From 92c1b858ef7855fea75162499fff93d3d04144f1 Mon Sep 17 00:00:00 2001
From: bjorn3 <bjorn3@users.noreply.github.com>
Date: Sat, 20 Feb 2021 16:55:30 +0100
Subject: [PATCH] Disable stack2reg optimization

It causes a miscompilation of lewton

Fixes #1142
---
 src/optimize/mod.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/optimize/mod.rs b/src/optimize/mod.rs
index 3ce7f8cd9a8..389f50e797e 100644
--- a/src/optimize/mod.rs
+++ b/src/optimize/mod.rs
@@ -19,7 +19,12 @@ pub(crate) fn optimize_function<'tcx>(
     if tcx.sess.opts.optimize == rustc_session::config::OptLevel::No {
         return; // FIXME classify optimizations over opt levels
     }
-    self::stack2reg::optimize_function(ctx, clif_comments);
+
+    // FIXME(#1142) stack2reg miscompiles lewton
+    if false {
+        self::stack2reg::optimize_function(ctx, clif_comments);
+    }
+
     crate::pretty_clif::write_clif_file(tcx, "stack2reg", None, instance, &ctx, &*clif_comments);
     crate::base::verify_func(tcx, &*clif_comments, &ctx.func);
 }