[v25,00/33] Optimize type traits compilation performance

Message ID 20231024020424.699427-1-kmatsui@gcc.gnu.org
Headers
Series Optimize type traits compilation performance |

Message

Ken Matsui Oct. 24, 2023, 2 a.m. UTC
  This patch series optimizes type traits compilation performance by
implementing built-in type traits and using them in libstdc++.

Changes in v25:

	* Optimized the __is_pointer implementation in cpp_type_traits.h.
	* Fix compilation error in cpp_type_traits.h with Clang 16.
	* Wrapped commit messages at 75 columns.
	* Used & instead of && for the new IDENTIFIER_TRAIT_P macro.
	* Made cp_lexer_peek_trait not to take cp_token.
	* Fixed indentation error in cp_lexer_peek_trait.

Changes in v24:

	* Fixed the way to handle an incomplete type error from __is_invocable
	in the test cases so that we can correctly test both the use of
	built-in and vice-versa.

Changes in v23:

	* Improved the comment in cp-tree.h.
	* Moved the definition of cp_traits to lex.cc from parser.cc.
	* Implemented __is_invocable built-in trait.

Changes in v22:

	* Included a missing patch in v21.

Changes in v21:

	* Used _GLIBCXX_USE_BUILTIN_TRAIT instead of __has_builtin in
	cpp_type_traits.h.
	* Added const char* name to struct cp_trait, and loop over cp_traits
	in init_cp_traits to get the name.
	* Isolated patches for integral-related built-in traits from
	this patch series since they are not ready for review yet.
	* Implemented __is_object built-in trait.

Changes in v20:

	* Used identifier node instead of gperf to look up built-in
	traits.

Changes in v19:

	* Fixed a typo.
	* Rebased on top of trunk.
	* Improved clarity of the commit message.

Changes in v18:

	* Removed all RID values for built-in traits and used cik_trait
	instead.
	* Improved to handle the use of non-function-like built-in trait
	identifiers.
	* Reverted all changes to conflicted identifiers with new built-ins
	in the existing code base.

Changes in v17:

	* Rebased on top of trunk.
	* Improved clarity of the commit message.
	* Simplified Make-lang.in.
	* Made ridpointers for RID_TRAIT_EXPR and RID_TRAIT_TYPE empty.

Changes in v16:

	* Rebased on top of trunk.
	* Improved clarity of the commit message.
	* Simplified Make-lang.in and gperf struct.
	* Supply -k option to gperf to support older versions than 2.8.

Changes in v15:

	* Rebased on top of trunk.
	* Use gperf to look up traits instead of enum rid.

Changes in v14:

	* Added padding calculation to the commit message.

Changes in v13:

	* Fixed ambiguous commit message and comment.

Changes in v12:

	* Evaluated all paddings affected by the enum rid change.

Changes in v11:

	* Merged all patches into one patch series.
	* Rebased on top of trunk.
	* Unified commit message style.
	* Used _GLIBCXX_USE_BUILTIN_TRAIT.

Ken Matsui (33):
  c++: Sort built-in traits alphabetically
  c-family, c++: Look up built-in traits via identifier node
  c++: Accept the use of built-in trait identifiers
  c++: Implement __is_const built-in trait
  libstdc++: Optimize std::is_const compilation performance
  c++: Implement __is_volatile built-in trait
  libstdc++: Optimize std::is_volatile compilation performance
  c++: Implement __is_array built-in trait
  libstdc++: Optimize std::is_array compilation performance
  c++: Implement __is_unbounded_array built-in trait
  libstdc++: Optimize std::is_unbounded_array compilation performance
  c++: Implement __is_bounded_array built-in trait
  libstdc++: Optimize std::is_bounded_array compilation performance
  c++: Implement __is_scoped_enum built-in trait
  libstdc++: Optimize std::is_scoped_enum compilation performance
  c++: Implement __is_member_pointer built-in trait
  libstdc++: Optimize std::is_member_pointer compilation performance
  c++: Implement __is_member_function_pointer built-in trait
  libstdc++: Optimize std::is_member_function_pointer compilation
    performance
  c++: Implement __is_member_object_pointer built-in trait
  libstdc++: Optimize std::is_member_object_pointer compilation
    performance
  c++: Implement __is_reference built-in trait
  libstdc++: Optimize std::is_reference compilation performance
  c++: Implement __is_function built-in trait
  libstdc++: Optimize std::is_function compilation performance
  c++: Implement __is_object built-in trait
  libstdc++: Optimize std::is_object compilation performance
  c++: Implement __remove_pointer built-in trait
  libstdc++: Optimize std::remove_pointer compilation performance
  c++: Implement __is_pointer built-in trait
  libstdc++: Optimize std::is_pointer compilation performance
  c++: Implement __is_invocable built-in trait
  libstdc++: Optimize std::is_invocable compilation performance

