Commit 282e2c714f

matu3ba <matu3ba@users.noreply.github.com>
2021-12-04 22:23:33
compiler_rt: add __ffssi2, __ffsdi2 and __ffsti2 (#10268)
See #1290
1 parent daa3e0b
lib/std/special/compiler_rt/count0bits.zig
@@ -9,6 +9,11 @@ const builtin = @import("builtin");
 // ctz - count trailing zeroes
 // - ctzXi2_generic for unoptimized little and big endian
 
+// ffs - find first set
+// * ffs = (a == 0) => 0, (a != 0) => ctz + 1
+// * dont pay for `if (x == 0) return shift;` inside ctz
+// - ffsXi2_generic for unoptimized little and big endian
+
 fn clzXi2_generic(comptime T: type) fn (a: T) callconv(.C) i32 {
     return struct {
         fn f(a: T) callconv(.C) i32 {
@@ -181,6 +186,43 @@ pub const __ctzdi2 = ctzXi2_generic(i64);
 
 pub const __ctzti2 = ctzXi2_generic(i128);
 
+fn ffsXi2_generic(comptime T: type) fn (a: T) callconv(.C) i32 {
+    return struct {
+        fn f(a: T) callconv(.C) i32 {
+            @setRuntimeSafety(builtin.is_test);
+
+            var x = switch (@bitSizeOf(T)) {
+                32 => @bitCast(u32, a),
+                64 => @bitCast(u64, a),
+                128 => @bitCast(u128, a),
+                else => unreachable,
+            };
+            var n: T = 1;
+            // adapted from Number of trailing zeroes (see ctzXi2_generic)
+            var mask: @TypeOf(x) = std.math.maxInt(@TypeOf(x));
+            comptime var shift = @bitSizeOf(T);
+            // In contrast to ctz return 0
+            if (x == 0) return 0;
+            inline while (shift > 1) {
+                shift = shift >> 1;
+                mask = mask >> shift;
+                if ((x & mask) == 0) {
+                    n = n + shift;
+                    x = x >> shift;
+                }
+            }
+            // return ctz + 1
+            return @intCast(i32, n - @bitCast(T, (x & 1))) + @as(i32, 1);
+        }
+    }.f;
+}
+
+pub const __ffssi2 = ffsXi2_generic(i32);
+
+pub const __ffsdi2 = ffsXi2_generic(i64);
+
+pub const __ffsti2 = ffsXi2_generic(i128);
+
 test {
     _ = @import("clzsi2_test.zig");
     _ = @import("clzdi2_test.zig");
@@ -189,4 +231,8 @@ test {
     _ = @import("ctzsi2_test.zig");
     _ = @import("ctzdi2_test.zig");
     _ = @import("ctzti2_test.zig");
+
+    _ = @import("ffssi2_test.zig");
+    _ = @import("ffsdi2_test.zig");
+    _ = @import("ffsti2_test.zig");
 }
lib/std/special/compiler_rt/ffsdi2_test.zig
@@ -0,0 +1,325 @@
+const ffs = @import("count0bits.zig");
+const testing = @import("std").testing;
+
+fn test__ffsdi2(a: u64, expected: i32) !void {
+    var x = @bitCast(i64, a);
+    var result = ffs.__ffsdi2(x);
+    try testing.expectEqual(expected, result);
+}
+
+test "ffsdi2" {
+    try test__ffsdi2(0x00000000_00000001, 1);
+    try test__ffsdi2(0x00000000_00000002, 2);
+    try test__ffsdi2(0x00000000_00000003, 1);
+    try test__ffsdi2(0x00000000_00000004, 3);
+    try test__ffsdi2(0x00000000_00000005, 1);
