docs/ReleaseNotes.rst - third_party/swift-clang - Git at Google

 =======================================
 Clang 4.0.0 (In-Progress) Release Notes
 =======================================

 .. contents::
    :local:
    :depth: 2

 Written by the `LLVM Team <http://llvm.org/>`_

 .. warning::

    These are in-progress notes for the upcoming Clang 4.0.0 release. You may
    prefer the `Clang 3.9 Release Notes
    <http://llvm.org/releases/3.9.0/tools/clang/docs/ReleaseNotes.html>`_.

 Introduction
 ============

 This document contains the release notes for the Clang C/C++/Objective-C/OpenCL
 frontend, part of the LLVM Compiler Infrastructure, release 4.0.0. Here we
 describe the status of Clang in some detail, including major
 improvements from the previous release and new feature work. For the
 general LLVM release notes, see `the LLVM
 documentation <http://llvm.org/docs/ReleaseNotes.html>`_. All LLVM
 releases may be downloaded from the `LLVM releases web
 site <http://llvm.org/releases/>`_.

 For more information about Clang or LLVM, including information about
 the latest release, please check out the main please see the `Clang Web
 Site <http://clang.llvm.org>`_ or the `LLVM Web
 Site <http://llvm.org>`_.

 What's New in Clang 4.0.0?
 ==========================

 Some of the major new features and improvements to Clang are listed
 here. Generic improvements to Clang as a whole or to its underlying
 infrastructure are described first, followed by language-specific
 sections with improvements to Clang's support for those languages.

 Major New Features
 ------------------

 - The ``diagnose_if`` attribute has been added to clang. This attribute allows
   clang to emit a warning or error if a function call meets one or more
   user-specified conditions.

 - Enhanced devirtualization with
   `-fstrict-vtable-pointers <UsersManual.html#cmdoption-fstrict-vtable-pointers>`_.
   Clang devirtualizes across different basic blocks, like loops:

   .. code-block:: c++

        struct A {
            virtual void foo();
        };
        void indirect(A &a, int n) {
            for (int i = 0 ; i < n; i++)
                a.foo();
        }
        void test(int n) {
            A a;
            indirect(a, n);
        }


 -  ...

 Improvements to ThinLTO (-flto=thin)
 ------------------------------------
 - Integration with profile data (PGO). When available, profile data enables
   more accurate function importing decisions, as well as cross-module indirect
   call promotion.
 - Significant build-time and binary-size improvements when compiling with debug
   info (-g).

 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 -  ...

 New Compiler Flags
 ------------------

 The option -Og has been added to optimize the debugging experience.
 For now, this option is exactly the same as -O1. However, in the future,
 some other optimizations might be enabled or disabled.

 The option -MJ has been added to simplify adding JSON compilation
 database output into existing build systems.

 The option ....

 New Pragmas in Clang
 -----------------------

 Clang now supports the ...


 Attribute Changes in Clang
 --------------------------

 -  ...

 Windows Support
 ---------------

 Clang's support for building native Windows programs ...


 C Language Changes in Clang
 ---------------------------

 - ...

 ...

 C11 Feature Support
 ^^^^^^^^^^^^^^^^^^^

 ...

 C++ Language Changes in Clang
 -----------------------------

 ...

 C++1z Feature Support
 ^^^^^^^^^^^^^^^^^^^^^

 ...

 Objective-C Language Changes in Clang
 -------------------------------------

 ...

 OpenCL C Language Changes in Clang
 ----------------------------------

 **The following bugs in the OpenCL header have been fixed:**

 * Added missing ``overloadable`` and ``convergent`` attributes.
 * Removed some erroneous extra ``native_*`` functions.

 **The following bugs in the generation of metadata have been fixed:**

 * Corrected the SPIR version depending on the OpenCL version.
 * Source level address spaces are taken from the SPIR specification.
 * Image types now contain no access qualifier.

 **The following bugs in the AMD target have been fixed:**

 * Corrected the bitwidth of ``size_t`` and NULL pointer value with respect to
   address spaces.
 * Added ``cl_khr_subgroups``, ``cl_amd_media_ops`` and ``cl_amd_media_ops2``
   extensions.
 * Added ``cl-denorms-are-zero`` support.
 * Changed address spaces for image objects to be ``constant``.
 * Added little-endian.

 **The following bugs in OpenCL 2.0 have been fixed:**

 * Fixed pipe builtin function return type, added extra argument to generated
   IR intrinsics to propagate size and alignment information of the pipe packed
   type.
 * Improved pipe type to accommodate access qualifiers.
 * Added correct address space to the ObjC block generation and ``enqueue_kernel``
   prototype.
 * Improved handling of integer parameters of ``enqueue_kernel`` prototype. We
   now allow ``size_t`` instead of ``int`` for specifying block parameter sizes.
 * Allow using NULL (aka ``CLK_NULL_QUEUE``) with ``queue_t``.


