Ping: [PATCH, resend] arm: fix extension feature disabling

["Jan Beulich" <JBeulich at suse dot com>]

As was the case when having sent this first 1.5 years ago - no response
at all. Not even a "this is a bad idea, drop it" (in which case I'd expect at
least an indication how to reasonably achieve by other means what this
patch arranges for). Marcus, in the context of an ARM64 patch, actually
suggested to resend this as he apparently agrees that how things work
currently isn't how they're meant to work...

Regards, Jan

>>> On 14.11.14 at 10:24, <JBeulich@suse.com> wrote:
> Using e.g.
> 
> 	.arch_extension simd
> 	.arch_extension nocrypto
> 
> so far results in SIMD support getting disabled, which I can't see being
> the purpose of the "no"-prefixed variants of architecture extension
> specifications.
> 
> Of course it is questionable whether the current, counter intuitive
> behavior needs to be retained, and the new behavior perhaps be made work
> through e.g. a newly recognized "no-" prefix.
> 
> gas/
> 2014-11-14  Jan Beulich <jbeulich@suse.com>
> 
> 	* gas/config/tc-arm.c (struct arm_option_extension_value_table):
> 	Split field "value" into fields "merge_value" and "clear_value".
> 	(arm_extensions): Adjust initializer accordingly.
> 
> --- 2014-11-14/gas/config/tc-arm.c
> +++ 2014-11-14/gas/config/tc-arm.c
> @@ -24493,40 +24493,51 @@ struct arm_option_extension_value_table
>  {
>    char *name;
>    size_t name_len;
> -  const arm_feature_set value;
> +  const arm_feature_set merge_value;
> +  const arm_feature_set clear_value;
>    const arm_feature_set allowed_archs;
>  };
>  
>  /* The following table must be in alphabetical order with a NULL last 
> entry.
>     */
> -#define ARM_EXT_OPT(N, V, AA) { N, sizeof (N) - 1, V, AA }
> +#define ARM_EXT_OPT(N, M, C, AA) { N, sizeof (N) - 1, M, C, AA }
>  static const struct arm_option_extension_value_table arm_extensions[] =
>  {
> -  ARM_EXT_OPT ("crc",  ARCH_CRC_ARMV8, ARM_FEATURE (ARM_EXT_V8, 0)),
> +  ARM_EXT_OPT ("crc",  ARCH_CRC_ARMV8, ARM_FEATURE (0, CRC_EXT_ARMV8),
> +			 ARM_FEATURE (ARM_EXT_V8, 0)),
>    ARM_EXT_OPT ("crypto", FPU_ARCH_CRYPTO_NEON_VFP_ARMV8,
> +			 ARM_FEATURE (0, FPU_CRYPTO_ARMV8),
>  				   ARM_FEATURE (ARM_EXT_V8, 0)),
> -  ARM_EXT_OPT ("fp",     FPU_ARCH_VFP_ARMV8,
> +  ARM_EXT_OPT ("fp",     FPU_ARCH_VFP_ARMV8, ARM_FEATURE (0, 
> FPU_VFP_ARMV8),
>  				   ARM_FEATURE (ARM_EXT_V8, 0)),
>    ARM_EXT_OPT ("idiv",	ARM_FEATURE (ARM_EXT_ADIV | ARM_EXT_DIV, 0),
> +			ARM_FEATURE (ARM_EXT_ADIV | ARM_EXT_DIV, 0),
>  				   ARM_FEATURE (ARM_EXT_V7A | ARM_EXT_V7R, 0)),
