intrinsics: Add early implementation for atomic_store_{seqcst, relaxed, release}

This commit adds support for three `atomic_store_*` intrinsics declared
in the core library. The mapping is as follows:

- atomic_store_seqcst(dst, val) -> __atomic_store_n(dst, val,
  __ATOMIC_SEQ_CST)
- atomic_store_release(dst, val) -> __atomic_store_n(dst, val,
  __ATOMIC_RELEASE)
- atomic_store_relaxed(dst, val) -> __atomic_store_n(dst, val,
  __ATOMIC_RELAXED)
- atomic_store_unordered(dst, val) -> __atomic_store_n(dst, val,
  __ATOMIC_RELAXED)

This commit also performs the overloading "by hand": Replacing
`atomic_store_release<i32>` with `__atomic_store_4` as I cannot get the
generic version to work. This will be done in future improvements.
Because of this, size type atomics are not handled and result in a call
to `rust_sorry_at`.

Co-authored-by: bjorn3 <bjorn3@github.com>
Co-authored-by: dafaust <dafaust@github.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/gcc/rust/backend/rust-builtins.h b/gcc/rust/backend/rust-builtins.h
index e421fa4..c282510 100644
--- a/gcc/rust/backend/rust-builtins.h
+++ b/gcc/rust/backend/rust-builtins.h
@@ -86,8 +86,8 @@ private:
   BuiltinsContext ();
 
   void setup_overflow_fns ();
-
   void setup_math_fns ();
+  void setup_atomic_fns ();
 
   void setup ();