k0kubun	2018-02-04 17:24:58 +0900 (Sun, 04 Feb 2018)

  New Revision: 62193

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=62193

  Log:
    mjit.c: use InterlockedExchangePointer
    
    for Windows, if it's available.
    
    Before this commit, Windows builds printed following warnings.
    mjit.c
    ../mjit.c(802) : warning C4047: 'function' : 'volatile LONG *' differs in levels of indirection from 'void **'
    ../mjit.c(802) : warning C4024: '_InterlockedExchange' : different types for formal and actual parameter 1
    ../mjit.c(802) : warning C4047: 'function' : 'LONG' differs in levels of indirection from 'void *'
    ../mjit.c(802) : warning C4024: '_InterlockedExchange' : different types for formal and actual parameter 2
    
    ATOMIC_SET is using InterlockedExchange which takes LONG as its value.
    As InterlockedExchangePointer takes PVOID, we should use this to set
    function pointer atomically.

  Modified files:
    trunk/mjit.c
Index: mjit.c
===================================================================
--- mjit.c	(revision 62192)
+++ mjit.c	(revision 62193)
@@ -118,6 +118,17 @@ typedef intptr_t pid_t; https://github.com/ruby/ruby/blob/trunk/mjit.c#L118
 #define va_copy(dest, src) ((dest) = (src))
 #endif
 
+/* Atomically set function pointer if possible. */
+#ifdef _WIN32
+# ifdef InterlockedExchangePointer
+#  define MJIT_ATOMIC_SET(var, val) InterlockedExchangePointer(&(var), val)
+# else
+#  define MJIT_ATOMIC_SET(var, val) (void)((var) = (val))
+# endif
+#else
+# define MJIT_ATOMIC_SET(var, val) ATOMIC_SET(var, val)
+#endif
+
 /* A copy of MJIT portion of MRI options since MJIT initialization.  We
    need them as MJIT threads still can work when the most MRI data were
    freed. */
@@ -800,7 +811,7 @@ worker(void) https://github.com/ruby/ruby/blob/trunk/mjit.c#L811
             CRITICAL_SECTION_START(3, "in jit func replace");
             if (node->unit->iseq) { /* Check whether GCed or not */
                 /* Usage of jit_code might be not in a critical section.  */
-                ATOMIC_SET(node->unit->iseq->body->jit_func, func);
+                MJIT_ATOMIC_SET(node->unit->iseq->body->jit_func, func);
             }
             remove_from_list(node, &unit_queue);
             CRITICAL_SECTION_FINISH(3, "in jit func replace");

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