 gcc/c-family/c-common.cc                      |   7 -
 gcc/c-family/c-common.h                       |   5 -
 gcc/cp/constraint.cc                          | 109 ++++--
 gcc/cp/cp-objcp-common.cc                     |   8 +-
 gcc/cp/cp-trait.def                           |  25 +-
 gcc/cp/cp-tree.h                              |  32 +-
 gcc/cp/lex.cc                                 |  34 ++
 gcc/cp/method.h                               |  28 ++
 gcc/cp/parser.cc                              | 120 ++++---
 gcc/cp/semantics.cc                           | 284 ++++++++++++---
 gcc/testsuite/g++.dg/ext/has-builtin-1.C      | 113 ++++--
 gcc/testsuite/g++.dg/ext/is_array.C           |  28 ++
 gcc/testsuite/g++.dg/ext/is_bounded_array.C   |  38 ++
 gcc/testsuite/g++.dg/ext/is_const.C           |  19 +
 gcc/testsuite/g++.dg/ext/is_function.C        |  58 +++
 gcc/testsuite/g++.dg/ext/is_invocable1.C      | 337 ++++++++++++++++++
 gcc/testsuite/g++.dg/ext/is_invocable2.C      | 139 ++++++++
 gcc/testsuite/g++.dg/ext/is_invocable3.C      |  51 +++
 gcc/testsuite/g++.dg/ext/is_invocable4.C      |  33 ++
 .../g++.dg/ext/is_member_function_pointer.C   |  31 ++
 .../g++.dg/ext/is_member_object_pointer.C     |  30 ++
 gcc/testsuite/g++.dg/ext/is_member_pointer.C  |  30 ++
 gcc/testsuite/g++.dg/ext/is_object.C          |  29 ++
 gcc/testsuite/g++.dg/ext/is_pointer.C         |  51 +++
 gcc/testsuite/g++.dg/ext/is_reference.C       |  34 ++
 gcc/testsuite/g++.dg/ext/is_scoped_enum.C     |  67 ++++
 gcc/testsuite/g++.dg/ext/is_unbounded_array.C |  37 ++
 gcc/testsuite/g++.dg/ext/is_volatile.C        |  19 +
 gcc/testsuite/g++.dg/ext/remove_pointer.C     |  51 +++
 libstdc++-v3/include/bits/cpp_type_traits.h   |  29 ++
 libstdc++-v3/include/std/type_traits          | 219 +++++++++++-
 .../is_invocable/incomplete_args_neg.cc       |   1 +
 .../20_util/is_invocable/incomplete_neg.cc    |   1 +
 33 files changed, 1901 insertions(+), 196 deletions(-)
 create mode 100644 gcc/cp/method.h
 create mode 100644 gcc/testsuite/g++.dg/ext/is_array.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_bounded_array.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_const.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_function.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable1.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable2.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable3.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable4.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_member_function_pointer.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_member_object_pointer.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_member_pointer.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_object.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_pointer.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_reference.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_scoped_enum.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_unbounded_array.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_volatile.C
 create mode 100644 gcc/testsuite/g++.dg/ext/remove_pointer.C
  

Comments

Ken Matsui Oct. 24, 2023, 2:07 a.m. UTC | #1
I accidentally sent is_invocable patches as well, but those have no changes.

