Re: [PATCH] PR gold/18695

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Wed, Aug 26, 2015 at 6:11 AM, Andrew Senkevich
<andrew.n.senkevich@gmail.com> wrote:
> Hi,
>
> is this patch ok?
>
> 2015-08-26  Andrew Senkevich  <andrew.senkevich@intel.com>
>
>         PR gold/18695
>         * x86_64.cc: Overflow checks added.
>
> diff --git a/gold/x86_64.cc b/gold/x86_64.cc
> index 007af1d..2d0712f 100644
> --- a/gold/x86_64.cc
> +++ b/gold/x86_64.cc
> @@ -3320,6 +3320,32 @@ Target_x86_64<size>::do_finalize_sections(
>      }
>  }
>
> +template<int size, int valsize>
> +class x86_64_overflow_check
> +{
> +public:
> +  typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
> +
> +  static inline bool
> +  has_overflow_signed(Address value)
> +  {
> +    // limit = 1 << (valsize - 1) without shift count exceeding size of type
> +    Address limit = static_cast<Address>(1) << ((valsize - 1) >> 1);
> +    limit <<= ((valsize - 1) >> 1);
> +    limit <<= ((valsize - 1) - 2 * ((valsize - 1) >> 1));
> +    return value + limit > (limit << 1) - 1;
> +  }
> +
> +  static inline bool
> +  has_overflow_unsigned(Address value)
> +  {
> +    Address limit = static_cast<Address>(1) << ((valsize - 1) >> 1);
> +    limit <<= ((valsize - 1) >> 1);
> +    limit <<= ((valsize - 1) - 2 * ((valsize - 1) >> 1));
> +    return value > (limit << 1) - 1;
> +  }
> +};
> +
>  // Perform a relocation.

Shouldn't there be generic address overflow checks which can be used
by all targets?

-- 
H.J.