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<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Hello,</div>
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<br>
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<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I have uploaded the prototype patches to continue refactoring the extensions. In this phase, I would like to address the extensions from list II which are implemented as regular libraries without any changes in the parsing of the language. The summary of the
refactoring are as follow:</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<ul>
<li>Provide dedicated mechanisms for adding predefined macros for extensions, that can be added in the TargetInfo or the implicit OpenCL headers:
<a href="https://reviews.llvm.org/D91531" id="LPlnk302913">https://reviews.llvm.org/D91531</a>.</li><li>The pragma for such extensions has no functionality but to allow compiling existing kernels without the warning the pragma will not be removed but moved to a new category. A new warning is proposed for such a category that is TURNED OFF by default:
<a href="https://reviews.llvm.org/D91534" id="LPlnk246904">https://reviews.llvm.org/D91534</a>.</li><li>Make the Tablegen header (enabled by <tt class="remarkup-monospaced">-fdeclare-opencl-builtins</tt>) work uniformly with extensions enabled via frontend and via implicit headers
<a href="https://reviews.llvm.org/D91538" id="LPlnk322012">https://reviews.llvm.org/D91538</a>.<br>
</li></ul>
</div>
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<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
Looking forward to any feedback.</div>
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<br>
</div>
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Cheers,</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
Anastasia<br>
</div>
<hr tabindex="-1" style="display:inline-block; width:98%">
<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Marco Antognini <Marco.Antognini@arm.com><br>
<b>Sent:</b> 14 October 2020 17:51<br>
<b>To:</b> clang developer list <cfe-dev@lists.llvm.org>; Anastasia Stulova <Anastasia.Stulova@arm.com><br>
<b>Cc:</b> nd <nd@arm.com><br>
<b>Subject:</b> Re: [OpenCL] Simplification in extensions</font>
<div> </div>
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<blockquote class="x_quotableTextTraining" style="border-left:3px solid rgb(200,200,200); border-top-color:rgb(200,200,200); border-right-color:rgb(200,200,200); border-bottom-color:rgb(200,200,200); padding-left:1ex; margin-left:0.8ex; color:rgb(102,102,102)">
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
<span style="color:rgb(32,31,30); font-size:15px; background-color:rgb(255,255,255); display:inline!important">As a first step, I would like to remove unused extensions described in the list III.</span><br>
</div>
</blockquote>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
To make progress on this RFC, the removal of unused extensions is covered by <a href="https://reviews.llvm.org/D89372" id="LPlnk542671" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">https://reviews.llvm.org/D89372</a>. Any additional
feedback is welcome.</div>
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<br>
</div>
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Thank you,</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
Marco</div>
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<hr tabindex="-1" style="display:inline-block; width:98%">
<div id="x_divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> cfe-dev <cfe-dev-bounces@lists.llvm.org> on behalf of Anastasia Stulova via cfe-dev <cfe-dev@lists.llvm.org><br>
<b>Sent:</b> 30 September 2020 11:24<br>
<b>To:</b> clang developer list <cfe-dev@lists.llvm.org><br>
<b>Cc:</b> nd <nd@arm.com><br>
<b>Subject:</b> [cfe-dev] [OpenCL] Simplification in extensions</font>
<div> </div>
</div>
<div dir="ltr">In this RFC I would like to discuss simplifications in the OpenCL extension
<div>implementation, that can affect existing code. Please, provide your feedback
</div>
<div>and concerns if any to reduce the possibility of a negative impact. </div>
<div><br>
</div>
<div>1. *Removal/prevention from adding unused extensions.* Currently, about 1/3 of
</div>
<div>extensions added to clang are unused - extensions that are added into the </div>
<div>OpenCLOptions data structure</div>
<div>(<a href="https://clang.llvm.org/doxygen/OpenCLOptions_8h_source.html" title="https://clang.llvm.org/doxygen/OpenCLOptions_8h_source.html">https://clang.llvm.org/doxygen/OpenCLOptions_8h_source.html</a>) but never</div>
<div>appear to be used in the rest of the source code except for setting them in the</div>
<div>targets. Note that some of the extensions that are added to clang don't even have
</div>
<div>corresponding kernel language changes and therefore it is very unclear why </div>
<div>they were added to clang in the first place (see cl_khr_spir, cl_khr_icd, </div>
<div>cl_khr_context_abort, etc). There are also other 1/3 that are added for the </div>
<div>sake of defining macros, however, I am wondering if more dedicated approaches</div>
<div>to defining macros could be used i.e. using clang::MacroBuilder for adding macros
</div>
<div>directly or using headers/pre-processor command-line options. </div>
<div><br>
</div>
<div>Below I provide the list summarizing the current status of the extension uses.
