Merge remote-tracking branch 'aosp/upstream-master'

Pulls in the following:
e1cd410 Merge pull request #232 from Qining/fix-spec-const-bool-to-int-conversion
189b203 Refine the code and address comments
e24aa5e SpecOp bool->uint/int and uint<->int conversion
cec24c9 Merge pull request #231 from dneto0/gtests-link-to-hlsl
6f29a1b SPV for OpenGL: Issue #229: don't allow gl_VertexIndex or gl_InstanceIndex under -G.
c079210 Unit test executable should link to libHLSL
d995241 Merge pull request #226 from baldurk/warning-fixes
4028916 Fix warning about function parameter shadowing class member variable
3cb57d3 Fix warning about losing information, use size_t instead of int
6e620c4 Nonfunctional: Remove stray ';' and fix Google Test sentence in README.
7e3e486 Memory: Don't use pool memory to store the entry point name in the intermediate representation.
78a6b78 Front-end: Get the right set of nodes marked as spec-const.
a8d9fab Merge pull request #216 from Qining/fix-non-const-array-size-from-spec-const
75d1d80 add SpecConstantOpModeGuard to GlslangToSpvTraverser::visitSymbol()
4088766 Turn on SpecConstantOpMode based on node qualifier
4c91261 fix the wrong generated code when a non-constant array is declared with its size derived from spec constant operations
aa0298b Merge pull request #220 from Qining/fix-built-in-spec-constants
4f4bb81 Built-in values declared as specialization constant
1c7e707 Merge branch 'master' into hlsl-frontend
9c2f1c7 Merge branch 'master' of github.com:KhronosGroup/glslang
79845ad Merge pull request #217 from baldurk/vs2010-compile-fixes
bb5743e Merge pull request #219 from 1ace/master
6a6d6dd fix spelling mistakes
f0bcb0a Comment: fix comment from gtest check in.
bd9f835 Specify explicit return type on lambda function
0dfbe3f Change {parameter} lists into explicit std::vector temporaries
a42533e Merge pull request #190 from antiagainst/gtest
af59197 Merge pull request #214 from amdrexu/bugfix
3dad506 Merge pull request #215 from Qining/spec-constants-operations
5c61d8e fix format; remove unnecessary parameters; rename some spec op mode guard class; remove support of float point comparison and composite type comparison; update the tests.
414eb60 Link in Google Test framework.
1354520 Spec Constant Operations
cb0e471 Parser: Update array size of gl_ClipDistance/gl_CullDistance in gl_in[].
c3869fe Merge pull request #211 from Qining/spec-constants-composite
0840838 Support specialization composite constants
28001b1 Merge pull request #212 from amdrexu/bugfix
4e8bf59 Parser: Fix a build issue (VS2012).
5ace09a Merge pull request #210 from AWoloszyn/fix-compilation
272afd2 Fixed compilation issue introduced by my last commit
56368b6 Merge pull request #198 from AWoloszyn/update-includer
ddb65a4 Front-end: Propagate spec-constness up through aggregate constructors.
a132af5 Updated the includer interface to allow relative includes.
aecd497 HLSL: Abstract accepting an identifier.
078d7f2 HLSL: Simplify appearances a bit to make easier to read.
5f934b0 HLSL: Accept basic funtion definitions.  (Not yet mapping input/output for entry point.)
48882ef HLSL: Get correct set of reserved words.
d016be1 HLSL: Hook up constructor expressions through the AST.
87142c7 HLSL: Add basic declaration syntax and AST generation.
e01a9bc HLSL: Plumb in HLSL parse context and keywords, and most basic HLSL parser and test.
b3dc3ac Refactor TParseContext into 3 level inheritance.
66e2faf Support multiple source languages, adding HLSL as an option.
4d65ee3 Generalize "main" to a settable entry point name.
tree: 2554083fe66c68c1b8215211fe84ce39a75fef5b
  1. .gitattributes
  2. .gitignore
  3. CMakeLists.txt
  4. ChooseMSVCCRT.cmake
  5. External/
  6. LinuxDoAll.bash
  7. OGLCompilersDLL/
  8. README-spirv-remap.txt
  9. README.md
  10. SPIRV/
  11. SetupLinux.sh
  12. StandAlone/
  13. Test/
  14. glslang/
  15. gtests/
  16. hlsl/
  17. index.php
  18. make-revision
README.md

Also see the Khronos landing page for glslang as a reference front end:

https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/

The above page includes where to get binaries, and is kept up to date regarding the feature level of glslang.

glslang

An OpenGL and OpenGL ES shader front end and validator.

There are two components:

  1. A front-end library for programmatic parsing of GLSL/ESSL into an AST.

  2. A standalone wrapper, glslangValidator, that can be used as a shader validation tool.

How to add a feature protected by a version/extension/stage/profile: See the comment in glslang/MachineIndependent/Versions.cpp.

Things left to do: See Todo.txt

Execution of Standalone Wrapper

To use the standalone binary form, execute glslangValidator, and it will print a usage statement. Basic operation is to give it a file containing a shader, and it will print out warnings/errors and optionally an AST.