On Mon, Oct 23, 2023 at 7:04 PM Ken Matsui <kmatsui@gcc.gnu.org> wrote:
>
> This patch series optimizes type traits compilation performance by
> implementing built-in type traits and using them in libstdc++.
>
> Changes in v25:
>
>         * Optimized the __is_pointer implementation in cpp_type_traits.h.
>         * Fix compilation error in cpp_type_traits.h with Clang 16.
>         * Wrapped commit messages at 75 columns.
>         * Used & instead of && for the new IDENTIFIER_TRAIT_P macro.
>         * Made cp_lexer_peek_trait not to take cp_token.
>         * Fixed indentation error in cp_lexer_peek_trait.
>
> Changes in v24:
>
>         * Fixed the way to handle an incomplete type error from __is_invocable
>         in the test cases so that we can correctly test both the use of
>         built-in and vice-versa.
>
> Changes in v23:
>
>         * Improved the comment in cp-tree.h.
>         * Moved the definition of cp_traits to lex.cc from parser.cc.
>         * Implemented __is_invocable built-in trait.
>
> Changes in v22:
>
>         * Included a missing patch in v21.
>
> Changes in v21:
>
>         * Used _GLIBCXX_USE_BUILTIN_TRAIT instead of __has_builtin in
>         cpp_type_traits.h.
>         * Added const char* name to struct cp_trait, and loop over cp_traits
>         in init_cp_traits to get the name.
>         * Isolated patches for integral-related built-in traits from
>         this patch series since they are not ready for review yet.
>         * Implemented __is_object built-in trait.
>
> Changes in v20:
>
>         * Used identifier node instead of gperf to look up built-in
>         traits.
>
> Changes in v19:
>
>         * Fixed a typo.
>         * Rebased on top of trunk.
>         * Improved clarity of the commit message.
>
> Changes in v18:
>
>         * Removed all RID values for built-in traits and used cik_trait
>         instead.
>         * Improved to handle the use of non-function-like built-in trait
>         identifiers.
>         * Reverted all changes to conflicted identifiers with new built-ins
>         in the existing code base.
>
> Changes in v17:
>
>         * Rebased on top of trunk.
>         * Improved clarity of the commit message.
>         * Simplified Make-lang.in.
>         * Made ridpointers for RID_TRAIT_EXPR and RID_TRAIT_TYPE empty.
>
> Changes in v16:
>
>         * Rebased on top of trunk.
>         * Improved clarity of the commit message.
>         * Simplified Make-lang.in and gperf struct.
>         * Supply -k option to gperf to support older versions than 2.8.
>
> Changes in v15:
>
>         * Rebased on top of trunk.
>         * Use gperf to look up traits instead of enum rid.
>
> Changes in v14:
>
>         * Added padding calculation to the commit message.
>
> Changes in v13:
>
>         * Fixed ambiguous commit message and comment.
>
> Changes in v12:
>
>         * Evaluated all paddings affected by the enum rid change.
>
> Changes in v11:
>
>         * Merged all patches into one patch series.
>         * Rebased on top of trunk.
>         * Unified commit message style.
>         * Used _GLIBCXX_USE_BUILTIN_TRAIT.
>
> Ken Matsui (33):
>   c++: Sort built-in traits alphabetically
>   c-family, c++: Look up built-in traits via identifier node
>   c++: Accept the use of built-in trait identifiers
>   c++: Implement __is_const built-in trait
>   libstdc++: Optimize std::is_const compilation performance
>   c++: Implement __is_volatile built-in trait
>   libstdc++: Optimize std::is_volatile compilation performance
>   c++: Implement __is_array built-in trait
>   libstdc++: Optimize std::is_array compilation performance
>   c++: Implement __is_unbounded_array built-in trait
>   libstdc++: Optimize std::is_unbounded_array compilation performance
>   c++: Implement __is_bounded_array built-in trait
>   libstdc++: Optimize std::is_bounded_array compilation performance
>   c++: Implement __is_scoped_enum built-in trait
>   libstdc++: Optimize std::is_scoped_enum compilation performance
>   c++: Implement __is_member_pointer built-in trait
>   libstdc++: Optimize std::is_member_pointer compilation performance
>   c++: Implement __is_member_function_pointer built-in trait
>   libstdc++: Optimize std::is_member_function_pointer compilation
>     performance
>   c++: Implement __is_member_object_pointer built-in trait
>   libstdc++: Optimize std::is_member_object_pointer compilation
>     performance
>   c++: Implement __is_reference built-in trait
>   libstdc++: Optimize std::is_reference compilation performance
>   c++: Implement __is_function built-in trait
>   libstdc++: Optimize std::is_function compilation performance
>   c++: Implement __is_object built-in trait
>   libstdc++: Optimize std::is_object compilation performance
>   c++: Implement __remove_pointer built-in trait
>   libstdc++: Optimize std::remove_pointer compilation performance
>   c++: Implement __is_pointer built-in trait
>   libstdc++: Optimize std::is_pointer compilation performance
>   c++: Implement __is_invocable built-in trait
>   libstdc++: Optimize std::is_invocable compilation performance
>
>  gcc/c-family/c-common.cc                      |   7 -
>  gcc/c-family/c-common.h                       |   5 -
>  gcc/cp/constraint.cc                          | 109 ++++--
>  gcc/cp/cp-objcp-common.cc                     |   8 +-
>  gcc/cp/cp-trait.def                           |  25 +-
>  gcc/cp/cp-tree.h                              |  32 +-
>  gcc/cp/lex.cc                                 |  34 ++
>  gcc/cp/method.h                               |  28 ++
>  gcc/cp/parser.cc                              | 120 ++++---
>  gcc/cp/semantics.cc                           | 284 ++++++++++++---
>  gcc/testsuite/g++.dg/ext/has-builtin-1.C      | 113 ++++--
>  gcc/testsuite/g++.dg/ext/is_array.C           |  28 ++
>  gcc/testsuite/g++.dg/ext/is_bounded_array.C   |  38 ++
>  gcc/testsuite/g++.dg/ext/is_const.C           |  19 +
>  gcc/testsuite/g++.dg/ext/is_function.C        |  58 +++
>  gcc/testsuite/g++.dg/ext/is_invocable1.C      | 337 ++++++++++++++++++
>  gcc/testsuite/g++.dg/ext/is_invocable2.C      | 139 ++++++++
>  gcc/testsuite/g++.dg/ext/is_invocable3.C      |  51 +++
>  gcc/testsuite/g++.dg/ext/is_invocable4.C      |  33 ++
>  .../g++.dg/ext/is_member_function_pointer.C   |  31 ++
>  .../g++.dg/ext/is_member_object_pointer.C     |  30 ++
>  gcc/testsuite/g++.dg/ext/is_member_pointer.C  |  30 ++
>  gcc/testsuite/g++.dg/ext/is_object.C          |  29 ++
>  gcc/testsuite/g++.dg/ext/is_pointer.C         |  51 +++
>  gcc/testsuite/g++.dg/ext/is_reference.C       |  34 ++
>  gcc/testsuite/g++.dg/ext/is_scoped_enum.C     |  67 ++++
>  gcc/testsuite/g++.dg/ext/is_unbounded_array.C |  37 ++
>  gcc/testsuite/g++.dg/ext/is_volatile.C        |  19 +
>  gcc/testsuite/g++.dg/ext/remove_pointer.C     |  51 +++
>  libstdc++-v3/include/bits/cpp_type_traits.h   |  29 ++
>  libstdc++-v3/include/std/type_traits          | 219 +++++++++++-
>  .../is_invocable/incomplete_args_neg.cc       |   1 +
>  .../20_util/is_invocable/incomplete_neg.cc    |   1 +
>  33 files changed, 1901 insertions(+), 196 deletions(-)
>  create mode 100644 gcc/cp/method.h
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_array.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_bounded_array.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_const.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_function.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable1.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable2.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable3.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable4.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_member_function_pointer.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_member_object_pointer.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_member_pointer.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_object.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_pointer.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_reference.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_scoped_enum.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_unbounded_array.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_volatile.C
>  create mode 100644 gcc/testsuite/g++.dg/ext/remove_pointer.C
>
> --
> 2.42.0
>
  
