misc.h: move out checked_int64_(add|subtract)

These inline functions are used only in exactly one place,
so no need to keep them in a public header.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1808>

Xext/sync.c

@@ -312,6 +312,35 @@ SyncCheckTriggerFence(SyncTrigger * pTrigger, int64_t unused)
     return (pFence == NULL || pFence->funcs.CheckTriggered(pFence));
 }
 
+static inline Bool
+checked_int64_add(int64_t *out, int64_t a, int64_t b)
+{
+    /* Do the potentially overflowing math as uint64_t, as signed
+     * integers in C are undefined on overflow (and the compiler may
+     * optimize out our overflow check below, otherwise)
+     */
+    int64_t result = (uint64_t)a + (uint64_t)b;
+    /* signed addition overflows if operands have the same sign, and
+     * the sign of the result doesn't match the sign of the inputs.
+     */
+    Bool overflow = (a < 0) == (b < 0) && (a < 0) != (result < 0);
+
+    *out = result;
+
+    return overflow;
+}
+
+static inline Bool
+checked_int64_subtract(int64_t *out, int64_t a, int64_t b)
+{
+    int64_t result = (uint64_t)a - (uint64_t)b;
+    Bool overflow = (a < 0) != (b < 0) && (a < 0) != (result < 0);
+
+    *out = result;
+
+    return overflow;
+}
+
 static int
 SyncInitTrigger(ClientPtr client, SyncTrigger * pTrigger, XID syncObject,
                 RESTYPE resType, Mask changes)

include/misc.h

@@ -285,35 +285,6 @@ bswap_32(uint32_t x)
             ((x & 0x000000FF) << 24));
 }
 
-static inline Bool
-checked_int64_add(int64_t *out, int64_t a, int64_t b)
-{
-    /* Do the potentially overflowing math as uint64_t, as signed
-     * integers in C are undefined on overflow (and the compiler may
-     * optimize out our overflow check below, otherwise)
-     */
-    int64_t result = (uint64_t)a + (uint64_t)b;
-    /* signed addition overflows if operands have the same sign, and
-     * the sign of the result doesn't match the sign of the inputs.
-     */
-    Bool overflow = (a < 0) == (b < 0) && (a < 0) != (result < 0);
-
-    *out = result;
-
-    return overflow;
-}
-
-static inline Bool
-checked_int64_subtract(int64_t *out, int64_t a, int64_t b)
-{
-    int64_t result = (uint64_t)a - (uint64_t)b;
-    Bool overflow = (a < 0) != (b < 0) && (a < 0) != (result < 0);
-
-    *out = result;
-
-    return overflow;
-}
-
 #define swapl(x) do { \
 		if (sizeof(*(x)) != 4) \
 			wrong_size(); \