From a29d8545b573d008e364571a83fcd865748a8ad8 Mon Sep 17 00:00:00 2001
From: John Kåre Alsaker <john.kare.alsaker@gmail.com>
Date: Thu, 16 Nov 2017 10:08:19 +0100
Subject: Make inline assembly volatile if it has no outputs. Fixes #46026

---
 src/libsyntax_ext/asm.rs | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'src/libsyntax_ext')

diff --git a/src/libsyntax_ext/asm.rs b/src/libsyntax_ext/asm.rs
index 3742fb8c804..d1de4dccd00 100644
--- a/src/libsyntax_ext/asm.rs
+++ b/src/libsyntax_ext/asm.rs
@@ -239,6 +239,12 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
         }
     }
 
+    // If there are no outputs, the inline assembly is executed just for its side effects,
+    // so ensure that it is volatile
+    if outputs.is_empty() {
+        volatile = true;
+    }
+
     MacEager::expr(P(ast::Expr {
         id: ast::DUMMY_NODE_ID,
         node: ast::ExprKind::InlineAsm(P(ast::InlineAsm {
-- 
cgit 1.4.1-3-g733a5