Remove the constraint for reductions

Author: Mel-Chen

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -1534,9 +1534,7 @@ class LoopVectorizationCostModel {
         TTI.hasActiveVectorLength(0, nullptr, Align()) &&
         !EnableVPlanNativePath &&
         // FIXME: implement support for max safe dependency distance.
-        Legal->isSafeForAnyVectorWidth() &&
-        // FIXME: remove this once reductions are supported.
-        Legal->getReductionVars().empty();
+        Legal->isSafeForAnyVectorWidth();
     if (!EVLIsLegal) {
       // If for some reason EVL mode is unsupported, fallback to
       // DataWithoutLaneMask to try to vectorize the loop with folded tail