From 0ec3011a3d04de741be642e4d36e826174657fdc Mon Sep 17 00:00:00 2001
From: iximeow <me@iximeow.net>
Date: Sun, 24 May 2026 21:57:39 +0000
Subject: 66-prefixed sha1rnds4 doesnt even real

---
 test/real_mode/mod.rs | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'test/real_mode/mod.rs')

diff --git a/test/real_mode/mod.rs b/test/real_mode/mod.rs
index b8a636c..544827a 100644
--- a/test/real_mode/mod.rs
+++ b/test/real_mode/mod.rs
@@ -231,6 +231,8 @@ fn test_real_mode() {
     test_display(&[0x0f, 0x3a, 0x0f, 0xc1, 0x23], "palignr mm0, mm1, 0x23");
     test_display(&[0x0f, 0x3a, 0xcc, 0x12, 0x40], "sha1rnds4 xmm2, xmmword [bp + si * 1], 0x40");
     test_display(&[0x0f, 0x3a, 0xcc, 0x12, 0xff], "sha1rnds4 xmm2, xmmword [bp + si * 1], 0xff");
+    // with astonishing dismay: 66-prefixed sha1rnds4 is #UD only in 32-bit and 16-bit mode.
+    test_invalid(&[0x66, 0x0f, 0x3a, 0xcc, 0x12, 0xff]);
     test_display(&[0x0f, 0x43, 0xec], "cmovnb bp, sp");
     test_display(&[0x0f, 0x50, 0xc1], "movmskps eax, xmm1");
     test_display(&[0x0f, 0x51, 0x01], "sqrtps xmm0, xmmword [bx + di * 1]");
-- 
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