Re: [PATCH 05/12] x86-64: adjust MOVQ to/from SReg attributes

["H.J. Lu" <hjl.tools@gmail.com>]

On Fri, Aug 5, 2022 at 5:22 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> It is unclear to me why the corresponding MOV (no Q suffix) can be
> issued without REX.W, but MOVQ has to have that prefix (bit). Add
> NoRex64 and in exchange drop Size64.
>
> --- a/gas/testsuite/gas/i386/x86-64-segment.l
> +++ b/gas/testsuite/gas/i386/x86-64-segment.l
> @@ -5,8 +5,15 @@
>     5 0002 8C18                 mov     %ds,\(%rax\)
>     6 0004 8E18                 movw    \(%rax\),%ds
>     7 0006 8E18                 mov     \(%rax\),%ds
> -   8                   # test segment reg insns with REX
> -   9 0008 488CD8               movq    %ds,%rax
> -  10 000b 488ED8               movq    %rax,%ds
> -  11                           # Force a good alignment.
> -  12 000e 0000                 .p2align        4,0
> +   8                   # test segment reg insns with avoided REX
> +   9 0008 8CD8                 mov     %ds,%rax
> +  10 000a 8CD8                 movq    %ds,%rax
> +  11 000c 8ED8                 mov     %rax,%ds
> +  12 000e 8ED8                 movq    %rax,%ds
> +  13                   # test segment reg insns with REX
> +  14 0010 418CD8               mov     %ds,%r8
> +  15 0013 418CD8               movq    %ds,%r8
> +  16 0016 418ED8               mov     %r8,%ds
> +  17 0019 418ED8               movq    %r8,%ds
> +  18                           # Force a good alignment.
> +  19 001c 0+ + *\.p2align      4,0
> --- a/gas/testsuite/gas/i386/x86-64-segment.s
> +++ b/gas/testsuite/gas/i386/x86-64-segment.s
> @@ -5,8 +5,15 @@
>         mov     %ds,(%rax)
>         movw    (%rax),%ds
>         mov     (%rax),%ds
> -# test segment reg insns with REX
> +# test segment reg insns with avoided REX
> +       mov     %ds,%rax
>         movq    %ds,%rax
> +       mov     %rax,%ds
>         movq    %rax,%ds
> +# test segment reg insns with REX
> +       mov     %ds,%r8
> +       movq    %ds,%r8
> +       mov     %r8,%ds
> +       movq    %r8,%ds
>         # Force a good alignment.
>         .p2align        4,0
> --- a/opcodes/i386-opc.tbl
> +++ b/opcodes/i386-opc.tbl
> @@ -148,7 +148,7 @@ movq, 0xb8, None, Cpu64, Size64|No_bSuf|
>  // implementation defined value is zero).
>  mov, 0x8c, None, 0, RegMem|No_bSuf|No_sSuf|No_qSuf|No_ldSuf|NoRex64, { SReg, Reg16|Reg32|Reg64 }
>  mov, 0x8c, None, 0, D|Modrm|IgnoreSize|No_bSuf|No_lSuf|No_sSuf|No_qSuf|No_ldSuf, { SReg, Word|Unspecified|BaseIndex }
> -movq, 0x8c, None, Cpu64, D|RegMem|Size64|No_bSuf|No_wSuf|No_lSuf|No_sSuf|No_qSuf|No_ldSuf, { SReg, Reg64 }
> +movq, 0x8c, None, Cpu64, D|RegMem|No_bSuf|No_wSuf|No_lSuf|No_sSuf|No_qSuf|No_ldSuf|NoRex64, { SReg, Reg64 }
>  mov, 0x8e, None, 0, Modrm|IgnoreSize|No_bSuf|No_sSuf|No_qSuf|No_ldSuf|NoRex64, { Reg16|Reg32|Reg64, SReg }
>  // Move to/from control debug registers.  In the 16 or 32bit modes
>  // they are 32bit.  In the 64bit mode they are 64bit.
>

OK.

Thanks.

-- 
H.J.