[LoopUnroll] Set correct thresholds for new recently enabled unrolling heuristic.

In r270478, where I enabled the new heuristic I posted testing results,
which I got when explicitly passed the thresholds values via CL options.
However, setting the CL options init-values is not enough to change the
default values of thresholds, so I'm changing them in another place now.

llvm-svn: 271615
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 95fd355..ddc1c60 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -114,8 +114,8 @@
 
   // Set up the defaults
   UP.Threshold = 150;
-  UP.PercentDynamicCostSavedThreshold = 20;
-  UP.DynamicCostSavingsDiscount = 2000;
+  UP.PercentDynamicCostSavedThreshold = 50;
+  UP.DynamicCostSavingsDiscount = 100;
   UP.OptSizeThreshold = 0;
   UP.PartialThreshold = UP.Threshold;
   UP.PartialOptSizeThreshold = 0;