[PATCH 1/2] x86/Intel: make sure MOVSD/CMPSD have their Size32 honored

[H.J. Lu]

On Thu, Nov 7, 2019 at 2:18 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> The combination of IgnoreSize and Size32 (or Size16) didn't work right:
> While at the top of process_suffix() Size<N> carefully get honored to
> force a respective suffix, code later in the function ignored the
> attribute when determining whether to emit an insn size prefix. This
> fixes a regression from d241b91073 ("x86/Intel: correct MOVSD and CMPSD
> handling"). (The Size16 aspect of this can be observed when, just for
> this purpose, also adding explicit "movsw" templates. The lack of an
> IgnoreSize check in 'q' suffix handling means that no such issue
> existed even if explicit "movsq" templates were added.)
>
> Also further extend the test cases added/extended by that commit.
>
> gas/
> 2019-11-07  Jan Beulich  <jbeulich@suse.com>
>
>         PR/gas 25167
>         * config/tc-i386.c (process_suffix): Honor size attribute when
>         checking whether to add operand size prefix.
>         * testsuite/gas/i386/intel-cmps.s,
>         testsuite/gas/i386/intel-movs.s: Extend.
>         * testsuite/gas/i386/intel-cmps32.d,
>         testsuite/gas/i386/intel-cmps64.d,
>         testsuite/gas/i386/intel-movs32.d,
>         testsuite/gas/i386/intel-movs64.d: Adjust expectations.
>         * testsuite/gas/i386/intel-cmps16.d,
>         testsuite/gas/i386/intel-movs16.d: New.
>         * testsuite/gas/i386/i386.exp: Run new tests.
>
> --- a/gas/config/tc-i386.c
> +++ b/gas/config/tc-i386.c
> @@ -6466,7 +6466,8 @@ process_suffix (void)
>               return 0;
>         }
>        else if (i.suffix != QWORD_MNEM_SUFFIX
> -              && !i.tm.opcode_modifier.ignoresize
> +              && (!i.tm.opcode_modifier.ignoresize
> +                  || i.tm.opcode_modifier.size)
>                && !i.tm.opcode_modifier.floatmf
>                && !is_any_vex_encoding (&i.tm)
>                && ((i.suffix == LONG_MNEM_SUFFIX) == (flag_code == CODE_16BIT)

Ignore IgnoreSize with Size looks very odd.  I much prefer to remove CMPSD and
MOVSD support with explicit operands from Intel syntax, which aren't
even in Intel SDM.
We need CMPSD and MOVSD with explicit operands for AT&T syntax only because AT&T
syntax uses suffixes for memory operand size.


--
H.J.