crbcc

crbcc is an R package that compiles R code to bytecode using a C implementation. It is intended as a fast, drop-in alternative to the base compiler package, for cases in which a reduced compilation time could be beneficial, eg. in research. However using crbcc for minor performance improvements inside R’s JIT pipeline is also possible.

This project was developed as part of a bachelor’s thesis at FIT CTU.

Acknowledgement

When possible, crbcc mirrors the architecture and logic used in the original GNU-R compiler package by Luke Tierney. The original compiler Noweb document is available at https://homepage.cs.uiowa.edu/~luke/R/compiler/compiler.pdf, or distributed as an R base package, available under the GPL-2 license. Most documentation provided in the document is relevant to crbcc as well.

Features

• 1:1 compatible output with current GNU-R compiler; cmpfun tested on a corpus consisting of around 339,000 lines of code
• 30x improvement on wall clock time when compiling base and recommended R packages

Interface

• Compile closures with crbcc::cmpfun()
• Compile generic language objects with crbcc::compile()
• Compile full source files with crbcc::cmpfile()
• Load compiled files with crbcc::loadcmp()

Requirements

• R >= 4.5.0
• Build toolchain for compiling native C code

Install

From source (local checkout)

R CMD INSTALL .

or with the provided Make target:

make install

Quick Start

library(crbcc)

f <- function(x) {
  y <- x + 1
  y * 2
}

cf <- cmpfun(f, options = list(optimize = 2))
cf(10)

Compile an R file

library(crbcc)

cmpfile("script.R", "script.Rc")
loadcmp("script.Rc", envir = .GlobalEnv)

Compiler options

The compiler accepts options as a named list:

• optimize (integer): optimization level (default 2)
• suppressAll (logical): suppress warnings (default TRUE)
• suppressNoSuperAssignVar (logical): suppress missing super-assignment variable warnings
• suppressUndefined (logical or character):
  • TRUE: suppress all undefined variable/function warnings
  • FALSE: suppress none
  • character(): suppress specific names

Example:

opts <- list(
  optimize = 2,
  suppressAll = FALSE,
  suppressUndefined = c("pi", "letters")
)

cf <- cmpfun(function(x) x + pi, options = opts)

Contributing

Contributions are welcome.

• Open an issue first for bugs, regressions, or feature proposals, especially if the compiler crashed on some expression or returned different results from GNU-R
• Keep pull requests focused and small when possible.
• Do not modify tests. Compatibility with GNU R compiler behavior is expected to remain 1:1.
• Run package checks before submitting (no new warnings or errors should rise):

R CMD check .

Known limitations

• Warning output is not guaranteed to be 1:1 with GNU R’s compiler package.
• cmpfile() currently does not support a functional verbose mode (the argument exists but is not implemented).
• Saving and loading functionality is not compatible with the GNU-R compiler, since it uses an .Internal call to manage the files.

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