[R-package] Add GPU install options (fixes #3765)

R-package/README.md

@@ -169,6 +169,27 @@ After installing these other libraries, follow the steps in ["Installing from So
 Rscript build_r.R --use-gpu
 ```
 
+You may also need or want to provide additional configuration, depending on your setup. For example, you may need to provide locations for Boost and OpenCL.
+
+```shell
+Rscript build_r.R \
+    --use-gpu \
+    --opencl-library=/usr/lib/x86_64-linux-gnu/libOpenCL.so \
+    --boost-librarydir=/usr/lib/x86_64-linux-gnu
+```
+
+The following options correspond to the [CMake FindBoost options](https://cmake.org/cmake/help/latest/module/FindBoost.html) by the same names.
+
+* `--boost-root`
+* `--boost-dir`
+* `--boost-include-dir`
+* `--boost-librarydir`
+
+The following options correspond to the [CMake FindOpenCL options](https://cmake.org/cmake/help/latest/module/FindOpenCL.html) by the same names.
+
+* `--opencl-include-dir`
+* `--opencl-library`
+
 ### Installing Precompiled Binaries
 
 Precompiled binaries for Mac and Windows are prepared by CRAN a few days after each release to CRAN. They can be installed with the following R code.

R-package/src/install.libs.R

@@ -135,6 +135,11 @@ build_cmd <- "make"
 build_args <- "_lightgbm"
 lib_folder <- file.path(source_dir, fsep = "/")
 
+# add in command-line arguments
+# NOTE: build_r.R replaces the line below
+command_line_args <- NULL
+cmake_args <- c(cmake_args, command_line_args)
+
 WINDOWS_BUILD_TOOLS <- list(
   "MinGW" = c(
     build_tool = "mingw32-make.exe"

build_r.R

@@ -10,17 +10,58 @@ INSTALL_AFTER_BUILD <- !("--skip-install" %in% args)
 TEMP_R_DIR <- file.path(getwd(), "lightgbm_r")
 TEMP_SOURCE_DIR <- file.path(TEMP_R_DIR, "src")
 
-USING_GPU <- "--use-gpu" %in% args
-USING_MINGW <- "--use-mingw" %in% args
-USING_MSYS2 <- "--use-msys2" %in% args
+# [description]
+#     Parse the content of commandArgs() into a structured
+#     list. This returns a list with two sections.
+#       * "flags" = a character of vector of flags like "--use-gpu"
+#       * "keyword_args" = a named character vector, where names
+#           refer to options and values are the option values. For
+#           example, c("--boost-librarydir" = "/usr/lib/x86_64-linux-gnu")
+.parse_args <- function(args) {
+  out_list <- list(
+    "flags" = character(0L)
+    , "keyword_args" = character(0L)
+  )
+  for (arg in args) {
+    if (any(grepl("=", arg))) {
+      split_arg <- strsplit(arg, "=")[[1L]]
+      arg_name <- split_arg[[1L]]
+      arg_value <- split_arg[[2L]]
+      out_list[["keyword_args"]][[arg_name]] <- arg_value
+    } else {
+      out_list[["flags"]] <- c(out_list[["flags"]], arg)
+    }
+  }
+  return(out_list)
+}
+parsed_args <- .parse_args(args)
+
+USING_GPU <- "--use-gpu" %in% parsed_args[["flags"]]
+USING_MINGW <- "--use-mingw" %in% parsed_args[["flags"]]
+USING_MSYS2 <- "--use-msys2" %in% parsed_args[["flags"]]
+
+# this maps command-line arguments to defines passed into CMake,
+ARGS_TO_DEFINES <- c(
+  "--boost-root" = "-DBOOST_ROOT"
+  , "--boost-dir" = "-DBoost_DIR"
+  , "--boost-include-dir" = "-DBoost_INCLUDE_DIR"
+  , "--boost-librarydir" = "-DBOOST_LIBRARYDIR"
+  , "--opencl-include-dir" = "-DOpenCL_INCLUDE_DIR"
+  , "--opencl-library" = "-DOpenCL_LIBRARY"
+)
 
 recognized_args <- c(
   "--skip-install"
   , "--use-gpu"
   , "--use-mingw"
   , "--use-msys2"
+  , names(ARGS_TO_DEFINES)
+)
+given_args <- c(
+  parsed_args[["flags"]]
+  , names(parsed_args[["keyword_args"]])
 )
-unrecognized_args <- setdiff(args, recognized_args)
+unrecognized_args <- setdiff(given_args, recognized_args)
 if (length(unrecognized_args) > 0L) {
   msg <- paste0(
     "Unrecognized arguments: "
@@ -47,6 +88,27 @@ install_libs_content <- .replace_flag("use_gpu", USING_GPU, install_libs_content
 install_libs_content <- .replace_flag("use_mingw", USING_MINGW, install_libs_content)
 install_libs_content <- .replace_flag("use_msys2", USING_MSYS2, install_libs_content)
 
+# set up extra flags based on keyword arguments
+keyword_args <- parsed_args[["keyword_args"]]
+if (length(keyword_args) > 0L) {
+  cmake_args_to_add <- NULL
+  for (i in seq_len(length(keyword_args))) {
+    arg_name <- names(keyword_args)[[i]]
+    define_name <- ARGS_TO_DEFINES[[arg_name]]
+    arg_value <- shQuote(keyword_args[[arg_name]])
+    cmake_args_to_add <- c(cmake_args_to_add, paste0(define_name, "=", arg_value))
+  }
+  install_libs_content <- gsub(
+    pattern = paste0("command_line_args <- NULL")
+    , replacement = paste0(
+      "command_line_args <- c(\""
+      , paste(cmake_args_to_add, collapse = "\", \"")
+      , "\")"
+    )
+    , x = install_libs_content
+  )
+}
+
 # R returns FALSE (not a non-zero exit code) if a file copy operation
 # breaks. Let's fix that
 .handle_result <- function(res) {