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/LoopVectorize.cpp

@@ -909,6 +909,11 @@ struct LoopVectorize : public LoopPass {
     DT = &getAnalysis<DominatorTree>();
     TLI = getAnalysisIfAvailable<TargetLibraryInfo>();
 
+    // If the target claims to have no vector registers don't attempt
+    // vectorization.
+    if (!TTI->getNumberOfRegisters(true))
+      return false;
+
     if (DL == NULL) {
       DEBUG(dbgs() << "LV: Not vectorizing because of missing data layout");
       return false;