[llvm] [LV]Fix max safe elements calculations (PR #122148)

[Alexey Bataev via llvm-commits]

================
@@ -3943,11 +3943,13 @@ FixedScalableVFPair LoopVectorizationCostModel::computeFeasibleMaxVF(
   // It is computed by MaxVF * sizeOf(type) * 8, where type is taken from
   // the memory accesses that is most restrictive (involved in the smallest
   // dependence distance).
-  unsigned MaxSafeElements =
-      llvm::bit_floor(Legal->getMaxSafeVectorWidthInBits() / WidestType);
+  unsigned MaxSafeElements = Legal->getMaxSafeVectorWidthInBits() / WidestType;
+  if (Legal->isSafeForAnyVectorWidth())
+    MaxSafeElements = bit_ceil(MaxSafeElements);
+  unsigned MaxSafeElementsPowerOf2 = 1ULL << countr_zero(MaxSafeElements);
----------------
alexey-bataev wrote:

Sure

https://github.com/llvm/llvm-project/pull/122148