn't have changed the
+    // sum of the weights, but let's double-check.
+    assert(Total == std::accumulate(Weights.begin(), Weights.end(), UINT64_C(0),
+                                    [](uint64_t Sum, const Weight &W) {
+                      return Sum + W.Amount;
+                    }) &&
+           "Expected total to be correct");
     return;
+  }
 
   // Recompute the total through accumulation (rather than shifting it) so that
-  // it's accurate after shifting.
+  // it's accurate after shifting and any changes combineWeights() made above.
   Total = 0;
 
   // Sum the weights to each node and shift right if necessary.
diff --git a/contrib/llvm/lib/Analysis/ValueTracking.cpp b/contrib/llvm/lib/Analysis/ValueTracking.cpp
index e6d09f4..b6a3c36 100644
--- a/contrib/llvm/lib/Analysis/ValueTracking.cpp
+++ b/contrib/llvm/lib/Analysis/ValueTracking.cpp
@@ -1987,23 +1987,31 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V,
   default:
     return true;
   case Instruction::UDiv:
-  case Instruction::URem:
-    // x / y is undefined if y == 0, but calculations like x / 3 are safe.
-    return isKnownNonZero(Inst->getOperand(1), TD);
+  case Instruction::URem: {
+    // x / y is undefined if y == 0.
+    const APInt *V;
+    if (match(Inst->getOperand(1), m_APInt(V)))
+      return *V != 0;
+    return false;
+  }
   case Instruction::SDiv:
   case Instruction::SRem: {
-    Value *Op = Inst->getOperand(1);
-    // x / y is undefined if y == 0
-    if (!isKnownNonZero(Op, TD))
-      return false;
-    // x / y might be undefined if y == -1
-    unsigned BitWidth = getBitWidth(Op->getType(), TD);
-    if (BitWidth == 0)
-      return false;
-    APInt KnownZero(BitWidth, 0);
-    APInt KnownOne(BitWidth, 0);
-    computeKnownBits(Op, KnownZero, KnownOne, TD);
-    return !!KnownZero;
+    // x / y is undefined if y == 0 or x == INT_MIN and y == -1
+    const APInt *X, *Y;
+    if (match(Inst->getOperand(1), m_APInt(Y))) {
+      if (*Y != 0) {
+        if (*Y == -1) {
+          // The numerator can't be MinSignedValue if the denominator is -1.
+          if (match(Inst->getOperand(0), m_APInt(X)))
+            return !Y->isMinSignedValue();
+          // The numerator *might* be MinSignedValue.
+          return false;
+        }
+        // The denominator is not 0 or -1, it's safe to proceed.
+        return true;
+      }
+    }
+    return false;
   }
   case Instruction::Load: {
     const LoadInst *LI = cast<LoadInst>(Inst);