From 6230387ee8831ca2d5e584547c74fab72b794ed8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20=C5=A0pa=C4=8Dek?= <jan.spacek@keyrock.eu>
Date: Wed, 1 Oct 2025 17:05:30 +0200
Subject: [PATCH] cranelift-jit: impl Send for JITModule

Send was implemented for JITModule in #8718, but this was (likely
intentionally) broken in #10512. This commit implements Send again and
adds a test to guard against any future regressions.
---
 cranelift/jit/src/backend.rs      | 17 ++++++++++++++---
 cranelift/jit/src/memory/arena.rs |  8 ++++++++
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/cranelift/jit/src/backend.rs b/cranelift/jit/src/backend.rs
index 18aaf44f5b4e..e320ba75f611 100644
--- a/cranelift/jit/src/backend.rs
+++ b/cranelift/jit/src/backend.rs
@@ -31,7 +31,7 @@ pub struct JITBuilder {
     symbols: HashMap<String, SendWrapper<*const u8>>,
     lookup_symbols: Vec<Box<dyn Fn(&str) -> Option<*const u8> + Send>>,
     libcall_names: Box<dyn Fn(ir::LibCall) -> String + Send + Sync>,
-    memory: Option<Box<dyn JITMemoryProvider>>,
+    memory: Option<Box<dyn JITMemoryProvider + Send>>,
 }
 
 impl JITBuilder {
@@ -150,7 +150,7 @@ impl JITBuilder {
     /// Set the memory provider for the module.
     ///
     /// If unset, defaults to [`SystemMemoryProvider`].
-    pub fn memory_provider(&mut self, provider: Box<dyn JITMemoryProvider>) -> &mut Self {
+    pub fn memory_provider(&mut self, provider: Box<dyn JITMemoryProvider + Send>) -> &mut Self {
         self.memory = Some(provider);
         self
     }
@@ -172,7 +172,7 @@ pub struct JITModule {
     symbols: RefCell<HashMap<String, SendWrapper<*const u8>>>,
     lookup_symbols: Vec<Box<dyn Fn(&str) -> Option<*const u8> + Send>>,
     libcall_names: Box<dyn Fn(ir::LibCall) -> String + Send + Sync>,
-    memory: Box<dyn JITMemoryProvider>,
+    memory: Box<dyn JITMemoryProvider + Send>,
     declarations: ModuleDeclarations,
     compiled_functions: SecondaryMap<FuncId, Option<CompiledBlob>>,
     compiled_data_objects: SecondaryMap<DataId, Option<CompiledBlob>>,
@@ -762,3 +762,14 @@ fn use_bti(isa_flags: &Vec<settings::Value>) -> bool {
         .find(|&f| f.name == "use_bti")
         .map_or(false, |f| f.as_bool().unwrap_or(false))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_jit_module_is_send() {
+        fn assert_is_send<T: Send>() {}
+        assert_is_send::<JITModule>();
+    }
+}
diff --git a/cranelift/jit/src/memory/arena.rs b/cranelift/jit/src/memory/arena.rs
index 5a598fcfccb9..1afb93f7cf16 100644
--- a/cranelift/jit/src/memory/arena.rs
+++ b/cranelift/jit/src/memory/arena.rs
@@ -101,6 +101,8 @@ pub struct ArenaMemoryProvider {
     segments: Vec<Segment>,
 }
 
+unsafe impl Send for ArenaMemoryProvider {}
+
 impl ArenaMemoryProvider {
     /// Create a new memory region with the given size.
     pub fn new_with_size(reserve_size: usize) -> Result<Self, region::Error> {
@@ -281,4 +283,10 @@ mod tests {
         let _ = arena.allocate_readwrite(900_000, 1).unwrap();
         let _ = arena.allocate_readwrite(200_000, 1).unwrap_err();
     }
+
+    #[test]
+    fn test_is_send() {
+        fn assert_is_send<T: Send>() {}
+        assert_is_send::<ArenaMemoryProvider>();
+    }
 }