From b7fb8ef89edf21ab1d6197ca8aff5a421d82c74c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Erik=20=C3=96sterlund?= <eosterlund@openjdk.org>
Date: Tue, 17 Jan 2023 12:16:05 +0000
Subject: [PATCH] 8299323: Allow extended registers for cmpw

Reviewed-by: sviswanathan, kvn
---
 src/hotspot/cpu/x86/assembler_x86.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/hotspot/cpu/x86/assembler_x86.cpp b/src/hotspot/cpu/x86/assembler_x86.cpp
index 67ff8a97c7a..1748a9fb06f 100644
--- a/src/hotspot/cpu/x86/assembler_x86.cpp
+++ b/src/hotspot/cpu/x86/assembler_x86.cpp
@@ -1763,8 +1763,9 @@ void Assembler::cmpl_imm32(Address dst, int32_t imm32) {
 
 void Assembler::cmpw(Address dst, int imm16) {
   InstructionMark im(this);
-  assert(!dst.base_needs_rex() && !dst.index_needs_rex(), "no extended registers");
-  emit_int16(0x66, (unsigned char)0x81);
+  emit_int8(0x66);
+  prefix(dst);
+  emit_int8((unsigned char)0x81);
   emit_operand(rdi, dst, 2);
   emit_int16(imm16);
 }