[llvm] [LoopInterchange] Add metadata to control loop-interchange (PR #127474)

[Michael Kruse via llvm-commits]

================
@@ -569,6 +609,152 @@ struct LoopInterchange {
 
     return true;
   }
+
+  bool processEnabledLoop(SmallVectorImpl<Loop *> &LoopList,
+                          std::vector<std::vector<char>> &DependencyMatrix,
+                          const DenseMap<const Loop *, unsigned> &CostMap) {
+    bool Changed = false;
+
+    // Manage the index so that LoopList[Loop2Index[L]] == L for each loop L.
+    DenseMap<Loop *, unsigned> Loop2Index;
+    for (unsigned I = 0; I != LoopList.size(); I++)
+      Loop2Index[LoopList[I]] = I;
+
+    // Hold outer loops to be exchanged (i.e., loops that have
+    // "llvm.loop.interchange.enable" is true), in the current nest order.
+    SmallVector<Loop *, 4> Worklist;
----------------
Meinersbur wrote:

That's fine, but also the less interesting case.

https://github.com/llvm/llvm-project/pull/127474