Thanks for the comments.
> On 2 Aug 2024, at 8:36 pm, Richard Biener <richard.guent...@gmail.com> wrote:
>
> External email: Use caution opening links or attachments
>
>
> On Fri, Aug 2, 2024 at 11:20 AM Kugan Vivekanandarajah
> <kvivekana...@nvidia.com> wrote:
>>
>>
>>
>>> On 1 Aug 2024, at 10:46 pm, Richard Biener <richard.guent...@gmail.com>
>>> wrote:
>>>
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> On Thu, Aug 1, 2024 at 5:31 AM Kugan Vivekanandarajah
>>> <kvivekana...@nvidia.com> wrote:
>>>>
>>>>
>>>> On Mon, Jul 29, 2024 at 10:11 AM Andrew Pinski <pins...@gmail.com> wrote:
>>>>>
>>>>> On Mon, Jul 29, 2024 at 12:57 AM Kugan Vivekanandarajah
>>>>> <kugan...@gmail.com> wrote:
>>>>>>
>>>>>> On Thu, Jul 25, 2024 at 10:19 PM Richard Biener
>>>>>> <richard.guent...@gmail.com> wrote:
>>>>>>>
>>>>>>> On Thu, Jul 25, 2024 at 4:42 AM Kugan Vivekanandarajah
>>>>>>> <kugan...@gmail.com> wrote:
>>>>>>>>
>>>>>>>> On Tue, Jul 23, 2024 at 11:56 PM Richard Biener
>>>>>>>> <richard.guent...@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>> On Tue, Jul 23, 2024 at 10:27 AM Kugan Vivekanandarajah
>>>>>>>>> <kugan...@gmail.com> wrote:
>>>>>>>>>>
>>>>>>>>>> On Tue, Jul 23, 2024 at 10:35 AM Andrew Pinski <pins...@gmail.com>
>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>> On Mon, Jul 22, 2024 at 5:26 PM Kugan Vivekanandarajah
>>>>>>>>>>> <kvivekana...@nvidia.com> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Revised based on the comment and moved it into existing patterns
>>>>>>>>>>>> as.
>>>>>>>>>>>>
>>>>>>>>>>>> gcc/ChangeLog:
>>>>>>>>>>>>
>>>>>>>>>>>> * match.pd: Extend A CMP 0 ? A : -A into (type)A CMP 0 ? A : -A.
>>>>>>>>>>>> Extend A CMP 0 ? A : -A into (type) A CMP 0 ? A : -A.
>>>>>>>>>>>>
>>>>>>>>>>>> gcc/testsuite/ChangeLog:
>>>>>>>>>>>>
>>>>>>>>>>>> * gcc.dg/tree-ssa/absfloat16.c: New test.
>>>>>>>>>>>
>>>>>>>>>>> The testcase needs to make sure it runs only for targets that
>>>>>>>>>>> support
>>>>>>>>>>> float16 so like:
>>>>>>>>>>>
>>>>>>>>>>> /* { dg-require-effective-target float16 } */
>>>>>>>>>>> /* { dg-add-options float16 } */
>>>>>>>>>> Added in the attached version.
>>>>>>>>>
>>>>>>>>> + /* (type)A >=/> 0 ? A : -A same as abs (A) */
>>>>>>>>> (for cmp (ge gt)
>>>>>>>>> (simplify
>>>>>>>>> - (cnd (cmp @0 zerop) @1 (negate @1))
>>>>>>>>> - (if (!HONOR_SIGNED_ZEROS (TREE_TYPE(@0))
>>>>>>>>> - && !TYPE_UNSIGNED (TREE_TYPE(@0))
>>>>>>>>> - && bitwise_equal_p (@0, @1))
>>>>>>>>> + (cnd (cmp (convert?@0 @1) zerop) @2 (negate @2))
>>>>>>>>> + (if (!HONOR_SIGNED_ZEROS (TREE_TYPE (@1))
>>>>>>>>> + && !TYPE_UNSIGNED (TREE_TYPE (@1))
>>>>>>>>> + && ((VECTOR_TYPE_P (type)
>>>>>>>>> + && tree_nop_conversion_p (TREE_TYPE (@0), TREE_TYPE
>>>>>>>>> (@1)))
>>>>>>>>> + || (!VECTOR_TYPE_P (type)
>>>>>>>>> + && (TYPE_PRECISION (TREE_TYPE (@1))
>>>>>>>>> + <= TYPE_PRECISION (TREE_TYPE (@0)))))
>>>>>>>>> + && bitwise_equal_p (@1, @2))
>>>>>>>>>
>>>>>>>>> I wonder about the bitwise_equal_p which tests @1 against @2 now
>>>>>>>>> with the convert still applied to @1 - that looks odd. You are
>>>>>>>>> allowing
>>>>>>>>> sign-changing conversions but doesn't that change ge/gt behavior?
