[PATCH 1/2] c++: implement __remove_pointer built-in trait

[Ken Matsui]

Just a quick update, the benchmark code link has been updated and can
now be accessed at
https://github.com/ken-matsui/gcc-benches/blob/main/remove_pointer.cc.
I have also created a report file which can be found at
https://github.com/ken-matsui/gcc-benches/blob/main/remove_pointer.md.

On Sat, Jun 17, 2023 at 5:35 AM Ken Matsui <kmatsui@cs.washington.edu> wrote:
>
> Hi,
>
> I conducted a benchmark for remove_pointer as well as is_object. Just
> like the is_object benchmark, here is the benchmark code:
>
> https://github.com/ken-matsui/gcc-benches/blob/main/remove_pointer_benchmark.cc
>
> On my computer, using the gcc HEAD of this patch for a release build,
> the patch with -DUSE_BUILTIN took 8.7% less time and used 4.3-4.9%
> less memory on average compared to not using it. Although the
> performance improvement was not as significant as with is_object, the
> benchmark demonstrated that the compilation was consistently more
> efficient.
>
> Sincerely,
> Ken Matsui
>
> On Thu, Jun 15, 2023 at 5:22 AM Ken Matsui <kmatsui@cs.washington.edu> wrote:
> >
> > This patch implements built-in trait for std::remove_pointer.
> >
> > gcc/cp/ChangeLog:
> >
> >         * cp-trait.def: Define __remove_pointer.
> >         * semantics.cc (finish_trait_type): Handle CPTK_REMOVE_POINTER.
> >
> > gcc/testsuite/ChangeLog:
> >
> >         * g++.dg/ext/has-builtin-1.C: Test existence of __remove_pointer.
> >         * g++.dg/ext/remove_pointer.C: New test.
> >
> > Signed-off-by: Ken Matsui <kmatsui@cs.washington.edu>
> > ---
> >  gcc/cp/cp-trait.def                       |  1 +
> >  gcc/cp/semantics.cc                       |  4 ++
> >  gcc/testsuite/g++.dg/ext/has-builtin-1.C  |  3 ++
> >  gcc/testsuite/g++.dg/ext/remove_pointer.C | 51 +++++++++++++++++++++++
> >  4 files changed, 59 insertions(+)
> >  create mode 100644 gcc/testsuite/g++.dg/ext/remove_pointer.C
> >
> > diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
> > index 8b7fece0cc8..07823e55579 100644
> > --- a/gcc/cp/cp-trait.def
> > +++ b/gcc/cp/cp-trait.def
> > @@ -90,6 +90,7 @@ DEFTRAIT_EXPR (IS_DEDUCIBLE, "__is_deducible ", 2)
> >  DEFTRAIT_TYPE (REMOVE_CV, "__remove_cv", 1)
> >  DEFTRAIT_TYPE (REMOVE_REFERENCE, "__remove_reference", 1)
> >  DEFTRAIT_TYPE (REMOVE_CVREF, "__remove_cvref", 1)
> > +DEFTRAIT_TYPE (REMOVE_POINTER, "__remove_pointer", 1)
> >  DEFTRAIT_TYPE (UNDERLYING_TYPE,  "__underlying_type", 1)
> >  DEFTRAIT_TYPE (TYPE_PACK_ELEMENT, "__type_pack_element", -1)
> >
> > diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> > index 8fb47fd179e..885c7a6fb64 100644
> > --- a/gcc/cp/semantics.cc
> > +++ b/gcc/cp/semantics.cc
> > @@ -12373,6 +12373,10 @@ finish_trait_type (cp_trait_kind kind, tree type1, tree type2,
> >        if (TYPE_REF_P (type1))
> >         type1 = TREE_TYPE (type1);
> >        return cv_unqualified (type1);
> > +    case CPTK_REMOVE_POINTER:
> > +      if (TYPE_PTR_P (type1))
> > +    type1 = TREE_TYPE (type1);
> > +      return type1;
> >
> >      case CPTK_TYPE_PACK_ELEMENT:
> >        return finish_type_pack_element (type1, type2, complain);
> > diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> > index f343e153e56..e21e0a95509 100644
> > --- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> > +++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> > @@ -146,3 +146,6 @@
