[RFC,PR64946] "abs" vectorization fails for char/short types

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  • [RFC,PR64946] "abs" vectorization fails for char/short types
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Commit Message

Kugan Vivekanandarajah May 17, 2018, 2:14 a.m.
As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
issue. In the attached patch, in fold_cond_expr_with_comparison I am
generating ABSU_EXPR for these cases. As I understand, absu_expr is
well defined in RTL. So, the issue is generating absu_expr  and
transferring to RTL in the correct way. I am not sure I am not doing
all that is needed. I will clean up and add more test-cases based on
the feedback.

Thanks,
Kugan


gcc/ChangeLog:

2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>

    * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
    * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
    (fold_unary_loc): Handle ABSU_EXPR.
    * optabs-tree.c (optab_for_tree_code): Likewise.
    * tree-cfg.c (verify_expr): Likewise.
    (verify_gimple_assign_unary):  Likewise.
    * tree-if-conv.c (fold_build_cond_expr):  Likewise.
    * tree-inline.c (estimate_operator_cost):  Likewise.
    * tree-pretty-print.c (dump_generic_node):  Likewise.
    * tree.def (ABSU_EXPR): New.

gcc/testsuite/ChangeLog:

2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>

    * gcc.dg/absu.c: New test.

Comments

Andrew Pinski May 17, 2018, 2:56 a.m. | #1
On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
<kugan.vivekanandarajah@linaro.org> wrote:
> As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
> issue. In the attached patch, in fold_cond_expr_with_comparison I am
> generating ABSU_EXPR for these cases. As I understand, absu_expr is
> well defined in RTL. So, the issue is generating absu_expr  and
> transferring to RTL in the correct way. I am not sure I am not doing
> all that is needed. I will clean up and add more test-cases based on
> the feedback.


diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
index 71e172c..2b812e5 100644
--- a/gcc/optabs-tree.c
+++ b/gcc/optabs-tree.c
@@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code, const_tree type,
       return trapv ? negv_optab : neg_optab;

     case ABS_EXPR:
+    case ABSU_EXPR:
       return trapv ? absv_optab : abs_optab;


This part is not correct, it should something like this:

     case ABS_EXPR:
       return trapv ? absv_optab : abs_optab;
+    case ABSU_EXPR:
+       return abs_optab ;

Because ABSU is not undefined at the TYPE_MAX.

Thanks,
Andrew

>
> Thanks,
> Kugan
>
>
> gcc/ChangeLog:
>
> 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>
>     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
>     * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
>     (fold_unary_loc): Handle ABSU_EXPR.
>     * optabs-tree.c (optab_for_tree_code): Likewise.
>     * tree-cfg.c (verify_expr): Likewise.
>     (verify_gimple_assign_unary):  Likewise.
>     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
>     * tree-inline.c (estimate_operator_cost):  Likewise.
>     * tree-pretty-print.c (dump_generic_node):  Likewise.
>     * tree.def (ABSU_EXPR): New.
>
> gcc/testsuite/ChangeLog:
>
> 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>
>     * gcc.dg/absu.c: New test.
Richard Biener May 17, 2018, 10:36 a.m. | #2
On Thu, May 17, 2018 at 4:56 AM Andrew Pinski <pinskia@gmail.com> wrote:

> On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
> <kugan.vivekanandarajah@linaro.org> wrote:
> > As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
> > issue. In the attached patch, in fold_cond_expr_with_comparison I am
> > generating ABSU_EXPR for these cases. As I understand, absu_expr is
> > well defined in RTL. So, the issue is generating absu_expr  and
> > transferring to RTL in the correct way. I am not sure I am not doing
> > all that is needed. I will clean up and add more test-cases based on
> > the feedback.


> diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
> index 71e172c..2b812e5 100644
> --- a/gcc/optabs-tree.c
> +++ b/gcc/optabs-tree.c
> @@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code, const_tree
type,
>         return trapv ? negv_optab : neg_optab;

>       case ABS_EXPR:
> +    case ABSU_EXPR:
>         return trapv ? absv_optab : abs_optab;


> This part is not correct, it should something like this:

>       case ABS_EXPR:
>         return trapv ? absv_optab : abs_optab;
> +    case ABSU_EXPR:
> +       return abs_optab ;

> Because ABSU is not undefined at the TYPE_MAX.

Also

        /* Unsigned abs is simply the operand.  Testing here means we don't
          risk generating incorrect code below.  */
-      if (TYPE_UNSIGNED (type))
+      if (TYPE_UNSIGNED (type)
+         && (code != ABSU_EXPR))
         return op0;

is wrong.  ABSU of an unsigned number is still just that number.

The change to fold_cond_expr_with_comparison looks odd to me
(premature optimization).  It should be done separately - it seems
you are doing

(simplify (abs (convert @0)) (convert (absu @0)))

here.

You touch one other place in fold-const.c but there seem to be many
more that need ABSU_EXPR handling (you touched the one needed
for correctness) - esp. you should at least handle constant folding
in const_unop and the nonnegative predicate.

@@ -3167,6 +3167,9 @@ verify_expr (tree *tp, int *walk_subtrees, void *data
ATTRIBUTE_UNUSED)
        CHECK_OP (0, "invalid operand to unary operator");
        break;

+    case ABSU_EXPR:
+      break;
+
      case REALPART_EXPR:
      case IMAGPART_EXPR:

verify_expr is no more.  Did you test this recently against trunk?

@@ -3937,6 +3940,9 @@ verify_gimple_assign_unary (gassign *stmt)
      case PAREN_EXPR:
      case CONJ_EXPR:
        break;
+    case ABSU_EXPR:
+      /* FIXME.  */
+      return false;

no - please not!  Please add verification here - ABSU should be only
called on INTEGRAL, vector or complex INTEGRAL types and the
type of the LHS should be always the unsigned variant of the
argument type.

    if (is_gimple_val (cond_expr))
      return cond_expr;

-  if (TREE_CODE (cond_expr) == ABS_EXPR)
+  if (TREE_CODE (cond_expr) == ABS_EXPR
+      || TREE_CODE (cond_expr) == ABSU_EXPR)
      {
        rhs1 = TREE_OPERAND (cond_expr, 1);
        STRIP_USELESS_TYPE_CONVERSION (rhs1);

err, but the next line just builds a ABS_EXPR ...

How did you identify spots that need adjustment?  I would expect that
once folding generates ABSU_EXPR that you need to adjust frontends
(C++ constexpr handling for example).  Also I miss adjustments
to gimple-pretty-print.c and the GIMPLE FE parser.

recursively grepping throughout the whole gcc/ tree doesn't reveal too many
cases of ABS_EXPR so I think it's reasonable to audit all of them.

I also miss some trivial absu simplifications in match.pd.  There are not
a lot of abs cases but similar ones would be good to have initially.

Thanks for tackling this!
Richard.

> Thanks,
> Andrew

> >
> > Thanks,
> > Kugan
> >
> >
> > gcc/ChangeLog:
> >
> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >
> >     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
> >     * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
> >     (fold_unary_loc): Handle ABSU_EXPR.
> >     * optabs-tree.c (optab_for_tree_code): Likewise.
> >     * tree-cfg.c (verify_expr): Likewise.
> >     (verify_gimple_assign_unary):  Likewise.
> >     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
> >     * tree-inline.c (estimate_operator_cost):  Likewise.
> >     * tree-pretty-print.c (dump_generic_node):  Likewise.
> >     * tree.def (ABSU_EXPR): New.
> >
> > gcc/testsuite/ChangeLog:
> >
> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >
> >     * gcc.dg/absu.c: New test.
Kugan Vivekanandarajah May 18, 2018, 2:36 a.m. | #3
Hi Richard,

Thanks for the review. I am revising the patch based on Andrew's comments too.

On 17 May 2018 at 20:36, Richard Biener <richard.guenther@gmail.com> wrote:
> On Thu, May 17, 2018 at 4:56 AM Andrew Pinski <pinskia@gmail.com> wrote:
>
>> On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
>> <kugan.vivekanandarajah@linaro.org> wrote:
>> > As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
>> > issue. In the attached patch, in fold_cond_expr_with_comparison I am
>> > generating ABSU_EXPR for these cases. As I understand, absu_expr is
>> > well defined in RTL. So, the issue is generating absu_expr  and
>> > transferring to RTL in the correct way. I am not sure I am not doing
>> > all that is needed. I will clean up and add more test-cases based on
>> > the feedback.
>
>
>> diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
>> index 71e172c..2b812e5 100644
>> --- a/gcc/optabs-tree.c
>> +++ b/gcc/optabs-tree.c
>> @@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code, const_tree
> type,
>>         return trapv ? negv_optab : neg_optab;
>
>>       case ABS_EXPR:
>> +    case ABSU_EXPR:
>>         return trapv ? absv_optab : abs_optab;
>
>
>> This part is not correct, it should something like this:
>
>>       case ABS_EXPR:
>>         return trapv ? absv_optab : abs_optab;
>> +    case ABSU_EXPR:
>> +       return abs_optab ;
>
>> Because ABSU is not undefined at the TYPE_MAX.
>
> Also
>
>         /* Unsigned abs is simply the operand.  Testing here means we don't
>           risk generating incorrect code below.  */
> -      if (TYPE_UNSIGNED (type))
> +      if (TYPE_UNSIGNED (type)
> +         && (code != ABSU_EXPR))
>          return op0;
>
> is wrong.  ABSU of an unsigned number is still just that number.
>
> The change to fold_cond_expr_with_comparison looks odd to me
> (premature optimization).  It should be done separately - it seems
> you are doing

FE seems to be using this to generate ABS_EXPR from
c_fully_fold_internal to fold_build3_loc and so on. I changed this to
generate ABSU_EXPR for the case in the testcase. So the question
should be, in what cases do we need ABS_EXPR and in what cases do we
need ABSU_EXPR. It is not very clear to me.


>
> (simplify (abs (convert @0)) (convert (absu @0)))
>
> here.
>
> You touch one other place in fold-const.c but there seem to be many
> more that need ABSU_EXPR handling (you touched the one needed
> for correctness) - esp. you should at least handle constant folding
> in const_unop and the nonnegative predicate.

OK.
>
> @@ -3167,6 +3167,9 @@ verify_expr (tree *tp, int *walk_subtrees, void *data
> ATTRIBUTE_UNUSED)
>         CHECK_OP (0, "invalid operand to unary operator");
>         break;
>
> +    case ABSU_EXPR:
> +      break;
> +
>       case REALPART_EXPR:
>       case IMAGPART_EXPR:
>
> verify_expr is no more.  Did you test this recently against trunk?

This patch is against slightly older trunk. I will rebase it.

>
> @@ -3937,6 +3940,9 @@ verify_gimple_assign_unary (gassign *stmt)
>       case PAREN_EXPR:
>       case CONJ_EXPR:
>         break;
> +    case ABSU_EXPR:
> +      /* FIXME.  */
> +      return false;
>
> no - please not!  Please add verification here - ABSU should be only
> called on INTEGRAL, vector or complex INTEGRAL types and the
> type of the LHS should be always the unsigned variant of the
> argument type.

OK.
>
>     if (is_gimple_val (cond_expr))
>       return cond_expr;
>
> -  if (TREE_CODE (cond_expr) == ABS_EXPR)
> +  if (TREE_CODE (cond_expr) == ABS_EXPR
> +      || TREE_CODE (cond_expr) == ABSU_EXPR)
>       {
>         rhs1 = TREE_OPERAND (cond_expr, 1);
>         STRIP_USELESS_TYPE_CONVERSION (rhs1);
>
> err, but the next line just builds a ABS_EXPR ...
>
> How did you identify spots that need adjustment?  I would expect that
> once folding generates ABSU_EXPR that you need to adjust frontends
> (C++ constexpr handling for example).  Also I miss adjustments
> to gimple-pretty-print.c and the GIMPLE FE parser.

I will add this.
>
> recursively grepping throughout the whole gcc/ tree doesn't reveal too many
> cases of ABS_EXPR so I think it's reasonable to audit all of them.
>
> I also miss some trivial absu simplifications in match.pd.  There are not
> a lot of abs cases but similar ones would be good to have initially.

I will add them in the next version.

Thanks,
Kugan

>
> Thanks for tackling this!
> Richard.
>
>> Thanks,
>> Andrew
>
>> >
>> > Thanks,
>> > Kugan
>> >
>> >
>> > gcc/ChangeLog:
>> >
>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>> >
>> >     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
>> >     * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
>> >     (fold_unary_loc): Handle ABSU_EXPR.
>> >     * optabs-tree.c (optab_for_tree_code): Likewise.
>> >     * tree-cfg.c (verify_expr): Likewise.
>> >     (verify_gimple_assign_unary):  Likewise.
>> >     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
>> >     * tree-inline.c (estimate_operator_cost):  Likewise.
>> >     * tree-pretty-print.c (dump_generic_node):  Likewise.
>> >     * tree.def (ABSU_EXPR): New.
>> >
>> > gcc/testsuite/ChangeLog:
>> >
>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>> >
>> >     * gcc.dg/absu.c: New test.
Richard Biener May 18, 2018, 7:58 a.m. | #4
On Fri, May 18, 2018 at 4:37 AM Kugan Vivekanandarajah <
kugan.vivekanandarajah@linaro.org> wrote:

> Hi Richard,

> Thanks for the review. I am revising the patch based on Andrew's comments
too.

> On 17 May 2018 at 20:36, Richard Biener <richard.guenther@gmail.com>
wrote:
> > On Thu, May 17, 2018 at 4:56 AM Andrew Pinski <pinskia@gmail.com> wrote:
> >
> >> On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
> >> <kugan.vivekanandarajah@linaro.org> wrote:
> >> > As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
> >> > issue. In the attached patch, in fold_cond_expr_with_comparison I am
> >> > generating ABSU_EXPR for these cases. As I understand, absu_expr is
> >> > well defined in RTL. So, the issue is generating absu_expr  and
> >> > transferring to RTL in the correct way. I am not sure I am not doing
> >> > all that is needed. I will clean up and add more test-cases based on
> >> > the feedback.
> >
> >
> >> diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
> >> index 71e172c..2b812e5 100644
> >> --- a/gcc/optabs-tree.c
> >> +++ b/gcc/optabs-tree.c
> >> @@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code,
const_tree
> > type,
> >>         return trapv ? negv_optab : neg_optab;
> >
> >>       case ABS_EXPR:
> >> +    case ABSU_EXPR:
> >>         return trapv ? absv_optab : abs_optab;
> >
> >
> >> This part is not correct, it should something like this:
> >
> >>       case ABS_EXPR:
> >>         return trapv ? absv_optab : abs_optab;
> >> +    case ABSU_EXPR:
> >> +       return abs_optab ;
> >
> >> Because ABSU is not undefined at the TYPE_MAX.
> >
> > Also
> >
> >         /* Unsigned abs is simply the operand.  Testing here means we
don't
> >           risk generating incorrect code below.  */
> > -      if (TYPE_UNSIGNED (type))
> > +      if (TYPE_UNSIGNED (type)
> > +         && (code != ABSU_EXPR))
> >          return op0;
> >
> > is wrong.  ABSU of an unsigned number is still just that number.
> >
> > The change to fold_cond_expr_with_comparison looks odd to me
> > (premature optimization).  It should be done separately - it seems
> > you are doing

> FE seems to be using this to generate ABS_EXPR from
> c_fully_fold_internal to fold_build3_loc and so on. I changed this to
> generate ABSU_EXPR for the case in the testcase. So the question
> should be, in what cases do we need ABS_EXPR and in what cases do we
> need ABSU_EXPR. It is not very clear to me.

Well, all existing ABS_EXPR generations are obviously fine.  Then there
are transforms that are not possible w/o ABSU_EXPR like the narrowing
you performed here.  This is becasue for ABS_EXPR you can't simply avoid
the undefined
behavior by performing the operation on unsigned integers... (that's similar
to signed integer division of -INT_MIN / -1 -- the result is representable
in
unsigned but not in signed).


> >
> > (simplify (abs (convert @0)) (convert (absu @0)))
> >
> > here.
> >
> > You touch one other place in fold-const.c but there seem to be many
> > more that need ABSU_EXPR handling (you touched the one needed
> > for correctness) - esp. you should at least handle constant folding
> > in const_unop and the nonnegative predicate.

> OK.
> >
> > @@ -3167,6 +3167,9 @@ verify_expr (tree *tp, int *walk_subtrees, void
*data
> > ATTRIBUTE_UNUSED)
> >         CHECK_OP (0, "invalid operand to unary operator");
> >         break;
> >
> > +    case ABSU_EXPR:
> > +      break;
> > +
> >       case REALPART_EXPR:
> >       case IMAGPART_EXPR:
> >
> > verify_expr is no more.  Did you test this recently against trunk?

> This patch is against slightly older trunk. I will rebase it.

> >
> > @@ -3937,6 +3940,9 @@ verify_gimple_assign_unary (gassign *stmt)
> >       case PAREN_EXPR:
> >       case CONJ_EXPR:
> >         break;
> > +    case ABSU_EXPR:
> > +      /* FIXME.  */
> > +      return false;
> >
> > no - please not!  Please add verification here - ABSU should be only
> > called on INTEGRAL, vector or complex INTEGRAL types and the
> > type of the LHS should be always the unsigned variant of the
> > argument type.

> OK.
> >
> >     if (is_gimple_val (cond_expr))
> >       return cond_expr;
> >
> > -  if (TREE_CODE (cond_expr) == ABS_EXPR)
> > +  if (TREE_CODE (cond_expr) == ABS_EXPR
> > +      || TREE_CODE (cond_expr) == ABSU_EXPR)
> >       {
> >         rhs1 = TREE_OPERAND (cond_expr, 1);
> >         STRIP_USELESS_TYPE_CONVERSION (rhs1);
> >
> > err, but the next line just builds a ABS_EXPR ...
> >
> > How did you identify spots that need adjustment?  I would expect that
> > once folding generates ABSU_EXPR that you need to adjust frontends
> > (C++ constexpr handling for example).  Also I miss adjustments
> > to gimple-pretty-print.c and the GIMPLE FE parser.

> I will add this.
> >
> > recursively grepping throughout the whole gcc/ tree doesn't reveal too
many
> > cases of ABS_EXPR so I think it's reasonable to audit all of them.
> >
> > I also miss some trivial absu simplifications in match.pd.  There are
not
> > a lot of abs cases but similar ones would be good to have initially.

> I will add them in the next version.

> Thanks,
> Kugan

> >
> > Thanks for tackling this!
> > Richard.
> >
> >> Thanks,
> >> Andrew
> >
> >> >
> >> > Thanks,
> >> > Kugan
> >> >
> >> >
> >> > gcc/ChangeLog:
> >> >
> >> > 2018-05-13  Kugan Vivekanandarajah  <
kugan.vivekanandarajah@linaro.org>
> >> >
> >> >     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
> >> >     * fold-const.c (fold_cond_expr_with_comparison): Generate
ABSU_EXPR
> >> >     (fold_unary_loc): Handle ABSU_EXPR.
> >> >     * optabs-tree.c (optab_for_tree_code): Likewise.
> >> >     * tree-cfg.c (verify_expr): Likewise.
> >> >     (verify_gimple_assign_unary):  Likewise.
> >> >     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
> >> >     * tree-inline.c (estimate_operator_cost):  Likewise.
> >> >     * tree-pretty-print.c (dump_generic_node):  Likewise.
> >> >     * tree.def (ABSU_EXPR): New.
> >> >
> >> > gcc/testsuite/ChangeLog:
> >> >
> >> > 2018-05-13  Kugan Vivekanandarajah  <
kugan.vivekanandarajah@linaro.org>
> >> >
> >> >     * gcc.dg/absu.c: New test.
Kugan Vivekanandarajah June 1, 2018, 2:11 a.m. | #5
Hi Richard,

This is the revised patch based on the review and the discussion in
https://gcc.gnu.org/ml/gcc/2018-05/msg00179.html.

