On Thu, Nov 7, 2013 at 6:47 PM, Richard Biener
<richard.guent...@gmail.com> wrote:
> On Wed, Nov 6, 2013 at 6:06 PM, Richard Sandiford
> <rdsandif...@googlemail.com> wrote:
>> Hi,
>>
>> "bin.cheng" <bin.ch...@arm.com> writes:
>>> Index: gcc/tree-ssa-loop-ivopts.c
>>> ===================================================================
>>> --- gcc/tree-ssa-loop-ivopts.c (revision 203267)
>>> +++ gcc/tree-ssa-loop-ivopts.c (working copy)
>>> @@ -2037,12 +2037,12 @@ find_interesting_uses (struct ivopts_data *data)
>>>
>>> static tree
>>> strip_offset_1 (tree expr, bool inside_addr, bool top_compref,
>>> - unsigned HOST_WIDE_INT *offset)
>>> + HOST_WIDE_INT *offset)
>>> {
>>> tree op0 = NULL_TREE, op1 = NULL_TREE, tmp, step;
>>> enum tree_code code;
>>> tree type, orig_type = TREE_TYPE (expr);
>>> - unsigned HOST_WIDE_INT off0, off1, st;
>>> + HOST_WIDE_INT off0, off1, st;
>>> tree orig_expr = expr;
>>>
>>> STRIP_NOPS (expr);
>>> @@ -2133,19 +2133,32 @@ strip_offset_1 (tree expr, bool inside_addr, bool
>>> break;
>>>
>>> case COMPONENT_REF:
>>> - if (!inside_addr)
>>> - return orig_expr;
>>> + {
>>> + tree field;
>>>
>>> - tmp = component_ref_field_offset (expr);
>>> - if (top_compref
>>> - && cst_and_fits_in_hwi (tmp))
>>> - {
>>> - /* Strip the component reference completely. */
>>> - op0 = TREE_OPERAND (expr, 0);
>>> - op0 = strip_offset_1 (op0, inside_addr, top_compref, &off0);
>>> - *offset = off0 + int_cst_value (tmp);
>>> - return op0;
>>> - }
>>> + if (!inside_addr)
>>> + return orig_expr;
>>> +
>>> + tmp = component_ref_field_offset (expr);
>>> + field = TREE_OPERAND (expr, 1);
>>> + if (top_compref
>>> + && cst_and_fits_in_hwi (tmp)
>>> + && cst_and_fits_in_hwi (DECL_FIELD_BIT_OFFSET (field)))
>>
>> While comparing output for wide-int and mainline, I noticed that
>> this condition is now always false on x86_64, since DECL_FIELD_BIT_OFFSET
>> is a 128-bit bitsizetype and since cst_and_fits_in_hwi rejects constants
>> with precision greater than HWI:
>>
>> if (TREE_CODE (x) != INTEGER_CST)
>> return false;
>>
>> if (TYPE_PRECISION (TREE_TYPE (x)) > HOST_BITS_PER_WIDE_INT)
>> return false;
>
> I think that's simply overly restrictive on the side of cst_and_fits_in_hwi.
> I suppose this function is meant to complement int_cst_value (digging
> in history might be nice here).
>
>> Should this be host_integerp (DECL_FIELD_BIT_OFFSET (field), 0) instead?
>
> That's not the same as it rejects -1U. The function seems to ask
> if the value, if casted to unsigned fits in a HOST_WIDE_INT.
>
> So just drop the precision check from cst_and_fits_in_hwi.
Hi,
With check in of patch lowering address expression in ivo, that piece
of code won't be executed anymore. So still need to drop precision
check in cst_and_fits_in_hwi? The major part of strip_offset_1 can be
cleaned now.
Thanks,
bin
--
Best Regards.
