From: Jan Beulich <jbeulich@suse.com>
Date: Tue, 21 Dec 2021 08:31:04 +0000 (+0100)
Subject: x86: -mfence-as-lock-add=yes doesn't work for 16-bit mode
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=47f4115a1b17f0918a484b935ffd0adcee1555a5;p=binutils-gdb.git

x86: -mfence-as-lock-add=yes doesn't work for 16-bit mode

Rather than trying to fix this (which would require making an assumption
on the upper half of %esp being zero), simply issue an error. While at
it, since the generated code is in conflict with -momit-lock-prefix=yes,
issue an error in that case as well.
---

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 9674ec4368b..dd12a0e9e22 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -9632,7 +9632,12 @@ output_insn (void)
 	{
 	  /* Encode lfence, mfence, and sfence as
 	     f0 83 04 24 00   lock addl $0x0, (%{re}sp).  */
-	  if (now_seg != absolute_section)
+	  if (flag_code == CODE_16BIT)
+	    as_bad (_("Cannot convert `%s' in 16-bit mode"), i.tm.name);
+	  else if (omit_lock_prefix)
+	    as_bad (_("Cannot convert `%s' with `-momit-lock-prefix=yes' in effect"),
+		    i.tm.name);
+	  else if (now_seg != absolute_section)
 	    {
 	      offsetT val = 0x240483f0ULL;