 **Improved the following diagnostics:**

 * Disallow address spaces other than ``global`` for kernel pointer parameters.
 * Correct the use of half type argument and pointer assignment with
   dereferencing.
 * Disallow variadic arguments in functions and blocks.
 * Allow partial initializer for array and struct.

 **Some changes to OpenCL extensions have been made:**

 * Added ``cl_khr_mipmap_image``.
 * Added ``-cl-ext`` flag to allow overwriting supported extensions otherwise
   set by the target compiled for (Example: ``-cl-ext=-all,+cl_khr_fp16``).
 * New types and functions can now be flexibly added to extensions using the
   following pragmas instead of modifying the Clang source code:

   .. code-block:: c

        #pragma OPENCL EXTENSION the_new_extension_name : begin
        // declare types and functions associated with the extension here
        #pragma OPENCL EXTENSION the_new_extension_name : end


 **Miscellaneous changes:**

 * Fix ``__builtin_astype`` to cast between different address space objects.
 * Allow using ``opencl_unroll_hint`` with earlier OpenCL versions than 2.0.
 * Improved handling of floating point literal to default to single precision if
   fp64 extension is not enabled.
 * Refactor ``sampler_t`` implementation to simplify initializer representation
   which is now handled as a compiler builtin function with an integer value
   passed into it.
 * Change fake address space map to use the SPIR convention.
 * Added `the OpenCL manual
   <https://clang.llvm.org/docs/UsersManual.html#opencl-features>`_ to Clang
   documentation.

 OpenMP Support in Clang
 ----------------------------------

 ...

 Internal API Changes
 --------------------

 These are major API changes that have happened since the 3.9 release of
 Clang. If upgrading an external codebase that uses Clang as a library,
 this section should help get you past the largest hurdles of upgrading.

 -  ...

 AST Matchers
 ------------

 ...

 libclang
 --------

 ...

 With the option --show-description, scan-build's list of defects will also
 show the description of the defects.


 Static Analyzer
 ---------------

 ...

 Core Analysis Improvements
 ==========================

 - ...

 New Issues Found
 ================

 - ...

 Python Binding Changes
 ----------------------

 The following methods have been added:

 -  ...

 Significant Known Problems
 ==========================

 Additional Information
 ======================

 A wide variety of additional information is available on the `Clang web
 page <http://clang.llvm.org/>`_. The web page contains versions of the
 API documentation which are up-to-date with the Subversion version of
 the source code. You can access versions of these documents specific to
 this release by going into the "``clang/docs/``" directory in the Clang
 tree.

 If you have any questions or comments about Clang, please feel free to
 contact us via the `mailing
 list <http://lists.llvm.org/mailman/listinfo/cfe-dev>`_.
	=======================================
	Clang 4.0.0 (In-Progress) Release Notes
	=======================================

	.. contents::
	:local:
	:depth: 2

	Written by the `LLVM Team <http://llvm.org/>`_

	.. warning::

	These are in-progress notes for the upcoming Clang 4.0.0 release. You may
	prefer the `Clang 3.9 Release Notes
	<http://llvm.org/releases/3.9.0/tools/clang/docs/ReleaseNotes.html>`_.

	Introduction
	============

	This document contains the release notes for the Clang C/C++/Objective-C/OpenCL
	frontend, part of the LLVM Compiler Infrastructure, release 4.0.0. Here we
	describe the status of Clang in some detail, including major
	improvements from the previous release and new feature work. For the
	general LLVM release notes, see `the LLVM
	documentation <http://llvm.org/docs/ReleaseNotes.html>`_. All LLVM
	releases may be downloaded from the `LLVM releases web
	site <http://llvm.org/releases/>`_.

	For more information about Clang or LLVM, including information about
	the latest release, please check out the main please see the `Clang Web
	Site <http://clang.llvm.org>`_ or the `LLVM Web
	Site <http://llvm.org>`_.

	What's New in Clang 4.0.0?
	==========================

	Some of the major new features and improvements to Clang are listed
	here. Generic improvements to Clang as a whole or to its underlying
	infrastructure are described first, followed by language-specific
	sections with improvements to Clang's support for those languages.

	Major New Features
	------------------

	- The ``diagnose_if`` attribute has been added to clang. This attribute allows
	clang to emit a warning or error if a function call meets one or more
	user-specified conditions.

	- Enhanced devirtualization with
	`-fstrict-vtable-pointers <UsersManual.html#cmdoption-fstrict-vtable-pointers>`_.
	Clang devirtualizes across different basic blocks, like loops:

	.. code-block:: c++

	struct A {
	virtual void foo();
	};
	void indirect(A &a, int n) {
	for (int i = 0 ; i < n; i++)
	a.foo();
	}
	void test(int n) {
	A a;
	indirect(a, n);
	}


	- ...

	Improvements to ThinLTO (-flto=thin)
	------------------------------------
	- Integration with profile data (PGO). When available, profile data enables
	more accurate function importing decisions, as well as cross-module indirect
	call promotion.
	- Significant build-time and binary-size improvements when compiling with debug
	info (-g).

	Improvements to Clang's diagnostics
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

	- ...

