third_party_spirv-tools/readme.md

SPIR-V Tools

Overview

The project includes an assembler, disassembler, and validator for SPIR-V, all based on a common static library. The library contains all of the implementation details and is used in the standalone tools whilst also enabling integration into other code bases directly.

Currently, the assembler and disassembler only support the core SPIR-V specification (i.e. nothing Vulkan or OpenCL-specific) and the validator is a work in progress. See the Future Work section for more information.

The repository is maintained by Kenneth Benzie k.benzie@codeplay.com, please submit any merge requests as stated in these instructions.

Build

The project uses CMake to generate platform-specific build configurations. To generate these build files issue the following commands.

mkdir <spirv-dir>/build
cd <spirv-dir>/build
cmake [-G<platform-generator>] ..

Once the build files have been generated, build using your preferred development environment.

CMake Options

• SPIRV_USE_SANITIZER=<sanitizer> - on UNIX platforms with an appropriate version of clang this option enables the use of the sanitizers documented here, this should only be used with a debug build, disabled by default
• SPIRV_COLOR_TERMINAL=ON - enables color console output, enabled by default
• SPIRV_WARN_EVERYTHING=OFF - on UNIX platforms enable the -Weverything compiler front end option, disabled by default
• SPIRV_WERROR=OFF - on UNIX platforms enable the -Werror compiler front end option, disabled by default

Library

Usage

In order to use the library from an application, the include path should point to <spirv-dir>/include, which will enable the application to include the header <spirv-dir>/include/libspirv/libspirv.h then linking against the static library in <spirv-build-dir>/bin/libSPIRV.a or <spirv-build-dir>/bin/SPIRV.lib. The intention is for this to be a C API, however currently it relies on the generated header spirv.h meaning this is currently a C++ API.

• SPIRV - the static library CMake target outputs <spirv-dir>/lib/libSPIRV.a on Linux/Mac or <spirv-dir>/lib/SPIRV.lib on Windows.

Entry Points

There are three main entry points into the library.

• spvTextToBinary implements the assembler functionality.
• spvBinaryToText implements the disassembler functionality.
• spvValidate implements the validator functionality.

Source

In addition to the interface header <spirv-dir>/include/libspirv/libspirv.h the implementation source files reside in <spirv-dir>/source/*.

Tools

Assembler

The standalone assembler is the binary called spirv-as and is located in <spirv-build-dir>/bin/spirv-as. The functionality of the assembler is implemented by the spvTextToBinary library function.

The assembler operates on the textual form.

• spirv-as - the standalone assembler
  • <spirv-dir>/bin/spirv-as

Options

• -o <filename> is used to specify the output file, otherwise this is set to out.spv.

Format

The assembly attempts to adhere to the binary form as closely as possible using text names from that specification. Here is an example.

OpCapability Shader
OpMemoryModel Logical Simple
OpEntryPoint GLCompute $3 "main"
OpExecutionMode $3 LocalSize 64 64 1
OpTypeVoid %1
OpTypeFunction %2 $1
OpFunction $1 %3 None $2
OpLabel %4
OpReturn
OpFunctionEnd

Each line encapsulates one and only one instruction, or an OpCode and all of its operands. OpCodes use the names provided in section 3.28 Instructions of the SPIR-V specification, immediate values such as Addressing Model, Memory Model, etc. use the names provided in sections 3.2 Source Language through 3.27 Capability of the SPIR-V specification. Literals strings are enclosed in quotes "<string>" while literal numbers have no special formatting.

ID Definitions & Usage

An ID definition pertains to the Result <id> of an OpCode, and ID usage is any input to an OpCode. To differentiate between definitions and uses, all ID definitions are prefixed with % and take the form %<id>, meanwhile all ID uses are prefixed with $ and take the form $<id>. See the above example to see this in action.

Named IDs

The assembler also supports named IDs, or virtual IDs, which greatly improves the readability of the assembly. The same ID definition and usage prefixes apply. Names must begin with an character in the range [a-z|A-Z]. The following example will result in identical SPIR-V binary as the example above.

OpCapability Shader
OpMemoryModel Logical Simple
OpEntryPoint GLCompute $main "main"
OpExecutionMode $main LocalSize 64 64 1
OpTypeVoid %void
OpTypeFunction %fnMain $void
OpFunction $void %main None $fnMain
OpLabel %lbMain
OpReturn
OpFunctionEnd

Arbitrary Integers

When writing tests it can be useful to emit an invalid 32 bit word into the binary stream at arbitrary positions within the assembly. To specify an arbitrary word into the stream the prefix ! is used, this takes the form !<integer>. Here is an example.

OpCapability !0x0000FF00

Disassembler

The standalone disassembler is the binary called spirv-dis and is located in <spirv-build-dir>/bin/spirv-dis. The functionality of the disassembler is implemented by the spvBinaryToText library function.

The disassembler operates on the binary form.

• spirv-dis - the standalone disassembler
  • <spirv-dir>/bin/spirv-dis

Options

• -o <filename> is used to specify the output file, otherwise this is set to out.spvasm.
• -p prints the assembly to the console on stdout, this includes colored output on Linux, Windows, and Mac.

Validator

The standalone validator is the binary called spirv-val and is located in <spirv-build-dir>/bin/spirv-val. The functionality of the validator is implemented by the spvValidate library function.

The validator operates on the binary form.

• spirv-val - the standalone validator
  • <spirv-dir>/bin/spirv-val

Options

• -basic performs basic stream validation, currently not implemented.
• -layout performs logical layout validation as described in section 2.16 Validation Rules, currently not implemented.
• -id performs ID validation according to the instruction rules in sections 3.28.1 through 3.28.22, enabled but is a work in progress.
• -capability performs capability validation and or reporting, currently not implemented.

Tests

The project contains a number of tests, implemented in the UnitSPIRV executable, used to drive the development and correctness of the tools, these use the googletest framework. The googletest source is not provided with this project, to enable the tests place the googletest source in the <spirv-dir>/external/googletest directory, rerun CMake if you have already done so previously, CMake will detect the existence of <spirv-dir>/external/googletest then build as normal.

Future Work

• Support extension libraries in spirv-as, spirv-dis, and spirv-val.
• Complete implementation of ID validation rules in spirv-val.
• Implement section 2.16 Validation Rules in spirv-val.
• Implement Capability validation and or report in spirv-val.
• Improve assembly output from spirv-dis.
• Improve diagnostic reports.

Known Issues

• Improve literal parsing in the assembler, currently only decimal integers and floating-point numbers are supported as literal operands and the parser is not contextually aware of the desired width of the operand.

Licence

Copyright (c) 2015 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 following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Materials.

MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT https://www.khronos.org/registry/

THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.