> -  ARM_EXT_OPT ("iwmmxt",ARM_FEATURE (0, ARM_CEXT_IWMMXT),	ARM_ANY),
> -  ARM_EXT_OPT ("iwmmxt2",
> -			ARM_FEATURE (0, ARM_CEXT_IWMMXT2),	ARM_ANY),
> -  ARM_EXT_OPT ("maverick",
> -			ARM_FEATURE (0, ARM_CEXT_MAVERICK),	ARM_ANY),
> +  ARM_EXT_OPT ("iwmmxt",ARM_FEATURE (0, ARM_CEXT_IWMMXT),
> +			ARM_FEATURE (0, ARM_CEXT_IWMMXT), ARM_ANY),
> +  ARM_EXT_OPT ("iwmmxt2", ARM_FEATURE (0, ARM_CEXT_IWMMXT2),
> +			ARM_FEATURE (0, ARM_CEXT_IWMMXT2), ARM_ANY),
> +  ARM_EXT_OPT ("maverick", ARM_FEATURE (0, ARM_CEXT_MAVERICK),
> +			ARM_FEATURE (0, ARM_CEXT_MAVERICK), ARM_ANY),
>    ARM_EXT_OPT ("mp",	ARM_FEATURE (ARM_EXT_MP, 0),
> +			ARM_FEATURE (ARM_EXT_MP, 0),
>  				   ARM_FEATURE (ARM_EXT_V7A | ARM_EXT_V7R, 0)),
>    ARM_EXT_OPT ("simd",   FPU_ARCH_NEON_VFP_ARMV8,
> +			ARM_FEATURE(0, FPU_NEON_ARMV8),
>  				   ARM_FEATURE (ARM_EXT_V8, 0)),
>    ARM_EXT_OPT ("os",	ARM_FEATURE (ARM_EXT_OS, 0),
> +			ARM_FEATURE (ARM_EXT_OS, 0),
>  				   ARM_FEATURE (ARM_EXT_V6M, 0)),
>    ARM_EXT_OPT ("sec",	ARM_FEATURE (ARM_EXT_SEC, 0),
> +			ARM_FEATURE (ARM_EXT_SEC, 0),
>  				   ARM_FEATURE (ARM_EXT_V6K | ARM_EXT_V7A, 0)),
>    ARM_EXT_OPT ("virt",	ARM_FEATURE (ARM_EXT_VIRT | ARM_EXT_ADIV
>  				     | ARM_EXT_DIV, 0),
> +			ARM_FEATURE (ARM_EXT_VIRT, 0),
>  				   ARM_FEATURE (ARM_EXT_V7A, 0)),
> -  ARM_EXT_OPT ("xscale",ARM_FEATURE (0, ARM_CEXT_XSCALE),	ARM_ANY),
> -  { NULL, 0, ARM_ARCH_NONE, ARM_ARCH_NONE }
> +  ARM_EXT_OPT ("xscale",ARM_FEATURE (0, ARM_CEXT_XSCALE),
> +			ARM_FEATURE (0, ARM_CEXT_XSCALE), ARM_ANY),
> +  { NULL, 0, ARM_ARCH_NONE, ARM_ARCH_NONE, ARM_ARCH_NONE }
>  };
>  #undef ARM_EXT_OPT
>  
> @@ -24701,9 +24712,9 @@ arm_parse_extension (char *str, const ar
>  
>  	    /* Add or remove the extension.  */
>  	    if (adding_value)
> -	      ARM_MERGE_FEATURE_SETS (*ext_set, *ext_set, opt->value);
> +	      ARM_MERGE_FEATURE_SETS (*ext_set, *ext_set, opt->merge_value);
>  	    else
> -	      ARM_CLEAR_FEATURE (*ext_set, *ext_set, opt->value);
> +	      ARM_CLEAR_FEATURE (*ext_set, *ext_set, opt->clear_value);
>  
>  	    break;
>  	  }
> @@ -25436,9 +25447,10 @@ s_arm_arch_extension (int ignored ATTRIB
>  	  }
>  
>  	if (adding_value)
> -	  ARM_MERGE_FEATURE_SETS (selected_cpu, selected_cpu, opt->value);
> +	  ARM_MERGE_FEATURE_SETS (selected_cpu, selected_cpu,
> +				  opt->merge_value);
>  	else
> -	  ARM_CLEAR_FEATURE (selected_cpu, selected_cpu, opt->value);
> +	  ARM_CLEAR_FEATURE (selected_cpu, selected_cpu, opt->clear_value);
>  
>  	mcpu_cpu_opt = &selected_cpu;
>  	ARM_MERGE_FEATURE_SETS (cpu_variant, *mcpu_cpu_opt, *mfpu_opt);