1 files changed, 38 insertions, 33 deletions

diff --git a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 5cd9a4b..61a8e5b 100644
--- a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -567,9 +567,20 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
                                LHSKnownZero, LHSKnownOne, Depth+1))
         return I;
     }
+
     // Otherwise just hand the sub off to ComputeMaskedBits to fill in
     // the known zeros and ones.
     ComputeMaskedBits(V, DemandedMask, KnownZero, KnownOne, Depth);
+
+    // Turn this into a xor if LHS is 2^n-1 and the remaining bits are known
+    // zero.
+    if (ConstantInt *C0 = dyn_cast<ConstantInt>(I->getOperand(0))) {
+      APInt I0 = C0->getValue();
+      if ((I0 + 1).isPowerOf2() && (I0 | KnownZero).isAllOnesValue()) {
+        Instruction *Xor = BinaryOperator::CreateXor(I->getOperand(1), C0);
+        return InsertNewInstWith(Xor, *I);
+      }
+    }
     break;
   case Instruction::Shl:
     if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
@@ -671,8 +682,9 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
       if (BitWidth <= ShiftAmt || KnownZero[BitWidth-ShiftAmt-1] || 
           (HighBits & ~DemandedMask) == HighBits) {
         // Perform the logical shift right.
-        Instruction *NewVal = BinaryOperator::CreateLShr(
-                          I->getOperand(0), SA, I->getName());
+        BinaryOperator *NewVal = BinaryOperator::CreateLShr(I->getOperand(0),
+                                                            SA, I->getName());
+        NewVal->setIsExact(cast<BinaryOperator>(I)->isExact());
         return InsertNewInstWith(NewVal, *I);
       } else if ((KnownOne & SignBit) != 0) { // New bits are known one.
         KnownOne |= HighBits;
@@ -822,46 +834,39 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
   }
 
   UndefElts = 0;
-  if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
+  
+  // Handle ConstantAggregateZero, ConstantVector, ConstantDataSequential.
+  if (Constant *C = dyn_cast<Constant>(V)) {
+    // Check if this is identity. If so, return 0 since we are not simplifying
+    // anything.
+    if (DemandedElts.isAllOnesValue())
+      return 0;
+
     Type *EltTy = cast<VectorType>(V->getType())->getElementType();
     Constant *Undef = UndefValue::get(EltTy);
-
-    std::vector<Constant*> Elts;
-    for (unsigned i = 0; i != VWidth; ++i)
+    
+    SmallVector<Constant*, 16> Elts;
+    for (unsigned i = 0; i != VWidth; ++i) {
       if (!DemandedElts[i]) {   // If not demanded, set to undef.
         Elts.push_back(Undef);
         UndefElts.setBit(i);
-      } else if (isa<UndefValue>(CV->getOperand(i))) {   // Already undef.
+        continue;
+      }
+      
+      Constant *Elt = C->getAggregateElement(i);
+      if (Elt == 0) return 0;
+      
+      if (isa<UndefValue>(Elt)) {   // Already undef.
         Elts.push_back(Undef);
         UndefElts.setBit(i);
       } else {                               // Otherwise, defined.
-        Elts.push_back(CV->getOperand(i));
+        Elts.push_back(Elt);
       }
-
-    // If we changed the constant, return it.
-    Constant *NewCP = ConstantVector::get(Elts);
-    return NewCP != CV ? NewCP : 0;
-  }
-  
-  if (isa<ConstantAggregateZero>(V)) {
-    // Simplify the CAZ to a ConstantVector where the non-demanded elements are
-    // set to undef.
-    
-    // Check if this is identity. If so, return 0 since we are not simplifying
-    // anything.
-    if (DemandedElts.isAllOnesValue())
-      return 0;
-    
-    Type *EltTy = cast<VectorType>(V->getType())->getElementType();
-    Constant *Zero = Constant::getNullValue(EltTy);
-    Constant *Undef = UndefValue::get(EltTy);
-    std::vector<Constant*> Elts;
-    for (unsigned i = 0; i != VWidth; ++i) {
-      Constant *Elt = DemandedElts[i] ? Zero : Undef;
-      Elts.push_back(Elt);
     }
-    UndefElts = DemandedElts ^ EltMask;
-    return ConstantVector::get(Elts);
+    
+    // If we changed the constant, return it.
+    Constant *NewCV = ConstantVector::get(Elts);
+    return NewCV != C ? NewCV : 0;
   }
   
   // Limit search depth.
@@ -977,7 +982,7 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
 
     if (NewUndefElts) {
       // Add additional discovered undefs.
-      std::vector<Constant*> Elts;
+      SmallVector<Constant*, 16> Elts;
       for (unsigned i = 0; i < VWidth; ++i) {
         if (UndefElts[i])
           Elts.push_back(UndefValue::get(Type::getInt32Ty(I->getContext())));