[PATCH] RISC-V: widen LEB128 support

[Nelson Chu]

Okay, looks good, thanks for fixing the xfail of the testcase :-)

Nelson

On Wed, Jan 22, 2025 at 4:55 PM Jan Beulich <jbeulich@suse.com> wrote:

> Do away with at least one of the limitations - all other targets permit
> multiple values to be specified with a single directive. Re-arrange the
> logic further to also overcome an internal error in
> riscv_insert_uleb128_fixes(), as e.g. observed by the all/sleb128-2
> testcase. This way there's also no need to parse expressions twice,
> thus also not raising the same diagnostics (if any) twice.
>
> Note how this addresses a pre-existing XFAIL (where the comment wasn't
> really applicable either for RISC-V).
>
> Also update documentation, also to mention that differences between
> symbols may be used with .uleb128 (albeit I'm uncertain whether there
> are limitations).
> ---
> Imo even for XFAILed testcases an internal error would better yield a
> real test failure.
>
> --- a/gas/config/tc-riscv.c
> +++ b/gas/config/tc-riscv.c
> @@ -5441,19 +5441,22 @@ riscv_elf_final_processing (void)
>  static void
>  s_riscv_leb128 (int sign)
>  {
> -  expressionS exp;
> -  char *save_in = input_line_pointer;
> +  do
> +    {
> +      expressionS exp;
>
> -  expression (&exp);
> -  if (sign && exp.X_op != O_constant)
> -    as_bad (_("non-constant .sleb128 is not supported"));
> -  else if (!sign && exp.X_op != O_constant && exp.X_op != O_subtract)
> -    as_bad (_(".uleb128 only supports constant or subtract expressions"));
> +      expression (&exp);
> +      if (sign && exp.X_op != O_constant)
> +       as_bad (_("non-constant .sleb128 is not supported"));
> +      else if (!sign && exp.X_op != O_constant && exp.X_op != O_subtract)
> +       as_bad (_(".uleb128 only supports constant or subtract
> expressions"));
> +      else
> +       emit_leb128_expr (&exp, sign);
> +    }
> +  while (*input_line_pointer++ == ',');
>
> +  input_line_pointer--;
>    demand_empty_rest_of_line ();
> -
> -  input_line_pointer = save_in;
> -  return s_leb128 (sign);
>  }
>
>  /* Parse the .insn directive.  There are three formats,
> --- a/gas/doc/c-riscv.texi
> +++ b/gas/doc/c-riscv.texi
> @@ -139,12 +139,13 @@ meant to be used by the compiler in shar
>  thread local variables.
>
>  @cindex LEB128 directives
> -@item .uleb128 @var{value}
> -@itemx .sleb128 @var{value}
> -Emits a signed or unsigned LEB128 value at the current position.  This
> only
> +@item .uleb128 @var{values}
> +@itemx .sleb128 @var{values}
> +Emits signed or unsigned LEB128 values at the current position.  This only
>  accepts constant expressions, because symbol addresses can change with
>  relaxation, and we don't support relocations to modify LEB128 values at
> link
> -time.
> +time.  An exception are differences between symbols, which may be used
> with
> +@code{.uleb128}.
>
>  @cindex Option directive
>  @cindex @code{option} directive
> --- a/gas/testsuite/gas/elf/dwarf2-6.d
> +++ b/gas/testsuite/gas/elf/dwarf2-6.d
> @@ -2,7 +2,7 @@
>  #readelf: -wlL
>  #name: DWARF2 6
>  # These targets either do not support or do not evaluate the subtraction
> of symbols at assembly time.
> -#xfail: cr16-* crx-* riscv*-*
> +#xfail: cr16-* crx-*
>
>  Raw dump of debug contents of section .debug_line:
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://sourceware.org/pipermail/binutils/attachments/20250122/8c17b804/attachment-0001.htm>