> >  #if !__has_builtin (__remove_cvref)
> >  # error "__has_builtin (__remove_cvref) failed"
> >  #endif
> > +#if !__has_builtin (__remove_pointer)
> > +# error "__has_builtin (__remove_pointer) failed"
> > +#endif
> > diff --git a/gcc/testsuite/g++.dg/ext/remove_pointer.C b/gcc/testsuite/g++.dg/ext/remove_pointer.C
> > new file mode 100644
> > index 00000000000..7b13db93950
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/ext/remove_pointer.C
> > @@ -0,0 +1,51 @@
> > +// { dg-do compile { target c++11 } }
> > +
> > +#define SA(X) static_assert((X),#X)
> > +
> > +SA(__is_same(__remove_pointer(int), int));
> > +SA(__is_same(__remove_pointer(int*), int));
> > +SA(__is_same(__remove_pointer(int**), int*));
> > +
> > +SA(__is_same(__remove_pointer(const int*), const int));
> > +SA(__is_same(__remove_pointer(const int**), const int*));
> > +SA(__is_same(__remove_pointer(int* const), int));
> > +SA(__is_same(__remove_pointer(int** const), int*));
> > +SA(__is_same(__remove_pointer(int* const* const), int* const));
> > +
> > +SA(__is_same(__remove_pointer(volatile int*), volatile int));
> > +SA(__is_same(__remove_pointer(volatile int**), volatile int*));
> > +SA(__is_same(__remove_pointer(int* volatile), int));
> > +SA(__is_same(__remove_pointer(int** volatile), int*));
> > +SA(__is_same(__remove_pointer(int* volatile* volatile), int* volatile));
> > +
> > +SA(__is_same(__remove_pointer(const volatile int*), const volatile int));
> > +SA(__is_same(__remove_pointer(const volatile int**), const volatile int*));
> > +SA(__is_same(__remove_pointer(const int* volatile), const int));
> > +SA(__is_same(__remove_pointer(volatile int* const), volatile int));
> > +SA(__is_same(__remove_pointer(int* const volatile), int));
> > +SA(__is_same(__remove_pointer(const int** volatile), const int*));
> > +SA(__is_same(__remove_pointer(volatile int** const), volatile int*));
> > +SA(__is_same(__remove_pointer(int** const volatile), int*));
> > +SA(__is_same(__remove_pointer(int* const* const volatile), int* const));
> > +SA(__is_same(__remove_pointer(int* volatile* const volatile), int* volatile));
> > +SA(__is_same(__remove_pointer(int* const volatile* const volatile), int* const volatile));
> > +
> > +SA(__is_same(__remove_pointer(int&), int&));
> > +SA(__is_same(__remove_pointer(const int&), const int&));
> > +SA(__is_same(__remove_pointer(volatile int&), volatile int&));
> > +SA(__is_same(__remove_pointer(const volatile int&), const volatile int&));
> > +
> > +SA(__is_same(__remove_pointer(int&&), int&&));
> > +SA(__is_same(__remove_pointer(const int&&), const int&&));
> > +SA(__is_same(__remove_pointer(volatile int&&), volatile int&&));
> > +SA(__is_same(__remove_pointer(const volatile int&&), const volatile int&&));
> > +
> > +SA(__is_same(__remove_pointer(int[3]), int[3]));
> > +SA(__is_same(__remove_pointer(const int[3]), const int[3]));
> > +SA(__is_same(__remove_pointer(volatile int[3]), volatile int[3]));
> > +SA(__is_same(__remove_pointer(const volatile int[3]), const volatile int[3]));
> > +
> > +SA(__is_same(__remove_pointer(int(int)), int(int)));
> > +SA(__is_same(__remove_pointer(int(*const)(int)), int(int)));
> > +SA(__is_same(__remove_pointer(int(*volatile)(int)), int(int)));
> > +SA(__is_same(__remove_pointer(int(*const volatile)(int)), int(int)));
> > --
> > 2.41.0
> >