	New Compiler Flags
	------------------

	The option -Og has been added to optimize the debugging experience.
	For now, this option is exactly the same as -O1. However, in the future,
	some other optimizations might be enabled or disabled.

	The option -MJ has been added to simplify adding JSON compilation
	database output into existing build systems.

	The option ....

	New Pragmas in Clang
	-----------------------

	Clang now supports the ...


	Attribute Changes in Clang
	--------------------------

	- ...

	Windows Support
	---------------

	Clang's support for building native Windows programs ...


	C Language Changes in Clang
	---------------------------

	- ...

	...

	C11 Feature Support
	^^^^^^^^^^^^^^^^^^^

	...

	C++ Language Changes in Clang
	-----------------------------

	...

	C++1z Feature Support
	^^^^^^^^^^^^^^^^^^^^^

	...

	Objective-C Language Changes in Clang
	-------------------------------------

	...

	OpenCL C Language Changes in Clang
	----------------------------------

	The following bugs in the OpenCL header have been fixed:

	* Added missing ``overloadable`` and ``convergent`` attributes.
	* Removed some erroneous extra ``native_*`` functions.

	The following bugs in the generation of metadata have been fixed:

	* Corrected the SPIR version depending on the OpenCL version.
	* Source level address spaces are taken from the SPIR specification.
	* Image types now contain no access qualifier.

	The following bugs in the AMD target have been fixed:

	* Corrected the bitwidth of ``size_t`` and NULL pointer value with respect to
	address spaces.
	* Added ``cl_khr_subgroups``, ``cl_amd_media_ops`` and ``cl_amd_media_ops2``
	extensions.
	* Added ``cl-denorms-are-zero`` support.
	* Changed address spaces for image objects to be ``constant``.
	* Added little-endian.

	The following bugs in OpenCL 2.0 have been fixed:

	* Fixed pipe builtin function return type, added extra argument to generated
	IR intrinsics to propagate size and alignment information of the pipe packed
	type.
	* Improved pipe type to accommodate access qualifiers.
	* Added correct address space to the ObjC block generation and ``enqueue_kernel``
	prototype.
	* Improved handling of integer parameters of ``enqueue_kernel`` prototype. We
	now allow ``size_t`` instead of ``int`` for specifying block parameter sizes.
	* Allow using NULL (aka ``CLK_NULL_QUEUE``) with ``queue_t``.


	Improved the following diagnostics:

	* Disallow address spaces other than ``global`` for kernel pointer parameters.
	* Correct the use of half type argument and pointer assignment with
	dereferencing.
	* Disallow variadic arguments in functions and blocks.
	* Allow partial initializer for array and struct.

	Some changes to OpenCL extensions have been made:

	* Added ``cl_khr_mipmap_image``.
	* Added ``-cl-ext`` flag to allow overwriting supported extensions otherwise
	set by the target compiled for (Example: ``-cl-ext=-all,+cl_khr_fp16``).
	* New types and functions can now be flexibly added to extensions using the
	following pragmas instead of modifying the Clang source code:

	.. code-block:: c

	#pragma OPENCL EXTENSION the_new_extension_name : begin
	// declare types and functions associated with the extension here
	#pragma OPENCL EXTENSION the_new_extension_name : end


	Miscellaneous changes:

	* Fix ``__builtin_astype`` to cast between different address space objects.
	* Allow using ``opencl_unroll_hint`` with earlier OpenCL versions than 2.0.
	* Improved handling of floating point literal to default to single precision if
	fp64 extension is not enabled.
	* Refactor ``sampler_t`` implementation to simplify initializer representation
	which is now handled as a compiler builtin function with an integer value
	passed into it.
	* Change fake address space map to use the SPIR convention.
	* Added `the OpenCL manual
	<https://clang.llvm.org/docs/UsersManual.html#opencl-features>`_ to Clang
	documentation.

	OpenMP Support in Clang
	----------------------------------

	...

	Internal API Changes
	--------------------

	These are major API changes that have happened since the 3.9 release of
	Clang. If upgrading an external codebase that uses Clang as a library,
	this section should help get you past the largest hurdles of upgrading.

	- ...

	AST Matchers
	------------

	...

	libclang
	--------

	...

	With the option --show-description, scan-build's list of defects will also
	show the description of the defects.


	Static Analyzer
	---------------

	...

	Core Analysis Improvements
	==========================

	- ...

	New Issues Found
	================

	- ...

	Python Binding Changes
	----------------------

	The following methods have been added:

	- ...

	Significant Known Problems
	==========================

	Additional Information
	======================

	A wide variety of additional information is available on the `Clang web
	page <http://clang.llvm.org/>`_. The web page contains versions of the
	API documentation which are up-to-date with the Subversion version of
	the source code. You can access versions of these documents specific to
	this release by going into the "``clang/docs/``" directory in the Clang
	tree.

	If you have any questions or comments about Clang, please feel free to
	contact us via the `mailing
	list <http://lists.llvm.org/mailman/listinfo/cfe-dev>`_.