Ken Matsui Dec. 7, 2023, 5:32 a.m. UTC | #2
This patch series optimizes type traits compilation performance by
implementing built-in type traits and using them in libstdc++.

Changes in v26:

	* Rebased on top of trunk.
	* Moved is_function_v under is_const_v.
	* Isolated is_const, is_volatile, is_pointer, and
	is_unbounded_array patches, which contain performance regression,
	from this patch series.

Changes in v25:

	* Optimized the __is_pointer implementation in cpp_type_traits.h.
	* Fix compilation error in cpp_type_traits.h with Clang 16.
	* Wrapped commit messages at 75 columns.
	* Used & instead of && for the new IDENTIFIER_TRAIT_P macro.
	* Made cp_lexer_peek_trait not to take cp_token.
	* Fixed indentation error in cp_lexer_peek_trait.

Changes in v24:

	* Fixed the way to handle an incomplete type error from __is_invocable
	in the test cases so that we can correctly test both the use of
	built-in and vice-versa.

Changes in v23:

	* Improved the comment in cp-tree.h.
	* Moved the definition of cp_traits to lex.cc from parser.cc.
	* Implemented __is_invocable built-in trait.

Changes in v22:

	* Included a missing patch in v21.

Changes in v21:

	* Used _GLIBCXX_USE_BUILTIN_TRAIT instead of __has_builtin in
	cpp_type_traits.h.
	* Added const char* name to struct cp_trait, and loop over cp_traits
	in init_cp_traits to get the name.
	* Isolated patches for integral-related built-in traits from
	this patch series since they are not ready for review yet.
	* Implemented __is_object built-in trait.

Changes in v20:

	* Used identifier node instead of gperf to look up built-in
	traits.

Changes in v19:

	* Fixed a typo.
	* Rebased on top of trunk.
	* Improved clarity of the commit message.

