From 3695af697efa26b0ea3b67739ade3ecc3929154e Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov@redhat.com>
Date: Mon, 19 Feb 2024 15:02:49 +0100
Subject: Set writable and dead_on_unwind attributes for sret arguments

---
 compiler/rustc_codegen_llvm/src/abi.rs      | 13 +++++++++++++
 compiler/rustc_codegen_llvm/src/llvm/ffi.rs |  2 ++
 2 files changed, 15 insertions(+)

(limited to 'compiler/rustc_codegen_llvm/src')

diff --git a/compiler/rustc_codegen_llvm/src/abi.rs b/compiler/rustc_codegen_llvm/src/abi.rs
index f918facc86d..94d67859f2f 100644
--- a/compiler/rustc_codegen_llvm/src/abi.rs
+++ b/compiler/rustc_codegen_llvm/src/abi.rs
@@ -2,6 +2,7 @@ use crate::attributes;
 use crate::builder::Builder;
 use crate::context::CodegenCx;
 use crate::llvm::{self, Attribute, AttributePlace};
+use crate::llvm_util;
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
@@ -420,6 +421,18 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
                     cx.type_array(cx.type_i8(), self.ret.layout.size.bytes()),
                 );
                 attributes::apply_to_llfn(llfn, llvm::AttributePlace::Argument(i), &[sret]);
+                if cx.sess().opts.optimize != config::OptLevel::No
+                    && llvm_util::get_version() >= (18, 0, 0)
+                {
+                    attributes::apply_to_llfn(
+                        llfn,
+                        llvm::AttributePlace::Argument(i),
+                        &[
+                            llvm::AttributeKind::Writable.create_attr(cx.llcx),
+                            llvm::AttributeKind::DeadOnUnwind.create_attr(cx.llcx),
+                        ],
+                    );
+                }
             }
             PassMode::Cast { cast, pad_i32: _ } => {
                 cast.attrs.apply_attrs_to_llfn(llvm::AttributePlace::ReturnValue, cx, llfn);
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 5509baaa3e9..96265043a1c 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -200,6 +200,8 @@ pub enum AttributeKind {
     AllocAlign = 39,
     SanitizeSafeStack = 40,
     FnRetThunkExtern = 41,
+    Writable = 42,
+    DeadOnUnwind = 43,
 }
 
 /// LLVMIntPredicate
-- 
cgit 1.4.1-3-g733a5