Fixed: Stencil test does not work on mobile UE-16664 (still doesn't work on metal)
#codereview Jack.Porter, Martin.Mittring
[CL 2600130 by Dmitriy Dyomin in Main branch]
These changes allow UE4 to compile and run (in Debug) on Clang 3.7 alpha (r231657 only!)
- Disabled editor source file discovery (crashes with Clang currently)
- Disabled FThreadIdleStats in UnrealHeaderTool with Clang on Windows (causes link errors due to inlining bugs with Clang and DLL imports)
- Use MSVC linker by default, even when compiling with Clang (can be tweaked with bAllowClangLinker)
- Enabled shadow variable warnings on Windows with Clang
- Limited max size of reflection code source files (Clang on Windows crashes with huge source files)
- Fixed UE4 deprecation warnings not showing up when using Clang on Windows
- Make sure initialization list order only triggers a warning on Clang for Windows
Other changes:
- Fixed issues with pushed pragmas not getting popped (PRAGMA_ENABLE_DEPRECATION_WARNINGS)
- Removed EMIT_DEPRECATED_WARNING_MESSAGE, wasn't used
- Fixed various third party library includes not being treated as system headers (prevents compiler warnings)
To test Clang on Windows (beta!!):
- Get latest UE4 main branch (4.9)
- Install LLVM+Clang for Windows version r231657. It's a quick install, you don't need to compile anything yourself.
- Open UEBuildWindows.cs, and change bCompileWithClang to true. Be careful not to check that in. We'll probably make this config-driven later, after the Clang toolchain gets more mature.
- Switch to Debug Editor configuration. (See below for more info.)
- Rebuild the game or engine
Notes:
- You must use Clang r231657 (3.7.0 alpha). There are no other releases that I've found that are able to compile UE4 successfully. Most of the newer releases crash during compiling, and older releases aren't able to digest Windows header files well enough.
- Compiling in Development currently will not work due to bugs with Clangs handling of inlining and DLL exports. Monolithic builds should work, though.
- Occasionally you may see runtime crashes (stack overflows or access violations) when running UE4 compiled with Clang on Windows. These may very well be bugs in Clang (remember, we're using an alpha release of Clang 3.7.0.) Unfortunately without better debugger support, it can be difficult to workaround these
- When debugging, you will only have functions and line numbers, no variables or parameters. Clang only has preliminary support for Microsoft's PDB format currently.
XGE is fully supported with Clang on Windows. Best case rebuild times I've seen are 3.5 minutes in Debug.
- Shared PCHs aren't supported yet (similar to on Mac and Linux), so iterative compile times may be slower compared to Visual C++. However the Clang compiler is actually quite fast for rebuilds, probably because of missing debug info though.
- There may be some compiler warnings that are different between Mac/Linux and Windows. We haven't done a line-by-line comparison yet.
- Build products and executables for Clang and VC++ overlap on disk. So you have to rebuild to switch back and forth. Sorry.
- Clang on Windows has a few bugs that we've had to work around. You might see some strange things from time to time. Every new release of Clang has different behavior on Windows.
- We still use the VC++ Linker, even when compiling using Clang. The new Clang linker (lld.exe) can be enabled with bAllowClangLinker but it will crash when linking some modules. It also doesn't produce usable debug symbols by Visual Studio (yet).
#codereview mikolaj.sieluzycki
[CL 2532260 by Mike Fricker in Main branch]
hlslcc - Fix empty if() generation
Converts from
if(!EXPR) {}
to
EXPR
#codereview Mark.Satterthwaite, Chris.Babcock, Dmitry.Rekman, Michael.Trepka
[CL 2457355 by Rolando Caloca in Main branch]
- Shaders which emit layout location data use INTERFACE_LOCATION & INTERFACE_BLOCK macros to defer to the runtime whether they can be used as separable or non-separable shaders.
- The runtime supplies the correct #define for each so that the shaders still work on platforms where the glLinkProgram implementation fails with separable shader code.
- Shader model 5 platforms (GLSL 430 or ES 3.10) which were already specifying & using layout location data continue to do so, even when using glLinkProgram.
- The 'OpenGL.UseSeparateShaderObjects' console variable allows switching between SSO/Link modes between executions, but not dynamically at runtime.
- Only defaults to on for Mac as that is the only platform which can guarantee that the extension is always available & so far the most tested platform.
- Updated hlslcc binaries are supplied for Mac, Linux & Windows.
- Added an OpenGL RHI stat for shader first draw time so that it is easy to see why hitches occur during runtime due to in-driver shader compilation.
reviewedby michael.trepka, nick.penwarden, dmitry.rekman, rolando.caloca
[CL 2435530 by Mark Satterthwaite in Main branch]