Changes in v18:

	* Removed all RID values for built-in traits and used cik_trait
	instead.
	* Improved to handle the use of non-function-like built-in trait
	identifiers.
	* Reverted all changes to conflicted identifiers with new built-ins
	in the existing code base.

Changes in v17:

	* Rebased on top of trunk.
	* Improved clarity of the commit message.
	* Simplified Make-lang.in.
	* Made ridpointers for RID_TRAIT_EXPR and RID_TRAIT_TYPE empty.

Changes in v16:

	* Rebased on top of trunk.
	* Improved clarity of the commit message.
	* Simplified Make-lang.in and gperf struct.
	* Supply -k option to gperf to support older versions than 2.8.

Changes in v15:

	* Rebased on top of trunk.
	* Use gperf to look up traits instead of enum rid.

Changes in v14:

	* Added padding calculation to the commit message.

Changes in v13:

	* Fixed ambiguous commit message and comment.

Changes in v12:

	* Evaluated all paddings affected by the enum rid change.

Changes in v11:

	* Merged all patches into one patch series.
	* Rebased on top of trunk.
	* Unified commit message style.
	* Used _GLIBCXX_USE_BUILTIN_TRAIT.

Ken Matsui (23):
  c++: Sort built-in traits alphabetically
  c-family, c++: Look up built-in traits via identifier node
  c++: Accept the use of built-in trait identifiers
  c++: Implement __is_array built-in trait
  libstdc++: Optimize std::is_array compilation performance
  c++: Implement __is_bounded_array built-in trait
  libstdc++: Optimize std::is_bounded_array compilation performance
  c++: Implement __is_scoped_enum built-in trait
  libstdc++: Optimize std::is_scoped_enum compilation performance
  c++: Implement __is_member_pointer built-in trait
  libstdc++: Optimize std::is_member_pointer compilation performance
  c++: Implement __is_member_function_pointer built-in trait
  libstdc++: Optimize std::is_member_function_pointer compilation
    performance
  c++: Implement __is_member_object_pointer built-in trait
  libstdc++: Optimize std::is_member_object_pointer compilation
    performance
  c++: Implement __is_reference built-in trait
  libstdc++: Optimize std::is_reference compilation performance
  c++: Implement __is_function built-in trait
  libstdc++: Optimize std::is_function compilation performance
  c++: Implement __is_object built-in trait
  libstdc++: Optimize std::is_object compilation performance
  c++: Implement __remove_pointer built-in trait
  libstdc++: Optimize std::remove_pointer compilation performance

 gcc/c-family/c-common.cc                      |   7 -
 gcc/c-family/c-common.h                       |   5 -
 gcc/cp/constraint.cc                          |  95 +++++++-----
 gcc/cp/cp-objcp-common.cc                     |   8 +-
 gcc/cp/cp-trait.def                           |  20 ++-
 gcc/cp/cp-tree.h                              |  32 +++--
 gcc/cp/lex.cc                                 |  34 +++++
 gcc/cp/parser.cc                              | 120 ++++++++++------
 gcc/cp/semantics.cc                           | 135 ++++++++++++------
 gcc/testsuite/g++.dg/ext/has-builtin-1.C      | 100 ++++++++-----
 gcc/testsuite/g++.dg/ext/is_array.C           |  28 ++++
 gcc/testsuite/g++.dg/ext/is_bounded_array.C   |  38 +++++
 gcc/testsuite/g++.dg/ext/is_function.C        |  58 ++++++++
 .../g++.dg/ext/is_member_function_pointer.C   |  31 ++++
 .../g++.dg/ext/is_member_object_pointer.C     |  30 ++++
 gcc/testsuite/g++.dg/ext/is_member_pointer.C  |  30 ++++
 gcc/testsuite/g++.dg/ext/is_object.C          |  29 ++++
 gcc/testsuite/g++.dg/ext/is_reference.C       |  34 +++++
 gcc/testsuite/g++.dg/ext/is_scoped_enum.C     |  67 +++++++++
 gcc/testsuite/g++.dg/ext/remove_pointer.C     |  51 +++++++
 libstdc++-v3/include/std/type_traits          | 135 +++++++++++++++++-
 21 files changed, 898 insertions(+), 189 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/ext/is_array.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_bounded_array.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_function.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_member_function_pointer.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_member_object_pointer.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_member_pointer.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_object.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_reference.C
 create mode 100644 gcc/testsuite/g++.dg/ext/is_scoped_enum.C
 create mode 100644 gcc/testsuite/g++.dg/ext/remove_pointer.C