[flang-commits] [flang] [flang] Rely on global initialization for simpler derived types (PR #114002)

[via flang-commits]

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@@ -797,8 +798,59 @@ void Fortran::lower::defaultInitializeAtRuntime(
         })
         .end();
   } else {
-    mlir::Value box = builder.createBox(loc, exv);
-    fir::runtime::genDerivedTypeInitialize(builder, loc, box);
+    /// For "simpler" types, relying on "_FortranAInitialize"
+    /// leads to poor runtime performance. Hence optimize
+    /// the same.
+    const Fortran::semantics::DeclTypeSpec *declTy = sym.GetType();
+    mlir::Type symTy = converter.genType(var);
+    const auto *details =
+        sym.detailsIf<Fortran::semantics::ObjectEntityDetails>();
+    if (details && Fortran::lower::hasDefaultInitialization(sym) &&
+        declTy->category() ==
+            Fortran::semantics::DeclTypeSpec::Category::TypeDerived &&
+        !mlir::isa<fir::SequenceType>(symTy) &&
+        !sym.test(Fortran::semantics::Symbol::Flag::OmpPrivate) &&
+        !sym.test(Fortran::semantics::Symbol::Flag::OmpFirstPrivate)) {
+      std::string globalName = converter.mangleName(*declTy->AsDerived());
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jeanPerier wrote:

Using the derived makes sense to me, but some prefix/suffix would be nice (fir.TypeInfoOp ops already uses that has MLIR symbol name, better avoid conflicts here), as well as using the compiler generated name prefix (doGenerated()).

I would go for `fir::NameUniquer::doGenerated(mangledName + kNameSeparator + kDerivedTypeInitSuffix)`
where `kDerivedTypeInitSuffix` can be defined as `init` in [Optimizer/Support/InternalNames.h](https://github.com/llvm/llvm-project/blob/main/flang/include/flang/Optimizer/Support/InternalNames.h).



https://github.com/llvm/llvm-project/pull/114002