From 075e74ed1356f2e5bb978ac541633ab46e34bf99 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 13 Oct 2022 11:08:29 -0700
Subject: [PATCH] [mono][s390x] Fix wrong implementation of OP_CHECK_THIS
 (#76920)

* Only access a single byte in memory for OP_CHECK_THIS

* Remove unnecessary ltgr instruction

* Fixes https://github.com/dotnet/runtime/issues/76915

Co-authored-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>
---
 src/mono/mono/mini/mini-s390x.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/mono/mono/mini/mini-s390x.c b/src/mono/mono/mini/mini-s390x.c
index 7c7a936ed9701..26e6ba1d32a3b 100644
--- a/src/mono/mono/mini/mini-s390x.c
+++ b/src/mono/mono/mini/mini-s390x.c
@@ -3594,8 +3594,7 @@ mono_arch_output_basic_block (MonoCompile *cfg, MonoBasicBlock *bb)
 			break;
 		case OP_CHECK_THIS: {
 			/* ensure ins->sreg1 is not NULL */
-			s390_lg   (code, s390_r0, 0, ins->sreg1, 0);
-			s390_ltgr (code, s390_r0, s390_r0);
+			s390_llgc (code, s390_r0, 0, ins->sreg1, 0);
 		}
 			break;
 		case OP_ARGLIST: {