In summary:
- I skipped  (element_precision (type) < element_precision (TREE_TYPE
(@0))) in the match.pd pattern as this would prevent transformation
for the case in PR.
that is, I am interested in is something like:
  char t = (char) ABS_EXPR <(int) x>
and I want to generate
char t = (char) ABSU_EXPR <x>

- I also haven't added all the necessary match.pd changes for
ABSU_EXPR. I have a patch for that but will submit separately based on
this reveiw.

- I also tried to add ABSU_EXPRsupport  in the places as necessary by
grepping for ABS_EXPR.

- I also had to add special casing in vectorizer for ABSU_EXP as its
result is unsigned type.

Is this OK. Patch bootstraps and the regression test is ongoing.

Thanks,
Kugan


On 18 May 2018 at 12:36, Kugan Vivekanandarajah
<kugan.vivekanandarajah@linaro.org> wrote:
> Hi Richard,
>
> Thanks for the review. I am revising the patch based on Andrew's comments too.
>
> On 17 May 2018 at 20:36, Richard Biener <richard.guenther@gmail.com> wrote:
>> On Thu, May 17, 2018 at 4:56 AM Andrew Pinski <pinskia@gmail.com> wrote:
>>
>>> On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
>>> <kugan.vivekanandarajah@linaro.org> wrote:
>>> > As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
>>> > issue. In the attached patch, in fold_cond_expr_with_comparison I am
>>> > generating ABSU_EXPR for these cases. As I understand, absu_expr is
>>> > well defined in RTL. So, the issue is generating absu_expr  and
>>> > transferring to RTL in the correct way. I am not sure I am not doing
>>> > all that is needed. I will clean up and add more test-cases based on
>>> > the feedback.
>>
>>
>>> diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
>>> index 71e172c..2b812e5 100644
>>> --- a/gcc/optabs-tree.c
>>> +++ b/gcc/optabs-tree.c
>>> @@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code, const_tree
>> type,
>>>         return trapv ? negv_optab : neg_optab;
>>
>>>       case ABS_EXPR:
>>> +    case ABSU_EXPR:
>>>         return trapv ? absv_optab : abs_optab;
>>
>>
>>> This part is not correct, it should something like this:
>>
>>>       case ABS_EXPR:
>>>         return trapv ? absv_optab : abs_optab;
>>> +    case ABSU_EXPR:
>>> +       return abs_optab ;
>>
>>> Because ABSU is not undefined at the TYPE_MAX.
>>
>> Also
>>
>>         /* Unsigned abs is simply the operand.  Testing here means we don't
>>           risk generating incorrect code below.  */
>> -      if (TYPE_UNSIGNED (type))
>> +      if (TYPE_UNSIGNED (type)
>> +         && (code != ABSU_EXPR))
>>          return op0;
>>
>> is wrong.  ABSU of an unsigned number is still just that number.
>>
>> The change to fold_cond_expr_with_comparison looks odd to me
>> (premature optimization).  It should be done separately - it seems
>> you are doing
>
> FE seems to be using this to generate ABS_EXPR from
> c_fully_fold_internal to fold_build3_loc and so on. I changed this to
> generate ABSU_EXPR for the case in the testcase. So the question
> should be, in what cases do we need ABS_EXPR and in what cases do we
> need ABSU_EXPR. It is not very clear to me.
>
>
>>
>> (simplify (abs (convert @0)) (convert (absu @0)))
>>
>> here.
>>
>> You touch one other place in fold-const.c but there seem to be many
>> more that need ABSU_EXPR handling (you touched the one needed
>> for correctness) - esp. you should at least handle constant folding
>> in const_unop and the nonnegative predicate.
>
> OK.
>>
>> @@ -3167,6 +3167,9 @@ verify_expr (tree *tp, int *walk_subtrees, void *data
>> ATTRIBUTE_UNUSED)
>>         CHECK_OP (0, "invalid operand to unary operator");
>>         break;
>>
>> +    case ABSU_EXPR:
>> +      break;
>> +
>>       case REALPART_EXPR:
>>       case IMAGPART_EXPR:
>>
>> verify_expr is no more.  Did you test this recently against trunk?
>
> This patch is against slightly older trunk. I will rebase it.
>
>>
>> @@ -3937,6 +3940,9 @@ verify_gimple_assign_unary (gassign *stmt)
>>       case PAREN_EXPR:
>>       case CONJ_EXPR:
>>         break;
>> +    case ABSU_EXPR:
>> +      /* FIXME.  */
>> +      return false;
>>
>> no - please not!  Please add verification here - ABSU should be only
>> called on INTEGRAL, vector or complex INTEGRAL types and the
>> type of the LHS should be always the unsigned variant of the
>> argument type.
>
> OK.
>>
>>     if (is_gimple_val (cond_expr))
>>       return cond_expr;
>>
>> -  if (TREE_CODE (cond_expr) == ABS_EXPR)
>> +  if (TREE_CODE (cond_expr) == ABS_EXPR
>> +      || TREE_CODE (cond_expr) == ABSU_EXPR)
>>       {
>>         rhs1 = TREE_OPERAND (cond_expr, 1);
>>         STRIP_USELESS_TYPE_CONVERSION (rhs1);
>>
>> err, but the next line just builds a ABS_EXPR ...
>>
>> How did you identify spots that need adjustment?  I would expect that
>> once folding generates ABSU_EXPR that you need to adjust frontends
>> (C++ constexpr handling for example).  Also I miss adjustments
>> to gimple-pretty-print.c and the GIMPLE FE parser.
>
> I will add this.
>>
>> recursively grepping throughout the whole gcc/ tree doesn't reveal too many
>> cases of ABS_EXPR so I think it's reasonable to audit all of them.
>>
>> I also miss some trivial absu simplifications in match.pd.  There are not
>> a lot of abs cases but similar ones would be good to have initially.
>
> I will add them in the next version.
>
> Thanks,
> Kugan
>
>>
>> Thanks for tackling this!
>> Richard.
>>
>>> Thanks,
>>> Andrew
>>
>>> >
>>> > Thanks,
>>> > Kugan
>>> >
>>> >
>>> > gcc/ChangeLog:
>>> >
>>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>>> >
>>> >     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
>>> >     * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
>>> >     (fold_unary_loc): Handle ABSU_EXPR.
>>> >     * optabs-tree.c (optab_for_tree_code): Likewise.
>>> >     * tree-cfg.c (verify_expr): Likewise.
>>> >     (verify_gimple_assign_unary):  Likewise.
>>> >     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
>>> >     * tree-inline.c (estimate_operator_cost):  Likewise.
>>> >     * tree-pretty-print.c (dump_generic_node):  Likewise.
>>> >     * tree.def (ABSU_EXPR): New.
>>> >
>>> > gcc/testsuite/ChangeLog:
>>> >
>>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>>> >
>>> >     * gcc.dg/absu.c: New test.
From 6675f0fe71b1de2c2def5c5d2bd150ae1e707b5c Mon Sep 17 00:00:00 2001
From: Kugan Vivekanandarajah <kugan.vivekanandarajah@linaro.org>
Date: Tue, 29 May 2018 10:26:23 +1000
Subject: [PATCH] absu v2

Change-Id: Id34948b4d585fbcdcb8ff6eb3728fd3cc6c41bfa
---
 gcc/c-family/c-common.c            |  1 +
 gcc/c/c-typeck.c                   | 10 ++++++++++
 gcc/c/gimple-parser.c              |  9 ++++++++-
 gcc/cfgexpand.c                    |  1 +
 gcc/config/i386/i386.c             |  1 +
 gcc/cp/constexpr.c                 |  1 +
 gcc/cp/cp-gimplify.c               |  1 +
 gcc/dojump.c                       |  1 +
 gcc/expr.c                         |  3 ++-
 gcc/fold-const.c                   |  6 +++++-
 gcc/gimple-pretty-print.c          |  7 +++++--
 gcc/gimple-ssa-backprop.c          |  2 ++
 gcc/match.pd                       |  8 ++++++++
 gcc/optabs-tree.c                  |  2 ++
 gcc/testsuite/gcc.dg/absu.c        | 41 ++++++++++++++++++++++++++++++++++++++
 gcc/testsuite/gcc.dg/gimplefe-29.c | 11 ++++++++++
 gcc/tree-cfg.c                     |  6 ++++++
 gcc/tree-eh.c                      |  1 +
 gcc/tree-inline.c                  |  1 +
 gcc/tree-pretty-print.c            |  6 ++++++
 gcc/tree-vect-patterns.c           |  3 ++-
 gcc/tree-vect-stmts.c              |  6 +++++-
 gcc/tree.def                       |  1 +
 23 files changed, 122 insertions(+), 7 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/absu.c
 create mode 100644 gcc/testsuite/gcc.dg/gimplefe-29.c

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 859eeb4..0e8efb5 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -3312,6 +3312,7 @@ c_common_truthvalue_conversion (location_t location, tree expr)
 
     case NEGATE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case FLOAT_EXPR:
     case EXCESS_PRECISION_EXPR:
       /* These don't change whether an object is nonzero or zero.  */
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 45a4529..5bb6804 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -4314,6 +4314,16 @@ build_unary_op (location_t location, enum tree_code code, tree xarg,
 	arg = default_conversion (arg);
       break;
 
+    case ABSU_EXPR:
+      if (!(typecode == INTEGER_TYPE))
+	{
+	  error_at (location, "wrong type argument to absu");
+	  return error_mark_node;
+	}
+      else if (!noconvert)
+	arg = default_conversion (arg);
+      break;
+
     case CONJ_EXPR:
       /* Conjugating a real value is a no-op, but allow it anyway.  */
       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
diff --git a/gcc/c/gimple-parser.c b/gcc/c/gimple-parser.c
index 8f1c442..1be5d14 100644
--- a/gcc/c/gimple-parser.c
+++ b/gcc/c/gimple-parser.c
@@ -328,7 +328,8 @@ c_parser_gimple_statement (c_parser *parser, gimple_seq *seq)
     case CPP_NAME:
       {
 	tree id = c_parser_peek_token (parser)->value;
-	if (strcmp (IDENTIFIER_POINTER (id), "__ABS") == 0)
+	if (strcmp (IDENTIFIER_POINTER (id), "__ABS") == 0
+	    || strcmp (IDENTIFIER_POINTER (id), "__ABSU") == 0)
 	  goto build_unary_expr;
 	break;
       }
@@ -638,6 +639,12 @@ c_parser_gimple_unary_expression (c_parser *parser)
 	      op = c_parser_gimple_postfix_expression (parser);
 	      return parser_build_unary_op (op_loc, ABS_EXPR, op);
 	    }
+	  else if (strcmp (IDENTIFIER_POINTER (id), "__ABSU") == 0)
+	    {
+	      c_parser_consume_token (parser);
+	      op = c_parser_gimple_postfix_expression (parser);
+	      return parser_build_unary_op (op_loc, ABSU_EXPR, op);
+	    }
 	  else
 	    return c_parser_gimple_postfix_expression (parser);
 	}
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 5c323be..d06224d 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -4620,6 +4620,7 @@ expand_debug_expr (tree exp)
       }
 
     case ABS_EXPR:
+    case ABSU_EXPR:
       return simplify_gen_unary (ABS, mode, op0, mode);
 
     case NEGATE_EXPR:
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 637c105..f5a4856 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -51232,6 +51232,7 @@ ix86_add_stmt_cost (void *data, int count, enum vect_cost_for_stmt kind,
 
 	case BIT_IOR_EXPR:
 	case ABS_EXPR:
+	case ABSU_EXPR:
 	case MIN_EXPR:
 	case MAX_EXPR:
 	case BIT_XOR_EXPR:
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index a099408..30ea091 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -5759,6 +5759,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
     case FLOAT_EXPR:
     case NEGATE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case TRUTH_NOT_EXPR:
     case FIXED_CONVERT_EXPR:
     case UNARY_PLUS_EXPR:
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index b4e23e2..4567365 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -2272,6 +2272,7 @@ cp_fold (tree x)
     case FLOAT_EXPR:
     case NEGATE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case BIT_NOT_EXPR:
     case TRUTH_NOT_EXPR:
     case FIXED_CONVERT_EXPR:
diff --git a/gcc/dojump.c b/gcc/dojump.c
index 9da8a0e..88cc96a 100644
--- a/gcc/dojump.c
+++ b/gcc/dojump.c
@@ -467,6 +467,7 @@ do_jump (tree exp, rtx_code_label *if_false_label,
       /* FALLTHRU */
     case NON_LVALUE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case NEGATE_EXPR:
     case LROTATE_EXPR:
     case RROTATE_EXPR:
diff --git a/gcc/expr.c b/gcc/expr.c
index ecc5292..a92c23f 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -9013,6 +9013,7 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
       return REDUCE_BIT_FIELD (temp);
 
     case ABS_EXPR:
+    case ABSU_EXPR:
       op0 = expand_expr (treeop0, subtarget,
 			 VOIDmode, EXPAND_NORMAL);
       if (modifier == EXPAND_STACK_PARM)
@@ -9024,7 +9025,7 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
 
       /* Unsigned abs is simply the operand.  Testing here means we don't
 	 risk generating incorrect code below.  */
-      if (TYPE_UNSIGNED (type))
+      if (TYPE_UNSIGNED (TREE_TYPE (treeop0)))
 	return op0;
 
       return expand_abs (mode, op0, target, unsignedp,
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 0f57f07..20b4271 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -1723,7 +1723,8 @@ const_unop (enum tree_code code, tree type, tree arg0)
       && HONOR_SNANS (TYPE_MODE (TREE_TYPE (arg0)))
       && REAL_VALUE_ISSIGNALING_NAN (TREE_REAL_CST (arg0))
       && code != NEGATE_EXPR
-      && code != ABS_EXPR)
+      && code != ABS_EXPR
+      && code != ABSU_EXPR)
     return NULL_TREE;
 
   switch (code)
@@ -1761,6 +1762,9 @@ const_unop (enum tree_code code, tree type, tree arg0)
       if (TREE_CODE (arg0) == INTEGER_CST || TREE_CODE (arg0) == REAL_CST)
 	return fold_abs_const (arg0, type);
       break;
+    case ABSU_EXPR:
+	return fold_convert (type, fold_abs_const (arg0,
+						   signed_type_for (type)));
 
     case CONJ_EXPR:
       if (TREE_CODE (arg0) == COMPLEX_CST)
diff --git a/gcc/gimple-pretty-print.c b/gcc/gimple-pretty-print.c
index 49e9e12..bb4d259 100644
--- a/gcc/gimple-pretty-print.c
+++ b/gcc/gimple-pretty-print.c
@@ -358,14 +358,17 @@ dump_unary_rhs (pretty_printer *buffer, gassign *gs, int spc,
       break;
 
     case ABS_EXPR:
+    case ABSU_EXPR:
       if (flags & TDF_GIMPLE)
 	{
-	  pp_string (buffer, "__ABS ");
+	  pp_string (buffer,
+		     rhs_code == ABS_EXPR ? "__ABS " : "__ABSU ");
 	  dump_generic_node (buffer, rhs, spc, flags, false);
 	}
       else
 	{
-	  pp_string (buffer, "ABS_EXPR <");
+	  pp_string (buffer,
+		     rhs_code == ABS_EXPR ? "ABS_EXPR <" : "ABSU_EXPR <");
 	  dump_generic_node (buffer, rhs, spc, flags, false);
 	  pp_greater (buffer);
 	}
diff --git a/gcc/gimple-ssa-backprop.c b/gcc/gimple-ssa-backprop.c
index 9ab655c..bb378a9 100644
--- a/gcc/gimple-ssa-backprop.c
+++ b/gcc/gimple-ssa-backprop.c
@@ -408,6 +408,7 @@ backprop::process_assign_use (gassign *assign, tree rhs, usage_info *info)
   switch (gimple_assign_rhs_code (assign))
     {
     case ABS_EXPR:
+    case ABSU_EXPR:
       /* The sign of the input doesn't matter.  */
       info->flags.ignore_sign = true;
       break;
@@ -675,6 +676,7 @@ strip_sign_op_1 (tree rhs)
     switch (gimple_assign_rhs_code (assign))
       {
       case ABS_EXPR:
+      case ABSU_EXPR:
       case NEGATE_EXPR:
 	return gimple_assign_rhs1 (assign);
 
diff --git a/gcc/match.pd b/gcc/match.pd
index 14386da..7d7c132 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -102,6 +102,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 (match (nop_convert @0)
  @0) 
 
+(simplify (abs (convert @0))
+ (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+      && !TYPE_UNSIGNED (TREE_TYPE (@0))
+      && !TYPE_UNSIGNED (type))
+  (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
+   (convert (absu:utype @0)))))
+
+
 /* Simplifications of operations with one constant operand and
    simplifications to constants or single values.  */
 
diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
index 73e6654..092663b 100644
--- a/gcc/optabs-tree.c
+++ b/gcc/optabs-tree.c
@@ -234,6 +234,8 @@ optab_for_tree_code (enum tree_code code, const_tree type,
     case ABS_EXPR:
       return trapv ? absv_optab : abs_optab;
 
+    case ABSU_EXPR:
+      return abs_optab;
     default:
       return unknown_optab;
     }
diff --git a/gcc/testsuite/gcc.dg/absu.c b/gcc/testsuite/gcc.dg/absu.c
new file mode 100644
index 0000000..81e37a4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/absu.c
@@ -0,0 +1,41 @@
+
+/* { dg-do run  } */
+/* { dg-options "-O0" } */
+
+#include <limits.h>
+#define ABS(x)	(((x) >= 0) ? (x) : -(x))
+
+#define DEF_TEST(TYPE)	\
+void foo_##TYPE (signed TYPE x, unsigned TYPE y){	\
+    TYPE t = ABS (x);				\
+    if (t != y)					\
+ 	__builtin_abort ();			\
+}						\
+
+DEF_TEST (char);
+DEF_TEST (short);
+DEF_TEST (int);
+DEF_TEST (long);
+void main ()
+{
+  foo_char (SCHAR_MIN + 1, SCHAR_MAX);
+  foo_char (0, 0);
+  foo_char (-1, 1);
+  foo_char (1, 1);
+  foo_char (SCHAR_MAX, SCHAR_MAX);
+
+  foo_int (-1, 1);
+  foo_int (0, 0);
+  foo_int (INT_MAX, INT_MAX);
+  foo_int (INT_MIN + 1, INT_MAX);
+
+  foo_short (-1, 1);
+  foo_short (0, 0);
+  foo_short (SHRT_MAX, SHRT_MAX);
+  foo_short (SHRT_MIN + 1, SHRT_MAX);
+
+  foo_long (-1, 1);
+  foo_long (0, 0);
+  foo_long (LONG_MAX, LONG_MAX);
+  foo_long (LONG_MIN + 1, LONG_MAX);
+}
diff --git a/gcc/testsuite/gcc.dg/gimplefe-29.c b/gcc/testsuite/gcc.dg/gimplefe-29.c
new file mode 100644
index 0000000..54b86ef
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gimplefe-29.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fgimple -fdump-tree-ssa-gimple" } */
+
+unsigned int __GIMPLE() f(int a)
+{
+  unsigned int t0;
+  t0_1 = __ABSU a;
+  return t0_1;
+}
+
+/* { dg-final { scan-tree-dump "__ABSU a" "ssa" } } */
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 68f4fd3..9b62583 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -3685,6 +3685,12 @@ verify_gimple_assign_unary (gassign *stmt)
     case PAREN_EXPR:
     case CONJ_EXPR:
       break;
+    case ABSU_EXPR:
+      if (!TYPE_UNSIGNED (lhs_type)
+	  || !ANY_INTEGRAL_TYPE_P (rhs1_type))
+	return true;
+      return false;
+      break;
 
     case VEC_DUPLICATE_EXPR:
       if (TREE_CODE (lhs_type) != VECTOR_TYPE
diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
index 30c6d9e..44b1399 100644
--- a/gcc/tree-eh.c
+++ b/gcc/tree-eh.c
@@ -2465,6 +2465,7 @@ operation_could_trap_helper_p (enum tree_code op,
 
     case NEGATE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case CONJ_EXPR:
       /* These operations don't trap with floating point.  */
       if (honor_trapv)
diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
index 7881131..665e53c 100644
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -3865,6 +3865,7 @@ estimate_operator_cost (enum tree_code code, eni_weights *weights,
     case MIN_EXPR:
     case MAX_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
 
     case LSHIFT_EXPR:
     case RSHIFT_EXPR:
diff --git a/gcc/tree-pretty-print.c b/gcc/tree-pretty-print.c
index 5a8c8eb..a950a9e 100644
--- a/gcc/tree-pretty-print.c
+++ b/gcc/tree-pretty-print.c
@@ -2463,6 +2463,12 @@ dump_generic_node (pretty_printer *pp, tree node, int spc, dump_flags_t flags,
       pp_greater (pp);
       break;
 
