2015-02-25 12:35 GMT+01:00 Richard Biener <richard.guent...@gmail.com>:
> On Wed, Feb 25, 2015 at 12:05 PM, Kai Tietz <ktiet...@googlemail.com> wrote:
>> 2015-02-25 11:57 GMT+01:00 Richard Biener <richard.guent...@gmail.com>:
>>> On Wed, Feb 25, 2015 at 11:06 AM, Kai Tietz <ktiet...@googlemail.com> wrote:
>>>> Hello,
>>>>
>>>> ChangeLog
>>>>
>>>> 2015-02-25 Kai Tietz <kti...@redhat.com>
>>>>
>>>> PR tree-optimization/61917
>>>> * tree-vect-loop.c (vectorizable_reduction): Allow
>>>> vect_internal_def without reduction to exit graceful.
>>>>
>>>> ChagneLog testsuite/
>>>>
>>>> 2015-02-25 Kai Tietz <kti...@redhat.com>
>>>>
>>>> PR tree-optimization/61917
>>>> * gcc.dg/vect/vect-pr61917.c: New file.
>>>>
>>>> Tested for x86_64-unkown-linux. Ok for apply?
>>>
>>> It doesn't make much sense to fail here as said in the comment
>>> because of patterns if the actual case isn't a pattern. Also
>>> the patch causing this made vect_external_def possible, so
>>> why does this affect vect_internal_def here?
>>>
>>> It may paper over the issue - but clearly the fix is bogus.
>>
>> Well, actually I don't see any good reason for failing here at all,
>> but I assumed that author wanted to get by it some missed cases.
>> AFAIU the code we actually don't need/want to assert here either on
>> internal (where it is pretty likely no pattern present), and also on
>> externals, too.
>> I would be fine to remove this assert here completely, but I thought
>> it might be of interest to see that orig_stmt isn't NULL for nested
>> case
>
> I agree that the code is overusing asserts but the path you bail out
> on is bogus. Fact is that we somehow detected a reduction here
> (via special-casing of minus I guess) but fail to properly handle it
> later. In fact we assert that we end up with a PHI node in the definition
> but would ICE there as well. Thus a better patch would be
>
> Index: gcc/tree-vect-loop.c
> ===================================================================
> --- gcc/tree-vect-loop.c (revision 220958)
> +++ gcc/tree-vect-loop.c (working copy)
> @@ -4981,6 +4981,13 @@ vectorizable_reduction (gimple stmt, gim
> if (!vectype_in)
> vectype_in = tem;
> gcc_assert (is_simple_use);
> +
> + /* If the defining stmt isn't a PHI node then this isn't a reduction. */
> + if (!found_nested_cycle_def)
> + reduc_def_stmt = def_stmt;
> + if (gimple_code (reduc_def_stmt) != GIMPLE_PHI)
> + return false;
> +
> if (!(dt == vect_reduction_def
> || dt == vect_nested_cycle
> || ((dt == vect_internal_def || dt == vect_external_def
> @@ -4993,10 +5000,7 @@ vectorizable_reduction (gimple stmt, gim
> gcc_assert (orig_stmt);
> return false;
> }
> - if (!found_nested_cycle_def)
> - reduc_def_stmt = def_stmt;
>
> - gcc_assert (gimple_code (reduc_def_stmt) == GIMPLE_PHI);
> if (orig_stmt)
> gcc_assert (orig_stmt == vect_is_simple_reduction (loop_vinfo,
> reduc_def_stmt,
>
> Richard.
Yes, your version is better for reader and shows the intention better.
I will give it a test.
Kai
>>> Richard.
>>>
>>>> Regards,
>>>> Kai
>>>>
>>>> Index: tree-vect-loop.c
>>>> ===================================================================
>>>> --- tree-vect-loop.c (Revision 220958)
>>>> +++ tree-vect-loop.c (Arbeitskopie)
>>>> @@ -4990,7 +4990,7 @@ vectorizable_reduction (gimple stmt, gimple_stmt_i
>>>> /* For pattern recognized stmts, orig_stmt might be a reduction,
>>>> but some helper statements for the pattern might not, or
>>>> might be COND_EXPRs with reduction uses in the condition. */
>>>> - gcc_assert (orig_stmt);
>>>> + gcc_assert (orig_stmt || dt == vect_internal_def);
>>>> return false;
>>>> }
>>>> if (!found_nested_cycle_def)
>>>> Index: gcc/gcc/testsuite/gcc.dg/vect/vect-pr61917.c
>>>> ===================================================================
>>>> --- /dev/null
>>>> +++ gcc/gcc/testsuite/gcc.dg/vect/vect-pr61917.c
>>>> @@ -0,0 +1,13 @@
>>>> +/* { dg-do compile } */
>>>> +/* { dg-additional-options "-O3" } */
>>>> +
>>>> +int a, b, c, d;
>>>> +
>>>> +int
>>>> +fn1 ()
>>>> +{
>>>> + for (; c; c++)
>>>> + for (b = 0; b < 2; b++)
>>>> + d = a - d;
>>>> + return d;
>>>> +}
