From 16525cc4c34649c564e9544ec1d9c45c4c4f4e52 Mon Sep 17 00:00:00 2001
From: 5225225 <5225225@mailbox.org>
Date: Sat, 16 Jul 2022 12:08:48 +0100
Subject: Emit noundef even for unoptimised code if msan is on

---
 compiler/rustc_codegen_llvm/src/abi.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'compiler/rustc_codegen_llvm')

diff --git a/compiler/rustc_codegen_llvm/src/abi.rs b/compiler/rustc_codegen_llvm/src/abi.rs
index 9eb3574e77b..461be98f210 100644
--- a/compiler/rustc_codegen_llvm/src/abi.rs
+++ b/compiler/rustc_codegen_llvm/src/abi.rs
@@ -19,6 +19,7 @@ use rustc_target::abi::call::ArgAbi;
 pub use rustc_target::abi::call::*;
 use rustc_target::abi::{self, HasDataLayout, Int};
 pub use rustc_target::spec::abi::Abi;
+use rustc_target::spec::SanitizerSet;
 
 use libc::c_uint;
 use smallvec::SmallVec;
@@ -90,6 +91,13 @@ fn get_attrs<'ll>(this: &ArgAttributes, cx: &CodegenCx<'ll, '_>) -> SmallVec<[&'
         if regular.contains(ArgAttribute::NoAliasMutRef) && should_use_mutable_noalias(cx) {
             attrs.push(llvm::AttributeKind::NoAlias.create_attr(cx.llcx));
         }
+    } else if cx.tcx.sess.opts.unstable_opts.sanitizer.contains(SanitizerSet::MEMORY) {
+        // If we're not optimising, *but* memory sanitizer is on, emit noundef, since it affects
+        // memory sanitizer's behavior.
+
+        if regular.contains(ArgAttribute::NoUndef) {
+            attrs.push(llvm::AttributeKind::NoUndef.create_attr(cx.llcx));
+        }
     }
 
     attrs
-- 
cgit 1.4.1-3-g733a5