+    case ABSU_EXPR:
+      pp_string (pp, "ABSU_EXPR <");
+      dump_generic_node (pp, TREE_OPERAND (node, 0), spc, flags, false);
+      pp_greater (pp);
+      break;
+
     case RANGE_EXPR:
       NIY;
       break;
diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c
index 6da784c..af6b9bd 100644
--- a/gcc/tree-vect-patterns.c
+++ b/gcc/tree-vect-patterns.c
@@ -615,7 +615,8 @@ vect_recog_sad_pattern (vec<gimple *> *stmts, tree *type_in,
   gcc_assert (abs_stmt_vinfo);
   if (STMT_VINFO_DEF_TYPE (abs_stmt_vinfo) != vect_internal_def)
     return NULL;
-  if (gimple_assign_rhs_code (abs_stmt) != ABS_EXPR)
+  if (gimple_assign_rhs_code (abs_stmt) != ABS_EXPR
+      && gimple_assign_rhs_code (abs_stmt) != ABSU_EXPR)
     return NULL;
 
   tree abs_oprnd = gimple_assign_rhs1 (abs_stmt);
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 66c78de..b52d714 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -5995,7 +5995,11 @@ vectorizable_operation (gimple *stmt, gimple_stmt_iterator *gsi,
                      "transform binary/unary operation.\n");
 
   /* Handle def.  */
-  vec_dest = vect_create_destination_var (scalar_dest, vectype);
+  if (code == ABSU_EXPR)
+    vec_dest = vect_create_destination_var (scalar_dest,
+					    unsigned_type_for (vectype));
+  else
+    vec_dest = vect_create_destination_var (scalar_dest, vectype);
 
   /* POINTER_DIFF_EXPR has pointer arguments which are vectorized as
      vectors with unsigned elements, but the result is signed.  So, we
diff --git a/gcc/tree.def b/gcc/tree.def
index c660b2c..5fec781 100644
--- a/gcc/tree.def
+++ b/gcc/tree.def
@@ -760,6 +760,7 @@ DEFTREECODE (MAX_EXPR, "max_expr", tcc_binary, 2)
    An ABS_EXPR must have either an INTEGER_TYPE or a REAL_TYPE.  The
    operand of the ABS_EXPR must have the same type.  */
 DEFTREECODE (ABS_EXPR, "abs_expr", tcc_unary, 1)
+DEFTREECODE (ABSU_EXPR, "absu_expr", tcc_unary, 1)
 
 /* Shift operations for shift and rotate.
    Shift means logical shift if done on an
Richard Biener June 1, 2018, 12:20 p.m. | #6
On Fri, Jun 1, 2018 at 4:12 AM Kugan Vivekanandarajah
<kugan.vivekanandarajah@linaro.org> wrote:
>
> Hi Richard,
>
> This is the revised patch based on the review and the discussion in
> https://gcc.gnu.org/ml/gcc/2018-05/msg00179.html.
>
> In summary:
> - I skipped  (element_precision (type) < element_precision (TREE_TYPE
> (@0))) in the match.pd pattern as this would prevent transformation
> for the case in PR.
> that is, I am interested in is something like:
>   char t = (char) ABS_EXPR <(int) x>
> and I want to generate
> char t = (char) ABSU_EXPR <x>
>
> - I also haven't added all the necessary match.pd changes for
> ABSU_EXPR. I have a patch for that but will submit separately based on
> this reveiw.
>
> - I also tried to add ABSU_EXPRsupport  in the places as necessary by
> grepping for ABS_EXPR.
>
> - I also had to add special casing in vectorizer for ABSU_EXP as its
> result is unsigned type.
>
> Is this OK. Patch bootstraps and the regression test is ongoing.

The c/c-typeck.c:build_unary_op change looks unnecessary - the
C FE should never generate this directly (the c-common one might
be triggered by early folding I guess).

@@ -1761,6 +1762,9 @@ const_unop (enum tree_code code, tree type, tree arg0)
       if (TREE_CODE (arg0) == INTEGER_CST || TREE_CODE (arg0) == REAL_CST)
        return fold_abs_const (arg0, type);
       break;
+    case ABSU_EXPR:
+       return fold_convert (type, fold_abs_const (arg0,
+                                                  signed_type_for (type)));

     case CONJ_EXPR:

I think this will get you bogus TREE_OVERFLOW flags set on ABSU (-INT_MIN).

I think you want to change fold_abs_const to properly deal with arg0 being
signed and type unsigned.  That is, sth like

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 6f80f1b1d69..f60f9c77e91 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -13843,18 +13843,19 @@ fold_abs_const (tree arg0, tree type)
       {
         /* If the value is unsigned or non-negative, then the absolute value
           is the same as the ordinary value.  */
-       if (!wi::neg_p (wi::to_wide (arg0), TYPE_SIGN (type)))
-         t = arg0;
+       wide_int val = wi::to_wide (arg0);
+       bool overflow = false;
+       if (!wi::neg_p (val, TYPE_SIGN (TREE_TYPE (arg0))))
+         ;

        /* If the value is negative, then the absolute value is
           its negation.  */
        else
-         {
-           bool overflow;
-           wide_int val = wi::neg (wi::to_wide (arg0), &overflow);
-           t = force_fit_type (type, val, -1,
-                               overflow | TREE_OVERFLOW (arg0));
-         }
+         wide_int val = wi::neg (val, &overflow);
+
+       /* Force to the destination type, set TREE_OVERFLOW for signed
+          TYPE only.  */
+       t = force_fit_type (type, val, 1, overflow | TREE_OVERFLOW (arg0));
       }
       break;

and then simply share the const_unop code with ABS_EXPR.

diff --git a/gcc/match.pd b/gcc/match.pd
index 14386da..7d7c132 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -102,6 +102,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 (match (nop_convert @0)
  @0)

+(simplify (abs (convert @0))
+ (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+      && !TYPE_UNSIGNED (TREE_TYPE (@0))
+      && !TYPE_UNSIGNED (type))
+  (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
+   (convert (absu:utype @0)))))
+
+

please put a comment before the pattern.  I believe there's no
need to check for !TYPE_UNSIGNED (type).  Note this
also converts abs ((char)int-var) to (char)absu(int-var) which
doesn't make sense.  The original issue you want to address
here is the case where TYPE_PRECISION of @0 is less than
the precision of type.  That is, you want to remove language
introduced integer promotion of @0 which only is possible
with ABSU.  So please do add such precision check
(I simply suggested the bogus direction of the test).

diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 68f4fd3..9b62583 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -3685,6 +3685,12 @@ verify_gimple_assign_unary (gassign *stmt)
     case PAREN_EXPR:
     case CONJ_EXPR:
       break;
+    case ABSU_EXPR:
+      if (!TYPE_UNSIGNED (lhs_type)
+         || !ANY_INTEGRAL_TYPE_P (rhs1_type))

 if (!ANY_INTEGRAL_TYPE_P (lhs_type)
     || !TYPE_UNSIGNED (lhs_type)
     || !ANY_INTEGRAL_TYPE_P (rhs1_type)
     || TYPE_UNSIGNED (rhs1_type)
     || element_precision (lhs_type) != element_precision (rhs1_type))
  {
      error ("invalid types for ABSU_EXPR");
      debug_generic_expr (lhs_type);
      debug_generic_expr (rhs1_type);
     return true;
  }

+       return true;
+      return false;
+      break;

diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
index 30c6d9e..44b1399 100644
--- a/gcc/tree-eh.c
+++ b/gcc/tree-eh.c
@@ -2465,6 +2465,7 @@ operation_could_trap_helper_p (enum tree_code op,

     case NEGATE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case CONJ_EXPR:
       /* These operations don't trap with floating point.  */
       if (honor_trapv)

ABSU never traps.  Please instead unconditionally return false.

diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 66c78de..b52d714 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -5995,7 +5995,11 @@ vectorizable_operation (gimple *stmt,
gimple_stmt_iterator *gsi,
                      "transform binary/unary operation.\n");

   /* Handle def.  */
-  vec_dest = vect_create_destination_var (scalar_dest, vectype);
+  if (code == ABSU_EXPR)
+    vec_dest = vect_create_destination_var (scalar_dest,
+                                           unsigned_type_for (vectype));
+  else
+    vec_dest = vect_create_destination_var (scalar_dest, vectype);

   /* POINTER_DIFF_EXPR has pointer arguments which are vectorized as
      vectors with unsigned elements, but the result is signed.  So, we

simply use vectype_out for creation of vec_dest.

diff --git a/gcc/tree.def b/gcc/tree.def
index c660b2c..5fec781 100644
--- a/gcc/tree.def
+++ b/gcc/tree.def
@@ -760,6 +760,7 @@ DEFTREECODE (MAX_EXPR, "max_expr", tcc_binary, 2)
    An ABS_EXPR must have either an INTEGER_TYPE or a REAL_TYPE.  The
    operand of the ABS_EXPR must have the same type.  */
 DEFTREECODE (ABS_EXPR, "abs_expr", tcc_unary, 1)
+DEFTREECODE (ABSU_EXPR, "absu_expr", tcc_unary, 1)

 /* Shift operations for shift and rotate.
    Shift means logical shift if done on an

You can clearly see that the comment before ABS_EXPR doesn't apply to ABSU_EXPR
so please add an appropriate one.  I suggest

/* Represents the unsigned absolute value of the operand.
    An ABSU_EXPR must have unsigned INTEGER_TYPE.  The operand of the ABSU_EXPR
    must have the corresponding signed type.  */

Otherwise looks OK.  (I didn't explicitely check for missing ABSU_EXPR
handling this time)

Thanks,
Richard.


> Thanks,
> Kugan
>
>
> On 18 May 2018 at 12:36, Kugan Vivekanandarajah
> <kugan.vivekanandarajah@linaro.org> wrote:
> > Hi Richard,
> >
> > Thanks for the review. I am revising the patch based on Andrew's comments too.
> >
> > On 17 May 2018 at 20:36, Richard Biener <richard.guenther@gmail.com> wrote:
> >> On Thu, May 17, 2018 at 4:56 AM Andrew Pinski <pinskia@gmail.com> wrote:
> >>
> >>> On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
> >>> <kugan.vivekanandarajah@linaro.org> wrote:
> >>> > As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
> >>> > issue. In the attached patch, in fold_cond_expr_with_comparison I am
> >>> > generating ABSU_EXPR for these cases. As I understand, absu_expr is
> >>> > well defined in RTL. So, the issue is generating absu_expr  and
> >>> > transferring to RTL in the correct way. I am not sure I am not doing
> >>> > all that is needed. I will clean up and add more test-cases based on
> >>> > the feedback.
> >>
> >>
> >>> diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
> >>> index 71e172c..2b812e5 100644
> >>> --- a/gcc/optabs-tree.c
> >>> +++ b/gcc/optabs-tree.c
> >>> @@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code, const_tree
> >> type,
> >>>         return trapv ? negv_optab : neg_optab;
> >>
> >>>       case ABS_EXPR:
> >>> +    case ABSU_EXPR:
> >>>         return trapv ? absv_optab : abs_optab;
> >>
> >>
> >>> This part is not correct, it should something like this:
> >>
> >>>       case ABS_EXPR:
> >>>         return trapv ? absv_optab : abs_optab;
> >>> +    case ABSU_EXPR:
> >>> +       return abs_optab ;
> >>
> >>> Because ABSU is not undefined at the TYPE_MAX.
> >>
> >> Also
> >>
> >>         /* Unsigned abs is simply the operand.  Testing here means we don't
> >>           risk generating incorrect code below.  */
> >> -      if (TYPE_UNSIGNED (type))
> >> +      if (TYPE_UNSIGNED (type)
> >> +         && (code != ABSU_EXPR))
> >>          return op0;
> >>
> >> is wrong.  ABSU of an unsigned number is still just that number.
> >>
> >> The change to fold_cond_expr_with_comparison looks odd to me
> >> (premature optimization).  It should be done separately - it seems
> >> you are doing
> >
> > FE seems to be using this to generate ABS_EXPR from
> > c_fully_fold_internal to fold_build3_loc and so on. I changed this to
> > generate ABSU_EXPR for the case in the testcase. So the question
> > should be, in what cases do we need ABS_EXPR and in what cases do we
> > need ABSU_EXPR. It is not very clear to me.
> >
> >
> >>
> >> (simplify (abs (convert @0)) (convert (absu @0)))
> >>
> >> here.
> >>
> >> You touch one other place in fold-const.c but there seem to be many
> >> more that need ABSU_EXPR handling (you touched the one needed
> >> for correctness) - esp. you should at least handle constant folding
> >> in const_unop and the nonnegative predicate.
> >
> > OK.
> >>
> >> @@ -3167,6 +3167,9 @@ verify_expr (tree *tp, int *walk_subtrees, void *data
> >> ATTRIBUTE_UNUSED)
> >>         CHECK_OP (0, "invalid operand to unary operator");
> >>         break;
> >>
> >> +    case ABSU_EXPR:
> >> +      break;
> >> +
> >>       case REALPART_EXPR:
> >>       case IMAGPART_EXPR:
> >>
> >> verify_expr is no more.  Did you test this recently against trunk?
> >
> > This patch is against slightly older trunk. I will rebase it.
> >
> >>
> >> @@ -3937,6 +3940,9 @@ verify_gimple_assign_unary (gassign *stmt)
> >>       case PAREN_EXPR:
> >>       case CONJ_EXPR:
> >>         break;
> >> +    case ABSU_EXPR:
> >> +      /* FIXME.  */
> >> +      return false;
> >>
> >> no - please not!  Please add verification here - ABSU should be only
> >> called on INTEGRAL, vector or complex INTEGRAL types and the
> >> type of the LHS should be always the unsigned variant of the
> >> argument type.
> >
> > OK.
> >>
> >>     if (is_gimple_val (cond_expr))
> >>       return cond_expr;
> >>
> >> -  if (TREE_CODE (cond_expr) == ABS_EXPR)
> >> +  if (TREE_CODE (cond_expr) == ABS_EXPR
> >> +      || TREE_CODE (cond_expr) == ABSU_EXPR)
> >>       {
> >>         rhs1 = TREE_OPERAND (cond_expr, 1);
> >>         STRIP_USELESS_TYPE_CONVERSION (rhs1);
> >>
> >> err, but the next line just builds a ABS_EXPR ...
> >>
> >> How did you identify spots that need adjustment?  I would expect that
> >> once folding generates ABSU_EXPR that you need to adjust frontends
> >> (C++ constexpr handling for example).  Also I miss adjustments
> >> to gimple-pretty-print.c and the GIMPLE FE parser.
> >
> > I will add this.
> >>
> >> recursively grepping throughout the whole gcc/ tree doesn't reveal too many
> >> cases of ABS_EXPR so I think it's reasonable to audit all of them.
> >>
> >> I also miss some trivial absu simplifications in match.pd.  There are not
> >> a lot of abs cases but similar ones would be good to have initially.
> >
> > I will add them in the next version.
> >
> > Thanks,
> > Kugan
> >
> >>
> >> Thanks for tackling this!
> >> Richard.
> >>
> >>> Thanks,
> >>> Andrew
> >>
> >>> >
> >>> > Thanks,
> >>> > Kugan
> >>> >
> >>> >
> >>> > gcc/ChangeLog:
> >>> >
> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >>> >
> >>> >     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
> >>> >     * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
> >>> >     (fold_unary_loc): Handle ABSU_EXPR.
> >>> >     * optabs-tree.c (optab_for_tree_code): Likewise.
> >>> >     * tree-cfg.c (verify_expr): Likewise.
> >>> >     (verify_gimple_assign_unary):  Likewise.
> >>> >     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
> >>> >     * tree-inline.c (estimate_operator_cost):  Likewise.
> >>> >     * tree-pretty-print.c (dump_generic_node):  Likewise.
> >>> >     * tree.def (ABSU_EXPR): New.
> >>> >
> >>> > gcc/testsuite/ChangeLog:
> >>> >
> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >>> >
> >>> >     * gcc.dg/absu.c: New test.
Kugan Vivekanandarajah June 4, 2018, 8:18 a.m. | #7
Hi Richard,

Thanks for the review.

On 1 June 2018 at 22:20, Richard Biener <richard.guenther@gmail.com> wrote:
> On Fri, Jun 1, 2018 at 4:12 AM Kugan Vivekanandarajah
> <kugan.vivekanandarajah@linaro.org> wrote:
>>
>> Hi Richard,
>>
>> This is the revised patch based on the review and the discussion in
>> https://gcc.gnu.org/ml/gcc/2018-05/msg00179.html.
>>
>> In summary:
>> - I skipped  (element_precision (type) < element_precision (TREE_TYPE
>> (@0))) in the match.pd pattern as this would prevent transformation
>> for the case in PR.
>> that is, I am interested in is something like:
>>   char t = (char) ABS_EXPR <(int) x>
>> and I want to generate
>> char t = (char) ABSU_EXPR <x>
>>
>> - I also haven't added all the necessary match.pd changes for
>> ABSU_EXPR. I have a patch for that but will submit separately based on
>> this reveiw.
>>
>> - I also tried to add ABSU_EXPRsupport  in the places as necessary by
>> grepping for ABS_EXPR.
>>
>> - I also had to add special casing in vectorizer for ABSU_EXP as its
>> result is unsigned type.
>>
>> Is this OK. Patch bootstraps and the regression test is ongoing.
>
> The c/c-typeck.c:build_unary_op change looks unnecessary - the
> C FE should never generate this directly (the c-common one might
> be triggered by early folding I guess).

The Gimple FE testcase is running into this.