>>>>>>>>> Also why are sign/zero-extensions not OK for vector types?
>>>>>>>> Thanks for the review.
>>>>>>>> My main motivation here is for _Float16 as below.
>>>>>>>>
>>>>>>>> _Float16 absfloat16 (_Float16 x)
>>>>>>>> {
>>>>>>>> float _1;
>>>>>>>> _Float16 _2;
>>>>>>>> _Float16 _4;
>>>>>>>> <bb 2> [local count: 1073741824]:
>>>>>>>> _1 = (float) x_3(D);
>>>>>>>> if (_1 < 0.0)
>>>>>>>> goto <bb 3>; [41.00%]
>>>>>>>> else
>>>>>>>> goto <bb 4>; [59.00%]
>>>>>>>> <bb 3> [local count: 440234144]:\
>>>>>>>> _4 = -x_3(D);
>>>>>>>> <bb 4> [local count: 1073741824]:
>>>>>>>> # _2 = PHI <_4(3), x_3(D)(2)>
>>>>>>>> return _2;
>>>>>>>> }
>>>>>>>>
>>>>>>>> This is why I added bitwise_equal_p test of @1 against @2 with
>>>>>>>> TYPE_PRECISION checks.
>>>>>>>> I agree that I will have to check for sign-changing conversions.
>>>>>>>>
>>>>>>>> Just to keep it simple, I disallowed vector types. I am not sure if
>>>>>>>> this would hit vec types. I am happy to handle this if that is
>>>>>>>> needed.
>>>>>>>
>>>>>>> I think with __builtin_convertvector you should be able to construct
>>>>>>> a testcase that does
>>>>>> Thanks.
>>>>>>
>>>>>> For the pattern,
>>>>>> ```
>>>>>> /* A >=/> 0 ? A : -A same as abs (A) */
>>>>>> (for cmp (ge gt)
>>>>>> (simplify
>>>>>> (cnd (cmp @0 zerop) @1 (negate @1))
>>>>>> (if (!HONOR_SIGNED_ZEROS (TREE_TYPE(@0))
>>>>>> && !TYPE_UNSIGNED (TREE_TYPE(@0))
>>>>>> && bitwise_equal_p (@0, @1))
>>>>>> (if (TYPE_UNSIGNED (type))
>>>>>> (absu:type @0)
>>>>>> (abs @0)))))
>>>>>> ```
>>>>>> the vector type doesn't seem right. For example, if we have a 4
>>>>>> element vector with some negative and positive, I don't think it
>>>>>> makes sense. Also, we dont seem to generate (cmp @0 zerop). Am I
>>>>>> missing it completely?
>>>>>
>>>>> Looks like I missed adding some vector testcases anyways here is one
>>>>> to get this, note it is C++ due to the C front-end not support `?:`
>>>>> for vectors yet (there is a patch).
>>>>> ```
>>>>> #define vect8 __attribute__((vector_size(8)))
>>>>> vect8 int f(vect8 int a)
>>>>> {
>>>>> vect8 int na = -a;
>>>>> return (a > 0) ? a : na;
>>>>> }
>>>>> ```
>>>>> At -O2 before forwprop1, we have:
>>>>> ```
>>>>> vector(2) intD.9 a_2(D) = aD.2796;
>>>>> vector(2) intD.9 naD.2799;
>>>>> vector(2) <signed-boolean:32> _1;
>>>>> vector(2) intD.9 _4;
>>>>>
>>>>> na_3 = -a_2(D);
>>>>> _1 = a_2(D) > { 0, 0 };
>>>>> _4 = VEC_COND_EXPR <_1, a_2(D), na_3>;
>>>>> ```
>>>>> And forwprop using match is able to do:
>>>>> ```
>>>>> Applying pattern match.pd:6306, gimple-match-10.cc:19843
>>>>> gimple_simplified to _4 = ABS_EXPR <a_2(D)>;
>>>>> Removing dead stmt:_1 = a_2(D) > { 0, 0 };
>>>>> Removing dead stmt:na_3 = -a_2(D);
>>>>> ```
>>>>> (replace int with float and add -fno-signed-zeros you can get the ABS
>>>>> also).
>>>>>
>>>>> Note comparisons with vector types always generate a vector boolean
>>>>> type. So cond_expr will never show up with a vector comparison; only
>>>>> vec_cond.
