[clang] [flang] [llvm] add -floop-fuse to clang and flang (PR #142686)

[Tarun Prabhu via llvm-commits]

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@@ -65,6 +65,9 @@ class PipelineTuningOptions {
   /// false.
   bool LoopInterchange;
 
+  /// Tuning option to enable/disable loop fuse. Its default value is false.
+  bool LoopFuse;
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tarunprabhu wrote:

NIT:
```suggestion
  bool LoopFusion;
```

https://github.com/llvm/llvm-project/pull/142686