>
> @@ -1761,6 +1762,9 @@ const_unop (enum tree_code code, tree type, tree arg0)
>        if (TREE_CODE (arg0) == INTEGER_CST || TREE_CODE (arg0) == REAL_CST)
>         return fold_abs_const (arg0, type);
>        break;
> +    case ABSU_EXPR:
> +       return fold_convert (type, fold_abs_const (arg0,
> +                                                  signed_type_for (type)));
>
>      case CONJ_EXPR:
>
> I think this will get you bogus TREE_OVERFLOW flags set on ABSU (-INT_MIN).
>
> I think you want to change fold_abs_const to properly deal with arg0 being
> signed and type unsigned.  That is, sth like
>
> diff --git a/gcc/fold-const.c b/gcc/fold-const.c
> index 6f80f1b1d69..f60f9c77e91 100644
> --- a/gcc/fold-const.c
> +++ b/gcc/fold-const.c
> @@ -13843,18 +13843,19 @@ fold_abs_const (tree arg0, tree type)
>        {
>          /* If the value is unsigned or non-negative, then the absolute value
>            is the same as the ordinary value.  */
> -       if (!wi::neg_p (wi::to_wide (arg0), TYPE_SIGN (type)))
> -         t = arg0;
> +       wide_int val = wi::to_wide (arg0);
> +       bool overflow = false;
> +       if (!wi::neg_p (val, TYPE_SIGN (TREE_TYPE (arg0))))
> +         ;
>
>         /* If the value is negative, then the absolute value is
>            its negation.  */
>         else
> -         {
> -           bool overflow;
> -           wide_int val = wi::neg (wi::to_wide (arg0), &overflow);
> -           t = force_fit_type (type, val, -1,
> -                               overflow | TREE_OVERFLOW (arg0));
> -         }
> +         wide_int val = wi::neg (val, &overflow);
> +
> +       /* Force to the destination type, set TREE_OVERFLOW for signed
> +          TYPE only.  */
> +       t = force_fit_type (type, val, 1, overflow | TREE_OVERFLOW (arg0));
>        }
>        break;
>
> and then simply share the const_unop code with ABS_EXPR.

Done.

> diff --git a/gcc/match.pd b/gcc/match.pd
> index 14386da..7d7c132 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -102,6 +102,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>  (match (nop_convert @0)
>   @0)
>
> +(simplify (abs (convert @0))
> + (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
> +      && !TYPE_UNSIGNED (TREE_TYPE (@0))
> +      && !TYPE_UNSIGNED (type))
> +  (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
> +   (convert (absu:utype @0)))))
> +
> +
>
> please put a comment before the pattern.  I believe there's no
> need to check for !TYPE_UNSIGNED (type).  Note this
> also converts abs ((char)int-var) to (char)absu(int-var) which
> doesn't make sense.  The original issue you want to address
> here is the case where TYPE_PRECISION of @0 is less than
> the precision of type.  That is, you want to remove language
> introduced integer promotion of @0 which only is possible
> with ABSU.  So please do add such precision check
> (I simply suggested the bogus direction of the test).

Done.
>
> diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
> index 68f4fd3..9b62583 100644
> --- a/gcc/tree-cfg.c
> +++ b/gcc/tree-cfg.c
> @@ -3685,6 +3685,12 @@ verify_gimple_assign_unary (gassign *stmt)
>      case PAREN_EXPR:
>      case CONJ_EXPR:
>        break;
> +    case ABSU_EXPR:
> +      if (!TYPE_UNSIGNED (lhs_type)
> +         || !ANY_INTEGRAL_TYPE_P (rhs1_type))
>
>  if (!ANY_INTEGRAL_TYPE_P (lhs_type)
>      || !TYPE_UNSIGNED (lhs_type)
>      || !ANY_INTEGRAL_TYPE_P (rhs1_type)
>      || TYPE_UNSIGNED (rhs1_type)
>      || element_precision (lhs_type) != element_precision (rhs1_type))
>   {
>       error ("invalid types for ABSU_EXPR");
>       debug_generic_expr (lhs_type);
>       debug_generic_expr (rhs1_type);
>      return true;
>   }
>
> +       return true;
> +      return false;
> +      break;
>
> diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
> index 30c6d9e..44b1399 100644
> --- a/gcc/tree-eh.c
> +++ b/gcc/tree-eh.c
> @@ -2465,6 +2465,7 @@ operation_could_trap_helper_p (enum tree_code op,
>
>      case NEGATE_EXPR:
>      case ABS_EXPR:
> +    case ABSU_EXPR:
>      case CONJ_EXPR:
>        /* These operations don't trap with floating point.  */
>        if (honor_trapv)
>
> ABSU never traps.  Please instead unconditionally return false.
Done.

>
> diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
> index 66c78de..b52d714 100644
> --- a/gcc/tree-vect-stmts.c
> +++ b/gcc/tree-vect-stmts.c
> @@ -5995,7 +5995,11 @@ vectorizable_operation (gimple *stmt,
> gimple_stmt_iterator *gsi,
>                       "transform binary/unary operation.\n");
>
>    /* Handle def.  */
> -  vec_dest = vect_create_destination_var (scalar_dest, vectype);
> +  if (code == ABSU_EXPR)
> +    vec_dest = vect_create_destination_var (scalar_dest,
> +                                           unsigned_type_for (vectype));
> +  else
> +    vec_dest = vect_create_destination_var (scalar_dest, vectype);
>
>    /* POINTER_DIFF_EXPR has pointer arguments which are vectorized as
>       vectors with unsigned elements, but the result is signed.  So, we
>
> simply use vectype_out for creation of vec_dest.
Done.

>
> diff --git a/gcc/tree.def b/gcc/tree.def
> index c660b2c..5fec781 100644
> --- a/gcc/tree.def
> +++ b/gcc/tree.def
> @@ -760,6 +760,7 @@ DEFTREECODE (MAX_EXPR, "max_expr", tcc_binary, 2)
>     An ABS_EXPR must have either an INTEGER_TYPE or a REAL_TYPE.  The
>     operand of the ABS_EXPR must have the same type.  */
>  DEFTREECODE (ABS_EXPR, "abs_expr", tcc_unary, 1)
> +DEFTREECODE (ABSU_EXPR, "absu_expr", tcc_unary, 1)
>
>  /* Shift operations for shift and rotate.
>     Shift means logical shift if done on an
>
> You can clearly see that the comment before ABS_EXPR doesn't apply to ABSU_EXPR
> so please add an appropriate one.  I suggest
>
> /* Represents the unsigned absolute value of the operand.
>     An ABSU_EXPR must have unsigned INTEGER_TYPE.  The operand of the ABSU_EXPR
>     must have the corresponding signed type.  */

Done.

Here is the reviesed patch. Is this OK?

Thanks,
Kugan

>
> Otherwise looks OK.  (I didn't explicitely check for missing ABSU_EXPR
> handling this time)
>
> Thanks,
> Richard.
>
>
>> Thanks,
>> Kugan
>>
>>
>> On 18 May 2018 at 12:36, Kugan Vivekanandarajah
>> <kugan.vivekanandarajah@linaro.org> wrote:
>> > Hi Richard,
>> >
>> > Thanks for the review. I am revising the patch based on Andrew's comments too.
>> >
>> > On 17 May 2018 at 20:36, Richard Biener <richard.guenther@gmail.com> wrote:
>> >> On Thu, May 17, 2018 at 4:56 AM Andrew Pinski <pinskia@gmail.com> wrote:
>> >>
>> >>> On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
>> >>> <kugan.vivekanandarajah@linaro.org> wrote:
>> >>> > As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
>> >>> > issue. In the attached patch, in fold_cond_expr_with_comparison I am
>> >>> > generating ABSU_EXPR for these cases. As I understand, absu_expr is
>> >>> > well defined in RTL. So, the issue is generating absu_expr  and
>> >>> > transferring to RTL in the correct way. I am not sure I am not doing
>> >>> > all that is needed. I will clean up and add more test-cases based on
>> >>> > the feedback.
>> >>
>> >>
>> >>> diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
>> >>> index 71e172c..2b812e5 100644
>> >>> --- a/gcc/optabs-tree.c
>> >>> +++ b/gcc/optabs-tree.c
>> >>> @@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code, const_tree
>> >> type,
>> >>>         return trapv ? negv_optab : neg_optab;
>> >>
>> >>>       case ABS_EXPR:
>> >>> +    case ABSU_EXPR:
>> >>>         return trapv ? absv_optab : abs_optab;
>> >>
>> >>
>> >>> This part is not correct, it should something like this:
>> >>
>> >>>       case ABS_EXPR:
>> >>>         return trapv ? absv_optab : abs_optab;
>> >>> +    case ABSU_EXPR:
>> >>> +       return abs_optab ;
>> >>
>> >>> Because ABSU is not undefined at the TYPE_MAX.
>> >>
>> >> Also
>> >>
>> >>         /* Unsigned abs is simply the operand.  Testing here means we don't
>> >>           risk generating incorrect code below.  */
>> >> -      if (TYPE_UNSIGNED (type))
>> >> +      if (TYPE_UNSIGNED (type)
>> >> +         && (code != ABSU_EXPR))
>> >>          return op0;
>> >>
>> >> is wrong.  ABSU of an unsigned number is still just that number.
>> >>
>> >> The change to fold_cond_expr_with_comparison looks odd to me
>> >> (premature optimization).  It should be done separately - it seems
>> >> you are doing
>> >
>> > FE seems to be using this to generate ABS_EXPR from
>> > c_fully_fold_internal to fold_build3_loc and so on. I changed this to
>> > generate ABSU_EXPR for the case in the testcase. So the question
>> > should be, in what cases do we need ABS_EXPR and in what cases do we
>> > need ABSU_EXPR. It is not very clear to me.
>> >
>> >
>> >>
>> >> (simplify (abs (convert @0)) (convert (absu @0)))
>> >>
>> >> here.
>> >>
>> >> You touch one other place in fold-const.c but there seem to be many
>> >> more that need ABSU_EXPR handling (you touched the one needed
>> >> for correctness) - esp. you should at least handle constant folding
>> >> in const_unop and the nonnegative predicate.
>> >
>> > OK.
>> >>
>> >> @@ -3167,6 +3167,9 @@ verify_expr (tree *tp, int *walk_subtrees, void *data
>> >> ATTRIBUTE_UNUSED)
>> >>         CHECK_OP (0, "invalid operand to unary operator");
>> >>         break;
>> >>
>> >> +    case ABSU_EXPR:
>> >> +      break;
>> >> +
>> >>       case REALPART_EXPR:
>> >>       case IMAGPART_EXPR:
>> >>
>> >> verify_expr is no more.  Did you test this recently against trunk?
>> >
>> > This patch is against slightly older trunk. I will rebase it.
>> >
>> >>
>> >> @@ -3937,6 +3940,9 @@ verify_gimple_assign_unary (gassign *stmt)
>> >>       case PAREN_EXPR:
>> >>       case CONJ_EXPR:
>> >>         break;
>> >> +    case ABSU_EXPR:
>> >> +      /* FIXME.  */
>> >> +      return false;
>> >>
>> >> no - please not!  Please add verification here - ABSU should be only
>> >> called on INTEGRAL, vector or complex INTEGRAL types and the
>> >> type of the LHS should be always the unsigned variant of the
>> >> argument type.
>> >
>> > OK.
>> >>
>> >>     if (is_gimple_val (cond_expr))
>> >>       return cond_expr;
>> >>
>> >> -  if (TREE_CODE (cond_expr) == ABS_EXPR)
>> >> +  if (TREE_CODE (cond_expr) == ABS_EXPR
>> >> +      || TREE_CODE (cond_expr) == ABSU_EXPR)
>> >>       {
>> >>         rhs1 = TREE_OPERAND (cond_expr, 1);
>> >>         STRIP_USELESS_TYPE_CONVERSION (rhs1);
>> >>
>> >> err, but the next line just builds a ABS_EXPR ...
>> >>
>> >> How did you identify spots that need adjustment?  I would expect that
>> >> once folding generates ABSU_EXPR that you need to adjust frontends
>> >> (C++ constexpr handling for example).  Also I miss adjustments
>> >> to gimple-pretty-print.c and the GIMPLE FE parser.
>> >
>> > I will add this.
>> >>
>> >> recursively grepping throughout the whole gcc/ tree doesn't reveal too many
>> >> cases of ABS_EXPR so I think it's reasonable to audit all of them.
>> >>
>> >> I also miss some trivial absu simplifications in match.pd.  There are not
>> >> a lot of abs cases but similar ones would be good to have initially.
>> >
>> > I will add them in the next version.
>> >
>> > Thanks,
>> > Kugan
>> >
>> >>
>> >> Thanks for tackling this!
>> >> Richard.
>> >>
>> >>> Thanks,
>> >>> Andrew
>> >>
>> >>> >
>> >>> > Thanks,
>> >>> > Kugan
>> >>> >
>> >>> >
>> >>> > gcc/ChangeLog:
>> >>> >
>> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>> >>> >
>> >>> >     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
>> >>> >     * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
>> >>> >     (fold_unary_loc): Handle ABSU_EXPR.
>> >>> >     * optabs-tree.c (optab_for_tree_code): Likewise.
>> >>> >     * tree-cfg.c (verify_expr): Likewise.
>> >>> >     (verify_gimple_assign_unary):  Likewise.
>> >>> >     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
>> >>> >     * tree-inline.c (estimate_operator_cost):  Likewise.
>> >>> >     * tree-pretty-print.c (dump_generic_node):  Likewise.
>> >>> >     * tree.def (ABSU_EXPR): New.
>> >>> >
>> >>> > gcc/testsuite/ChangeLog:
>> >>> >
>> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>> >>> >
>> >>> >     * gcc.dg/absu.c: New test.
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 859eeb4..0e8efb5 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -3312,6 +3312,7 @@ c_common_truthvalue_conversion (location_t location, tree expr)
 
     case NEGATE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case FLOAT_EXPR:
     case EXCESS_PRECISION_EXPR:
       /* These don't change whether an object is nonzero or zero.  */
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 45a4529..5bb6804 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -4314,6 +4314,16 @@ build_unary_op (location_t location, enum tree_code code, tree xarg,
 	arg = default_conversion (arg);
       break;
 
+    case ABSU_EXPR:
+      if (!(typecode == INTEGER_TYPE))
+	{
+	  error_at (location, "wrong type argument to absu");
+	  return error_mark_node;
+	}
+      else if (!noconvert)
+	arg = default_conversion (arg);
+      break;
+
     case CONJ_EXPR:
       /* Conjugating a real value is a no-op, but allow it anyway.  */
       if (!(typecode == INTEGER_TYPE || typecode == REAL_TYPE
diff --git a/gcc/c/gimple-parser.c b/gcc/c/gimple-parser.c
index c9abe24..11e76ff 100644
--- a/gcc/c/gimple-parser.c
+++ b/gcc/c/gimple-parser.c
@@ -328,7 +328,8 @@ c_parser_gimple_statement (c_parser *parser, gimple_seq *seq)
     case CPP_NAME:
       {
 	tree id = c_parser_peek_token (parser)->value;
-	if (strcmp (IDENTIFIER_POINTER (id), "__ABS") == 0)
+	if (strcmp (IDENTIFIER_POINTER (id), "__ABS") == 0
+	    || strcmp (IDENTIFIER_POINTER (id), "__ABSU") == 0)
 	  goto build_unary_expr;
 	break;
       }
@@ -638,6 +639,12 @@ c_parser_gimple_unary_expression (c_parser *parser)
 	      op = c_parser_gimple_postfix_expression (parser);
 	      return parser_build_unary_op (op_loc, ABS_EXPR, op);
 	    }
+	  else if (strcmp (IDENTIFIER_POINTER (id), "__ABSU") == 0)
+	    {
+	      c_parser_consume_token (parser);
+	      op = c_parser_gimple_postfix_expression (parser);
+	      return parser_build_unary_op (op_loc, ABSU_EXPR, op);
+	    }
 	  else
 	    return c_parser_gimple_postfix_expression (parser);
 	}
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index ef143a3..ba4543c 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -4621,6 +4621,7 @@ expand_debug_expr (tree exp)
       }
 
     case ABS_EXPR:
+    case ABSU_EXPR:
       return simplify_gen_unary (ABS, mode, op0, mode);
 
     case NEGATE_EXPR:
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index e19864d..487127c 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -51228,6 +51228,7 @@ ix86_add_stmt_cost (void *data, int count, enum vect_cost_for_stmt kind,
 
 	case BIT_IOR_EXPR:
 	case ABS_EXPR:
+	case ABSU_EXPR:
 	case MIN_EXPR:
 	case MAX_EXPR:
 	case BIT_XOR_EXPR:
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 8c6ec55..bea9147 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -5760,6 +5760,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
     case FLOAT_EXPR:
     case NEGATE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case TRUTH_NOT_EXPR:
     case FIXED_CONVERT_EXPR:
     case UNARY_PLUS_EXPR:
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index eda5f05..bca0c59 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -2271,6 +2271,7 @@ cp_fold (tree x)
     case FLOAT_EXPR:
     case NEGATE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case BIT_NOT_EXPR:
     case TRUTH_NOT_EXPR:
     case FIXED_CONVERT_EXPR:
diff --git a/gcc/dojump.c b/gcc/dojump.c
index 9da8a0e..88cc96a 100644
--- a/gcc/dojump.c
+++ b/gcc/dojump.c
@@ -467,6 +467,7 @@ do_jump (tree exp, rtx_code_label *if_false_label,
       /* FALLTHRU */
     case NON_LVALUE_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
     case NEGATE_EXPR:
     case LROTATE_EXPR:
     case RROTATE_EXPR:
diff --git a/gcc/expr.c b/gcc/expr.c
index 00a802c..9efa535 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -9074,6 +9074,7 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
       return REDUCE_BIT_FIELD (temp);
 
     case ABS_EXPR:
+    case ABSU_EXPR:
       op0 = expand_expr (treeop0, subtarget,
 			 VOIDmode, EXPAND_NORMAL);
       if (modifier == EXPAND_STACK_PARM)
@@ -9085,7 +9086,7 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
 
       /* Unsigned abs is simply the operand.  Testing here means we don't
 	 risk generating incorrect code below.  */
-      if (TYPE_UNSIGNED (type))
+      if (TYPE_UNSIGNED (TREE_TYPE (treeop0)))
 	return op0;
 
       return expand_abs (mode, op0, target, unsignedp,
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index faa184a..c19614e 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -1723,7 +1723,8 @@ const_unop (enum tree_code code, tree type, tree arg0)
       && HONOR_SNANS (TYPE_MODE (TREE_TYPE (arg0)))
       && REAL_VALUE_ISSIGNALING_NAN (TREE_REAL_CST (arg0))
       && code != NEGATE_EXPR
-      && code != ABS_EXPR)
+      && code != ABS_EXPR
+      && code != ABSU_EXPR)
     return NULL_TREE;
 
   switch (code)
@@ -1758,6 +1759,7 @@ const_unop (enum tree_code code, tree type, tree arg0)
       }
 
     case ABS_EXPR:
+    case ABSU_EXPR:
       if (TREE_CODE (arg0) == INTEGER_CST || TREE_CODE (arg0) == REAL_CST)
 	return fold_abs_const (arg0, type);
       break;
@@ -13846,20 +13848,21 @@ fold_abs_const (tree arg0, tree type)
       {
         /* If the value is unsigned or non-negative, then the absolute value
 	   is the same as the ordinary value.  */
-	if (!wi::neg_p (wi::to_wide (arg0), TYPE_SIGN (type)))
-	  t = arg0;
+	wide_int val = wi::to_wide (arg0);
+	bool overflow = false;
+	if (!wi::neg_p (val, TYPE_SIGN (TREE_TYPE (arg0))))
+	  ;
 