+    try test__ffsdi2(0x00000000_00000006, 2);
+    try test__ffsdi2(0x00000000_00000007, 1);
+    try test__ffsdi2(0x00000000_00000008, 4);
+    try test__ffsdi2(0x00000000_00000009, 1);
+    try test__ffsdi2(0x00000000_0000000A, 2);
+    try test__ffsdi2(0x00000000_0000000B, 1);
+    try test__ffsdi2(0x00000000_0000000C, 3);
+    try test__ffsdi2(0x00000000_0000000D, 1);
+    try test__ffsdi2(0x00000000_0000000E, 2);
+    try test__ffsdi2(0x00000000_0000000F, 1);
+    try test__ffsdi2(0x00000000_00000010, 5);
+    try test__ffsdi2(0x00000000_00000011, 1);
+    try test__ffsdi2(0x00000000_00000012, 2);
+    try test__ffsdi2(0x00000000_00000013, 1);
+    try test__ffsdi2(0x00000000_00000014, 3);
+    try test__ffsdi2(0x00000000_00000015, 1);
+    try test__ffsdi2(0x00000000_00000016, 2);
+    try test__ffsdi2(0x00000000_00000017, 1);
+    try test__ffsdi2(0x00000000_00000018, 4);
+    try test__ffsdi2(0x00000000_00000019, 1);
+    try test__ffsdi2(0x00000000_0000001A, 2);
+    try test__ffsdi2(0x00000000_0000001B, 1);
+    try test__ffsdi2(0x00000000_0000001C, 3);
+    try test__ffsdi2(0x00000000_0000001D, 1);
+    try test__ffsdi2(0x00000000_0000001E, 2);
+    try test__ffsdi2(0x00000000_0000001F, 1);
+    try test__ffsdi2(0x00000000_00000020, 6);
+    try test__ffsdi2(0x00000000_00000021, 1);
+    try test__ffsdi2(0x00000000_00000022, 2);
+    try test__ffsdi2(0x00000000_00000023, 1);
+    try test__ffsdi2(0x00000000_00000024, 3);
+    try test__ffsdi2(0x00000000_00000025, 1);
+    try test__ffsdi2(0x00000000_00000026, 2);
+    try test__ffsdi2(0x00000000_00000027, 1);
+    try test__ffsdi2(0x00000000_00000028, 4);
+    try test__ffsdi2(0x00000000_00000029, 1);
+    try test__ffsdi2(0x00000000_0000002A, 2);
+    try test__ffsdi2(0x00000000_0000002B, 1);
+    try test__ffsdi2(0x00000000_0000002C, 3);
+    try test__ffsdi2(0x00000000_0000002D, 1);
+    try test__ffsdi2(0x00000000_0000002E, 2);
+    try test__ffsdi2(0x00000000_0000002F, 1);
+    try test__ffsdi2(0x00000000_00000030, 5);
+    try test__ffsdi2(0x00000000_00000031, 1);
+    try test__ffsdi2(0x00000000_00000032, 2);
+    try test__ffsdi2(0x00000000_00000033, 1);
+    try test__ffsdi2(0x00000000_00000034, 3);
+    try test__ffsdi2(0x00000000_00000035, 1);
+    try test__ffsdi2(0x00000000_00000036, 2);
+    try test__ffsdi2(0x00000000_00000037, 1);
+    try test__ffsdi2(0x00000000_00000038, 4);
+    try test__ffsdi2(0x00000000_00000039, 1);
+    try test__ffsdi2(0x00000000_0000003A, 2);
+    try test__ffsdi2(0x00000000_0000003B, 1);
+    try test__ffsdi2(0x00000000_0000003C, 3);
+    try test__ffsdi2(0x00000000_0000003D, 1);
+    try test__ffsdi2(0x00000000_0000003E, 2);
+    try test__ffsdi2(0x00000000_0000003F, 1);
+    try test__ffsdi2(0x00000000_00000040, 7);
+    try test__ffsdi2(0x00000000_00000041, 1);
+    try test__ffsdi2(0x00000000_00000042, 2);
