Use firstIndexOfValue

lib/std/mem.zig

@@ -999,28 +999,10 @@ pub fn indexOfSentinel(comptime Elem: type, comptime sentinel: Elem, ptr: [*:sen
         i += 1;
     } else return i;
 
-    const all_sentinel: V = @splat(sentinel);
-
     while (true) : (i += v_len) {
         const v: V = @bitCast(ptr[i..][0..v_len].*);
-
-        const equal_mask = v == all_sentinel;
-
-        if (comptime builtin.cpu.arch.isX86()) {
-            // HACK: This /should/ work on other architectures as well, but
-            // as a safety measure, it is only done on x86.
-
-            const equal_int: meta.Int(.unsigned, v_len) = @bitCast(equal_mask);
-
-            if (equal_int != 0) {
-                return i + @ctz(equal_int);
-            }
-        } else {
-            // use the slow guaranteed-to-work method
-            const maybe_first_true = simd.firstTrue(equal_mask);
-            if (maybe_first_true) |first_true| {
-                return i + first_true;
-            }
+        if (simd.firstIndexOfValue(v, sentinel)) |index| {
+            return i + index;
         }
     }
 }