 	/* If the value is negative, then the absolute value is
 	   its negation.  */
 	else
-	  {
-	    bool overflow;
-	    wide_int val = wi::neg (wi::to_wide (arg0), &overflow);
-	    t = force_fit_type (type, val, -1,
-				overflow | TREE_OVERFLOW (arg0));
-	  }
+	  val = wi::neg (val, &overflow);
+
+	/* Force to the destination type, set TREE_OVERFLOW for signed
+	   TYPE only.  */
+	t = force_fit_type (type, val, 1, overflow | TREE_OVERFLOW (arg0));
       }
-      break;
+    break;
 
     case REAL_CST:
       if (REAL_VALUE_NEGATIVE (TREE_REAL_CST (arg0)))
diff --git a/gcc/gimple-pretty-print.c b/gcc/gimple-pretty-print.c
index afe0147..4fa992d 100644
--- a/gcc/gimple-pretty-print.c
+++ b/gcc/gimple-pretty-print.c
@@ -358,14 +358,17 @@ dump_unary_rhs (pretty_printer *buffer, gassign *gs, int spc,
       break;
 
     case ABS_EXPR:
+    case ABSU_EXPR:
       if (flags & TDF_GIMPLE)
 	{
-	  pp_string (buffer, "__ABS ");
+	  pp_string (buffer,
+		     rhs_code == ABS_EXPR ? "__ABS " : "__ABSU ");
 	  dump_generic_node (buffer, rhs, spc, flags, false);
 	}
       else
 	{
-	  pp_string (buffer, "ABS_EXPR <");
+	  pp_string (buffer,
+		     rhs_code == ABS_EXPR ? "ABS_EXPR <" : "ABSU_EXPR <");
 	  dump_generic_node (buffer, rhs, spc, flags, false);
 	  pp_greater (buffer);
 	}
diff --git a/gcc/gimple-ssa-backprop.c b/gcc/gimple-ssa-backprop.c
index 27aa575..a38b5eb 100644
--- a/gcc/gimple-ssa-backprop.c
+++ b/gcc/gimple-ssa-backprop.c
@@ -405,6 +405,7 @@ backprop::process_assign_use (gassign *assign, tree rhs, usage_info *info)
   switch (gimple_assign_rhs_code (assign))
     {
     case ABS_EXPR:
+    case ABSU_EXPR:
       /* The sign of the input doesn't matter.  */
       info->flags.ignore_sign = true;
       break;
@@ -681,6 +682,7 @@ strip_sign_op_1 (tree rhs)
     switch (gimple_assign_rhs_code (assign))
       {
       case ABS_EXPR:
+      case ABSU_EXPR:
       case NEGATE_EXPR:
 	return gimple_assign_rhs1 (assign);
 
diff --git a/gcc/match.pd b/gcc/match.pd
index 7033730..ba52bb0 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -90,6 +90,17 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 (match (nop_convert @0)
  @0) 
 
+/* Transform likes of (char) ABS_EXPR <(int) x> into (char) ABSU_EXPR <x>
+   ABSU_EXPR returns unsigned absolute value of the operand and the operand
+   of the ABSU_EXPR will have the corresponding signed type.  */
+(simplify (abs (convert @0))
+ (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+      && !TYPE_UNSIGNED (TREE_TYPE (@0))
+      && element_precision (type) > element_precision (TREE_TYPE (@0)))
+  (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
+   (convert (absu:utype @0)))))
+
+
 /* Simplifications of operations with one constant operand and
    simplifications to constants or single values.  */
 
diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
index 71e172c..aa119ec 100644
--- a/gcc/optabs-tree.c
+++ b/gcc/optabs-tree.c
@@ -237,6 +237,8 @@ optab_for_tree_code (enum tree_code code, const_tree type,
     case ABS_EXPR:
       return trapv ? absv_optab : abs_optab;
 
+    case ABSU_EXPR:
+      return abs_optab;
     default:
       return unknown_optab;
     }
diff --git a/gcc/testsuite/gcc.dg/absu.c b/gcc/testsuite/gcc.dg/absu.c
index e69de29..063da28 100644
--- a/gcc/testsuite/gcc.dg/absu.c
+++ b/gcc/testsuite/gcc.dg/absu.c
@@ -0,0 +1,85 @@
+
+/* { dg-do run  } */
+/* { dg-options "-O0" } */
+
+#include <limits.h>
+#define ABS(x)	(((x) >= 0) ? (x) : -(x))
+
+#define DEF_TEST(TYPE)	\
+void foo_##TYPE (signed TYPE x, unsigned TYPE y){	\
+    TYPE t = ABS (x);				\
+    if (t != y)					\
+ 	__builtin_abort ();			\
+}						\
+
+DEF_TEST (char);
+DEF_TEST (short);
+DEF_TEST (int);
+DEF_TEST (long);
+
+int main ()
+{
+  foo_char (SCHAR_MIN + 1, SCHAR_MAX);
+  foo_char (0, 0);
+  foo_char (-1, 1);
+  foo_char (1, 1);
+  foo_char (SCHAR_MAX, SCHAR_MAX);
+
+  foo_int (-1, 1);
+  foo_int (0, 0);
+  foo_int (INT_MAX, INT_MAX);
+  foo_int (INT_MIN + 1, INT_MAX);
+
+  foo_short (-1, 1);
+  foo_short (0, 0);
+  foo_short (SHRT_MAX, SHRT_MAX);
+  foo_short (SHRT_MIN + 1, SHRT_MAX);
+
+  foo_long (-1, 1);
+  foo_long (0, 0);
+  foo_long (LONG_MAX, LONG_MAX);
+  foo_long (LONG_MIN + 1, LONG_MAX);
+
+  return 0;
+}
+
+/* { dg-do run  } */
+/* { dg-options "-O0" } */
+
+#include <limits.h>
+#define ABS(x)	(((x) >= 0) ? (x) : -(x))
+
+#define DEF_TEST(TYPE)	\
+void foo_##TYPE (signed TYPE x, unsigned TYPE y){	\
+    TYPE t = ABS (x);				\
+    if (t != y)					\
+ 	__builtin_abort ();			\
+}						\
+
+DEF_TEST (char);
+DEF_TEST (short);
+DEF_TEST (int);
+DEF_TEST (long);
+void main ()
+{
+  foo_char (SCHAR_MIN + 1, SCHAR_MAX);
+  foo_char (0, 0);
+  foo_char (-1, 1);
+  foo_char (1, 1);
+  foo_char (SCHAR_MAX, SCHAR_MAX);
+
+  foo_int (-1, 1);
+  foo_int (0, 0);
+  foo_int (INT_MAX, INT_MAX);
+  foo_int (INT_MIN + 1, INT_MAX);
+
+  foo_short (-1, 1);
+  foo_short (0, 0);
+  foo_short (SHRT_MAX, SHRT_MAX);
+  foo_short (SHRT_MIN + 1, SHRT_MAX);
+
+  foo_long (-1, 1);
+  foo_long (0, 0);
+  foo_long (LONG_MAX, LONG_MAX);
+  foo_long (LONG_MIN + 1, LONG_MAX);
+}
diff --git a/gcc/testsuite/gcc.dg/gimplefe-29.c b/gcc/testsuite/gcc.dg/gimplefe-29.c
index e69de29..54b86ef 100644
--- a/gcc/testsuite/gcc.dg/gimplefe-29.c
+++ b/gcc/testsuite/gcc.dg/gimplefe-29.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fgimple -fdump-tree-ssa-gimple" } */
+
+unsigned int __GIMPLE() f(int a)
+{
+  unsigned int t0;
+  t0_1 = __ABSU a;
+  return t0_1;
+}
+
+/* { dg-final { scan-tree-dump "__ABSU a" "ssa" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/pr64946.c b/gcc/testsuite/gcc.target/aarch64/pr64946.c
index e69de29..736656f 100644
--- a/gcc/testsuite/gcc.target/aarch64/pr64946.c
+++ b/gcc/testsuite/gcc.target/aarch64/pr64946.c
@@ -0,0 +1,13 @@
+
+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+
+signed char a[100],b[100];
+void absolute_s8 (void)
+{
+  int i;
+  for (i=0; i<16; i++)
+    a[i] = (b[i] > 0 ? b[i] : -b[i]);
+};
+
+/* { dg-final { scan-assembler-times "abs\tv\[0-9\]+.16b, v\[0-9\]+.16b" 1 } } */
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 7f48d2d..6df42cc 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -3685,6 +3685,12 @@ verify_gimple_assign_unary (gassign *stmt)
     case PAREN_EXPR:
     case CONJ_EXPR:
       break;
+    case ABSU_EXPR:
+      if (!TYPE_UNSIGNED (lhs_type)
+	  || !ANY_INTEGRAL_TYPE_P (rhs1_type))
+	return true;
+      return false;
+      break;
 
     case VEC_DUPLICATE_EXPR:
       if (TREE_CODE (lhs_type) != VECTOR_TYPE
diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
index 3609bca..da87466 100644
--- a/gcc/tree-eh.c
+++ b/gcc/tree-eh.c
@@ -2471,6 +2471,10 @@ operation_could_trap_helper_p (enum tree_code op,
 	return true;
       return false;
 
+    case ABSU_EXPR:
+      /* ABSU_EXPR never traps.  */
+      return false;
+
     case PLUS_EXPR:
     case MINUS_EXPR:
     case MULT_EXPR:
diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
index 5a0a252..d272974 100644
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -3866,6 +3866,7 @@ estimate_operator_cost (enum tree_code code, eni_weights *weights,
     case MIN_EXPR:
     case MAX_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
 
     case LSHIFT_EXPR:
     case RSHIFT_EXPR:
diff --git a/gcc/tree-pretty-print.c b/gcc/tree-pretty-print.c
index bc36c28..612a18f 100644
--- a/gcc/tree-pretty-print.c
+++ b/gcc/tree-pretty-print.c
@@ -2463,6 +2463,12 @@ dump_generic_node (pretty_printer *pp, tree node, int spc, dump_flags_t flags,
       pp_greater (pp);
       break;
 
+    case ABSU_EXPR:
+      pp_string (pp, "ABSU_EXPR <");
+      dump_generic_node (pp, TREE_OPERAND (node, 0), spc, flags, false);
+      pp_greater (pp);
+      break;
+
     case RANGE_EXPR:
       NIY;
       break;
diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c
index 5c2578f..e4df6c8 100644
--- a/gcc/tree-vect-patterns.c
+++ b/gcc/tree-vect-patterns.c
@@ -614,7 +614,8 @@ vect_recog_sad_pattern (vec<gimple *> *stmts, tree *type_in,
   gcc_assert (abs_stmt_vinfo);
   if (STMT_VINFO_DEF_TYPE (abs_stmt_vinfo) != vect_internal_def)
     return NULL;
-  if (gimple_assign_rhs_code (abs_stmt) != ABS_EXPR)
+  if (gimple_assign_rhs_code (abs_stmt) != ABS_EXPR
+      && gimple_assign_rhs_code (abs_stmt) != ABSU_EXPR)
     return NULL;
 
   tree abs_oprnd = gimple_assign_rhs1 (abs_stmt);
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 4539f6a..c71b688 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -5995,7 +5995,10 @@ vectorizable_operation (gimple *stmt, gimple_stmt_iterator *gsi,
                      "transform binary/unary operation.\n");
 
   /* Handle def.  */
-  vec_dest = vect_create_destination_var (scalar_dest, vectype);
+  if (code == ABSU_EXPR)
+    vec_dest = vect_create_destination_var (scalar_dest, vectype_out);
+  else
+    vec_dest = vect_create_destination_var (scalar_dest, vectype);
 
   /* POINTER_DIFF_EXPR has pointer arguments which are vectorized as
      vectors with unsigned elements, but the result is signed.  So, we
diff --git a/gcc/tree.def b/gcc/tree.def
index 31de6c0..a1766e4 100644
--- a/gcc/tree.def
+++ b/gcc/tree.def
@@ -761,6 +761,11 @@ DEFTREECODE (MAX_EXPR, "max_expr", tcc_binary, 2)
    operand of the ABS_EXPR must have the same type.  */
 DEFTREECODE (ABS_EXPR, "abs_expr", tcc_unary, 1)
 
+/* Represents the unsigned absolute value of the operand.
+   An ABSU_EXPR must have unsigned INTEGER_TYPE.  The operand of the ABSU_EXPR
+   must have the corresponding signed type.  */
+DEFTREECODE (ABSU_EXPR, "absu_expr", tcc_unary, 1)
+
 /* Shift operations for shift and rotate.
    Shift means logical shift if done on an
    unsigned type, arithmetic shift if done on a signed type.
Richard Biener June 4, 2018, 8:38 a.m. | #8
On Mon, Jun 4, 2018 at 10:18 AM Kugan Vivekanandarajah
<kugan.vivekanandarajah@linaro.org> wrote:
>
> Hi Richard,
>
> Thanks for the review.
>
> On 1 June 2018 at 22:20, Richard Biener <richard.guenther@gmail.com> wrote:
> > On Fri, Jun 1, 2018 at 4:12 AM Kugan Vivekanandarajah
> > <kugan.vivekanandarajah@linaro.org> wrote:
> >>
> >> Hi Richard,
> >>
> >> This is the revised patch based on the review and the discussion in
> >> https://gcc.gnu.org/ml/gcc/2018-05/msg00179.html.
> >>
> >> In summary:
> >> - I skipped  (element_precision (type) < element_precision (TREE_TYPE
> >> (@0))) in the match.pd pattern as this would prevent transformation
> >> for the case in PR.
> >> that is, I am interested in is something like:
> >>   char t = (char) ABS_EXPR <(int) x>
> >> and I want to generate
> >> char t = (char) ABSU_EXPR <x>
> >>
> >> - I also haven't added all the necessary match.pd changes for
> >> ABSU_EXPR. I have a patch for that but will submit separately based on
> >> this reveiw.
> >>
> >> - I also tried to add ABSU_EXPRsupport  in the places as necessary by
> >> grepping for ABS_EXPR.
> >>
> >> - I also had to add special casing in vectorizer for ABSU_EXP as its
> >> result is unsigned type.
> >>
> >> Is this OK. Patch bootstraps and the regression test is ongoing.
> >
> > The c/c-typeck.c:build_unary_op change looks unnecessary - the
> > C FE should never generate this directly (the c-common one might
> > be triggered by early folding I guess).
>
> The Gimple FE testcase is running into this.

Ah, OK then.

> >
> > @@ -1761,6 +1762,9 @@ const_unop (enum tree_code code, tree type, tree arg0)
> >        if (TREE_CODE (arg0) == INTEGER_CST || TREE_CODE (arg0) == REAL_CST)
> >         return fold_abs_const (arg0, type);
> >        break;
> > +    case ABSU_EXPR:
> > +       return fold_convert (type, fold_abs_const (arg0,
> > +                                                  signed_type_for (type)));
> >
> >      case CONJ_EXPR:
> >
> > I think this will get you bogus TREE_OVERFLOW flags set on ABSU (-INT_MIN).
> >
> > I think you want to change fold_abs_const to properly deal with arg0 being
> > signed and type unsigned.  That is, sth like
> >
> > diff --git a/gcc/fold-const.c b/gcc/fold-const.c
> > index 6f80f1b1d69..f60f9c77e91 100644
> > --- a/gcc/fold-const.c
> > +++ b/gcc/fold-const.c
> > @@ -13843,18 +13843,19 @@ fold_abs_const (tree arg0, tree type)
> >        {
> >          /* If the value is unsigned or non-negative, then the absolute value
> >            is the same as the ordinary value.  */
> > -       if (!wi::neg_p (wi::to_wide (arg0), TYPE_SIGN (type)))
> > -         t = arg0;
> > +       wide_int val = wi::to_wide (arg0);
> > +       bool overflow = false;
> > +       if (!wi::neg_p (val, TYPE_SIGN (TREE_TYPE (arg0))))
> > +         ;
> >
> >         /* If the value is negative, then the absolute value is
> >            its negation.  */
> >         else
> > -         {
> > -           bool overflow;
> > -           wide_int val = wi::neg (wi::to_wide (arg0), &overflow);
> > -           t = force_fit_type (type, val, -1,
> > -                               overflow | TREE_OVERFLOW (arg0));
> > -         }
> > +         wide_int val = wi::neg (val, &overflow);
> > +
> > +       /* Force to the destination type, set TREE_OVERFLOW for signed
> > +          TYPE only.  */
> > +       t = force_fit_type (type, val, 1, overflow | TREE_OVERFLOW (arg0));
> >        }
> >        break;
> >
> > and then simply share the const_unop code with ABS_EXPR.
>
> Done.
>
> > diff --git a/gcc/match.pd b/gcc/match.pd
> > index 14386da..7d7c132 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -102,6 +102,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> >  (match (nop_convert @0)
> >   @0)
> >
> > +(simplify (abs (convert @0))
> > + (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
> > +      && !TYPE_UNSIGNED (TREE_TYPE (@0))
> > +      && !TYPE_UNSIGNED (type))
> > +  (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
> > +   (convert (absu:utype @0)))))
> > +
> > +
> >
> > please put a comment before the pattern.  I believe there's no
> > need to check for !TYPE_UNSIGNED (type).  Note this
> > also converts abs ((char)int-var) to (char)absu(int-var) which
> > doesn't make sense.  The original issue you want to address
> > here is the case where TYPE_PRECISION of @0 is less than
> > the precision of type.  That is, you want to remove language
> > introduced integer promotion of @0 which only is possible
> > with ABSU.  So please do add such precision check
> > (I simply suggested the bogus direction of the test).
>
> Done.
> >
> > diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
> > index 68f4fd3..9b62583 100644
> > --- a/gcc/tree-cfg.c
> > +++ b/gcc/tree-cfg.c
> > @@ -3685,6 +3685,12 @@ verify_gimple_assign_unary (gassign *stmt)
> >      case PAREN_EXPR:
> >      case CONJ_EXPR:
> >        break;
> > +    case ABSU_EXPR:
> > +      if (!TYPE_UNSIGNED (lhs_type)
> > +         || !ANY_INTEGRAL_TYPE_P (rhs1_type))
> >
> >  if (!ANY_INTEGRAL_TYPE_P (lhs_type)
> >      || !TYPE_UNSIGNED (lhs_type)
> >      || !ANY_INTEGRAL_TYPE_P (rhs1_type)
> >      || TYPE_UNSIGNED (rhs1_type)
> >      || element_precision (lhs_type) != element_precision (rhs1_type))
> >   {
> >       error ("invalid types for ABSU_EXPR");
> >       debug_generic_expr (lhs_type);
> >       debug_generic_expr (rhs1_type);
> >      return true;
> >   }
> >

^^^  you forgot this one.


> > +       return true;
> > +      return false;
> > +      break;
> >
> > diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
> > index 30c6d9e..44b1399 100644
> > --- a/gcc/tree-eh.c
> > +++ b/gcc/tree-eh.c
> > @@ -2465,6 +2465,7 @@ operation_could_trap_helper_p (enum tree_code op,
> >
> >      case NEGATE_EXPR:
> >      case ABS_EXPR:
> > +    case ABSU_EXPR:
> >      case CONJ_EXPR:
> >        /* These operations don't trap with floating point.  */
> >        if (honor_trapv)
> >
> > ABSU never traps.  Please instead unconditionally return false.
> Done.
>
> >
> > diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
> > index 66c78de..b52d714 100644
> > --- a/gcc/tree-vect-stmts.c
> > +++ b/gcc/tree-vect-stmts.c
> > @@ -5995,7 +5995,11 @@ vectorizable_operation (gimple *stmt,
> > gimple_stmt_iterator *gsi,
> >                       "transform binary/unary operation.\n");
> >
> >    /* Handle def.  */
> > -  vec_dest = vect_create_destination_var (scalar_dest, vectype);
> > +  if (code == ABSU_EXPR)
> > +    vec_dest = vect_create_destination_var (scalar_dest,
> > +                                           unsigned_type_for (vectype));
> > +  else
> > +    vec_dest = vect_create_destination_var (scalar_dest, vectype);
> >
> >    /* POINTER_DIFF_EXPR has pointer arguments which are vectorized as
> >       vectors with unsigned elements, but the result is signed.  So, we
> >
> > simply use vectype_out for creation of vec_dest.
> Done.

