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
@@ -43,8 +43,14 @@ static U32 FSE_ctz(U32 val)
    assert(val != 0);
    {
 #   if defined(_MSC_VER)   /* Visual */
-        unsigned long r;
-        return _BitScanForward(&r, val) ? (unsigned)r : 0;
+        if (val != 0) {
+            unsigned long r;
+            _BitScanForward(&r, val);
+            return (unsigned)r;
+        } else {
+            /* Should not reach this code path */
+            __assume(0);
+        }
 #   elif defined(__GNUC__) && (__GNUC__ >= 3)   /* GCC Intrinsic */
        return __builtin_ctz(val);
 #   elif defined(__ICCARM__)    /* IAR Intrinsic */