R Programming By Example

Just-in-time (JIT) compilation of R code

R also supports Just-in-time (JIT) compilation. When JIT compilation is enabled, R will automatically byte code compile any code that is executed without explicitly having called one of the compile functions. To activate JIT compilation, use the enableJIT() function.

The level argument tells R how much code to compile before execution; 0 disables JIT, 1 compiles functions before their first use, 2 also compiles functions before they are duplicated, and 3 also compiles loops before they are executed:

library(compiler)
enableJIT(level = 3)

JIT compilation can also be enabled by setting the R_ENABLE_JIT environment in the operating system before starting R. The value of R_ENABLE_JIT should be set to the ...