+    try test__ffsdi2(0x00000000_00000043, 1);
+    try test__ffsdi2(0x00000000_00000044, 3);
+    try test__ffsdi2(0x00000000_00000045, 1);
+    try test__ffsdi2(0x00000000_00000046, 2);
+    try test__ffsdi2(0x00000000_00000047, 1);
+    try test__ffsdi2(0x00000000_00000048, 4);
+    try test__ffsdi2(0x00000000_00000049, 1);
+    try test__ffsdi2(0x00000000_0000004A, 2);
+    try test__ffsdi2(0x00000000_0000004B, 1);
+    try test__ffsdi2(0x00000000_0000004C, 3);
+    try test__ffsdi2(0x00000000_0000004D, 1);
+    try test__ffsdi2(0x00000000_0000004E, 2);
+    try test__ffsdi2(0x00000000_0000004F, 1);
+    try test__ffsdi2(0x00000000_00000050, 5);
+    try test__ffsdi2(0x00000000_00000051, 1);
+    try test__ffsdi2(0x00000000_00000052, 2);
+    try test__ffsdi2(0x00000000_00000053, 1);
+    try test__ffsdi2(0x00000000_00000054, 3);
+    try test__ffsdi2(0x00000000_00000055, 1);
+    try test__ffsdi2(0x00000000_00000056, 2);
+    try test__ffsdi2(0x00000000_00000057, 1);
+    try test__ffsdi2(0x00000000_00000058, 4);
+    try test__ffsdi2(0x00000000_00000059, 1);
+    try test__ffsdi2(0x00000000_0000005A, 2);
+    try test__ffsdi2(0x00000000_0000005B, 1);
+    try test__ffsdi2(0x00000000_0000005C, 3);
+    try test__ffsdi2(0x00000000_0000005D, 1);
+    try test__ffsdi2(0x00000000_0000005E, 2);
+    try test__ffsdi2(0x00000000_0000005F, 1);
+    try test__ffsdi2(0x00000000_00000060, 6);
+    try test__ffsdi2(0x00000000_00000061, 1);
+    try test__ffsdi2(0x00000000_00000062, 2);
+    try test__ffsdi2(0x00000000_00000063, 1);
+    try test__ffsdi2(0x00000000_00000064, 3);
+    try test__ffsdi2(0x00000000_00000065, 1);
+    try test__ffsdi2(0x00000000_00000066, 2);
+    try test__ffsdi2(0x00000000_00000067, 1);
+    try test__ffsdi2(0x00000000_00000068, 4);
+    try test__ffsdi2(0x00000000_00000069, 1);
+    try test__ffsdi2(0x00000000_0000006A, 2);
+    try test__ffsdi2(0x00000000_0000006B, 1);
+    try test__ffsdi2(0x00000000_0000006C, 3);
+    try test__ffsdi2(0x00000000_0000006D, 1);
+    try test__ffsdi2(0x00000000_0000006E, 2);
+    try test__ffsdi2(0x00000000_0000006F, 1);
+    try test__ffsdi2(0x00000000_00000070, 5);
+    try test__ffsdi2(0x00000000_00000071, 1);
+    try test__ffsdi2(0x00000000_00000072, 2);
+    try test__ffsdi2(0x00000000_00000073, 1);
+    try test__ffsdi2(0x00000000_00000074, 3);
+    try test__ffsdi2(0x00000000_00000075, 1);
+    try test__ffsdi2(0x00000000_00000076, 2);
+    try test__ffsdi2(0x00000000_00000077, 1);
+    try test__ffsdi2(0x00000000_00000078, 4);
+    try test__ffsdi2(0x00000000_00000079, 1);
+    try test__ffsdi2(0x00000000_0000007A, 2);
+    try test__ffsdi2(0x00000000_0000007B, 1);
+    try test__ffsdi2(0x00000000_0000007C, 3);
+    try test__ffsdi2(0x00000000_0000007D, 1);
+    try test__ffsdi2(0x00000000_0000007E, 2);
+    try test__ffsdi2(0x00000000_0000007F, 1);
+    try test__ffsdi2(0x00000000_00000080, 8);