   /* Handle def.  */
-  vec_dest = vect_create_destination_var (scalar_dest, vectype);
+  if (code == ABSU_EXPR)
+    vec_dest = vect_create_destination_var (scalar_dest, vectype_out);
+  else
+    vec_dest = vect_create_destination_var (scalar_dest, vectype);

I meant _always_ vectype_out.  Thus unconditionally

  vec_dest = vect_create_destination_var (scalar_dest, vectype_out);

OK with those two changes.

Thanks,
Richard.

> >
> > diff --git a/gcc/tree.def b/gcc/tree.def
> > index c660b2c..5fec781 100644
> > --- a/gcc/tree.def
> > +++ b/gcc/tree.def
> > @@ -760,6 +760,7 @@ DEFTREECODE (MAX_EXPR, "max_expr", tcc_binary, 2)
> >     An ABS_EXPR must have either an INTEGER_TYPE or a REAL_TYPE.  The
> >     operand of the ABS_EXPR must have the same type.  */
> >  DEFTREECODE (ABS_EXPR, "abs_expr", tcc_unary, 1)
> > +DEFTREECODE (ABSU_EXPR, "absu_expr", tcc_unary, 1)
> >
> >  /* Shift operations for shift and rotate.
> >     Shift means logical shift if done on an
> >
> > You can clearly see that the comment before ABS_EXPR doesn't apply to ABSU_EXPR
> > so please add an appropriate one.  I suggest
> >
> > /* Represents the unsigned absolute value of the operand.
> >     An ABSU_EXPR must have unsigned INTEGER_TYPE.  The operand of the ABSU_EXPR
> >     must have the corresponding signed type.  */
>
> Done.
>
> Here is the reviesed patch. Is this OK?
>
> Thanks,
> Kugan
>
> >
> > Otherwise looks OK.  (I didn't explicitely check for missing ABSU_EXPR
> > handling this time)
> >
> > Thanks,
> > Richard.
> >
> >
> >> Thanks,
> >> Kugan
> >>
> >>
> >> On 18 May 2018 at 12:36, Kugan Vivekanandarajah
> >> <kugan.vivekanandarajah@linaro.org> wrote:
> >> > Hi Richard,
> >> >
> >> > Thanks for the review. I am revising the patch based on Andrew's comments too.
> >> >
> >> > On 17 May 2018 at 20:36, Richard Biener <richard.guenther@gmail.com> wrote:
> >> >> On Thu, May 17, 2018 at 4:56 AM Andrew Pinski <pinskia@gmail.com> wrote:
> >> >>
> >> >>> On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
> >> >>> <kugan.vivekanandarajah@linaro.org> wrote:
> >> >>> > As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
> >> >>> > issue. In the attached patch, in fold_cond_expr_with_comparison I am
> >> >>> > generating ABSU_EXPR for these cases. As I understand, absu_expr is
> >> >>> > well defined in RTL. So, the issue is generating absu_expr  and
> >> >>> > transferring to RTL in the correct way. I am not sure I am not doing
> >> >>> > all that is needed. I will clean up and add more test-cases based on
> >> >>> > the feedback.
> >> >>
> >> >>
> >> >>> diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
> >> >>> index 71e172c..2b812e5 100644
> >> >>> --- a/gcc/optabs-tree.c
> >> >>> +++ b/gcc/optabs-tree.c
> >> >>> @@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code, const_tree
> >> >> type,
> >> >>>         return trapv ? negv_optab : neg_optab;
> >> >>
> >> >>>       case ABS_EXPR:
> >> >>> +    case ABSU_EXPR:
> >> >>>         return trapv ? absv_optab : abs_optab;
> >> >>
> >> >>
> >> >>> This part is not correct, it should something like this:
> >> >>
> >> >>>       case ABS_EXPR:
> >> >>>         return trapv ? absv_optab : abs_optab;
> >> >>> +    case ABSU_EXPR:
> >> >>> +       return abs_optab ;
> >> >>
> >> >>> Because ABSU is not undefined at the TYPE_MAX.
> >> >>
> >> >> Also
> >> >>
> >> >>         /* Unsigned abs is simply the operand.  Testing here means we don't
> >> >>           risk generating incorrect code below.  */
> >> >> -      if (TYPE_UNSIGNED (type))
> >> >> +      if (TYPE_UNSIGNED (type)
> >> >> +         && (code != ABSU_EXPR))
> >> >>          return op0;
> >> >>
> >> >> is wrong.  ABSU of an unsigned number is still just that number.
> >> >>
> >> >> The change to fold_cond_expr_with_comparison looks odd to me
> >> >> (premature optimization).  It should be done separately - it seems
> >> >> you are doing
> >> >
> >> > FE seems to be using this to generate ABS_EXPR from
> >> > c_fully_fold_internal to fold_build3_loc and so on. I changed this to
> >> > generate ABSU_EXPR for the case in the testcase. So the question
> >> > should be, in what cases do we need ABS_EXPR and in what cases do we
> >> > need ABSU_EXPR. It is not very clear to me.
> >> >
> >> >
> >> >>
> >> >> (simplify (abs (convert @0)) (convert (absu @0)))
> >> >>
> >> >> here.
> >> >>
> >> >> You touch one other place in fold-const.c but there seem to be many
> >> >> more that need ABSU_EXPR handling (you touched the one needed
> >> >> for correctness) - esp. you should at least handle constant folding
> >> >> in const_unop and the nonnegative predicate.
> >> >
> >> > OK.
> >> >>
> >> >> @@ -3167,6 +3167,9 @@ verify_expr (tree *tp, int *walk_subtrees, void *data
> >> >> ATTRIBUTE_UNUSED)
> >> >>         CHECK_OP (0, "invalid operand to unary operator");
> >> >>         break;
> >> >>
> >> >> +    case ABSU_EXPR:
> >> >> +      break;
> >> >> +
> >> >>       case REALPART_EXPR:
> >> >>       case IMAGPART_EXPR:
> >> >>
> >> >> verify_expr is no more.  Did you test this recently against trunk?
> >> >
> >> > This patch is against slightly older trunk. I will rebase it.
> >> >
> >> >>
> >> >> @@ -3937,6 +3940,9 @@ verify_gimple_assign_unary (gassign *stmt)
> >> >>       case PAREN_EXPR:
> >> >>       case CONJ_EXPR:
> >> >>         break;
> >> >> +    case ABSU_EXPR:
> >> >> +      /* FIXME.  */
> >> >> +      return false;
> >> >>
> >> >> no - please not!  Please add verification here - ABSU should be only
> >> >> called on INTEGRAL, vector or complex INTEGRAL types and the
> >> >> type of the LHS should be always the unsigned variant of the
> >> >> argument type.
> >> >
> >> > OK.
> >> >>
> >> >>     if (is_gimple_val (cond_expr))
> >> >>       return cond_expr;
> >> >>
> >> >> -  if (TREE_CODE (cond_expr) == ABS_EXPR)
> >> >> +  if (TREE_CODE (cond_expr) == ABS_EXPR
> >> >> +      || TREE_CODE (cond_expr) == ABSU_EXPR)
> >> >>       {
> >> >>         rhs1 = TREE_OPERAND (cond_expr, 1);
> >> >>         STRIP_USELESS_TYPE_CONVERSION (rhs1);
> >> >>
> >> >> err, but the next line just builds a ABS_EXPR ...
> >> >>
> >> >> How did you identify spots that need adjustment?  I would expect that
> >> >> once folding generates ABSU_EXPR that you need to adjust frontends
> >> >> (C++ constexpr handling for example).  Also I miss adjustments
> >> >> to gimple-pretty-print.c and the GIMPLE FE parser.
> >> >
> >> > I will add this.
> >> >>
> >> >> recursively grepping throughout the whole gcc/ tree doesn't reveal too many
> >> >> cases of ABS_EXPR so I think it's reasonable to audit all of them.
> >> >>
> >> >> I also miss some trivial absu simplifications in match.pd.  There are not
> >> >> a lot of abs cases but similar ones would be good to have initially.
> >> >
> >> > I will add them in the next version.
> >> >
> >> > Thanks,
> >> > Kugan
> >> >
> >> >>
> >> >> Thanks for tackling this!
> >> >> Richard.
> >> >>
> >> >>> Thanks,
> >> >>> Andrew
> >> >>
> >> >>> >
> >> >>> > Thanks,
> >> >>> > Kugan
> >> >>> >
> >> >>> >
> >> >>> > gcc/ChangeLog:
> >> >>> >
> >> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >> >>> >
> >> >>> >     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
> >> >>> >     * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
> >> >>> >     (fold_unary_loc): Handle ABSU_EXPR.
> >> >>> >     * optabs-tree.c (optab_for_tree_code): Likewise.
> >> >>> >     * tree-cfg.c (verify_expr): Likewise.
> >> >>> >     (verify_gimple_assign_unary):  Likewise.
> >> >>> >     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
> >> >>> >     * tree-inline.c (estimate_operator_cost):  Likewise.
> >> >>> >     * tree-pretty-print.c (dump_generic_node):  Likewise.
> >> >>> >     * tree.def (ABSU_EXPR): New.
> >> >>> >
> >> >>> > gcc/testsuite/ChangeLog:
> >> >>> >
> >> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >> >>> >
> >> >>> >     * gcc.dg/absu.c: New test.
Kugan Vivekanandarajah June 11, 2018, 8:27 a.m. | #9
Hi Richard,

Thanks for the review and sorry for getting back to you late.

On 4 June 2018 at 18:38, Richard Biener <richard.guenther@gmail.com> wrote:
> On Mon, Jun 4, 2018 at 10:18 AM Kugan Vivekanandarajah
> <kugan.vivekanandarajah@linaro.org> wrote:
>>
>> Hi Richard,
>>
>> Thanks for the review.
>>
>> On 1 June 2018 at 22:20, Richard Biener <richard.guenther@gmail.com> wrote:
>> > On Fri, Jun 1, 2018 at 4:12 AM Kugan Vivekanandarajah
>> > <kugan.vivekanandarajah@linaro.org> wrote:
>> >>
>> >> Hi Richard,
>> >>
>> >> This is the revised patch based on the review and the discussion in
>> >> https://gcc.gnu.org/ml/gcc/2018-05/msg00179.html.
>> >>
>> >> In summary:
>> >> - I skipped  (element_precision (type) < element_precision (TREE_TYPE
>> >> (@0))) in the match.pd pattern as this would prevent transformation
>> >> for the case in PR.
>> >> that is, I am interested in is something like:
>> >>   char t = (char) ABS_EXPR <(int) x>
>> >> and I want to generate
>> >> char t = (char) ABSU_EXPR <x>
>> >>
>> >> - I also haven't added all the necessary match.pd changes for
>> >> ABSU_EXPR. I have a patch for that but will submit separately based on
>> >> this reveiw.
>> >>
>> >> - I also tried to add ABSU_EXPRsupport  in the places as necessary by
>> >> grepping for ABS_EXPR.
>> >>
>> >> - I also had to add special casing in vectorizer for ABSU_EXP as its
>> >> result is unsigned type.
>> >>
>> >> Is this OK. Patch bootstraps and the regression test is ongoing.
>> >
>> > The c/c-typeck.c:build_unary_op change looks unnecessary - the
>> > C FE should never generate this directly (the c-common one might
>> > be triggered by early folding I guess).
>>
>> The Gimple FE testcase is running into this.
>
> Ah, OK then.
>
>> >
>> > @@ -1761,6 +1762,9 @@ const_unop (enum tree_code code, tree type, tree arg0)
>> >        if (TREE_CODE (arg0) == INTEGER_CST || TREE_CODE (arg0) == REAL_CST)
>> >         return fold_abs_const (arg0, type);
>> >        break;
>> > +    case ABSU_EXPR:
>> > +       return fold_convert (type, fold_abs_const (arg0,
>> > +                                                  signed_type_for (type)));
>> >
>> >      case CONJ_EXPR:
>> >
>> > I think this will get you bogus TREE_OVERFLOW flags set on ABSU (-INT_MIN).
>> >
>> > I think you want to change fold_abs_const to properly deal with arg0 being
>> > signed and type unsigned.  That is, sth like
>> >
>> > diff --git a/gcc/fold-const.c b/gcc/fold-const.c
>> > index 6f80f1b1d69..f60f9c77e91 100644
>> > --- a/gcc/fold-const.c
>> > +++ b/gcc/fold-const.c
>> > @@ -13843,18 +13843,19 @@ fold_abs_const (tree arg0, tree type)
>> >        {
>> >          /* If the value is unsigned or non-negative, then the absolute value
>> >            is the same as the ordinary value.  */
>> > -       if (!wi::neg_p (wi::to_wide (arg0), TYPE_SIGN (type)))
>> > -         t = arg0;
>> > +       wide_int val = wi::to_wide (arg0);
>> > +       bool overflow = false;
>> > +       if (!wi::neg_p (val, TYPE_SIGN (TREE_TYPE (arg0))))
>> > +         ;
>> >
>> >         /* If the value is negative, then the absolute value is
>> >            its negation.  */
>> >         else
>> > -         {
>> > -           bool overflow;
>> > -           wide_int val = wi::neg (wi::to_wide (arg0), &overflow);
>> > -           t = force_fit_type (type, val, -1,
>> > -                               overflow | TREE_OVERFLOW (arg0));
>> > -         }
>> > +         wide_int val = wi::neg (val, &overflow);
>> > +
>> > +       /* Force to the destination type, set TREE_OVERFLOW for signed
>> > +          TYPE only.  */
>> > +       t = force_fit_type (type, val, 1, overflow | TREE_OVERFLOW (arg0));
>> >        }
>> >        break;
>> >
>> > and then simply share the const_unop code with ABS_EXPR.
>>
>> Done.
>>
>> > diff --git a/gcc/match.pd b/gcc/match.pd
>> > index 14386da..7d7c132 100644
>> > --- a/gcc/match.pd
>> > +++ b/gcc/match.pd
>> > @@ -102,6 +102,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>> >  (match (nop_convert @0)
>> >   @0)
>> >
>> > +(simplify (abs (convert @0))
>> > + (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
>> > +      && !TYPE_UNSIGNED (TREE_TYPE (@0))
>> > +      && !TYPE_UNSIGNED (type))
>> > +  (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
>> > +   (convert (absu:utype @0)))))
>> > +
>> > +
>> >
>> > please put a comment before the pattern.  I believe there's no
>> > need to check for !TYPE_UNSIGNED (type).  Note this
>> > also converts abs ((char)int-var) to (char)absu(int-var) which
>> > doesn't make sense.  The original issue you want to address
>> > here is the case where TYPE_PRECISION of @0 is less than
>> > the precision of type.  That is, you want to remove language
>> > introduced integer promotion of @0 which only is possible
>> > with ABSU.  So please do add such precision check
>> > (I simply suggested the bogus direction of the test).
>>
>> Done.
>> >
>> > diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
>> > index 68f4fd3..9b62583 100644
>> > --- a/gcc/tree-cfg.c
>> > +++ b/gcc/tree-cfg.c
>> > @@ -3685,6 +3685,12 @@ verify_gimple_assign_unary (gassign *stmt)
>> >      case PAREN_EXPR:
>> >      case CONJ_EXPR:
>> >        break;
>> > +    case ABSU_EXPR:
>> > +      if (!TYPE_UNSIGNED (lhs_type)
>> > +         || !ANY_INTEGRAL_TYPE_P (rhs1_type))
>> >
>> >  if (!ANY_INTEGRAL_TYPE_P (lhs_type)
>> >      || !TYPE_UNSIGNED (lhs_type)
>> >      || !ANY_INTEGRAL_TYPE_P (rhs1_type)
>> >      || TYPE_UNSIGNED (rhs1_type)
>> >      || element_precision (lhs_type) != element_precision (rhs1_type))
>> >   {
>> >       error ("invalid types for ABSU_EXPR");
>> >       debug_generic_expr (lhs_type);
>> >       debug_generic_expr (rhs1_type);
>> >      return true;
>> >   }
>> >
>
> ^^^  you forgot this one.
>
>
>> > +       return true;
>> > +      return false;
>> > +      break;
>> >
>> > diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
>> > index 30c6d9e..44b1399 100644
>> > --- a/gcc/tree-eh.c
>> > +++ b/gcc/tree-eh.c
>> > @@ -2465,6 +2465,7 @@ operation_could_trap_helper_p (enum tree_code op,
>> >
>> >      case NEGATE_EXPR:
>> >      case ABS_EXPR:
>> > +    case ABSU_EXPR:
>> >      case CONJ_EXPR:
>> >        /* These operations don't trap with floating point.  */
>> >        if (honor_trapv)
>> >
>> > ABSU never traps.  Please instead unconditionally return false.
>> Done.
>>
>> >
>> > diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
>> > index 66c78de..b52d714 100644
>> > --- a/gcc/tree-vect-stmts.c
>> > +++ b/gcc/tree-vect-stmts.c
>> > @@ -5995,7 +5995,11 @@ vectorizable_operation (gimple *stmt,
>> > gimple_stmt_iterator *gsi,
>> >                       "transform binary/unary operation.\n");
>> >
>> >    /* Handle def.  */
>> > -  vec_dest = vect_create_destination_var (scalar_dest, vectype);
>> > +  if (code == ABSU_EXPR)
>> > +    vec_dest = vect_create_destination_var (scalar_dest,
>> > +                                           unsigned_type_for (vectype));
>> > +  else
>> > +    vec_dest = vect_create_destination_var (scalar_dest, vectype);
>> >
>> >    /* POINTER_DIFF_EXPR has pointer arguments which are vectorized as
>> >       vectors with unsigned elements, but the result is signed.  So, we
>> >
>> > simply use vectype_out for creation of vec_dest.
>> Done.
>
>    /* Handle def.  */
> -  vec_dest = vect_create_destination_var (scalar_dest, vectype);
> +  if (code == ABSU_EXPR)
> +    vec_dest = vect_create_destination_var (scalar_dest, vectype_out);
> +  else
> +    vec_dest = vect_create_destination_var (scalar_dest, vectype);
>
> I meant _always_ vectype_out.  Thus unconditionally
>
>   vec_dest = vect_create_destination_var (scalar_dest, vectype_out);

Some testcases are failing with the changes.

gcc:gcc.dg/tree-ssa/pr83329.c (internal compiler error) : This seems
to be due to POINTER_DIFF_EXPR (?)

