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kc3-lang/angle/extensions/KHR_parallel_shader_compile.txt
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jchen10
Date : 2018-06-22 10:59:52
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Message : ParallelCompile: Add entry points. Add the extension text, entry points and validations. BUG=chromium:849576 TEST=angle_end2end_tests Change-Id: I4c06ee30e4f4fe9bb1c1fecada747b9c78fed0ea Reviewed-on: https://chromium-review.googlesource.com/1103789 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jie A Chen <jie.a.chen@intel.com>
- extensions/KHR_parallel_shader_compile.txt
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Name KHR_parallel_shader_compile Name Strings GL_KHR_parallel_shader_compile Contact Geoff Lang, (geofflang 'at' google.com) Contributors Timothy Lottes, AMD Graham Sellers, AMD Eric Werness, NVIDIA Geoff Lang, Google Daniel Koch, NVIDIA Notice Copyright (c) 2015 The Khronos Group Inc. Copyright terms at http://www.khronos.org/registry/speccopyright.html Status Complete Version Last Modified Date: 2017-04-24 Revision: 2 Number ARB Extension #192 OpenGL ES Extension #288 Dependencies This extension is written against OpenGL 4.5 (CoreProfile) dated May 28 2015. OpenGL ES 2.0 is required (for mobile). Overview Compiling GLSL into implementation-specific code can be a time consuming process, so a GL implementation may wish to perform the compilation in a separate CPU thread. This extension provides a mechanism for the application to provide a hint to limit the number of threads it wants to be used to compile shaders, as well as a query to determine if the compilation process is complete. New Procedures and Functions void MaxShaderCompilerThreadsKHR(uint count); New Tokens Accepted by the <pname> parameter of GetBooleanv, GetIntegerv, GetInteger64v, GetFloatv, and GetDoublev: MAX_SHADER_COMPILER_THREADS_KHR 0x91B0 Accepted as part of the <pname> parameter to GetShaderiv and accepted as part of the <pname> parameter to GetProgramiv: COMPLETION_STATUS_KHR 0x91B1 IP Status None. Additions to Chapter 7 "Programs and Shaders", Append to the end of 7.1 "Shader Objects", Applications may use the following to hint to the driver the maximum number background threads it would like to be used in the process of compiling shaders or linking programs, void MaxShaderCompilerThreadsKHR(uint count); where <count> is the number of background threads. A <count> of zero specifies a request for no parallel compiling or linking and a <count> of 0xFFFFFFFF requests an implementation-specific maximum. An implementation may combine the maximum compiler thread request from multiple contexts in a share group in an implementation-specific way. An application can query the current MaxShaderCompilerThreadsKHR <count> by calling GetIntegerv with <pname> set to MAX_SHADER_COMPILER_THREADS_KHR, which returns the value of the current state (Table 23.51). Add to 7.13 "Shader, Program, and Program Pipeline Queries" under the descriptions for "pname" for "GetShaderiv", If <pname> is COMPLETION_STATUS_KHR, TRUE is returned if the shader compilation has completed, FALSE otherwise. Add to 7.13 "Shader, Program, and Program Pipeline Queries" under the descriptions for "pname" for "GetProgramiv", If <pname> is COMPLETION_STATUS_KHR, TRUE is returned if the program linking has completed, FALSE otherwise. New State Add to Table 23.51: Hints Get Value Type Get Command Initial Value Description Sec ------------------------------- ---- ------------ ------------- -------------------- ---- MAX_SHADER_COMPILER_THREADS_KHR Z+ GetIntegerv 0xFFFFFFFF Max compile threads 7.13 Add to Table 23.32: Program Object State Get Value Type Get Command Initial Value Description Sec ---------------------- ---- ------------ ------------- -------------------- ---- COMPLETION_STATUS_KHR B GetProgramiv TRUE Program linking has 7.13 completed Add to Table 23.30: Shader Object State Get Value Type Get Command Initial Value Description Sec --------------------- ---- ------------ ------------- -------------------- ---- COMPLETION_STATUS_KHR B GetShaderiv TRUE Shader compilation 7.13 has completed Interactions with OpenGL ES If implemented in OpenGL ES ignore all references to GetDoublev. If the supported ES version is less than 3.0, ignore all references to GetInteger64v. Issues 1) Where should the hint state be stored? UNRESOLVED: Each context has its own value which may be specified and queried, but an implementation may choose to combine the hints from multiple contexts in an implementation-specific manner. There isn't really any precedent for per-share group state. 2) Can we make the requirements more strict? RESOLVED: We could, but making sure all of the error behavior is correct and fully specified would likely take more time than we have. This spec allows an application to clearly request its intent even if there aren't guarantees that the implementation will exactly obey the request. 3) Does glGetIntegerv(MAX_SHADER_COMPILER_THREADS_KHR) just return the value set by MaxShaderCompilerThreadsKHR? Or, if the state is 0xFFFFFFFF ("do something implementation specific"), does it return the number of threads the implementation has actually chosen to use? RESOLVED: As with other state queries, this returns the value that was last set, or if no value was set by the application it returns the default state value (0xFFFFFFFF). Revision History Rev Date Author Changes --- ---------- -------- --------------------------------------------- 1 2017-03-23 glang Cast as KHR based on v6 of ARB_parallel_shader_compile. 2 2017-04-24 dgkoch Spec clarifications, add issue 3.