From ebef9d7f6387fb0541a0dab48d1cd1f86556df04 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov@redhat.com>
Date: Fri, 8 Aug 2025 12:39:30 +0200
Subject: Set dead_on_return attribute for indirect arguments

Set the dead_on_return attribute (added in LLVM 21) for arguments
that are passed indirectly, but not byval.

This indicates that the value of the argument on return does not
matter, enabling additional dead store elimination.
---
 compiler/rustc_codegen_llvm/src/llvm/ffi.rs | 1 +
 1 file changed, 1 insertion(+)

(limited to 'compiler/rustc_codegen_llvm/src/llvm/ffi.rs')

diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 75d3d27f74e..ad3c3d5932e 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -249,6 +249,7 @@ pub(crate) enum AttributeKind {
     FnRetThunkExtern = 41,
     Writable = 42,
     DeadOnUnwind = 43,
+    DeadOnReturn = 44,
 }
 
 /// LLVMIntPredicate
-- 
cgit 1.4.1-3-g733a5