There is also

gcc:gcc.target/i386/avx2-vshift-1.c (internal compiler error)
gcc:gcc.target/i386/xop-vshift-1.c (internal compiler error)

Example:
/home/tcwg-buildslave/workspace/tcwg-buildfarm_2/tcwg-x86_32-build/snapshots/gcc.git~master_rev_bfa6b77/gcc/testsuite/gcc.target/i386/xop-vshift-1.c:73:1:
error: type mismatch in binary expression^M
vector(4) long long unsigned int^M
^M
vector(4) long long int^M
^M
vector(4) long long int^M
^M
vect_patt_17.54_21 = vect__2.53_16 & vect_cst__20;^M
during GIMPLE pass: vect^M

Thanks,
Kugan



>
> OK with those two changes.
>
> Thanks,
> Richard.
>
>> >
>> > diff --git a/gcc/tree.def b/gcc/tree.def
>> > index c660b2c..5fec781 100644
>> > --- a/gcc/tree.def
>> > +++ b/gcc/tree.def
>> > @@ -760,6 +760,7 @@ DEFTREECODE (MAX_EXPR, "max_expr", tcc_binary, 2)
>> >     An ABS_EXPR must have either an INTEGER_TYPE or a REAL_TYPE.  The
>> >     operand of the ABS_EXPR must have the same type.  */
>> >  DEFTREECODE (ABS_EXPR, "abs_expr", tcc_unary, 1)
>> > +DEFTREECODE (ABSU_EXPR, "absu_expr", tcc_unary, 1)
>> >
>> >  /* Shift operations for shift and rotate.
>> >     Shift means logical shift if done on an
>> >
>> > You can clearly see that the comment before ABS_EXPR doesn't apply to ABSU_EXPR
>> > so please add an appropriate one.  I suggest
>> >
>> > /* Represents the unsigned absolute value of the operand.
>> >     An ABSU_EXPR must have unsigned INTEGER_TYPE.  The operand of the ABSU_EXPR
>> >     must have the corresponding signed type.  */
>>
>> Done.
>>
>> Here is the reviesed patch. Is this OK?
>>
>> Thanks,
>> Kugan
>>
>> >
>> > Otherwise looks OK.  (I didn't explicitely check for missing ABSU_EXPR
>> > handling this time)
>> >
>> > Thanks,
>> > Richard.
>> >
>> >
>> >> Thanks,
>> >> Kugan
>> >>
>> >>
>> >> On 18 May 2018 at 12:36, Kugan Vivekanandarajah
>> >> <kugan.vivekanandarajah@linaro.org> wrote:
>> >> > Hi Richard,
>> >> >
>> >> > Thanks for the review. I am revising the patch based on Andrew's comments too.
>> >> >
>> >> > On 17 May 2018 at 20:36, Richard Biener <richard.guenther@gmail.com> wrote:
>> >> >> On Thu, May 17, 2018 at 4:56 AM Andrew Pinski <pinskia@gmail.com> wrote:
>> >> >>
>> >> >>> On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
>> >> >>> <kugan.vivekanandarajah@linaro.org> wrote:
>> >> >>> > As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
>> >> >>> > issue. In the attached patch, in fold_cond_expr_with_comparison I am
>> >> >>> > generating ABSU_EXPR for these cases. As I understand, absu_expr is
>> >> >>> > well defined in RTL. So, the issue is generating absu_expr  and
>> >> >>> > transferring to RTL in the correct way. I am not sure I am not doing
>> >> >>> > all that is needed. I will clean up and add more test-cases based on
>> >> >>> > the feedback.
>> >> >>
>> >> >>
>> >> >>> diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
>> >> >>> index 71e172c..2b812e5 100644
>> >> >>> --- a/gcc/optabs-tree.c
>> >> >>> +++ b/gcc/optabs-tree.c
>> >> >>> @@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code, const_tree
>> >> >> type,
>> >> >>>         return trapv ? negv_optab : neg_optab;
>> >> >>
>> >> >>>       case ABS_EXPR:
>> >> >>> +    case ABSU_EXPR:
>> >> >>>         return trapv ? absv_optab : abs_optab;
>> >> >>
>> >> >>
>> >> >>> This part is not correct, it should something like this:
>> >> >>
>> >> >>>       case ABS_EXPR:
>> >> >>>         return trapv ? absv_optab : abs_optab;
>> >> >>> +    case ABSU_EXPR:
>> >> >>> +       return abs_optab ;
>> >> >>
>> >> >>> Because ABSU is not undefined at the TYPE_MAX.
>> >> >>
>> >> >> Also
>> >> >>
>> >> >>         /* Unsigned abs is simply the operand.  Testing here means we don't
>> >> >>           risk generating incorrect code below.  */
>> >> >> -      if (TYPE_UNSIGNED (type))
>> >> >> +      if (TYPE_UNSIGNED (type)
>> >> >> +         && (code != ABSU_EXPR))
>> >> >>          return op0;
>> >> >>
>> >> >> is wrong.  ABSU of an unsigned number is still just that number.
>> >> >>
>> >> >> The change to fold_cond_expr_with_comparison looks odd to me
>> >> >> (premature optimization).  It should be done separately - it seems
>> >> >> you are doing
>> >> >
>> >> > FE seems to be using this to generate ABS_EXPR from
>> >> > c_fully_fold_internal to fold_build3_loc and so on. I changed this to
>> >> > generate ABSU_EXPR for the case in the testcase. So the question
>> >> > should be, in what cases do we need ABS_EXPR and in what cases do we
>> >> > need ABSU_EXPR. It is not very clear to me.
>> >> >
>> >> >
>> >> >>
>> >> >> (simplify (abs (convert @0)) (convert (absu @0)))
>> >> >>
>> >> >> here.
>> >> >>
>> >> >> You touch one other place in fold-const.c but there seem to be many
>> >> >> more that need ABSU_EXPR handling (you touched the one needed
>> >> >> for correctness) - esp. you should at least handle constant folding
>> >> >> in const_unop and the nonnegative predicate.
>> >> >
>> >> > OK.
>> >> >>
>> >> >> @@ -3167,6 +3167,9 @@ verify_expr (tree *tp, int *walk_subtrees, void *data
>> >> >> ATTRIBUTE_UNUSED)
>> >> >>         CHECK_OP (0, "invalid operand to unary operator");
>> >> >>         break;
>> >> >>
>> >> >> +    case ABSU_EXPR:
>> >> >> +      break;
>> >> >> +
>> >> >>       case REALPART_EXPR:
>> >> >>       case IMAGPART_EXPR:
>> >> >>
>> >> >> verify_expr is no more.  Did you test this recently against trunk?
>> >> >
>> >> > This patch is against slightly older trunk. I will rebase it.
>> >> >
>> >> >>
>> >> >> @@ -3937,6 +3940,9 @@ verify_gimple_assign_unary (gassign *stmt)
>> >> >>       case PAREN_EXPR:
>> >> >>       case CONJ_EXPR:
>> >> >>         break;
>> >> >> +    case ABSU_EXPR:
>> >> >> +      /* FIXME.  */
>> >> >> +      return false;
>> >> >>
>> >> >> no - please not!  Please add verification here - ABSU should be only
>> >> >> called on INTEGRAL, vector or complex INTEGRAL types and the
>> >> >> type of the LHS should be always the unsigned variant of the
>> >> >> argument type.
>> >> >
>> >> > OK.
>> >> >>
>> >> >>     if (is_gimple_val (cond_expr))
>> >> >>       return cond_expr;
>> >> >>
>> >> >> -  if (TREE_CODE (cond_expr) == ABS_EXPR)
>> >> >> +  if (TREE_CODE (cond_expr) == ABS_EXPR
>> >> >> +      || TREE_CODE (cond_expr) == ABSU_EXPR)
>> >> >>       {
>> >> >>         rhs1 = TREE_OPERAND (cond_expr, 1);
>> >> >>         STRIP_USELESS_TYPE_CONVERSION (rhs1);
>> >> >>
>> >> >> err, but the next line just builds a ABS_EXPR ...
>> >> >>
>> >> >> How did you identify spots that need adjustment?  I would expect that
>> >> >> once folding generates ABSU_EXPR that you need to adjust frontends
>> >> >> (C++ constexpr handling for example).  Also I miss adjustments
>> >> >> to gimple-pretty-print.c and the GIMPLE FE parser.
>> >> >
>> >> > I will add this.
>> >> >>
>> >> >> recursively grepping throughout the whole gcc/ tree doesn't reveal too many
>> >> >> cases of ABS_EXPR so I think it's reasonable to audit all of them.
>> >> >>
>> >> >> I also miss some trivial absu simplifications in match.pd.  There are not
>> >> >> a lot of abs cases but similar ones would be good to have initially.
>> >> >
>> >> > I will add them in the next version.
>> >> >
>> >> > Thanks,
>> >> > Kugan
>> >> >
>> >> >>
>> >> >> Thanks for tackling this!
>> >> >> Richard.
>> >> >>
>> >> >>> Thanks,
>> >> >>> Andrew
>> >> >>
>> >> >>> >
>> >> >>> > Thanks,
>> >> >>> > Kugan
>> >> >>> >
>> >> >>> >
>> >> >>> > gcc/ChangeLog:
>> >> >>> >
>> >> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>> >> >>> >
>> >> >>> >     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
>> >> >>> >     * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
>> >> >>> >     (fold_unary_loc): Handle ABSU_EXPR.
>> >> >>> >     * optabs-tree.c (optab_for_tree_code): Likewise.
>> >> >>> >     * tree-cfg.c (verify_expr): Likewise.
>> >> >>> >     (verify_gimple_assign_unary):  Likewise.
>> >> >>> >     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
>> >> >>> >     * tree-inline.c (estimate_operator_cost):  Likewise.
>> >> >>> >     * tree-pretty-print.c (dump_generic_node):  Likewise.
>> >> >>> >     * tree.def (ABSU_EXPR): New.
>> >> >>> >
>> >> >>> > gcc/testsuite/ChangeLog:
>> >> >>> >
>> >> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
>> >> >>> >
>> >> >>> >     * gcc.dg/absu.c: New test.
Richard Biener June 13, 2018, 12:07 p.m. | #10
On Mon, Jun 11, 2018 at 10:28 AM Kugan Vivekanandarajah
<kugan.vivekanandarajah@linaro.org> wrote:
>
> Hi Richard,
>
> Thanks for the review and sorry for getting back to you late.
>
> On 4 June 2018 at 18:38, Richard Biener <richard.guenther@gmail.com> wrote:
> > On Mon, Jun 4, 2018 at 10:18 AM Kugan Vivekanandarajah
> > <kugan.vivekanandarajah@linaro.org> wrote:
> >>
> >> Hi Richard,
> >>
> >> Thanks for the review.
> >>
> >> On 1 June 2018 at 22:20, Richard Biener <richard.guenther@gmail.com> wrote:
> >> > On Fri, Jun 1, 2018 at 4:12 AM Kugan Vivekanandarajah
> >> > <kugan.vivekanandarajah@linaro.org> wrote:
> >> >>
> >> >> Hi Richard,
> >> >>
> >> >> This is the revised patch based on the review and the discussion in
> >> >> https://gcc.gnu.org/ml/gcc/2018-05/msg00179.html.
> >> >>
> >> >> In summary:
> >> >> - I skipped  (element_precision (type) < element_precision (TREE_TYPE
> >> >> (@0))) in the match.pd pattern as this would prevent transformation
> >> >> for the case in PR.
> >> >> that is, I am interested in is something like:
> >> >>   char t = (char) ABS_EXPR <(int) x>
> >> >> and I want to generate
> >> >> char t = (char) ABSU_EXPR <x>
> >> >>
> >> >> - I also haven't added all the necessary match.pd changes for
> >> >> ABSU_EXPR. I have a patch for that but will submit separately based on
> >> >> this reveiw.
> >> >>
> >> >> - I also tried to add ABSU_EXPRsupport  in the places as necessary by
> >> >> grepping for ABS_EXPR.
> >> >>
> >> >> - I also had to add special casing in vectorizer for ABSU_EXP as its
> >> >> result is unsigned type.
> >> >>
> >> >> Is this OK. Patch bootstraps and the regression test is ongoing.
> >> >
> >> > The c/c-typeck.c:build_unary_op change looks unnecessary - the
> >> > C FE should never generate this directly (the c-common one might
> >> > be triggered by early folding I guess).
> >>
> >> The Gimple FE testcase is running into this.
> >
> > Ah, OK then.
> >
> >> >
> >> > @@ -1761,6 +1762,9 @@ const_unop (enum tree_code code, tree type, tree arg0)
> >> >        if (TREE_CODE (arg0) == INTEGER_CST || TREE_CODE (arg0) == REAL_CST)
> >> >         return fold_abs_const (arg0, type);
> >> >        break;
> >> > +    case ABSU_EXPR:
> >> > +       return fold_convert (type, fold_abs_const (arg0,
> >> > +                                                  signed_type_for (type)));
> >> >
> >> >      case CONJ_EXPR:
> >> >
> >> > I think this will get you bogus TREE_OVERFLOW flags set on ABSU (-INT_MIN).
> >> >
> >> > I think you want to change fold_abs_const to properly deal with arg0 being
> >> > signed and type unsigned.  That is, sth like
> >> >
> >> > diff --git a/gcc/fold-const.c b/gcc/fold-const.c
> >> > index 6f80f1b1d69..f60f9c77e91 100644
> >> > --- a/gcc/fold-const.c
> >> > +++ b/gcc/fold-const.c
> >> > @@ -13843,18 +13843,19 @@ fold_abs_const (tree arg0, tree type)
> >> >        {
> >> >          /* If the value is unsigned or non-negative, then the absolute value
> >> >            is the same as the ordinary value.  */
> >> > -       if (!wi::neg_p (wi::to_wide (arg0), TYPE_SIGN (type)))
> >> > -         t = arg0;
> >> > +       wide_int val = wi::to_wide (arg0);
> >> > +       bool overflow = false;
> >> > +       if (!wi::neg_p (val, TYPE_SIGN (TREE_TYPE (arg0))))
> >> > +         ;
> >> >
> >> >         /* If the value is negative, then the absolute value is
> >> >            its negation.  */
> >> >         else
> >> > -         {
> >> > -           bool overflow;
> >> > -           wide_int val = wi::neg (wi::to_wide (arg0), &overflow);
> >> > -           t = force_fit_type (type, val, -1,
> >> > -                               overflow | TREE_OVERFLOW (arg0));
> >> > -         }
> >> > +         wide_int val = wi::neg (val, &overflow);
> >> > +
> >> > +       /* Force to the destination type, set TREE_OVERFLOW for signed
> >> > +          TYPE only.  */
> >> > +       t = force_fit_type (type, val, 1, overflow | TREE_OVERFLOW (arg0));
> >> >        }
> >> >        break;
> >> >
> >> > and then simply share the const_unop code with ABS_EXPR.
> >>
> >> Done.
> >>
> >> > diff --git a/gcc/match.pd b/gcc/match.pd
> >> > index 14386da..7d7c132 100644
> >> > --- a/gcc/match.pd
> >> > +++ b/gcc/match.pd
> >> > @@ -102,6 +102,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> >> >  (match (nop_convert @0)
> >> >   @0)
> >> >
> >> > +(simplify (abs (convert @0))
> >> > + (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
> >> > +      && !TYPE_UNSIGNED (TREE_TYPE (@0))
> >> > +      && !TYPE_UNSIGNED (type))
> >> > +  (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
> >> > +   (convert (absu:utype @0)))))
> >> > +
> >> > +
> >> >
> >> > please put a comment before the pattern.  I believe there's no
> >> > need to check for !TYPE_UNSIGNED (type).  Note this
> >> > also converts abs ((char)int-var) to (char)absu(int-var) which
> >> > doesn't make sense.  The original issue you want to address
> >> > here is the case where TYPE_PRECISION of @0 is less than
> >> > the precision of type.  That is, you want to remove language
> >> > introduced integer promotion of @0 which only is possible
> >> > with ABSU.  So please do add such precision check
> >> > (I simply suggested the bogus direction of the test).
> >>
> >> Done.
> >> >
> >> > diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
> >> > index 68f4fd3..9b62583 100644
> >> > --- a/gcc/tree-cfg.c
> >> > +++ b/gcc/tree-cfg.c
> >> > @@ -3685,6 +3685,12 @@ verify_gimple_assign_unary (gassign *stmt)
> >> >      case PAREN_EXPR:
> >> >      case CONJ_EXPR:
> >> >        break;
> >> > +    case ABSU_EXPR:
> >> > +      if (!TYPE_UNSIGNED (lhs_type)
> >> > +         || !ANY_INTEGRAL_TYPE_P (rhs1_type))
> >> >
> >> >  if (!ANY_INTEGRAL_TYPE_P (lhs_type)
> >> >      || !TYPE_UNSIGNED (lhs_type)
> >> >      || !ANY_INTEGRAL_TYPE_P (rhs1_type)
> >> >      || TYPE_UNSIGNED (rhs1_type)
> >> >      || element_precision (lhs_type) != element_precision (rhs1_type))
> >> >   {
> >> >       error ("invalid types for ABSU_EXPR");
> >> >       debug_generic_expr (lhs_type);
> >> >       debug_generic_expr (rhs1_type);
> >> >      return true;
> >> >   }
> >> >
> >
> > ^^^  you forgot this one.
> >
> >
> >> > +       return true;
> >> > +      return false;
> >> > +      break;
> >> >
> >> > diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
> >> > index 30c6d9e..44b1399 100644
> >> > --- a/gcc/tree-eh.c
> >> > +++ b/gcc/tree-eh.c
> >> > @@ -2465,6 +2465,7 @@ operation_could_trap_helper_p (enum tree_code op,
> >> >
> >> >      case NEGATE_EXPR:
> >> >      case ABS_EXPR:
> >> > +    case ABSU_EXPR:
> >> >      case CONJ_EXPR:
> >> >        /* These operations don't trap with floating point.  */
> >> >        if (honor_trapv)
> >> >
> >> > ABSU never traps.  Please instead unconditionally return false.
> >> Done.
> >>
> >> >
> >> > diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
> >> > index 66c78de..b52d714 100644
> >> > --- a/gcc/tree-vect-stmts.c
> >> > +++ b/gcc/tree-vect-stmts.c
> >> > @@ -5995,7 +5995,11 @@ vectorizable_operation (gimple *stmt,
> >> > gimple_stmt_iterator *gsi,
> >> >                       "transform binary/unary operation.\n");
> >> >
> >> >    /* Handle def.  */
> >> > -  vec_dest = vect_create_destination_var (scalar_dest, vectype);
> >> > +  if (code == ABSU_EXPR)
> >> > +    vec_dest = vect_create_destination_var (scalar_dest,
> >> > +                                           unsigned_type_for (vectype));
> >> > +  else
> >> > +    vec_dest = vect_create_destination_var (scalar_dest, vectype);
> >> >
> >> >    /* POINTER_DIFF_EXPR has pointer arguments which are vectorized as
> >> >       vectors with unsigned elements, but the result is signed.  So, we
> >> >
> >> > simply use vectype_out for creation of vec_dest.
> >> Done.
> >
> >    /* Handle def.  */
> > -  vec_dest = vect_create_destination_var (scalar_dest, vectype);
> > +  if (code == ABSU_EXPR)
> > +    vec_dest = vect_create_destination_var (scalar_dest, vectype_out);
> > +  else
> > +    vec_dest = vect_create_destination_var (scalar_dest, vectype);
> >
> > I meant _always_ vectype_out.  Thus unconditionally
> >
> >   vec_dest = vect_create_destination_var (scalar_dest, vectype_out);
>
> Some testcases are failing with the changes.
>
> gcc:gcc.dg/tree-ssa/pr83329.c (internal compiler error) : This seems
> to be due to POINTER_DIFF_EXPR (?)

Ah, yes.  I'd simply handle that in a more clear way.

