[flang-commits] [flang] [Flang] Fix symbol name clash when dummy procedure name is the same as common-block-name (PR #155508)

[Slava Zakharin via flang-commits]

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@@ -82,6 +82,46 @@ void ExternalNameConversionPass::runOnOperation() {
         mlir::SymbolTable::getSymbolAttrName());
     auto deconstructedName = fir::NameUniquer::deconstruct(symName);
     if (fir::NameUniquer::isExternalFacingUniquedName(deconstructedName)) {
+      // Check if this is a private function that would conflict with a common
+      // block and get its mangled name.
+      if (auto funcOp = llvm::dyn_cast<mlir::func::FuncOp>(funcOrGlobal)) {
+        if (funcOp.isPrivate()) {
+          std::string mangledName =
+              mangleExternalName(deconstructedName, appendUnderscoreOpt);
+          auto mod = funcOp->getParentOfType<mlir::ModuleOp>();
+          bool hasConflictingCommonBlock = false;
+
+          // Check if any existing global has the same mangled name.
+          mlir::SymbolTable symbolTable(mod);
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vzakhari wrote:

Please note that the the initial construction of the symbol table for an operation is the expensive operation.  The lookups/insertions happening after the initial construction are cheaper.

I would suggest creating the symbol table once at the beginning of the pass, and then update it and use it for lookups for each `funcOrGlobal`.

https://github.com/llvm/llvm-project/pull/155508