The ir-only subdirectory contains libraries which are designed for use with solc's ir pipeline and will not be gas efficient without viaIR and optimization enabled. This is largely due to the use of internal functions which are expected to be inlined by the compiler.

The non-ir-only subdirectory contains libraries which are designed for use without solc's ir pipeline and will not be gas efficient when viaIR is enabled. This is mostly relevant for jump tables, as the ir pipeline causes internal functions to be represented as sequential identifiers (with switch statements for function calls) rather than jumpdests.

The uniswap subdirectory contains libraries for interacting with and making calculations for Uniswap, primarily V2.

The test subdirectory contains libraries that help with contract testing.