Prevent LoopVectorizer and SLPVectorizer running if the target has no vector registers.

XCore target: Add XCoreTargetTransformInfo
This is where getNumberOfRegisters() resides, which in turn returns the
number of vector registers (=0).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190936 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -1572,6 +1572,11 @@ struct SLPVectorizer : public FunctionPass {
     StoreRefs.clear();
     bool Changed = false;
 
+    // If the target claims to have no vector registers don't attempt
+    // vectorization.
+    if (!TTI->getNumberOfRegisters(true))
+      return false;
+
     // Must have DataLayout. We can't require it because some tests run w/o
     // triple.
     if (!DL)