+    try test__ffsdi2(0x00000000_00000081, 1);
+    try test__ffsdi2(0x00000000_00000082, 2);
+    try test__ffsdi2(0x00000000_00000083, 1);
+    try test__ffsdi2(0x00000000_00000084, 3);
+    try test__ffsdi2(0x00000000_00000085, 1);
+    try test__ffsdi2(0x00000000_00000086, 2);
+    try test__ffsdi2(0x00000000_00000087, 1);
+    try test__ffsdi2(0x00000000_00000088, 4);
+    try test__ffsdi2(0x00000000_00000089, 1);
+    try test__ffsdi2(0x00000000_0000008A, 2);
+    try test__ffsdi2(0x00000000_0000008B, 1);
+    try test__ffsdi2(0x00000000_0000008C, 3);
+    try test__ffsdi2(0x00000000_0000008D, 1);
+    try test__ffsdi2(0x00000000_0000008E, 2);
+    try test__ffsdi2(0x00000000_0000008F, 1);
+    try test__ffsdi2(0x00000000_00000090, 5);
+    try test__ffsdi2(0x00000000_00000091, 1);
+    try test__ffsdi2(0x00000000_00000092, 2);
+    try test__ffsdi2(0x00000000_00000093, 1);
+    try test__ffsdi2(0x00000000_00000094, 3);
+    try test__ffsdi2(0x00000000_00000095, 1);
+    try test__ffsdi2(0x00000000_00000096, 2);
+    try test__ffsdi2(0x00000000_00000097, 1);
+    try test__ffsdi2(0x00000000_00000098, 4);
+    try test__ffsdi2(0x00000000_00000099, 1);
+    try test__ffsdi2(0x00000000_0000009A, 2);
+    try test__ffsdi2(0x00000000_0000009B, 1);
+    try test__ffsdi2(0x00000000_0000009C, 3);
+    try test__ffsdi2(0x00000000_0000009D, 1);
+    try test__ffsdi2(0x00000000_0000009E, 2);
+    try test__ffsdi2(0x00000000_0000009F, 1);
+    try test__ffsdi2(0x00000000_000000A0, 6);
+    try test__ffsdi2(0x00000000_000000A1, 1);
+    try test__ffsdi2(0x00000000_000000A2, 2);
+    try test__ffsdi2(0x00000000_000000A3, 1);
+    try test__ffsdi2(0x00000000_000000A4, 3);
+    try test__ffsdi2(0x00000000_000000A5, 1);
+    try test__ffsdi2(0x00000000_000000A6, 2);
+    try test__ffsdi2(0x00000000_000000A7, 1);
+    try test__ffsdi2(0x00000000_000000A8, 4);
+    try test__ffsdi2(0x00000000_000000A9, 1);
+    try test__ffsdi2(0x00000000_000000AA, 2);
+    try test__ffsdi2(0x00000000_000000AB, 1);
+    try test__ffsdi2(0x00000000_000000AC, 3);
+    try test__ffsdi2(0x00000000_000000AD, 1);
+    try test__ffsdi2(0x00000000_000000AE, 2);
+    try test__ffsdi2(0x00000000_000000AF, 1);
+    try test__ffsdi2(0x00000000_000000B0, 5);
+    try test__ffsdi2(0x00000000_000000B1, 1);
+    try test__ffsdi2(0x00000000_000000B2, 2);
+    try test__ffsdi2(0x00000000_000000B3, 1);
+    try test__ffsdi2(0x00000000_000000B4, 3);
+    try test__ffsdi2(0x00000000_000000B5, 1);
+    try test__ffsdi2(0x00000000_000000B6, 2);
+    try test__ffsdi2(0x00000000_000000B7, 1);
+    try test__ffsdi2(0x00000000_000000B8, 4);
+    try test__ffsdi2(0x00000000_000000B9, 1);
+    try test__ffsdi2(0x00000000_000000BA, 2);
+    try test__ffsdi2(0x00000000_000000BB, 1);
+    try test__ffsdi2(0x00000000_000000BC, 3);
+    try test__ffsdi2(0x00000000_000000BD, 1);
+    try test__ffsdi2(0x00000000_000000BE, 2);
