SYCL™ Specification Generic heterogeneous computing for modern C++ Version 2020 provisional Document Revision: 1 Revision Date: June 30, 2020 Git revision: tags/SYCL-2020/provisional-rev1-0-gfaaae8e88 Khronos® SYCL™ Working Group Editors: Ronan Keryell, Maria Rovatsou & Lee Howes Copyright 2011-2020 The Khronos® Group, Inc. All Rights Reserved SYCL 2020 provisional Copyright© 2011-2020 The Khronos® Group, Inc. All Rights Reserved. This specification is protected by copyright laws and contains material proprietary to the Khronos® Group, Inc. It or any components may not be reproduced, republished, distributed, transmitted, displayed, broadcast, or other- wise exploited in any manner without the express prior written permission of Khronos® Group. 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All other product names, trademarks, and/or company names are used solely for identification and belong to their respective owners. 2 Contents 1 Acknowledgements 25 2 Introduction 27 3 SYCL architecture 29 3.1 Overview . 29 3.2 Anatomy of a SYCL application . 30 3.3 Normative references . 31 3.4 The SYCL platform model . 31 3.5 The SYCL backendmodel ...................................... 32 3.5.1 Platform mixed version support . 33 3.6 SYCL execution model . 33 3.6.1 SYCL application execution model . 34 3.6.1.1 SYCL backend resources managed by the SYCL application . 34 3.6.1.2 SYCL command groups and execution order . 35 3.6.2 SYCL kernel execution model . 36 3.7 Memory model . 37 3.7.1 SYCL application memory model . 37 3.7.2 SYCL device memory model . 40 3.7.2.1 Access to memory . 41 3.7.2.2 Memory consistency inside SYCL kernels . 41 3.7.2.3 Atomic operations . 43 3.8 The SYCL programming model . 43 3.8.1 Minimum version of C++ . 43 3.8.2 Alignment with future versions of C++ . 43 3.8.3 Basic data parallel kernels . 43 3.8.4 Work-group data parallel kernels . 44 3.8.5 Hierarchical data parallel kernels . 44 3.8.6 Kernels that are not launched over parallel instances . 45 3.8.7 Pre-defined kernels . 45 3.8.8 Synchronization . 45 3.8.8.1 Synchronization in the SYCL application . 45 3.8.8.2 Synchronization in SYCL kernels . 46 3.8.9 Error handling . 46 3.8.10 Fallback mechanism . 46 3.8.11 Scheduling of kernels and data movement . 47 3.8.12 Managing object lifetimes . 47 3.8.13 Device discovery and selection . 48 3.8.14 Interfacing with SYCL backend API............................. 48 3.9 Memory objects . 48 3.10 SYCL device compiler . 49 3.10.1 Building a SYCL program . 49 3.10.2 Naming of kernels . 50 3 CONTENTS SYCL 2020 provisional 3.11 Language restrictions in kernels . 50 3.11.1 SYCL linker . 51 3.11.2 Functions and data types available in kernels . 51 3.12 Endianness support . 51 3.13 Example SYCL application . 51 4 SYCL programming interface 55 4.1 Backends . 55 4.1.1 Backend macros . 55 4.2 Generic vs non-generic SYCL . 55 4.3 Header files and namespaces . 56 4.4 Class availability . 56 4.5 Common interface . 57 4.5.1 Param traits class . 57 4.5.2 Backend interoperability . 57 4.5.2.1 Type traits backend_traits ............................ 57 4.5.2.2 Template function get_native .......................... 58 4.5.2.3 Template functions make_* ............................ 58 4.5.3 Common reference semantics . 60 4.5.4 Common by-value semantics . 62 4.5.5 Properties . 64 4.5.5.1 Properties interface . 64 4.6 SYCL runtime classes . 66 4.6.1 Device selection . 66 4.6.1.1 Device selector . 66 4.6.2 Platform class . 68 4.6.2.1 Platform interface . 69 4.6.2.2 Platform information descriptors . 71 4.6.3 Context class . 72 4.6.3.1 Context interface . 72 4.6.3.2 Context information descriptors . 74 4.6.3.3 Context properties . 75 4.6.4 Device class . 75 4.6.4.1 Device interface . 76 4.6.4.2 Device information descriptors . 79 4.6.4.3 Device aspects . 91 4.6.5 Queue class . 94 4.6.5.1 Queue interface . 95 4.6.5.2 Queue information descriptors . 103 4.6.5.3 Queue properties . 103 4.6.5.4 Queue error handling . 104 4.6.6 Event class . 105 4.6.6.1 Event information and profiling descriptors . 108 4.7 Data access and storage in SYCL . 109 4.7.1 Host allocation . 109 4.7.1.1 Default allocators . 109 4.7.2 Buffers . ..