Changeset 2144 in vbox for trunk/include/iprt

Timestamp:

Apr 17, 2007 8:44:42 PM (18 years ago)

Author:

vboxsync

Message:

added ASMMemoryClobber()

File:

• trunk/include/iprt/asm.h (modified) (1 diff)

trunk/include/iprt/asm.h

@@ -1505 +1505 @@
 
 
-/** @deprecated */
-#define ASMOutB(p, b)   ASMOutU8(p,b)
-/** @deprecated */
-#define ASMInB(p)       ASMInU8(p)
+/**
+ * Ensure that gcc does not use any register value before this instruction. This function is used
+ * for assembler instructions with side-effects, e.g. port writes to magical guest ports causing
+ * guest memory changes by the host
+ */
+#if RT_INLINE_ASM_GNU_STYLE
+DECLINLINE(void) ASMMemoryClobber(void)
+{
+    __asm__ __volatile__ ("" : : : "memory");
+}
+#else
+DECLINLINE(void) ASMMemoryClobber(void)
+{
+}
+#endif
 
 /**