[Bug target/124678] New: assemble failure of enqcmds with -masm=intel

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124678

            Bug ID: 124678
           Summary: assemble failure of enqcmds with -masm=intel
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: assemble-failure
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu

Created attachment 64063
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=64063&action=edit
reduced testcase

Similar to PR124337

$ x86_64-pc-linux-gnu-gcc -menqcmd testcase.c -masm=intel
/tmp/ccxoh3Td.s: Assembler messages:
/tmp/ccxoh3Td.s:16: Error: operand size mismatch for `enqcmds'

$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-20260328082301-r16-8319-g48616938660a9f-checking-yes-rtl-df-extra-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/16.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--disable-bootstrap --build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
--target=x86_64-pc-linux-gnu --with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --enable-libsanitizer
--disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-20260328082301-r16-8319-g48616938660a9f-checking-yes-rtl-df-extra-nobootstrap-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.0.1 20260328 (experimental) (GCC) 

$ as --version
GNU assembler (Gentoo 9999 p1) 2.46.50.20260302
Copyright (C) 2026 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or later.
This program has absolutely no warranty.
This assembler was configured for a target of `x86_64-pc-linux-gnu'.