From 84e7ae284266cfb77487c580945dcc9f5f107e45 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 27 Mar 2021 14:03:31 +0100
Subject: [PATCH 1/2] Run Miri test suite with mir-opt-level=4

---
 src/bootstrap/test.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index 86d940cd733da..b3cf30672c82f 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -452,7 +452,14 @@ impl Step for Miri {
 
             cargo.add_rustc_lib_path(builder, compiler);
 
-            if !try_run(builder, &mut cargo.into()) {
+            let mut cargo = Command::from(cargo);
+            if !try_run(builder, &mut cargo) {
+                return;
+            }
+
+            // # Run `cargo test` with `-Zmir-opt-level=4`.
+            cargo.env("MIRIFLAGS", "-O -Zmir-opt-level=4");
+            if !try_run(builder, &mut cargo) {
                 return;
             }
 

From a515cfd966d68a5a0a1b2d90425580f81cdabdbf Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 27 Mar 2021 14:23:29 +0100
Subject: [PATCH 2/2] update Miri

---
 src/tools/miri | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/tools/miri b/src/tools/miri
index 12dac5c0f7acd..2cdd1744b896e 160000
--- a/src/tools/miri
+++ b/src/tools/miri
@@ -1 +1 @@
-Subproject commit 12dac5c0f7acd106401aa14fec758f0ff552f678
+Subproject commit 2cdd1744b896e8129322229f253f95fd7ad491f1