Make vectoriser use operand_equal_p to compare base addresses

[H.J. Lu]

On Tue, Apr 19, 2011 at 7:59 AM, Richard Sandiford
<richard.sandiford@linaro.org> wrote:
> In the attached testcase, we treat:
>
>    sum += x[i][0] * x[i][0] + x[i][1] * x[i][1];
>
> as being two independent strided loads: x[i][0] and x[i][1].
> On targets with appropriate support, we therefore use two interleaved
> loads rather than one, then discard one half of each result.
> This does not happen if bar() is compiled on its own.
>
> The code before vectorisation looks like this:
>
> <bb 3>:
>  i.0_5 = (unsigned int) i_32;
>  D.3532_6 = i.0_5 * 320;
>  D.3533_8 = x_7(D) + D.3532_6;
>
> <bb 4>:
>  i.1_14 = (unsigned int) i_34;
>  D.3559_15 = i.1_14 * 8;
>  D.3558_16 = D.3533_8 + D.3559_15;
>  D.3557_17 = *D.3558_16[0];
>  D.3555_19 = *D.3558_16[1];
>  ...
>
> The two DR_BASE_ADDRESSES are therefore the expansion of D.3558_8:
>
>    x_7(D) + (unsigned int) i_32 * 320
>
> which we don't think are equal.  The comment in tree-data-refs.h
> made me think that (unsigned int) i_32 * 320 ought really to be
> in the DR_OFFSET, but that only seems to apply to offsets that
> occur in the memory reference itself.
>
> Fixed by using operand_equal_p to compare base addresses.
> Tested on x86_64-linux-gnu and arm-linux-gnueabi.  OK to install?
>
> I've not made the test dependent on a target selector because
> it seemed like the message should be printed regardless.
>
> Richard
>
>
> gcc/
>        * tree-vect-data-refs.c (vect_drs_dependent_in_basic_block): Use
>        operand_equal_p to compare DR_BASE_ADDRESSes.
>        (vect_check_interleaving): Likewise.
>

This caused:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53366

-- 
H.J.