>>>>
>>>>
>>>> Thanks for the information. I have revised the patch by adding test case
>>>> for the vector type. I will look at removing the VEC_COND_EXPR as a follow
>>>> up.
>>>
>>> This is likely a major task so do not get you distracted - I just mentioned
>>> it.
>>>
>>>> This is still rejected by the type checker.
>>>> v2hi absvect2 (v2hi x, int i) {
>>>> v2hi neg = -x;
>>>> v2si tmp = __builtin_convertvector (x, v2si);
>>>> return (tmp > 0) ? x : neg;
>>>> }
>>>> as:
>>>> error: incompatible vector types in conditional expression: '__vector(2)
>>>> int', 'v2hi' {aka '__vector(2) short int'} and 'v2hi' {aka '__vector(2)
>>>> short int'}
>>>> 8 | return (tmp > 0) ? x : neg;
>>>> | ~~~~~~~~~~^~~~~~~~~
>>>>
>>>> Also
>>>>
>>>> - (absu:type @0)
>>>> - (abs @0)))))
>>>> + (absu:type @1)
>>>> + (abs @1)))))
>>>>
>>>> Changing the @1 to @2 is resulting in failures. Existing tests like the
>>>> following would be optimized away in this case.
>>>> ```
>>>> unsigned abs_with_convert0 (int x)
>>>> {
>>>> unsigned int y = x;
>>>>
>>>> if (x < 0)
>>>> y = -y;
>>>>
>>>> return y;
>>>> }
>>>
>>> How so - the TYPE_UNSIGNED tests should make the pattern not trigger here?
>>>
>>>> ```
>>>> This follows the same intent as the original pattern.
>>>>
>>>> Bootstrapped and regression tested on aarch64-linux-gnu. Is this OK for
>>>> trunk.
>>>
>>>
>>>
>>> - (cnd (cmp @0 zerop) @1 (negate @1))
>>> - (if (!HONOR_SIGNED_ZEROS (TREE_TYPE(@0))
>>> - && !TYPE_UNSIGNED (TREE_TYPE(@0))
>>> - && bitwise_equal_p (@0, @1))
>>> + (cnd (cmp (convert?@0 @1) zerop) @2 (negate @2))
>>> + (if (!HONOR_SIGNED_ZEROS (TREE_TYPE (@1))
>>> + && !TYPE_UNSIGNED (TREE_TYPE (@1))
>>> + && !TYPE_UNSIGNED (TREE_TYPE (@0))
>>>
>>> I think the outer type could be allowed signed if ...
>>>
>>> + && ((VECTOR_TYPE_P (TREE_TYPE (@0))
>>> + && VECTOR_TYPE_P (TREE_TYPE (@1))
>>> + && known_eq (TYPE_VECTOR_SUBPARTS (TREE_TYPE (@0)),
>>> + TYPE_VECTOR_SUBPARTS (TREE_TYPE (@1)))
>>>
>>> this is always true
>>>
>>> + && element_precision (TREE_TYPE (@1))
>>> + <= element_precision (TREE_TYPE (@0)))
>>> + || (!VECTOR_TYPE_P (TREE_TYPE (@0))
>>> + && (TYPE_PRECISION (TREE_TYPE (@1))
>>> + <= TYPE_PRECISION (TREE_TYPE (@0)))))
>>>
>>> ... you make the precision strictly larger. With both unsigned the same
>>> precision case should have been stripped anyway.
>>>
>>> You can use element_precision for both vector and non-vector so I think this
>>> should simplify to just checking element_precision.
>>>
>>> + (absu:type @1)
>>> + (abs @1)))))
>>>
>>> I still think this needs to be @2 for type correctness. @1 is only
>>> bitwise equal,
>>> it could have different sign. I think we should drop bitwise_equal_p with
>>> the
>>> convert now in and instead have a matching constraint.
>>
>> Thanks, so this should translate to:
>>
>> /* (type)A >=/> 0 ? A : -A same as abs (A) */
>> (for cmp (ge gt)
>> (simplify
>> (cnd (cmp (convert?@0 @1) zerop) @2 (negate @2))
>> (if (!HONOR_SIGNED_ZEROS (TREE_TYPE (@1))
>> && !TYPE_UNSIGNED (TREE_TYPE (@1))
>
> Oh, I mis-read this as unsigned, so this makes the conversions
> to always sign-extend which means it's important to ensure
> the type of @0 is also signed.