</div>
<div>As a first step, I would like to remove unused extensions described in the list III.</div>
<div>As a second step, I would like to find an alternative way to add extension macro
</div>
<div>for the extensions that only add functionality in the header - list II (i.e. those</div>
<div>that do not affect the parser in any way), so that they can be moved out of clang</div>
<div>and live in headers or in pre-processor command-line options i.e. -D. I, therefore,
</div>
<div>suggest that we create a mechanism for adding the macro corresponding to the
</div>
<div>extensions: either by adding a target hook for loading a vendor header that </div>
<div>could contain a definition of those macros or a hook for adding the pre-</div>
<div>processor options to define those macros. </div>
<div><br>
</div>
<div>2. *Removal/prevention from adding the redundant extension pragma.* Currently,</div>
<div>every extension registered in clang via OpenCLOptions will add an extension</div>
<div>pragma too. However, in the majority of cases, the pragma seems to be unused or</div>
<div>used without adding any value leading to the increase of the complexity in </div>
<div>applications and tools - one example is guarding the use of types or even </div>
<div>functions by the pragma (see detailed explanation in</div>
<div><a href="https: //github.com/KhronosGroup/OpenCL-Docs/pull/355#issuecomment-662679499" title="https: //github.com/KhronosGroup/OpenCL-Docs/pull/355#issuecomment-662679499">https://github.com/KhronosGroup/OpenCL-Docs/pull/355#issuecomment-662679499</a>).</div>
<div>Currently only cl_khr_fp64 seems to require pragma genuinely for switching the
</div>
<div>floating-point literal between single and double precision. I would like to </div>
<div>remove such pragmas together with unused pragmas. Note that removal of old </div>
<div>pragmas doesn't necessarily break backward compatibility as the use of unknown
</div>
<div>pragmas is ignored with a warning. And only in cases where warnings are </div>
<div>undesirable the application code is to be updated. </div>
<div><br>
</div>
<div>Both 1 and 2 have two actions: (a) refactoring of existing code and (b) </div>
<div>establishing clear guidelines for future development in particular OpenCL 3.0.
</div>
<div>So even if we won't be able to achieve all the refactoring described above, I
</div>
<div>would at least like to set the directions for the future development that will
</div>
keep our codebase cleaner and more maintainable.
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
<div><br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">==================================</span><br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">List of the OpenCL extensions classified by their use</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">==================================</span></div>
<div><br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">I. Used by the parser (and optionally in internal headers)
</span>
<div><br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_fp64</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_fp16</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_gl_msaa_sharing</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_3d_image_writes</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_subgroups</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_int64_base_atomics</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_int64_extended_atomics</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_mipmap_image</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_mipmap_image_writes</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_intel_subgroups</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_intel_device_side_avc_motion_estimation<br>
</span></div>
<div><br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">II. Used in internal headers</span></div>
<div><br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_depth_images</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_subgroup_extended_types</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_subgroup_non_uniform_vote</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_subgroup_ballot</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_subgroup_non_uniform_arithmetic</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_subgroup_extended_type</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_subgroup_shuffle</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_subgroup_shuffle_relative</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_subgroup_clustered_reduce</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_global_int32_base_atomics</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_global_int32_extended_atomics</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_local_int32_base_atomics</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_local_int32_extended_atomics</span></div>
<div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_amd_media_ops</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_amd_media_ops2</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_arm_integer_dot_product_int8</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_arm_integer_dot_product_accumulate_int8</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_arm_integer_dot_product_accumulate_int16</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_arm_integer_dot_product_accumulate_saturate_int8</span></div>
<br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">III. Unused (defined and optionally set by the targets, but not used in parser or header)</span><br>
</div>
<div><br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_icd</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_initialize_memory</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_d3d10_sharing</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_gl_event</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_egl_image</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_context_abort</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_d3d11_sharing</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_dx9_media_sharing</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_image2d_from_buffer</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_gl_depth_images</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_spir</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_srgb_image_writes</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_khr_terminate_context</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)"><span style="font-size:12pt; background-color:rgba(0,0,0,0)">cles_khr_int64</span><br>
</span></div>
<span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">cl_intel_subgroups_short</span><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">Looking forward to any feedback!</span><br>
</div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">Thank you,</span></div>
<div><span style="font-size:12pt; color:rgb(50,49,48); background-color:rgba(0,0,0,0)">Anastasia</span><br>
</div>
</div>
</div>
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