Provided by: opencl-1.2-man-doc_1.0~svn33624-1_all 
NAME
EXTENSION - A #pragma directive to set the behavior for OpenCL extensions.
#pragma OPENCL EXTENSION extension_name :
behavior #pragma OPENCL EXTENSION all : behavior
PARAMETERS
extension_name
The name of the extension. The extension_name will have names of the form
cl_khr_<name> for an extension approved by the OpenCL working group and will have
names of the form cl_<vendor_name>_<name> for vendor extensions. The token all means
that the behavior applies to all extensions supported by the compiler. The table below
shows the legal values for extension_name:
┌────────────────────────────────────┬──────────────────────────────────┐
│Extension name │ Description │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_int64_base_atomics(3clc) │ 64-bit integer base atomic │
│ │ operations │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_int64_extended_atomics(3clc) │ 64-bit integer extended atomic │
│ │ operations │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_3d_image_writes(3clc) │ Writes to 3D image objects │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_fp16(3clc) │ Half-precision floating-point │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_apple_gl_sharing │ MacOS X OpenGL sharing │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_gl_sharing(3clc) │ OpenGL sharing │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_gl_event(3clc) │ CL event objects from GL sync │
│ │ objects │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_d3d10_sharing(3clc) │ Sharing memory objects wth │
│ │ Direct3D 10 │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_d3d11_sharing(3clc) │ Sharing memory objects wth │
│ │ Direct3D 11 │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_dx9_media_sharing(3clc) │ Sharing memory objects wth │
│ │ Direct3D 9 │
├────────────────────────────────────┼──────────────────────────────────┤
│cl_khr_icd(3clc) │ Access Khronos OpenCL │
│ │ installable client driver loader │
│ │ (ICD Loader. │
└────────────────────────────────────┴──────────────────────────────────┘
behavior
One of the following values:
┌─────────┬─────────────────────────────────────────────────────────────────────────┐
│behavior │ Description │
├─────────┼─────────────────────────────────────────────────────────────────────────┤
│enable │ Behave as specified by the extension extension_name. │
│ │ │
│ │ Report an error on the #pragma OPENCL EXTENSION if the │
│ │ extension_name is not supported, or if all is specified. │
│ │ │
├─────────┼─────────────────────────────────────────────────────────────────────────┤
│disable │ Behave (including issuing errors and warnings) as if the extension │
│ │ extension_name is not part of the language definition. │
│ │ │
│ │ If all is specified, then behavior must revert back to that of the │
│ │ non-extended core version of the language being compiled to. │
│ │ │
│ │ Warn on the #pragma OPENCL EXTENSION if the extension extension_name is │
│ │ not supported. │
└─────────┴─────────────────────────────────────────────────────────────────────────┘
DESCRIPTION
The #pragma OPENCL EXTENSION directive is a simple, low-level mechanism to set the
behavior for each extension. It does not define policies such as which combinations are
appropriate; those must be defined elsewhere. The order of directives matter in setting
the behavior for each extension. Directives that occur later override those seen earlier.
The all variant sets the behavior for all extensions, overriding all previously issued
extension directives, but only if the behavior is set to disable.
The initial state of the compiler is as if the directive #pragma OPENCL EXTENSION all :
disable was issued, telling the compiler that all error and warning reporting must be done
according to this specification, ignoring any extensions.
Every extension which affects the OpenCL language semantics, syntax or adds built-in
functions to the language must create a preprocessor #define that matches the extension
name string. This #define would be available in the language if and only if the extension
is supported on a given implementation.
NOTES
This document describes the list of optional features supported by OpenCL 1.2. Optional
extensions may be supported by some OpenCL devices. Optional extensions are not required
to be supported by a conformant OpenCL implementation, but are expected to be widely
available; they define functionality that is likely to move into the required feature set
in a future revision of the OpenCL specification
OpenCL extensions approved by the OpenCL working group can be promoted to required core
features in later revisions of OpenCL. When this occurs, the extension specifications are
merged into the core specification. Functions and enumerants that are part of such
promoted extensions will have the KHR affix removed. OpenCL implementations of such later
revisions must also export the name strings of promoted extensions in the
CL_PLATFORM_EXTENSIONS or CL_DEVICE_EXTENSIONS string, and support the KHR-affixed
versions of functions and enumerants as a transition aid.
Example
An extension which adds the extension string "cl_khr_3d_image_writes" should also add a
preprocessor #define called cl_khr_3d_image_writes. A kernel can now use this preprocessor
#define to do something like the following:
#ifdef cl_khr_3d_image_writes // do something
using the extension #else // do something else
or #error! #endif
SPECIFICATION
OpenCL Specification[1]
AUTHORS
The Khronos Group
COPYRIGHT
Copyright © 2007-2011 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and/or associated documentation files (the "Materials"), to deal in the Materials
without restriction, including without limitation the rights to use, copy, modify, merge,
publish, distribute, sublicense, and/or sell copies of the Materials, and to permit
persons to whom the Materials are furnished to do so, subject to the condition that this
copyright notice and permission notice shall be included in all copies or substantial
portions of the Materials.
NOTES
1. OpenCL Specification
page 6, section 9.1 - Compiler Directives for Optional Extensions