do not try to analyze bitcasts from i64 to <2 x i32> in ComputedMaskedBits.  While
we could do this, doing so requires adjusting the demanded mask and the code isn't 
doing that yet.  This fixes PR4495


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74699 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 7509e91..07a18fe 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -249,7 +249,10 @@
   }
   case Instruction::BitCast: {
     const Type *SrcTy = I->getOperand(0)->getType();
-    if (SrcTy->isInteger() || isa<PointerType>(SrcTy)) {
+    if ((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
+        // TODO: For now, not handling conversions like:
+        // (bitcast i64 %x to <2 x i32>)
+        !isa<VectorType>(I->getType())) {
       ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, TD,
                         Depth+1);
       return;