> There is also
>
> gcc:gcc.target/i386/avx2-vshift-1.c (internal compiler error)
> gcc:gcc.target/i386/xop-vshift-1.c (internal compiler error)
>
> Example:
> /home/tcwg-buildslave/workspace/tcwg-buildfarm_2/tcwg-x86_32-build/snapshots/gcc.git~master_rev_bfa6b77/gcc/testsuite/gcc.target/i386/xop-vshift-1.c:73:1:
> error: type mismatch in binary expression^M
> vector(4) long long unsigned int^M
> ^M
> vector(4) long long int^M
> ^M
> vector(4) long long int^M
> ^M
> vect_patt_17.54_21 = vect__2.53_16 & vect_cst__20;^M
> during GIMPLE pass: vect^M

That one is odd and looks like a latent bug in pattern creation:

diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c
index 507c5b94f07..6786ffcd4c6 100644
--- a/gcc/tree-vect-patterns.c
+++ b/gcc/tree-vect-patterns.c
@@ -2185,6 +2185,11 @@ vect_recog_vector_vector_shift_pattern
(vec<gimple *> *stmts,
                                       TYPE_PRECISION (TREE_TYPE (oprnd1)));
              def = vect_recog_temp_ssa_var (TREE_TYPE (rhs1), NULL);
              def_stmt = gimple_build_assign (def, BIT_AND_EXPR, rhs1, mask);
+             stmt_vec_info new_stmt_info
+               = new_stmt_vec_info (def_stmt, vinfo);
+             set_vinfo_for_stmt (def_stmt, new_stmt_info);
+             STMT_VINFO_VECTYPE (new_stmt_info)
+               = get_vectype_for_scalar_type (TREE_TYPE (rhs1));
              new_pattern_def_seq (stmt_vinfo, def_stmt);
            }
        }


I can see if I can make this change independently of yours (that is,
I'm bootstrapping
and testing the above together with an equivalent vectorizable_operation hunk).

Richard.

>
> Thanks,
> Kugan
>
>
>
> >
> > OK with those two changes.
> >
> > Thanks,
> > Richard.
> >
> >> >
> >> > diff --git a/gcc/tree.def b/gcc/tree.def
> >> > index c660b2c..5fec781 100644
> >> > --- a/gcc/tree.def
> >> > +++ b/gcc/tree.def
> >> > @@ -760,6 +760,7 @@ DEFTREECODE (MAX_EXPR, "max_expr", tcc_binary, 2)
> >> >     An ABS_EXPR must have either an INTEGER_TYPE or a REAL_TYPE.  The
> >> >     operand of the ABS_EXPR must have the same type.  */
> >> >  DEFTREECODE (ABS_EXPR, "abs_expr", tcc_unary, 1)
> >> > +DEFTREECODE (ABSU_EXPR, "absu_expr", tcc_unary, 1)
> >> >
> >> >  /* Shift operations for shift and rotate.
> >> >     Shift means logical shift if done on an
> >> >
> >> > You can clearly see that the comment before ABS_EXPR doesn't apply to ABSU_EXPR
> >> > so please add an appropriate one.  I suggest
> >> >
> >> > /* Represents the unsigned absolute value of the operand.
> >> >     An ABSU_EXPR must have unsigned INTEGER_TYPE.  The operand of the ABSU_EXPR
> >> >     must have the corresponding signed type.  */
> >>
> >> Done.
> >>
> >> Here is the reviesed patch. Is this OK?
> >>
> >> Thanks,
> >> Kugan
> >>
> >> >
> >> > Otherwise looks OK.  (I didn't explicitely check for missing ABSU_EXPR
> >> > handling this time)
> >> >
> >> > Thanks,
> >> > Richard.
> >> >
> >> >
> >> >> Thanks,
> >> >> Kugan
> >> >>
> >> >>
> >> >> On 18 May 2018 at 12:36, Kugan Vivekanandarajah
> >> >> <kugan.vivekanandarajah@linaro.org> wrote:
> >> >> > Hi Richard,
> >> >> >
> >> >> > Thanks for the review. I am revising the patch based on Andrew's comments too.
> >> >> >
> >> >> > On 17 May 2018 at 20:36, Richard Biener <richard.guenther@gmail.com> wrote:
> >> >> >> On Thu, May 17, 2018 at 4:56 AM Andrew Pinski <pinskia@gmail.com> wrote:
> >> >> >>
> >> >> >>> On Wed, May 16, 2018 at 7:14 PM, Kugan Vivekanandarajah
> >> >> >>> <kugan.vivekanandarajah@linaro.org> wrote:
> >> >> >>> > As mentioned in the PR, I am trying to add ABSU_EXPR to fix this
> >> >> >>> > issue. In the attached patch, in fold_cond_expr_with_comparison I am
> >> >> >>> > generating ABSU_EXPR for these cases. As I understand, absu_expr is
> >> >> >>> > well defined in RTL. So, the issue is generating absu_expr  and
> >> >> >>> > transferring to RTL in the correct way. I am not sure I am not doing
> >> >> >>> > all that is needed. I will clean up and add more test-cases based on
> >> >> >>> > the feedback.
> >> >> >>
> >> >> >>
> >> >> >>> diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
> >> >> >>> index 71e172c..2b812e5 100644
> >> >> >>> --- a/gcc/optabs-tree.c
> >> >> >>> +++ b/gcc/optabs-tree.c
> >> >> >>> @@ -235,6 +235,7 @@ optab_for_tree_code (enum tree_code code, const_tree
> >> >> >> type,
> >> >> >>>         return trapv ? negv_optab : neg_optab;
> >> >> >>
> >> >> >>>       case ABS_EXPR:
> >> >> >>> +    case ABSU_EXPR:
> >> >> >>>         return trapv ? absv_optab : abs_optab;
> >> >> >>
> >> >> >>
> >> >> >>> This part is not correct, it should something like this:
> >> >> >>
> >> >> >>>       case ABS_EXPR:
> >> >> >>>         return trapv ? absv_optab : abs_optab;
> >> >> >>> +    case ABSU_EXPR:
> >> >> >>> +       return abs_optab ;
> >> >> >>
> >> >> >>> Because ABSU is not undefined at the TYPE_MAX.
> >> >> >>
> >> >> >> Also
> >> >> >>
> >> >> >>         /* Unsigned abs is simply the operand.  Testing here means we don't
> >> >> >>           risk generating incorrect code below.  */
> >> >> >> -      if (TYPE_UNSIGNED (type))
> >> >> >> +      if (TYPE_UNSIGNED (type)
> >> >> >> +         && (code != ABSU_EXPR))
> >> >> >>          return op0;
> >> >> >>
> >> >> >> is wrong.  ABSU of an unsigned number is still just that number.
> >> >> >>
> >> >> >> The change to fold_cond_expr_with_comparison looks odd to me
> >> >> >> (premature optimization).  It should be done separately - it seems
> >> >> >> you are doing
> >> >> >
> >> >> > FE seems to be using this to generate ABS_EXPR from
> >> >> > c_fully_fold_internal to fold_build3_loc and so on. I changed this to
> >> >> > generate ABSU_EXPR for the case in the testcase. So the question
> >> >> > should be, in what cases do we need ABS_EXPR and in what cases do we
> >> >> > need ABSU_EXPR. It is not very clear to me.
> >> >> >
> >> >> >
> >> >> >>
> >> >> >> (simplify (abs (convert @0)) (convert (absu @0)))
> >> >> >>
> >> >> >> here.
> >> >> >>
> >> >> >> You touch one other place in fold-const.c but there seem to be many
> >> >> >> more that need ABSU_EXPR handling (you touched the one needed
> >> >> >> for correctness) - esp. you should at least handle constant folding
> >> >> >> in const_unop and the nonnegative predicate.
> >> >> >
> >> >> > OK.
> >> >> >>
> >> >> >> @@ -3167,6 +3167,9 @@ verify_expr (tree *tp, int *walk_subtrees, void *data
> >> >> >> ATTRIBUTE_UNUSED)
> >> >> >>         CHECK_OP (0, "invalid operand to unary operator");
> >> >> >>         break;
> >> >> >>
> >> >> >> +    case ABSU_EXPR:
> >> >> >> +      break;
> >> >> >> +
> >> >> >>       case REALPART_EXPR:
> >> >> >>       case IMAGPART_EXPR:
> >> >> >>
> >> >> >> verify_expr is no more.  Did you test this recently against trunk?
> >> >> >
> >> >> > This patch is against slightly older trunk. I will rebase it.
> >> >> >
> >> >> >>
> >> >> >> @@ -3937,6 +3940,9 @@ verify_gimple_assign_unary (gassign *stmt)
> >> >> >>       case PAREN_EXPR:
> >> >> >>       case CONJ_EXPR:
> >> >> >>         break;
> >> >> >> +    case ABSU_EXPR:
> >> >> >> +      /* FIXME.  */
> >> >> >> +      return false;
> >> >> >>
> >> >> >> no - please not!  Please add verification here - ABSU should be only
> >> >> >> called on INTEGRAL, vector or complex INTEGRAL types and the
> >> >> >> type of the LHS should be always the unsigned variant of the
> >> >> >> argument type.
> >> >> >
> >> >> > OK.
> >> >> >>
> >> >> >>     if (is_gimple_val (cond_expr))
> >> >> >>       return cond_expr;
> >> >> >>
> >> >> >> -  if (TREE_CODE (cond_expr) == ABS_EXPR)
> >> >> >> +  if (TREE_CODE (cond_expr) == ABS_EXPR
> >> >> >> +      || TREE_CODE (cond_expr) == ABSU_EXPR)
> >> >> >>       {
> >> >> >>         rhs1 = TREE_OPERAND (cond_expr, 1);
> >> >> >>         STRIP_USELESS_TYPE_CONVERSION (rhs1);
> >> >> >>
> >> >> >> err, but the next line just builds a ABS_EXPR ...
> >> >> >>
> >> >> >> How did you identify spots that need adjustment?  I would expect that
> >> >> >> once folding generates ABSU_EXPR that you need to adjust frontends
> >> >> >> (C++ constexpr handling for example).  Also I miss adjustments
> >> >> >> to gimple-pretty-print.c and the GIMPLE FE parser.
> >> >> >
> >> >> > I will add this.
> >> >> >>
> >> >> >> recursively grepping throughout the whole gcc/ tree doesn't reveal too many
> >> >> >> cases of ABS_EXPR so I think it's reasonable to audit all of them.
> >> >> >>
> >> >> >> I also miss some trivial absu simplifications in match.pd.  There are not
> >> >> >> a lot of abs cases but similar ones would be good to have initially.
> >> >> >
> >> >> > I will add them in the next version.
> >> >> >
> >> >> > Thanks,
> >> >> > Kugan
> >> >> >
> >> >> >>
> >> >> >> Thanks for tackling this!
> >> >> >> Richard.
> >> >> >>
> >> >> >>> Thanks,
> >> >> >>> Andrew
> >> >> >>
> >> >> >>> >
> >> >> >>> > Thanks,
> >> >> >>> > Kugan
> >> >> >>> >
> >> >> >>> >
> >> >> >>> > gcc/ChangeLog:
> >> >> >>> >
> >> >> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >> >> >>> >
> >> >> >>> >     * expr.c (expand_expr_real_2): Handle ABSU_EXPR.
> >> >> >>> >     * fold-const.c (fold_cond_expr_with_comparison): Generate ABSU_EXPR
> >> >> >>> >     (fold_unary_loc): Handle ABSU_EXPR.
> >> >> >>> >     * optabs-tree.c (optab_for_tree_code): Likewise.
> >> >> >>> >     * tree-cfg.c (verify_expr): Likewise.
> >> >> >>> >     (verify_gimple_assign_unary):  Likewise.
> >> >> >>> >     * tree-if-conv.c (fold_build_cond_expr):  Likewise.
> >> >> >>> >     * tree-inline.c (estimate_operator_cost):  Likewise.
> >> >> >>> >     * tree-pretty-print.c (dump_generic_node):  Likewise.
> >> >> >>> >     * tree.def (ABSU_EXPR): New.
> >> >> >>> >
> >> >> >>> > gcc/testsuite/ChangeLog:
> >> >> >>> >
> >> >> >>> > 2018-05-13  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
> >> >> >>> >
> >> >> >>> >     * gcc.dg/absu.c: New test.

Patch

diff --git a/gcc/expr.c b/gcc/expr.c
index 5e3d9a5..67f8dd1 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -9063,6 +9063,7 @@  expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
       return REDUCE_BIT_FIELD (temp);
 
     case ABS_EXPR:
+    case ABSU_EXPR:
       op0 = expand_expr (treeop0, subtarget,
 			 VOIDmode, EXPAND_NORMAL);
       if (modifier == EXPAND_STACK_PARM)
@@ -9074,7 +9075,8 @@  expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
 
       /* Unsigned abs is simply the operand.  Testing here means we don't
 	 risk generating incorrect code below.  */
-      if (TYPE_UNSIGNED (type))
+      if (TYPE_UNSIGNED (type)
+	  && (code != ABSU_EXPR))
 	return op0;
 
       return expand_abs (mode, op0, target, unsignedp,
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 3a99b66..6e80178 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -5324,8 +5324,17 @@  fold_cond_expr_with_comparison (location_t loc, tree type,
       case GT_EXPR:
 	if (TYPE_UNSIGNED (TREE_TYPE (arg1)))
 	  break;
-	tem = fold_build1_loc (loc, ABS_EXPR, TREE_TYPE (arg1), arg1);
-	return fold_convert_loc (loc, type, tem);
+	if (TREE_CODE (arg1) == NOP_EXPR)
+	  {
+	    arg1 = TREE_OPERAND (arg1, 0);
+	    tem = fold_build1_loc (loc, ABSU_EXPR, unsigned_type_for (arg1_type), arg1);
+	    return fold_convert_loc (loc, type, tem);
+	  }
+	else
+	  {
+	    tem = fold_build1_loc (loc, ABS_EXPR, TREE_TYPE (arg1), arg1);
+	    return fold_convert_loc (loc, type, tem);
+	  }
       case UNLE_EXPR:
       case UNLT_EXPR:
 	if (flag_trapping_math)
@@ -7698,7 +7707,8 @@  fold_unary_loc (location_t loc, enum tree_code code, tree type, tree op0)
   if (arg0)
     {
       if (CONVERT_EXPR_CODE_P (code)
-	  || code == FLOAT_EXPR || code == ABS_EXPR || code == NEGATE_EXPR)
+	  || code == FLOAT_EXPR || code == ABS_EXPR
+	  || code == ABSU_EXPR || code == NEGATE_EXPR)
 	{
 	  /* Don't use STRIP_NOPS, because signedness of argument type
 	     matters.  */
diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
index 71e172c..2b812e5 100644
--- a/gcc/optabs-tree.c
+++ b/gcc/optabs-tree.c
@@ -235,6 +235,7 @@  optab_for_tree_code (enum tree_code code, const_tree type,
       return trapv ? negv_optab : neg_optab;
 
     case ABS_EXPR:
+    case ABSU_EXPR:
       return trapv ? absv_optab : abs_optab;
 
     default:
diff --git a/gcc/testsuite/gcc.dg/absu.c b/gcc/testsuite/gcc.dg/absu.c
index e69de29..43e651b 100644
--- a/gcc/testsuite/gcc.dg/absu.c
+++ b/gcc/testsuite/gcc.dg/absu.c
@@ -0,0 +1,39 @@ 
+
+/* { dg-do run  } */
+/* { dg-options "-O0" } */
+
+#include <limits.h>
+#define ABS(x)	(((x) >= 0) ? (x) : -(x))
+
+#define DEF_TEST(TYPE)	\
+void foo_##TYPE (signed TYPE x, unsigned TYPE y){	\
+    TYPE t = ABS (x);				\
+    if (t != y)					\
+ 	__builtin_abort ();			\
+}						\
+
+DEF_TEST (char);
+DEF_TEST (short);
+DEF_TEST (int);
+DEF_TEST (long);
+void main ()
+{
+  foo_char (SCHAR_MIN + 1, SCHAR_MAX);
+  foo_char (0, 0);
+  foo_char (SCHAR_MAX, SCHAR_MAX);
+
+  foo_int (-1, 1);
+  foo_int (0, 0);
+  foo_int (INT_MAX, INT_MAX);
+  foo_int (INT_MIN + 1, INT_MAX);
+
+  foo_short (-1, 1);
+  foo_short (0, 0);
+  foo_short (SHRT_MAX, SHRT_MAX);
+  foo_short (SHRT_MIN + 1, SHRT_MAX);
+
+  foo_long (-1, 1);
+  foo_long (0, 0);
+  foo_long (LONG_MAX, LONG_MAX);
+  foo_long (LONG_MIN + 1, LONG_MAX);
+}
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 9485f73..59a115c 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -3167,6 +3167,9 @@  verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
       CHECK_OP (0, "invalid operand to unary operator");
       break;
 
+    case ABSU_EXPR:
+      break;
+
     case REALPART_EXPR:
     case IMAGPART_EXPR:
     case BIT_FIELD_REF:
@@ -3937,6 +3940,9 @@  verify_gimple_assign_unary (gassign *stmt)
     case PAREN_EXPR:
     case CONJ_EXPR:
       break;
+    case ABSU_EXPR:
+      /* FIXME.  */
+      return false;
 
     case VEC_DUPLICATE_EXPR:
       if (TREE_CODE (lhs_type) != VECTOR_TYPE
diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 71dac4f..13d4c25 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -466,7 +466,8 @@  fold_build_cond_expr (tree type, tree cond, tree rhs, tree lhs)
   if (is_gimple_val (cond_expr))
     return cond_expr;
 
-  if (TREE_CODE (cond_expr) == ABS_EXPR)
+  if (TREE_CODE (cond_expr) == ABS_EXPR
+      || TREE_CODE (cond_expr) == ABSU_EXPR)
     {
       rhs1 = TREE_OPERAND (cond_expr, 1);
       STRIP_USELESS_TYPE_CONVERSION (rhs1);
diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
index 5a0a252..d272974 100644
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -3866,6 +3866,7 @@  estimate_operator_cost (enum tree_code code, eni_weights *weights,
     case MIN_EXPR:
     case MAX_EXPR:
     case ABS_EXPR:
+    case ABSU_EXPR:
 
     case LSHIFT_EXPR:
     case RSHIFT_EXPR:
diff --git a/gcc/tree-pretty-print.c b/gcc/tree-pretty-print.c
index 276ad00..b74d8c9 100644
--- a/gcc/tree-pretty-print.c
+++ b/gcc/tree-pretty-print.c
@@ -2460,6 +2460,12 @@  dump_generic_node (pretty_printer *pp, tree node, int spc, dump_flags_t flags,
       pp_greater (pp);
       break;
 
+    case ABSU_EXPR:
+      pp_string (pp, "ABSU_EXPR <");
+      dump_generic_node (pp, TREE_OPERAND (node, 0), spc, flags, false);
+      pp_greater (pp);
+      break;
+
     case RANGE_EXPR:
       NIY;
       break;
diff --git a/gcc/tree.def b/gcc/tree.def
index 31de6c0..768167b 100644
--- a/gcc/tree.def
+++ b/gcc/tree.def
@@ -760,6 +760,7 @@  DEFTREECODE (MAX_EXPR, "max_expr", tcc_binary, 2)
    An ABS_EXPR must have either an INTEGER_TYPE or a REAL_TYPE.  The
    operand of the ABS_EXPR must have the same type.  */
 DEFTREECODE (ABS_EXPR, "abs_expr", tcc_unary, 1)
+DEFTREECODE (ABSU_EXPR, "absu_expr", tcc_unary, 1)
 
 /* Shift operations for shift and rotate.
    Shift means logical shift if done on an