[PATCH v5] RISC-V: Add support for RISC-V Profiles.

[Nelson Chu]

Basically looks good, I am fine with the current implementation, just some
minor issues probably need to be clarified,

On Wed, Aug 7, 2024 at 11:44 PM Jiawei <jiawei@iscas.ac.cn> wrote:

> Supports RISC-V profiles[1] in -march option.
>
> Default input set the profile before other formal extensions.
>
> [1]https://github.com/riscv/riscv-profiles/blob/main/profiles.adoc


404 link needs to be updated :P


> +/* This table records the mapping form RISC-V Profiles into march
> string.  */
> +static struct riscv_profiles riscv_profiles_table[] =
> +{
> +  /* RVI20U only contains the base extension 'i' as mandatory extension.
> */
> +  {"RVI20U64", "rv64i"},
> +  {"RVI20U32", "rv32i"},
> +
> +  /* RVA20U contains the
> 'i,m,a,f,d,c,zicsr,zicntr,ziccif,ziccrse,ziccamoa,
> +     zicclsm,za128rs' as mandatory extensions.  */
> +  {"RVA20U64", "rv64imafdc_zicsr_zicntr_ziccif_ziccrse_ziccamoa"
> +   "_zicclsm_za128rs"},
> +
> +  /* RVA22U contains the
> 'i,m,a,f,d,c,zicsr,zihintpause,zba,zbb,zbs,zicntr,
> +     zihpm,ziccif,ziccrse,ziccamoa,
> zicclsm,zic64b,za64rs,zicbom,zicbop,zicboz,
> +     zfhmin,zkt' as mandatory extensions.  */
> +  {"RVA22U64", "rv64imafdc_zicsr_zicntr_ziccif_ziccrse_ziccamoa"
> +   "_zicclsm_zic64b_za64rs_zihintpause_zba_zbb_zbs_zicbom_zicbop"
> +   "_zicboz_zfhmin_zkt"},
>

According to the commit e8d4709e, RISC-V: Don't allow any uppercase letter
in the arch string - Do the profile strings also need to be lower cases
since they still belong to the -march option?  For example,
-march=rvi20u64+fdc


>
> @@ -2148,6 +2179,45 @@ riscv_set_default_arch (riscv_parse_subset_t *rps)
>      }
>  }
>
> +const char *
> +riscv_handle_profiles (const char *p)
> +{
> +  /* Checking if input string contains a Profiles.
> +     There are two cases use Profiles in -march option:
> +
> +       1. Only use Profiles as -march input
> +       2. Mixed Profiles with other extensions
> +
> +     Use '+' to split Profiles and other extensions.  */
>

Not sure if using `+' as the separator is a good idea, since its usage
seems confused with the `+' in .option arch.  I think maybe we can clarify
the architecture string that must be started with, rv32, rv64, or defined
profile string.  So that the other extensions can simply be attached after
`_'.  That is - startswith (arch, string), string can be "rv32", "rv64", or
profile strings "rvi20u64", ....


> diff --git a/gas/doc/as.texi b/gas/doc/as.texi
> index 0b4109e1149..3240427fabe 100644
> --- a/gas/doc/as.texi
> +++ b/gas/doc/as.texi
> @@ -557,7 +557,7 @@ gcc(1), ld(1), and the Info entries for
> @file{binutils} and @file{ld}.
>
>  @emph{Target RISC-V options:}
>     [@b{-fpic}|@b{-fPIC}|@b{-fno-pic}]
> -   [@b{-march}=@var{ISA}]
> +   [@b{-march}=@var{ISA/Profiles/Profiles+ISA}]

    [@b{-mabi}=@var{ABI}]
>     [@b{-mlittle-endian}|@b{-mbig-endian}]
>  @end ifset
> diff --git a/gas/doc/c-riscv.texi b/gas/doc/c-riscv.texi
> index cec7457fe81..6334b637275 100644
> --- a/gas/doc/c-riscv.texi
> +++ b/gas/doc/c-riscv.texi
> @@ -41,9 +41,10 @@ Generate position-independent code
>  @item -fno-pic
>  Don't generate position-independent code (default)
>
> -@cindex @samp{-march=ISA} option, RISC-V
> -@item -march=ISA
> -Select the base isa, as specified by ISA.  For example -march=rv32ima.
> +@cindex @samp{-march=ISA/Profiles/Profies+ISA} option, RISC-V
> +@item -march=ISA/Profiles/Profiles+ISA
> +Select the base isa, as specified by ISA or Profiles or Profies+ISA.
> +For example -march=rv32ima -march=RVI20U64 -march=RVI20U64+d.
>  If this option and the architecture attributes aren't set, then assembler
>  will check the default configure setting --with-arch=ISA.
>

The ISA means architecture string, and must be start with rv[32|64][i|e|g]
before, so -march=Profiles+ISA looks confused since -march=rvi20u64+rv32i
should be correct according to the rule, but in fact it's an illegal usage
for the current implementation.  Personally, I think the profile strings
belonged to the base isa may be a good idea, which is rv32i, rv32e, rv32g,
rv64i, rv64g, rvi20u64, rvi20u32, rva20u64 or rva22u64.

Thanks
Nelson
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