+    try test__ffsdi2(0x00000000_000000BF, 1);
+    try test__ffsdi2(0x00000000_000000C0, 7);
+    try test__ffsdi2(0x00000000_000000C1, 1);
+    try test__ffsdi2(0x00000000_000000C2, 2);
+    try test__ffsdi2(0x00000000_000000C3, 1);
+    try test__ffsdi2(0x00000000_000000C4, 3);
+    try test__ffsdi2(0x00000000_000000C5, 1);
+    try test__ffsdi2(0x00000000_000000C6, 2);
+    try test__ffsdi2(0x00000000_000000C7, 1);
+    try test__ffsdi2(0x00000000_000000C8, 4);
+    try test__ffsdi2(0x00000000_000000C9, 1);
+    try test__ffsdi2(0x00000000_000000CA, 2);
+    try test__ffsdi2(0x00000000_000000CB, 1);
+    try test__ffsdi2(0x00000000_000000CC, 3);
+    try test__ffsdi2(0x00000000_000000CD, 1);
+    try test__ffsdi2(0x00000000_000000CE, 2);
+    try test__ffsdi2(0x00000000_000000CF, 1);
+    try test__ffsdi2(0x00000000_000000D0, 5);
+    try test__ffsdi2(0x00000000_000000D1, 1);
+    try test__ffsdi2(0x00000000_000000D2, 2);
+    try test__ffsdi2(0x00000000_000000D3, 1);
+    try test__ffsdi2(0x00000000_000000D4, 3);
+    try test__ffsdi2(0x00000000_000000D5, 1);
+    try test__ffsdi2(0x00000000_000000D6, 2);
+    try test__ffsdi2(0x00000000_000000D7, 1);
+    try test__ffsdi2(0x00000000_000000D8, 4);
+    try test__ffsdi2(0x00000000_000000D9, 1);
+    try test__ffsdi2(0x00000000_000000DA, 2);
+    try test__ffsdi2(0x00000000_000000DB, 1);
+    try test__ffsdi2(0x00000000_000000DC, 3);
+    try test__ffsdi2(0x00000000_000000DD, 1);
+    try test__ffsdi2(0x00000000_000000DE, 2);
+    try test__ffsdi2(0x00000000_000000DF, 1);
+    try test__ffsdi2(0x00000000_000000E0, 6);
+    try test__ffsdi2(0x00000000_000000E1, 1);
+    try test__ffsdi2(0x00000000_000000E2, 2);
+    try test__ffsdi2(0x00000000_000000E3, 1);
+    try test__ffsdi2(0x00000000_000000E4, 3);
+    try test__ffsdi2(0x00000000_000000E5, 1);
+    try test__ffsdi2(0x00000000_000000E6, 2);
+    try test__ffsdi2(0x00000000_000000E7, 1);
+    try test__ffsdi2(0x00000000_000000E8, 4);
+    try test__ffsdi2(0x00000000_000000E9, 1);
+    try test__ffsdi2(0x00000000_000000EA, 2);
+    try test__ffsdi2(0x00000000_000000EB, 1);
+    try test__ffsdi2(0x00000000_000000EC, 3);
+    try test__ffsdi2(0x00000000_000000ED, 1);
+    try test__ffsdi2(0x00000000_000000EE, 2);
+    try test__ffsdi2(0x00000000_000000EF, 1);
+    try test__ffsdi2(0x00000000_000000F0, 5);
+    try test__ffsdi2(0x00000000_000000F1, 1);
+    try test__ffsdi2(0x00000000_000000F2, 2);
+    try test__ffsdi2(0x00000000_000000F3, 1);
+    try test__ffsdi2(0x00000000_000000F4, 3);
+    try test__ffsdi2(0x00000000_000000F5, 1);
+    try test__ffsdi2(0x00000000_000000F6, 2);
+    try test__ffsdi2(0x00000000_000000F7, 1);
+    try test__ffsdi2(0x00000000_000000F8, 4);
+    try test__ffsdi2(0x00000000_000000F9, 1);
+    try test__ffsdi2(0x00000000_000000FA, 2);
+    try test__ffsdi2(0x00000000_000000FB, 1);
+    try test__ffsdi2(0x00000000_000000FC, 3);
