[clang] [flang] [llvm] [openmp] [Clang][OpenMP][LoopTransformations] Add support for "#pragma omp fuse" loop transformation direcrive and "looprange" clause (PR #139293)

[Walter J.T.V via llvm-commits]

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@@ -962,6 +962,9 @@ class OMPLoopTransformationDirective : public OMPLoopBasedDirective {
 
   /// Number of loops generated by this loop transformation.
   unsigned NumGeneratedLoops = 0;
+  /// Number of top level canonical loop nests generated by this loop
+  /// transformation
+  unsigned NumGeneratedLoopNests = 0;
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eZWALT wrote:

Maybe the name is a bit unfortunate and could be improved, but they are 2 completely different fields conceptually. This top level loops are the ones actually managed by loop Sequence constructs like fuse and the upcoming split. A loop sequence contains loops which may contain several inner nestes loops, but these should not be taken into account for performing fusion or splitting.  This was not taken into account originally due to all transformations having a fixed number of generated top level nests (1). However fuse or split may generate several loop nests with inner nested loops.

https://github.com/llvm/llvm-project/pull/139293