The applied stage-specific rules are based on the file extension:

  • .vert for a vertex shader
  • .tesc for a tessellation control shader
  • .tese for a tessellation evaluation shader
  • .geom for a geometry shader
  • .frag for a fragment shader
  • .comp for a compute shader

There is also a non-shader extension

  • .conf for a configuration file of limits, see usage statement for example

Building

CMake: The currently maintained and preferred way of building is through CMake. In MSVC, after running CMake, you may need to use the Configuration Manager to check the INSTALL project.

The grammar in glslang/MachineIndependent/glslang.y has to be recompiled with bison if it changes, the output files are committed to the repo to avoid every developer needing to have bison configured to compile the project when grammar changes are quite infrequent. For windows you can get binaries from GnuWin32.

The command to rebuild is:

bison --defines=MachineIndependent/glslang_tab.cpp.h
      -t MachineIndependent/glslang.y
      -o MachineIndependent/glslang_tab.cpp

Glslang is adding the ability to test with Google Test framework. If you want to build and run those tests, please make sure you have a copy of Google Tests checked out in the External/ directory: git clone https://github.com/google/googletest.git.

Programmatic Interfaces

Another piece of software can programmatically translate shaders to an AST using one of two different interfaces:

  • A new C++ class-oriented interface, or
  • The original C functional interface

The main() in StandAlone/StandAlone.cpp shows examples using both styles.

C++ Class Interface (new, preferred)

This interface is in roughly the last 1/3 of ShaderLang.h. It is in the glslang namespace and contains the following.

const char* GetEsslVersionString();
const char* GetGlslVersionString();
bool InitializeProcess();
void FinalizeProcess();

class TShader
    bool parse(...);
    void setStrings(...);
    const char* getInfoLog();

class TProgram
    void addShader(...);
    bool link(...);
    const char* getInfoLog();
    Reflection queries

See ShaderLang.h and the usage of it in StandAlone/StandAlone.cpp for more details.

C Functional Interface (orignal)

This interface is in roughly the first 2/3 of ShaderLang.h, and referred to as the Sh*() interface, as all the entry points start Sh.

The Sh*() interface takes a “compiler” call-back object, which it calls after building call back that is passed the AST and can then execute a backend on it.

The following is a simplified resulting run-time call stack:

ShCompile(shader, compiler) -> compiler(AST) -> <back end>

In practice, ShCompile() takes shader strings, default version, and warning/error and other options for controlling compilation.

Testing

Test results should always be included with a pull request that modifies functionality. And since glslang added the ability to test with Google Test framework, please write your new tests using Google Test.

The old (deprecated) testing process is:

Test is an active test directory that contains test input and a subdirectory baseResults that contains the expected results of the tests. Both the tests and baseResults are under source-code control. Executing the script ./runtests will generate current results in the localResults directory and diff them against the baseResults.

When you want to update the tracked test results, they need to be copied from localResults to baseResults. This can be done by the bump shell script.

The list of files tested comes from testlist, and lists input shaders in this directory, which must all be public for this to work. However, you can add your own private list of tests, not tracked here, by using localtestlist to list non-tracked tests. This is automatically read by runtests and included in the diff and bump process.

Basic Internal Operation

  • Initial lexical analysis is done by the preprocessor in MachineIndependent/Preprocessor, and then refined by a GLSL scanner in MachineIndependent/Scan.cpp. There is currently no use of flex.

  • Code is parsed using bison on MachineIndependent/glslang.y with the aid of a symbol table and an AST. The symbol table is not passed on to the back-end; the intermediate representation stands on its own. The tree is built by the grammar productions, many of which are offloaded into ParseHelper.cpp, and by Intermediate.cpp.

  • The intermediate representation is very high-level, and represented as an in-memory tree. This serves to lose no information from the original program, and to have efficient transfer of the result from parsing to the back-end. In the AST, constants are propogated and folded, and a very small amount of dead code is eliminated.

    To aid linking and reflection, the last top-level branch in the AST lists all global symbols.

  • The primary algorithm of the back-end compiler is to traverse the tree (high-level intermediate representation), and create an internal object code representation. There is an example of how to do this in MachineIndependent/intermOut.cpp.

  • Reduction of the tree to a linear byte-code style low-level intermediate representation is likely a good way to generate fully optimized code.

  • There is currently some dead old-style linker-type code still lying around.

  • Memory pool: parsing uses types derived from C++ std types, using a custom allocator that puts them in a memory pool. This makes allocation of individual container/contents just few cycles and deallocation free. This pool is popped after the AST is made and processed.

    The use is simple: if you are going to call new, there are three cases:

    • the object comes from the pool (its base class has the macro POOL_ALLOCATOR_NEW_DELETE in it) and you do not have to call delete

    • it is a TString, in which case call NewPoolTString(), which gets it from the pool, and there is no corresponding delete

    • the object does not come from the pool, and you have to do normal C++ memory management of what you new