[ValueTracking, InstSimplify] extend isKnownNonZero() to handle vector constants
Similar in spirit to D20497 :
If all elements of a constant vector are known non-zero, then we can say that the
whole vector is known non-zero.
It seems like we could extend this to FP scalar/vector too, but isKnownNonZero()
says it only works for integers and pointers for now.
Differential Revision: http://reviews.llvm.org/D20544
llvm-svn: 270562
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index d4602dd..8a0695c 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1678,7 +1678,20 @@
if (isa<ConstantInt>(C))
// Must be non-zero due to null test above.
return true;
- // TODO: Handle vectors
+
+ // For constant vectors, check that all elements are undefined or known
+ // non-zero to determine that the whole vector is known non-zero.
+ if (auto *VecTy = dyn_cast<VectorType>(C->getType())) {
+ for (unsigned i = 0, e = VecTy->getNumElements(); i != e; ++i) {
+ Constant *Elt = C->getAggregateElement(i);
+ if (!Elt || Elt->isNullValue())
+ return false;
+ if (!isa<UndefValue>(Elt) && !isa<ConstantInt>(Elt))
+ return false;
+ }
+ return true;
+ }
+
return false;
}