>
>> && !TYPE_UNSIGNED (TREE_TYPE (@2))
>> && ((element_precision (TREE_TYPE (@1))
>> < element_precision (TREE_TYPE (@0))
>> || operand_equal_p (@1, @0)))
>
> which means <= might be better then.
>
>
>> && bitwise_equal_p (@1, @2))
>> (if (TYPE_UNSIGNED (type))
>> (absu:type @2)
>> (abs @2)))))
>>
>> However with this, I am seeing: Note that the @2 for these are unsigned.
>
> I see, so we rely on @1 being the signed equivalent of @2 which might or
> might not be signed. I guess that indeed we want @2 here.
Sorry I am not sure I understand this. When @2 is unsigned, ABS_EXPR and
ABSU_EXPR is not
For example:
With
/* (type)A >=/> 0 ? A : -A same as abs (A) */
(for cmp (ge gt)
(simplify
(cnd (cmp (convert?@0 @1) zerop) @2 (negate @2))
(if (!HONOR_SIGNED_ZEROS (TREE_TYPE (@1))
&& !TYPE_UNSIGNED (TREE_TYPE (@0))
&& !TYPE_UNSIGNED (TREE_TYPE (@1))
&& element_precision (TREE_TYPE (@1))
<= element_precision (TREE_TYPE (@0))
&& bitwise_equal_p (@1, @2))
(if (TYPE_UNSIGNED (type))
(absu:type @2)
(abs @2)))))
The test case below becomes:
unsigned abs_with_convert0 (int x)
{
unsigned int y = x;
if (x < 0)
y = -y;
return y;
}
unsigned int abs_with_convert0 (int x)
{
unsigned int y;
<bb 2> :
y_3 = (unsigned int) x_2(D);
if (x_2(D) < 0)
goto <bb 3>; [INV]
else
goto <bb 4>; [INV]
<bb 3> :
y_4 = -y_3;
<bb 4> :
# y_1 = PHI <y_3(2), y_4(3)>
return y_1;
}
To:
unsigned int abs_with_convert0 (int x)
{
unsigned int y;
unsigned int _5;
<bb 2> :
y_3 = (unsigned int) x_2(D);
_5 = ABSU_EXPR <y_3>;
return _5;
}
This is an invalid gimple. Are you suggesting that we should also check if @2
is not UNSIGNED? If that is what you want, couple of test cases in the test
suite including phi-opt-37.c would fail.
Thanks,
Kugan
>
>> Tests that now fail, but worked before (4 tests):
>>
>> gcc: gcc.dg/tree-ssa/phi-opt-36.c scan-tree-dump-not phiopt2 "if "
>> gcc: gcc.dg/tree-ssa/phi-opt-36.c scan-tree-dump-times phiopt1 "if " 2
>> gcc: gcc.dg/tree-ssa/phi-opt-37.c scan-tree-dump-not phiopt1 "if "gcc:
>> gcc.dg/tree-ssa/phi-opt-37.c scan-tree-dump-times phiopt1 "ABSU_EXPR <" 2
>>
>>
>> unsigned f2(int A)
>> {
>> unsigned t = A;
>> // A >= 0? A : -A same as abs (A)
>> if (A >= 0) return t;
>> return -t;
>> }
>>
>> unsigned abs_with_convert0 (int x)
>> {
>> unsigned int y = x;
>>
>> if (x < 0)
>> y = -y;
>>
>> return y;
>> }
>> unsigned abs_with_convert1 (unsigned x)
>> {
>> int y = x;
>>
>> if (y < 0)
>> x = -x;
>>
>> return x;
>> }
>>
>> In the original pattern, we have check for !TYPE_UNSIGNED (TREE_TYPE(@0))
>> and (absu:type @0)
>>
>> Shouldnt that translate !TYPE_UNSIGNED (TREE_TYPE(@1)) and (absu:type @1)
>> in the new pattern
>>
>> Thanks,
>> Kugan
>>
>>>
>>> Same comments apply to the 2nd pattern update.
>>>
>>> Richard.
>>>
>>>> Thanks,
>>>> Kugan
>>>>
>>>> gcc/ChangeLog:
>>>>
>>>> * match.pd: Extend A CMP 0 ? A : -A into (type)A CMP 0 ? A : -A.
>>>> Extend A CMP 0 ? A : -A into (type) A CMP 0 ? A : -A.
>>>>
>>>> gcc/testsuite/ChangeLog:
>>>>
>>>> * g++.dg/absvect.C: New test.
>>>> * gcc.dg/tree-ssa/absfloat16.c: New test.
