* [PATCH] x86: simplify and slightly correct XCHG vs NOP checking
@ 2022-12-01 9:11 Jan Beulich
2022-12-01 16:43 ` H.J. Lu
0 siblings, 1 reply; 2+ messages in thread
From: Jan Beulich @ 2022-12-01 9:11 UTC (permalink / raw)
To: Binutils; +Cc: H.J. Lu
For one, because of CheckRegSize, there's no need to check the size of
both (register) operands. And then in process_suffix() check opcode
space rather than the (potentially ambiguous) extension opcode.
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -6686,8 +6686,7 @@ match_template (char mnem_suffix)
&& t->opcode_modifier.opcodespace == SPACE_BASE
&& i.types[0].bitfield.instance == Accum
&& i.types[0].bitfield.dword
- && i.types[1].bitfield.instance == Accum
- && i.types[1].bitfield.dword)
+ && i.types[1].bitfield.instance == Accum)
continue;
/* xrelease mov %eax, <disp> is another special case. It must not
match the accumulator-only encoding of mov. */
@@ -7408,11 +7407,10 @@ process_suffix (void)
need rex64. */
&& ! (i.operands == 2
&& i.tm.base_opcode == 0x90
- && i.tm.extension_opcode == None
+ && i.tm.opcode_modifier.opcodespace == SPACE_BASE
&& i.types[0].bitfield.instance == Accum
&& i.types[0].bitfield.qword
- && i.types[1].bitfield.instance == Accum
- && i.types[1].bitfield.qword))
+ && i.types[1].bitfield.instance == Accum))
i.rex |= REX_W;
break;
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] x86: simplify and slightly correct XCHG vs NOP checking
2022-12-01 9:11 [PATCH] x86: simplify and slightly correct XCHG vs NOP checking Jan Beulich
@ 2022-12-01 16:43 ` H.J. Lu
0 siblings, 0 replies; 2+ messages in thread
From: H.J. Lu @ 2022-12-01 16:43 UTC (permalink / raw)
To: Jan Beulich; +Cc: Binutils
On Thu, Dec 1, 2022 at 1:11 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> For one, because of CheckRegSize, there's no need to check the size of
> both (register) operands. And then in process_suffix() check opcode
> space rather than the (potentially ambiguous) extension opcode.
>
> --- a/gas/config/tc-i386.c
> +++ b/gas/config/tc-i386.c
> @@ -6686,8 +6686,7 @@ match_template (char mnem_suffix)
> && t->opcode_modifier.opcodespace == SPACE_BASE
> && i.types[0].bitfield.instance == Accum
> && i.types[0].bitfield.dword
> - && i.types[1].bitfield.instance == Accum
> - && i.types[1].bitfield.dword)
> + && i.types[1].bitfield.instance == Accum)
> continue;
> /* xrelease mov %eax, <disp> is another special case. It must not
> match the accumulator-only encoding of mov. */
> @@ -7408,11 +7407,10 @@ process_suffix (void)
> need rex64. */
> && ! (i.operands == 2
> && i.tm.base_opcode == 0x90
> - && i.tm.extension_opcode == None
> + && i.tm.opcode_modifier.opcodespace == SPACE_BASE
> && i.types[0].bitfield.instance == Accum
> && i.types[0].bitfield.qword
> - && i.types[1].bitfield.instance == Accum
> - && i.types[1].bitfield.qword))
> + && i.types[1].bitfield.instance == Accum))
> i.rex |= REX_W;
>
> break;
OK.
Thanks.
--
H.J.
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