[PATCH] Add support for sparc GOTDATA optimizations in Gold.

[Ian Lance Taylor]

David Miller <davem@davemloft.net> writes:

> gold/
>
> 	* sparc.cc (Target_sparc::got_address): New function.
> 	(Sparc_relocate_functions::gdop_hix22): New function.
> 	(Sparc_relocate_functions::gdop_lox10): New function.
> 	(Target_sparc::Scan::local): Do not emit a GOT entry for GOTDATA
> 	relocs.
> 	(Target_sparc::Scan::local): Likewise if the global symbol is not
> 	preemptible and is not IFUNC.
> 	(Target_sparc::Relocate::relocate): Perform GOTDATA code
> 	transformations for local and non-preemptible non-IFUNC global
> 	symbols.

> +  // R_SPARC_GOTDATA_OP_HIX22: @gdopoff(Symbol + Addend) >> 10
> +  static inline void
> +  gdop_hix22(unsigned char* view,
> +	     typename elfcpp::Elf_types<size>::Elf_Addr value,
> +	     typename elfcpp::Elf_types<size>::Elf_Addr addend)
> +  {
> +    typedef typename elfcpp::Swap<32, true>::Valtype Valtype;
> +    Valtype* wv = reinterpret_cast<Valtype*>(view);
> +    Valtype val = elfcpp::Swap<32, true>::readval(wv);
> +    int32_t reloc = (value + addend);
> +
> +    val &= ~0x3fffff;
> +
> +    if (reloc < 0)
> +      reloc ^= ~(Valtype)0;
> +    reloc >>= 10;
> +
> +    reloc &= 0x3fffff;
> +
> +    elfcpp::Swap<32, true>::writeval(wv, val | reloc);
> +  }

I think I would change the line setting reloc to
    int32_t reloc = static_cast<int32_t>(value + addend);
to make clear that you are intentionally dropping some bits for the
64-bit target.

The line
    reloc ^= ~(Valtype)0;
should probably be
    reloc ^= ~static_cast<int32_t>(0);
or perhaps even, for extreme clarity,
    reloc = static_cast<int32_t>(static_cast<uint32_t>(reloc) 
                                 ^ static_cast<uint32_t>(0));
to avoid bit operations on signed types.

This is OK with changes along those lines.

Thanks.

Ian