[clang] [flang] [flang] add -floop-interchange and enable it with opt levels (PR #140182)

[Sebastian Pop via cfe-commits]

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@@ -421,7 +421,8 @@ static void CheckSubscripts(
 
 static void CheckSubscripts(
     semantics::SemanticsContext &context, CoarrayRef &ref) {
-  const Symbol &coarraySymbol{ref.GetBase().GetLastSymbol()};
+  const auto &base = ref.GetBase();
+  const Symbol &coarraySymbol{base.GetLastSymbol()};
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sebpop wrote:

This has been submitted separately https://github.com/llvm/llvm-project/pull/138793

Without this change I cannot build flang on arm64-linux ubuntu 24.04 machine. 

https://github.com/llvm/llvm-project/pull/140182