[clang] [clang][CodeGen] Set `dead_on_return` on indirect pointer arguments (PR #148159)

[Antonio Frighetto via cfe-commits]

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@@ -2852,8 +2852,21 @@ void CodeGenModule::ConstructAttributeList(StringRef Name,
       if (AI.getInReg())
         Attrs.addAttribute(llvm::Attribute::InReg);
 
-      if (AI.getIndirectByVal())
+      // Depending on the ABI, this may be either a byval or a dead_on_return
+      // argument.
+      if (AI.getIndirectByVal()) {
         Attrs.addByValAttr(getTypes().ConvertTypeForMem(ParamType));
+      } else {
+        // Add dead_on_return when the object's lifetime ends in the callee.
+        // This includes trivially-destructible C++ objects, as well as objects
+        // whose destruction / clean-up is carried out within the callee (e.g.,
+        // Obj-C++ ARC-managed structs, MSVC callee-destroyed objects).
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antoniofrighetto wrote:

Oh, sure thing, thanks!

https://github.com/llvm/llvm-project/pull/148159