autodiff

The tracking issue for this feature is: #124509.

This feature allows you to differentiate functions using automatic differentiation. Set the -Zautodiff=<options> compiler flag to adjust the behaviour of the autodiff feature. Multiple options can be separated with a comma.

Syntax

rustc -Z autodiff=Enable[,options]

Where options can be:

• Enable - Required flag to enable autodiff
• PrintTA - print Type Analysis Information
• PrintTAFn=<fn_name> - print Type Analysis Information for a specific function (consider combining it with no_mangle)
• PrintAA - print Activity Analysis Information
• PrintPerf - print Performance Warnings from Enzyme
• PrintSteps - prints all intermediate transformations
• PrintModBefore - print the whole module, before running opts
• PrintModAfter - print the module after Enzyme differentiated everything
• LooseTypes - Enzyme's loose type debug helper (can cause incorrect gradients)
• Inline - runs Enzyme specific Inlining
• RuntimeActivity - allow specifying activity at runtime

Examples

# Enable autodiff via cargo, assuming `enzyme` being a toolchain that supports autodiff
"RUSTFLAGS=-Zautodiff=Enable" cargo +enzyme build

# Enable autodiff directly via rustc
rustc -Z autodiff=Enable

# Print TypeAnalysis updates for the function `foo`, as well as Activity Analysis for all differentiated code.
rustc -Z autodiff=Enable,PrintTAFn=foo,PrintAA