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

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

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@@ -508,6 +512,43 @@ OMPInterchangeDirective::CreateEmpty(const ASTContext &C, unsigned NumClauses,
       SourceLocation(), SourceLocation(), NumLoops);
 }
 
+OMPFuseDirective *OMPFuseDirective::Create(
+    const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
+    ArrayRef<OMPClause *> Clauses, unsigned NumLoops, unsigned NumLoopNests,
+    Stmt *AssociatedStmt, Stmt *TransformedStmt, Stmt *PreInits) {
+
+  OMPFuseDirective *Dir = createDirective<OMPFuseDirective>(
+      C, Clauses, AssociatedStmt, TransformedStmtOffset + 1, StartLoc, EndLoc,
+      NumLoops);
+  Dir->setTransformedStmt(TransformedStmt);
+  Dir->setPreInits(PreInits);
+  // The number of top level canonical nests could 
+  // not match the total number of generated loops
+  // Example:
+  // Before fusion:
+  //   for (int i = 0; i < N; ++i)   
+  //     for (int j = 0; j < M; ++j) 
+  //       A[i][j] = i + j;
+  //   
+  //   for (int k = 0; k < P; ++k) 
+  //     B[k] = k * 2;
+  // Here, NumLoopNests = 2, but NumLoops = 3.
----------------
eZWALT wrote:

Yes I guessed that probably this information would not be used... However i wanted to be consistent with other loop transformations and avoid changing the structure for loop nest only related transformations, so I did the visitor just for the sake of consistency. I know it might not be the best solution in terms of redundancy and extra lines of code, but i believe its more consistent with the rest of loop transformations. But again, you are 100% correct, the total number of loops does not really mater without the loop nest structure.

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