From b28363a8381fd4e93d1254e71486e0185a84c9c5 Mon Sep 17 00:00:00 2001
From: John Hawthorn <john@hawthorn.email>
Date: Fri, 28 Mar 2025 22:23:48 -0700
Subject: [PATCH] Work on ATOMIC_VALUE_SET

---
 include/ruby/atomic.h | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/include/ruby/atomic.h b/include/ruby/atomic.h
index 18072f4810..e0977d21aa 100644
--- a/include/ruby/atomic.h
+++ b/include/ruby/atomic.h
@@ -315,6 +315,19 @@ typedef unsigned int rb_atomic_t;
 #define RUBY_ATOMIC_PTR_CAS(var, oldval, newval) \
     RBIMPL_CAST(rbimpl_atomic_ptr_cas((void **)&(var), (void *)(oldval), (void *)(newval)))
 
+/**
+ * Identical  to #RUBY_ATOMIC_SET,  except  it expects  its arguments  are
+ * ::VALUE.   There are  cases where  ::rb_atomic_t is  32bit while  ::VALUE is
+ * 64bit.  This should  be used for pointer related operations  to support such
+ * platforms.
+ *
+ * @param   var  A variable of ::VALUE.
+ * @param   val   Value to set.
+ * @post    `var` holds `val`.
+ */
+#define RUBY_ATOMIC_VALUE_SET(var, val) \
+    rbimpl_atomic_value_set(&(var), (val))
+
 /**
  * Identical  to #RUBY_ATOMIC_EXCHANGE,  except  it expects  its arguments  are
  * ::VALUE.   There are  cases where  ::rb_atomic_t is  32bit while  ::VALUE is
@@ -730,6 +743,23 @@ rbimpl_atomic_size_exchange(volatile size_t *ptr, size_t val)
 #endif
 }
 
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_NOALIAS()
+RBIMPL_ATTR_NONNULL((1))
+static inline void
+rbimpl_atomic_size_set(volatile size_t *ptr, size_t val)
+{
+#if 0
+
+#elif defined(HAVE_GCC_ATOMIC_BUILTINS)
+    __atomic_store_n(ptr, val, __ATOMIC_SEQ_CST);
+
+#else
+    rbimpl_atomic_size_exchange(ptr, val);
+
+#endif
+}
+
 RBIMPL_ATTR_ARTIFICIAL()
 RBIMPL_ATTR_NOALIAS()
 RBIMPL_ATTR_NONNULL((1))
@@ -772,6 +802,19 @@ rbimpl_atomic_value_exchange(volatile VALUE *ptr, VALUE val)
     return RBIMPL_CAST((VALUE)sret);
 }
 
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_NOALIAS()
+RBIMPL_ATTR_NONNULL((1))
+static inline void
+rbimpl_atomic_value_set(volatile VALUE *ptr, VALUE val)
+{
+    RBIMPL_STATIC_ASSERT(sizeof_value, sizeof *ptr == sizeof(size_t));
+
+    const size_t sval = RBIMPL_CAST((size_t)val);
+    volatile size_t *const sptr = RBIMPL_CAST((volatile size_t *)ptr);
+    rbimpl_atomic_size_set(sptr, sval);
+}
+
 RBIMPL_ATTR_ARTIFICIAL()
 RBIMPL_ATTR_NOALIAS()
 RBIMPL_ATTR_NONNULL((1))