Re: [PATCH v5 2/8] x86: introduce Pass2 insn attribute

[Jan Beulich <jbeulich@suse.com>]

I'm sorry, I've typo-ed the title of the original submission - this is of
course patch 2/8 (reflected in the subject here).

Jan

On 25.10.2022 09:25, Jan Beulich via Binutils wrote:
> Subsequently we will want to mark templates for mnemonics which, due to
> their last character also possibly being a suffix, are "shadowing" other
> templates (and hence may require a second parsing pass). Introduce this
> attribute in a standalone patch, largely to ease looking at the actual
> later change. To simplify logic the later change is going to look for
> the new attribute only on the first template of a group. Make i386-gen
> warn about misplaced Pass2 (redundant ones are okay).
> 
> While there convert "active_isstring" to bool, matching the new static
> variable.
> ---
> As to redundant attributes: An open question is whether - to avoid
> surprises when e.g. templates are re-ordered - it wouldn't be desirable
> to add Pass2 on all templates of a group.
> ---
> v3: New.
> 
> --- a/opcodes/i386-gen.c
> +++ b/opcodes/i386-gen.c
> @@ -18,6 +18,7 @@
>     MA 02110-1301, USA.  */
>  
>  #include "sysdep.h"
> +#include <stdbool.h>
>  #include <stdio.h>
>  #include <errno.h>
>  #include "getopt.h"
> @@ -702,6 +703,7 @@ static bitfield opcode_modifiers[] =
>    BITFIELD (FWait),
>    BITFIELD (IsString),
>    BITFIELD (RegMem),
> +  BITFIELD (Pass2),
>    BITFIELD (BNDPrefixOk),
>    BITFIELD (RegKludge),
>    BITFIELD (Implicit1stXmm0),
> @@ -800,7 +802,7 @@ static bitfield operand_types[] =
>  
>  static const char *filename;
>  static i386_cpu_flags active_cpu_flags;
> -static int active_isstring;
> +static bool active_isstring, active_pass2;
>  
>  struct template_arg {
>    const struct template_arg *next;
> @@ -1168,7 +1170,8 @@ process_i386_opcode_modifier (FILE *tabl
>    char *str, *next, *last;
>    bitfield modifiers [ARRAY_SIZE (opcode_modifiers)];
>  
> -  active_isstring = 0;
> +  active_isstring = false;
> +  active_pass2 = false;
>  
>    /* Copy the default opcode modifier.  */
>    memcpy (modifiers, opcode_modifiers, sizeof (modifiers));
> @@ -1191,8 +1194,11 @@ process_i386_opcode_modifier (FILE *tabl
>  
>  	      set_bitfield (str, modifiers, val, ARRAY_SIZE (modifiers),
>  			    lineno);
> +
>  	      if (strcasecmp(str, "IsString") == 0)
> -		active_isstring = 1;
> +		active_isstring = true;
> +	      if (strcasecmp(str, "Pass2") == 0)
> +		active_pass2 = true;
>  
>  	      if (strcasecmp(str, "W") == 0)
>  		have_w = 1;
> @@ -1867,6 +1873,7 @@ process_i386_opcodes (FILE *table)
>    for (j = 0; j < i; j++)
>      {
>        struct opcode_hash_entry *next;
> +      bool first_pass2 = false;
>  
>        for (next = opcode_array[j]; next; next = next->next)
>  	{
> @@ -1875,6 +1882,14 @@ process_i386_opcodes (FILE *table)
>  	  lineno = next->lineno;
>  	  last = str + strlen (str);
>  	  output_i386_opcode (table, name, str, last, lineno);
> +
> +	  if (next == opcode_array[j])
> +	    first_pass2 = active_pass2;
> +	  else if (!first_pass2 && active_pass2)
> +	    fprintf (stderr,
> +		     "Warning: %s:%d: %s: "
> +		     "'Pass2' is recognized only on the first template in a group\n",
> +		     filename, lineno, name);
>  	}
>      }
>  
> --- a/opcodes/i386-opc.h
> +++ b/opcodes/i386-opc.h
> @@ -504,6 +504,9 @@ enum
>       Normally, it will be encoded in the reg field. We add a RegMem
>       flag to indicate that it should be encoded in the regmem field.  */
>    RegMem,
> +  /* The (unsuffixed) mnemonic represents itself the suffixed form of another
> +     mnemonic, potentially requiring a second parsing pass.  */
> +  Pass2,
>    /* quick test if branch instruction is MPX supported */
>    BNDPrefixOk,
>    /* fake an extra reg operand for clr, imul and special register
> @@ -730,6 +733,7 @@ typedef struct i386_opcode_modifier
>    unsigned int fwait:1;
>    unsigned int isstring:2;
>    unsigned int regmem:1;
> +  unsigned int pass2:1;
>    unsigned int bndprefixok:1;
>    unsigned int regkludge:1;
>    unsigned int implicit1stxmm0:1;
>