Unity Build Merger: Faster Builds, Smarter Optimizations
emmtrix Tech Posts
Category: General Transformations
Part of our transformation series in emmtrix Studio
Why compile 20 files when you can compile just one?
Our Unity Build Merger transformation combines all C source files in a project into a single translation unit — drastically reducing compile time and enabling powerful cross-file optimizations.
Benefits at a glance
▪️ Shorter compile times thanks to shared headers parsed only once
▪️ Enables inlining and whole-program optimization
▪️ Simplifies test case reduction workflows
▪️ Eliminates manual unity file creation
▪️ Automatically resolves conflicts (functions, variables, types)
How it works
Instead of compiling foo.c and bar.c separately, emmtrix Studio generates a single, unified C file.
The image below shows a before/after comparison: merged content, renamed declarations (if needed), and ready for direct compilation – giving your compiler full program visibility.
Figure 1: Example Unity Build Merger Transformation
Integration
Use via #pragma EMX_TRANSFORMATION UnityBuildMerger
or apply directly through the GUI in emmtrix Studio. Results are deterministic and semantically correct.