[flang-commits] [flang] [flang] Add debug information for module variables. (PR #91582)

[Kiran Chandramohan via flang-commits]

================
@@ -99,6 +109,68 @@ void AddDebugInfoPass::handleDeclareOp(fir::cg::XDeclareOp declOp,
   declOp->setLoc(builder.getFusedLoc({declOp->getLoc()}, localVarAttr));
 }
 
+// The `module` does not have a first class representation in the `FIR`. We
+// extract information about it from the name of the identifiers and keep a
+// map to avoid duplication.
+mlir::LLVM::DIModuleAttr AddDebugInfoPass::getOrCreateModuleAttr(
+    const std::string &name, mlir::LLVM::DIFileAttr fileAttr,
+    mlir::LLVM::DIScopeAttr scope, unsigned line, bool decl) {
+  mlir::MLIRContext *context = &getContext();
+  mlir::LLVM::DIModuleAttr modAttr;
+  if (auto iter{moduleMap.find(name)}; iter != moduleMap.end())
+    modAttr = iter->getValue();
+  else {
+    modAttr = mlir::LLVM::DIModuleAttr::get(
+        context, fileAttr, scope, mlir::StringAttr::get(context, name),
+        mlir::StringAttr(), mlir::StringAttr(), mlir::StringAttr(), line, decl);
+    moduleMap[name] = modAttr;
+  }
+  return modAttr;
+}
+
+void AddDebugInfoPass::handleGlobalOp(fir::GlobalOp globalOp,
+                                      mlir::LLVM::DIFileAttr fileAttr,
+                                      mlir::LLVM::DIScopeAttr scope) {
+  mlir::ModuleOp module = getOperation();
+  mlir::MLIRContext *context = &getContext();
+  fir::DebugTypeGenerator typeGen(module);
+  mlir::OpBuilder builder(context);
+
+  auto result = fir::NameUniquer::deconstruct(globalOp.getSymName());
+  if (result.first != fir::NameUniquer::NameKind::VARIABLE)
+    return;
+
+  unsigned line = getLineFromLoc(globalOp.getLoc());
+
+  // DWARF5 says following about the fortran modules:
+  // A Fortran 90 module may also be represented by a module entry
+  // (but no declaration attribute is warranted because Fortran has no concept
+  // of a corresponding module body).
+  // But in practice, compilers use declaration attribute with a module in cases
+  // where module was defined in another source file (only being used in this
+  // one). The isInitialized() seems to provide the right information
+  // but inverted. It is true where module is actually defined but false where
+  // it is used.
+  // FIXME: Currently we don't have the line number on which a module was
+  // declared. We are using a best guess of line - 1 where line is the source
+  // line of the first member of the module that we encounter.
+
+  if (result.second.modules.empty())
+    return;
+
+  scope = getOrCreateModuleAttr(result.second.modules[0], fileAttr, scope,
+                                line - 1, !globalOp.isInitialized());
+
+  auto diType = typeGen.convertType(globalOp.getType(), fileAttr, scope,
----------------
kiranchandramohan wrote:

Nit: Spell the type.

https://github.com/llvm/llvm-project/pull/91582