Use __assume(0) for unreachable code path in msvc

msvc will optimize away the condition check.
2021-09-27 19:23:57 +08:00
parent e5ba858270
commit ae986fcdb8
6 changed files with 113 additions and 32 deletions
@@ -881,11 +881,14 @@ typedef U64 ZSTD_VecMask;   /* Clarifies when we are interacting with a U64 repr
 static U32 ZSTD_VecMask_next(ZSTD_VecMask val) {
    assert(val != 0);
 #   if defined(_MSC_VER) && defined(_WIN64)
-    {
-        unsigned long r;
-        /* _BitScanForward64 is not defined outside of x64 */
-        return _BitScanForward64(&r, val) ? (U32)r : 0;
-    }
+        if (val != 0) {
+            unsigned long r;
+            _BitScanForward64(&r, val);
+            return (U32)(r);
+        } else {
+            /* Should not reach this code path */
+            __assume(0);
+        }
 #   elif (defined(__GNUC__) && ((__GNUC__ > 3) || ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 4))))
    if (sizeof(size_t) == 4) {
        U32 mostSignificantWord = (U32)(val >> 32);