[PATCH] MIPS: make mipsisa32 and mipsisa64 link more systematic

[Richard Sandiford]

Sorry for the slow review, been away.

YunQiang Su <yunqiang.su@cipunited.com> writes:
> Introduce `static const struct mips_mach_extension mips_mach_32_64[]`
> and `mips_mach_extends_32_64 (unsigned long base, unsigned long extension)`,
> to make mipsisa32 and mipsisa64 interlink more systemtic.
>
> Normally, the ISA mipsisa64rN has two subset: mipsisa64r(N-1) and
> mipsisa32rN. `mips_mach_extensions` can hold only mipsisa64r(N-1),
> so we need to introduce a new instruction `mips_mach_32_64`, which holds the pair 32vs64.
>
> Note: R6 is not compatible with pre-R6.
>
> bfd/ChangeLog:
>
> 	* elfxx-mips.c (mips_mach_extends_p): make mipsisa32 and
> 	  mipsisa64 interlink more systematic.
> 	  (mips_mach_32_64): new struct added.
> 	  (mips_mach_extends_32_64): new function added.
> ---
>  bfd/elfxx-mips.c | 38 ++++++++++++++++++++++++++++----------
>  1 file changed, 28 insertions(+), 10 deletions(-)
>
> diff --git a/bfd/elfxx-mips.c b/bfd/elfxx-mips.c
> index e9fb61ff9e7..e9480ea3954 100644
> --- a/bfd/elfxx-mips.c
> +++ b/bfd/elfxx-mips.c
> @@ -14505,6 +14505,16 @@ struct mips_mach_extension
>    unsigned long extension, base;
>  };
>  
> +/* An array describing how BFD machines relate to one another. The entries
> +   are ordered topologically. */

I don't this comment really applies to the new array.  How about:

/* An array that maps 64-bit architectures to the corresponding 32-bit
   architectures.  */

> +static const struct mips_mach_extension mips_mach_32_64[] =
> +{
> +  { bfd_mach_mipsisa64r6, bfd_mach_mipsisa32r6 },
> +  { bfd_mach_mipsisa64r5, bfd_mach_mipsisa32r5 },
> +  { bfd_mach_mipsisa64r3, bfd_mach_mipsisa32r3 },
> +  { bfd_mach_mipsisa64r2, bfd_mach_mipsisa32r2 },
> +  { bfd_mach_mipsisa64,   bfd_mach_mipsisa32 }
> +};
>  
>  /* An array describing how BFD machines relate to one another.  The entries
>     are ordered topologically with MIPS I extensions listed last.  */
> @@ -14584,27 +14594,35 @@ static const struct mips_mach_extension mips_mach_extensions[] =
>  
>  /* Return true if bfd machine EXTENSION is an extension of machine BASE.  */
>  
> +static bool
> +mips_mach_extends_32_64 (unsigned long base, unsigned long extension)
> +{
> +  size_t i;
> +
> +  if (extension == base)
> +    return true;
> +
> +  for (i = 0; i < ARRAY_SIZE (mips_mach_64_32); i++)
> +    if (extension == mips_mach_32_64[i].extension)
> +      return base == mips_mach_32_64[i].base;
> +
> +  return false;
> +}
> +

I think this should go before the "Return true if..." comment and should
have its own comment.  How about:

/* Return true if bfd machine EXTENSION is the same as BASE, or if
   EXTENSION is the 64-bit equivalent of a 32-bit BASE.  */

OK with those changes, thanks.

Richard

>  static bool
>  mips_mach_extends_p (unsigned long base, unsigned long extension)
>  {
>    size_t i;
> +  unsigned long extension1 = extension;
>  
> -  if (extension == base)
> -    return true;
> -
> -  if (base == bfd_mach_mipsisa32
> -      && mips_mach_extends_p (bfd_mach_mipsisa64, extension))
> -    return true;
> -
> -  if (base == bfd_mach_mipsisa32r2
> -      && mips_mach_extends_p (bfd_mach_mipsisa64r2, extension))
> +  if (mips_mach_extends_32_64 (base, extension))
>      return true;
>  
>    for (i = 0; i < ARRAY_SIZE (mips_mach_extensions); i++)
>      if (extension == mips_mach_extensions[i].extension)
>        {
>  	extension = mips_mach_extensions[i].base;
> -	if (extension == base)
> +	if (mips_mach_extends_32_64 (base, extension))
>  	  return true;
>        }