+    try test__ffsdi2(0x00000000_000000FD, 1);
+    try test__ffsdi2(0x00000000_000000FE, 2);
+    try test__ffsdi2(0x00000000_000000FF, 1);
+
+    try test__ffsdi2(0x00000000_00000000, 0);
+    try test__ffsdi2(0x80000000_00000000, 64);
+    try test__ffsdi2(0x40000000_00000000, 63);
+    try test__ffsdi2(0x20000000_00000000, 62);
+    try test__ffsdi2(0x10000000_00000000, 61);
+    try test__ffsdi2(0x08000000_00000000, 60);
+    try test__ffsdi2(0x04000000_00000000, 59);
+    try test__ffsdi2(0x02000000_00000000, 58);
+    try test__ffsdi2(0x01000000_00000000, 57);
+    try test__ffsdi2(0x00800000_00000000, 56);
+    try test__ffsdi2(0x00400000_00000000, 55);
+    try test__ffsdi2(0x00200000_00000000, 54);
+    try test__ffsdi2(0x00100000_00000000, 53);
+    try test__ffsdi2(0x00080000_00000000, 52);
+    try test__ffsdi2(0x00040000_00000000, 51);
+    try test__ffsdi2(0x00020000_00000000, 50);
+    try test__ffsdi2(0x00010000_00000000, 49);
+    try test__ffsdi2(0x00008000_00000000, 48);
+    try test__ffsdi2(0x00004000_00000000, 47);
+    try test__ffsdi2(0x00002000_00000000, 46);
+    try test__ffsdi2(0x00001000_00000000, 45);
+    try test__ffsdi2(0x00000800_00000000, 44);
+    try test__ffsdi2(0x00000400_00000000, 43);
+    try test__ffsdi2(0x00000200_00000000, 42);
+    try test__ffsdi2(0x00000100_00000000, 41);
+    try test__ffsdi2(0x00000080_00000000, 40);
+    try test__ffsdi2(0x00000040_00000000, 39);
+    try test__ffsdi2(0x00000020_00000000, 38);
+    try test__ffsdi2(0x00000010_00000000, 37);
+    try test__ffsdi2(0x00000008_00000000, 36);
+    try test__ffsdi2(0x00000004_00000000, 35);
+    try test__ffsdi2(0x00000002_00000000, 34);
+    try test__ffsdi2(0x00000001_00000000, 33);
+
+    try test__ffsdi2(0x00000000_80000000, 32);
+    try test__ffsdi2(0x00000000_40000000, 31);
+    try test__ffsdi2(0x00000000_20000000, 30);
+    try test__ffsdi2(0x00000000_10000000, 29);
+    try test__ffsdi2(0x00000000_08000000, 28);
+    try test__ffsdi2(0x00000000_04000000, 27);
+    try test__ffsdi2(0x00000000_02000000, 26);
+    try test__ffsdi2(0x00000000_01000000, 25);
+    try test__ffsdi2(0x00000000_00800000, 24);
+    try test__ffsdi2(0x00000000_00400000, 23);
+    try test__ffsdi2(0x00000000_00200000, 22);
+    try test__ffsdi2(0x00000000_00100000, 21);
+    try test__ffsdi2(0x00000000_00080000, 20);
+    try test__ffsdi2(0x00000000_00040000, 19);
+    try test__ffsdi2(0x00000000_00020000, 18);
+    try test__ffsdi2(0x00000000_00010000, 17);
+    try test__ffsdi2(0x00000000_00008000, 16);
+    try test__ffsdi2(0x00000000_00004000, 15);
+    try test__ffsdi2(0x00000000_00002000, 14);
+    try test__ffsdi2(0x00000000_00001000, 13);
+    try test__ffsdi2(0x00000000_00000800, 12);
+    try test__ffsdi2(0x00000000_00000400, 11);
+    try test__ffsdi2(0x00000000_00000200, 10);
+    try test__ffsdi2(0x00000000_00000100, 9);
