From 7fcf9daa2237400a3c73832178b2e4e5acf810af Mon Sep 17 00:00:00 2001
From: Kevin Ushey <kevinushey@gmail.com>
Date: Wed, 21 Feb 2024 12:47:42 -0800
Subject: [PATCH] support aarch64 on Windows

Adapted from a patch shared by Tomas Kalibera.
---
 R/tbb.R         | 4 ++++
 R/zzz.R         | 6 +++++-
 src/Makevars.in | 8 ++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/R/tbb.R b/R/tbb.R
index 00fccd3b..d881fd8f 100644
--- a/R/tbb.R
+++ b/R/tbb.R
@@ -81,6 +81,10 @@ tbbLdFlags <- function() {
       return(sprintf(fmt, asBuildPath(tbbLib)))
    }
    
+   # on Aarch64 builds, use the version of TBB provided by Rtools
+   if (is_windows() && R.version$arch == "aarch64")
+      return("-ltbb12 -ltbbmalloc")
+   
    # on Mac, Windows and Solaris, we need to explicitly link (#206)
    needsExplicitFlags <- is_mac() || is_windows() || (is_solaris() && !is_sparc())
    if (needsExplicitFlags) {
diff --git a/R/zzz.R b/R/zzz.R
index 31c40a3e..2e284705 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -27,8 +27,12 @@ loadTbbLibrary <- function(name) {
 
 .onLoad <- function(libname, pkgname) {
    
+   tbbLibraryName <- "tbb"
+   if (is_windows() && R.version$arch == "aarch64")
+      tbbLibraryName <- "tbb12"
+   
    # load tbb, tbbmalloc
-   .tbbDllInfo       <<- loadTbbLibrary("tbb")
+   .tbbDllInfo       <<- loadTbbLibrary(tbbLibraryName)
    .tbbMallocDllInfo <<- loadTbbLibrary("tbbmalloc")
    
    # load tbbmalloc_proxy, but only if requested
diff --git a/src/Makevars.in b/src/Makevars.in
index 83e78fb3..af771924 100644
--- a/src/Makevars.in
+++ b/src/Makevars.in
@@ -88,6 +88,14 @@ ifeq ($(USE_TBB), Windows)
 	# Linker needs access to the tbb dll; otherwise you get errors such as:
 	# "undefined reference to `tbb::task_scheduler_init::terminate()'"
 	PKG_LIBS += -Ltbb/build/lib_release -ltbb -ltbbmalloc
+	
+	# override for aarch64 (experimental) to use Rtools TBB
+	ARCH=$(shell "${R_HOME}/bin/R" --vanilla -s -e 'cat(R.version$$arch)')
+	ifeq "$(ARCH)" "aarch64"
+		TBB_LIB = ${R_TOOLS_SOFT}
+		TBB_INC = ${R_TOOLS_SOFT}
+		PKG_LIBS = -ltbb12 -ltbbmalloc
+	endif
 
 endif