>>>>
>>>>
>>>> signed-off-by: Kugan Vivekanandarajah <kvivekana...@nvidia.com>
>>>>
>>>>
>>>> Note I think we should be able to merge VEC_COND_EXPR and COND_EXPR
>>>> codes by instead looking whether the condition is vector or scalar.
>>>> Fallout
>>>> might be a bit too big, but it might be a thing to try.
>>>>
>>>> Richard.
>>>>
>>>>> Thanks,
>>>>> Andrew Pinski
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Kugan
>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> + (absu:type @1)
>>>>>>>>> + (abs @1)))))
>>>>>>>>>
>>>>>>>>> I think this should use @2 now.
>>>>>>>> I will change this.
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Kugan
>>>>>>>>
>>>>>>>>>
>>>>>>>>>> Thanks.
>>>>>>>>>> Kugan
>>>>>>>>>>>
>>>>>>>>>>> (like what is in gcc.dg/c11-floatn-3.c and others).
>>>>>>>>>>>
>>>>>>>>>>> Other than that it looks good but I can't approve it.
>>>>>>>>>>>
>>>>>>>>>>> Thanks,
>>>>>>>>>>> Andrew Pinski
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Signed-off-by: Kugan Vivekanandarajah <kvivekana...@nvidia.com>
>>>>>>>>>>>>
>>>>>>>>>>>> Bootstrapped and regression test on aarch64-linux-gnu. Is this OK
>>>>>>>>>>>> for trunk?
>>>>>>>>>>>> Thanks,
>>>>>>>>>>>> Kugan
>>>>>>>>>>>>
>>>>>>>>>>>> ________________________________
>>>>>>>>>>>> From: Andrew Pinski <pins...@gmail.com>
>>>>>>>>>>>> Sent: Monday, 15 July 2024 5:30 AM
>>>>>>>>>>>> To: Kugan Vivekanandarajah <kvivekana...@nvidia.com>
>>>>>>>>>>>> Cc: gcc-patches@gcc.gnu.org <gcc-patches@gcc.gnu.org>;
>>>>>>>>>>>> richard.guent...@gmail.com <richard.guent...@gmail.com>
>>>>>>>>>>>> Subject: Re: [PATCH] MATCH: add abs support for half float
>>>>>>>>>>>>
>>>>>>>>>>>> External email: Use caution opening links or attachments
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On Sun, Jul 14, 2024 at 1:12 AM Kugan Vivekanandarajah
>>>>>>>>>>>> <kvivekana...@nvidia.com> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>> This patch extends abs detection in matched for half float.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Bootstrapped and regression test on aarch64-linux-gnu. Is this OK
>>>>>>>>>>>>> for trunk?
>>>>>>>>>>>>
>>>>>>>>>>>> This is basically this pattern:
>>>>>>>>>>>> ```
>>>>>>>>>>>> /* A >=/> 0 ? A : -A same as abs (A) */
>>>>>>>>>>>> (for cmp (ge gt)
>>>>>>>>>>>> (simplify
>>>>>>>>>>>> (cnd (cmp @0 zerop) @1 (negate @1))
>>>>>>>>>>>> (if (!HONOR_SIGNED_ZEROS (TREE_TYPE(@0))
>>>>>>>>>>>> && !TYPE_UNSIGNED (TREE_TYPE(@0))
>>>>>>>>>>>> && bitwise_equal_p (@0, @1))
>>>>>>>>>>>> (if (TYPE_UNSIGNED (type))
>>>>>>>>>>>> (absu:type @0)
>>>>>>>>>>>> (abs @0)))))
>>>>>>>>>>>> ```
>>>>>>>>>>>>
>>>>>>>>>>>> except extended to handle an optional convert. Why didn't you just
>>>>>>>>>>>> extend the above pattern to handle the convert instead? Also I
>>>>>>>>>>>> think
>>>>>>>>>>>> you have an issue with unsigned types with the comparison.
>>>>>>>>>>>> Also you should extend the -abs(A) pattern right below it in a
>>>>>>>>>>>> similar fashion.
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks,
>>>>>>>>>>>> Andrew Pinski
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> gcc/ChangeLog:
>>>>>>>>>>>>>
>>>>>>>>>>>>> * match.pd: Add pattern to convert (type)A >=/> 0 ? A : -A into
>>>>>>>>>>>>> abs (A) for half float.
>>>>>>>>>>>>>
>>>>>>>>>>>>> gcc/testsuite/ChangeLog:
>>>>>>>>>>>>>
>>>>>>>>>>>>> * gcc.dg/tree-ssa/absfloat16.c: New test.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Signed-off-by: Kugan Vivekanandarajah <kvivekana...@nvidia.com>
