RUSTFLAGSTo support you while debugging or profiling, we have added support for an experimental -Z autodiff rustc flag (which can be passed to cargo via RUSTFLAGS), which allow changing the behaviour of Enzyme, without recompiling rustc. We currently support the following values for autodiff.
PrintTA // Print TypeAnalysis information PrintTAFn // Print TypeAnalysis information for a specific function PrintAA // Print ActivityAnalysis information Print // Print differentiated functions while they are being generated and optimized PrintPerf // Print AD related Performance warnings PrintModBefore // Print the whole LLVM-IR module directly before running AD PrintModAfter // Print the whole LLVM-IR module after running AD, before optimizations PrintModFinal // Print the whole LLVM-IR module after running optimizations and AD LooseTypes // Risk incorrect derivatives instead of aborting when missing Type Info
LooseTypes is often helpful to get rid of Enzyme errors stating Can not deduce type of <X> and to be able to run some code. But please keep in mind that this flag absolutely has the chance to cause incorrect gradients. Even worse, the gradients might be correct for certain input values, but not for others. So please create issues about such bugs and only use this flag temporarily while you wait for your bug to be fixed.
For performance experiments and benchmarking we also support
NoPostopt // We won't optimize the LLVM-IR Module after AD RuntimeActivity // Enables the runtime activity feature from Enzyme Inline // Instructs Enzyme to maximize inlining as far as possible, beyond LLVM's default
You can combine multiple autodiff values using a comma as separator:
RUSTFLAGS="-Z autodiff=Enable,LooseTypes,PrintPerf" cargo +enzyme build
Using -Zautodiff=Enable will allow using autodiff and update your normal rustc compilation pipeline: