[llvm-branch-commits] [clang] [flang] [llvm] [Clang][OpenMP] Add permutation clause (PR #92030)

[Alexey Bataev via llvm-branch-commits]

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@@ -15980,7 +15985,44 @@ StmtResult SemaOpenMP::ActOnOpenMPInterchangeDirective(
          "affected loops");
 
   // Decode the permutation clause.
-  constexpr uint64_t Permutation[] = {1, 0};
+  SmallVector<uint64_t, 2> Permutation;
+  if (!PermutationClause) {
+    Permutation = {1, 0};
+  } else {
+    ArrayRef<Expr *> PermArgs = PermutationClause->getArgsRefs();
+    llvm::BitVector Flags(PermArgs.size());
+    for (Expr *PermArg : PermArgs) {
+      std::optional<llvm::APSInt> PermCstExpr =
+          PermArg->getIntegerConstantExpr(Context);
+      if (!PermCstExpr)
+        continue;
+      uint64_t PermInt = PermCstExpr->getZExtValue();
+      assert(1 <= PermInt && PermInt <= NumLoops &&
+             "Must be a permutation; diagnostic emitted in "
+             "ActOnOpenMPPermutationClause");
+      if (Flags[PermInt - 1]) {
+        SourceRange ExprRange(PermArg->getBeginLoc(), PermArg->getEndLoc());
+        Diag(PermArg->getExprLoc(),
+             diag::err_omp_interchange_permutation_value_repeated)
+            << PermInt << ExprRange;
+        continue;
+      }
+      Flags[PermInt - 1] = true;
+
+      Permutation.push_back(PermInt - 1);
+    }
+
+    if (Permutation.size() != NumLoops)
+      return StmtError();
+  }
+
+  // Nothing to transform with trivial permutation.
+  if (NumLoops <= 1 || llvm::all_of(llvm::enumerate(Permutation), [](auto p) {
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alexey-bataev wrote:

`auto P`

https://github.com/llvm/llvm-project/pull/92030