[clang] [openmp] [Clang][OpenMP] Fix tile/unroll on iterator- and foreach-loops. (PR #91459)

[Alexey Bataev via cfe-commits]

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@@ -15097,14 +15125,75 @@ bool SemaOpenMP::checkTransformableLoopNest(
           llvm_unreachable("Unhandled loop transformation");
         if (!DependentPreInits)
           return;
-        llvm::append_range(OriginalInits.back(),
-                           cast<DeclStmt>(DependentPreInits)->getDeclGroup());
+        // CompoundStmts are used as lists of other statements, add their
+        // contents, not the lists themselves to avoid nesting. This is
+        // necessary because DeclStmts need to be visible after the pre-init.
+        else if (auto *CS = dyn_cast<CompoundStmt>(DependentPreInits))
+          llvm::append_range(OriginalInits.back(), CS->body());
+        else
+          OriginalInits.back().push_back(DependentPreInits);
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alexey-bataev wrote:

Suggest moving this pattern to a function to avoid copying it.

https://github.com/llvm/llvm-project/pull/91459