- Collapsed and renamed some of the new UBT settings for fast build iteration
- New 'BuildConfiguration.bUseUBTMakefiles' that replaces the old experimental settings (defaults to off in this changelist.)
- Cleaned up some comments
- No effective changes
[CL 2400071 by Mike Fricker in Main branch]
UnrealBuildTool 'Makefiles' allow for very fast iterative builds.
- New BuildConfiguration.xml setting added: "bUseExperimentalFastBuildIteration" (disabled by default)
- Turning this on causes Unreal Build Tool to emit 'UBT Makefiles' for targets when they're built the first time.
- Subsequent builds will load these Makefiles and begin outdatedness checking and build invocation very quickly.
- The caveat is that if source files are added or removed to the project, UBT will need to gather information about those in order for your build to complete successfully.
- Currently, you must run the project file generator after adding/removing source files to tell UBT to re-gather this information.
- Events that can invalidate the 'UBT Makefile':
- Adding/removing .cpp files
- Adding/removing .h files with UObjects
- Adding new UObject types to a file that didn't previously have any
- Changing global build settings (most settings in this file qualify.)
- Changed code that affects how Unreal Header Tool works
- You can force regeneration of the 'UBT Makefile' by passing the '-Gather' argument, or simply regenerating project files
- New command-line parameters added:
- "-Gather": Tells UBT to always perform the gather step (slower but will catch project structural changes)
- "-NoGather": Disables the gather step, unless UBT detects that it must be done. This is the default when bUseExperimentalFastBuildIteration is enabled
- "-GatherOnly": Runs the gather step and saves a UBTMakefile, but doesn't build anything
- "-Assemble": Tells UBT to also assemble build products. This always defaults to enabled
- "-NoAssemble": Tells UBT to skip the assemble step, whether we gathered build products or not
- "-AssembleOnly": Tells UBT to only assemble build products and not to gather, unless UBT determines it must
Other changes:
- UBT now keeps track of which targets it was building in an intermediate file, to help it invalidate cached includes in subsequent runs when the targets are different
- C++ includes are now stored in a class separate from the C++ compile enviroment (for easier serialization)
- The method that UBT uses to find the CoreUObject module timestamp was rewritten
- Various '@todo ubtmake' comments added to tag possible remaining Makefile tasks
- The 'FileItem' class had some member variable comments and code cleaned up, while making it serializable
- Cleaned up the comments and member variables in the "Action" class, while making it serializable
- Some UBT classes are now "serializable". This is because we need to store the data in UBTMakefiles.
- Removed support for Actions to tinker with Stdout and Stderror (was not used for anything)
- Moved PrecompileHeaderEnvironment class to the UEBuildModule.cs source file
- Plugin intermediate include directories are now selected on demand rather than cached early
- Toolchain code for gathering prerequisite headers is now shared in a single function (AddPrerequisiteSourceFile)
- Removed Action.StatusDetailedDescription, was not used for anything
- Removed UEBuildConfiguration.bExcludePlugins, was not used for anything
- Removed ECompilationResult.FailedDueToHeaderChange, was not used for anything
[CL 2254472 by Mike Fricker in Main branch]
- Adds experimental super-fast C++ outdated file checking
- This feature is turned off for now as we continue to test and improve it
- You can try it out by enabling "bUseExperimentalFastDependencyScan" option in your BuildConfiguration.xml
- Here is the basic idea:
- We no longer exhaustively scan all includes and build up a big graph every invocation
- Instead, source files whose build products are missing have their includes scanned asynchronously while being compiled
- The flat list of dependent includes for every outdated C++ is saved into a new cache file ("FlatCPPIncludes.bin")
- On the next run, we quickly load that up and "just know" which files to check timestamps on to determine what is out of date
- Lots of "@todo fastubt" comments were added to UnrealBuildTool for potential performance optimizations and further improvements on this feature.
UnrealBuildTool: Determination of which modules have UObjects is now faster
- We now cache which modules have UObjects and load those for the next session
UnrealBuildTool: Module "shared" precompiled header determination is now much faster
- We no longer scan all C++ includes for a module to figure out which "shared" PCH to use
- Instead, we use the module dependencies specified in the module's *.Build.cs file
- For example, if your module depends on "Engine" and "UnrealEd", we choose "UnrealEd"'s shared PCH
Other UBT optimizations:
- Reduced calls to string formatting functions when setting up API definitions for all modules
- Added new performance diagnostics when bPrintPerformanceInfo is enabled in BuildConfiguration.xml
- We no longer check for "external" headers when scanning includes (this code didn't work at all)
- Optimized CleanDirectorySeparators() utility function to avoid string copies
Fixed UnrealBuildTool not saving DependencyCache under a platform-named folder
[CL 2238266 by Mike Fricker in Main branch]
#fix FileItem.CreateIntermediateTextFile now creates the text file in UTF-8 if the contents string contains non-ASCII characters.
#change ResponseFile.Create now calls FileItem.CreateIntermediateTextFile.
This fix was made in relation to TTP# 334906, even though that problem was not fixed in the end.
#codereview robert.manuszewski
[CL 2075498 by Steve Robb in Main branch]
