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Re: IVOPT improvement patch


This looks fine to me -- Zdenek or other reviewers --- is this one ok?

Thanks,

David

On Fri, Jul 30, 2010 at 8:45 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, Jul 29, 2010 at 6:04 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> It looks strange:
>>
>> + ? ? ?width = (GET_MODE_BITSIZE (address_mode) < ?HOST_BITS_PER_WIDE_INT - 1)
>> + ? ? ? ? ?? GET_MODE_BITSIZE (address_mode) : HOST_BITS_PER_WIDE_INT - 1;
>> ? ? ? addr = gen_rtx_fmt_ee (PLUS, address_mode, reg1, NULL_RTX);
>> - ? ? ?for (i = start; i <= 1 << 20; i <<= 1)
>> + ? ? ?for (i = 1; i < width; i++)
>> ? ? ? ?{
>> - ? ? ? ? XEXP (addr, 1) = gen_int_mode (i, address_mode);
>> + ? ? ? ? ?HOST_WIDE_INT offset = (1ll << i);
>> + ? ? ? ? XEXP (addr, 1) = gen_int_mode (offset, address_mode);
>> ? ? ? ? ?if (!memory_address_addr_space_p (mem_mode, addr, as))
>> ? ? ? ? ? ?break;
>> ? ? ? ?}
>>
>> HOST_WIDE_INT may be long or long long. "1ll" isn't always correct.
>> I think width can be >= 31. Depending on HOST_WIDE_INT,
>>
>> HOST_WIDE_INT offset = -(1ll << i);
>>
>> may have different values. The whole function looks odd to me.
>>
>>
>
> Here is a different approach to check address overflow.
>
>
> --
> H.J.
> --
> 2010-07-29 ?H.J. Lu ?<hongjiu.lu@intel.com>
>
> ? ? ? ?PR bootstrap/45119
> ? ? ? ?* tree-ssa-loop-ivopts.c (get_address_cost): Re-apply revision
> ? ? ? ?162652. ?Check address overflow.
>


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