[PATCH] D18898: [Loop Rotation] Make default max rotation header size threshold dependent on target CPU

[Z. Zheng via llvm-commits]

zzheng added a subscriber: zzheng.
zzheng added a comment.

Minor suggestion to use Optional<unsigned>.


================
Comment at: lib/Transforms/Scalar/LoopRotation.cpp:569
@@ +568,3 @@
+                                    const TargetTransformInfo *TTI) {
+  if (SpecifiedThreshold == -1)
+    return RotationThreshold.getNumOccurrences() > 0
----------------
```
if (SpecifiedThreshold.hasValue())
  return *SpecifiedThreshold;
else {
...
}
```

================
Comment at: lib/Transforms/Scalar/LoopRotation.cpp:584
@@ -571,2 +583,3 @@
   static char ID; // Pass ID, replacement for typeid
-  LoopRotate(int SpecifiedMaxHeaderSize = -1) : LoopPass(ID) {
+  LoopRotate(int SpecifiedMaxHeaderSize = -1)
+      : LoopPass(ID), SpecifiedThreshold(SpecifiedMaxHeaderSize) {
----------------
Can we take this opportunity to change it to

```
Optional<unsigned> SpecifiedMaxHeaderSize
```


http://reviews.llvm.org/D18898