+}
lib/std/special/compiler_rt/ffssi2_test.zig
@@ -0,0 +1,292 @@
+const ffs = @import("count0bits.zig");
+const testing = @import("std").testing;
+
+fn test__ffssi2(a: u32, expected: i32) !void {
+    var x = @bitCast(i32, a);
+    var result = ffs.__ffssi2(x);
+    try testing.expectEqual(expected, result);
+}
+
+test "ffssi2" {
+    try test__ffssi2(0x00000001, 1);
+    try test__ffssi2(0x00000002, 2);
+    try test__ffssi2(0x00000003, 1);
+    try test__ffssi2(0x00000004, 3);
+    try test__ffssi2(0x00000005, 1);
+    try test__ffssi2(0x00000006, 2);
+    try test__ffssi2(0x00000007, 1);
+    try test__ffssi2(0x00000008, 4);
+    try test__ffssi2(0x00000009, 1);
+    try test__ffssi2(0x0000000A, 2);
+    try test__ffssi2(0x0000000B, 1);
+    try test__ffssi2(0x0000000C, 3);
+    try test__ffssi2(0x0000000D, 1);
+    try test__ffssi2(0x0000000E, 2);
+    try test__ffssi2(0x0000000F, 1);
+    try test__ffssi2(0x00000010, 5);
+    try test__ffssi2(0x00000011, 1);
+    try test__ffssi2(0x00000012, 2);
+    try test__ffssi2(0x00000013, 1);
+    try test__ffssi2(0x00000014, 3);
+    try test__ffssi2(0x00000015, 1);
+    try test__ffssi2(0x00000016, 2);
+    try test__ffssi2(0x00000017, 1);
+    try test__ffssi2(0x00000018, 4);
+    try test__ffssi2(0x00000019, 1);
+    try test__ffssi2(0x0000001A, 2);
+    try test__ffssi2(0x0000001B, 1);
+    try test__ffssi2(0x0000001C, 3);
+    try test__ffssi2(0x0000001D, 1);
+    try test__ffssi2(0x0000001E, 2);
+    try test__ffssi2(0x0000001F, 1);
+    try test__ffssi2(0x00000020, 6);
+    try test__ffssi2(0x00000021, 1);
+    try test__ffssi2(0x00000022, 2);
+    try test__ffssi2(0x00000023, 1);
+    try test__ffssi2(0x00000024, 3);
+    try test__ffssi2(0x00000025, 1);
+    try test__ffssi2(0x00000026, 2);
+    try test__ffssi2(0x00000027, 1);
+    try test__ffssi2(0x00000028, 4);
+    try test__ffssi2(0x00000029, 1);
+    try test__ffssi2(0x0000002A, 2);
+    try test__ffssi2(0x0000002B, 1);
+    try test__ffssi2(0x0000002C, 3);
+    try test__ffssi2(0x0000002D, 1);
+    try test__ffssi2(0x0000002E, 2);
+    try test__ffssi2(0x0000002F, 1);
+    try test__ffssi2(0x00000030, 5);
+    try test__ffssi2(0x00000031, 1);
+    try test__ffssi2(0x00000032, 2);
+    try test__ffssi2(0x00000033, 1);
+    try test__ffssi2(0x00000034, 3);
+    try test__ffssi2(0x00000035, 1);
+    try test__ffssi2(0x00000036, 2);
+    try test__ffssi2(0x00000037, 1);
+    try test__ffssi2(0x00000038, 4);
+    try test__ffssi2(0x00000039, 1);
+    try test__ffssi2(0x0000003A, 2);
+    try test__ffssi2(0x0000003B, 1);
+    try test__ffssi2(0x0000003C, 3);
+    try test__ffssi2(0x0000003D, 1);
+    try test__ffssi2(0x0000003E, 2);
+    try test__ffssi2(0x0000003F, 1);
+    try test__ffssi2(0x00000040, 7);
+    try test__ffssi2(0x00000041, 1);
+    try test__ffssi2(0x00000042, 2);
+    try test__ffssi2(0x00000043, 1);
+    try test__ffssi2(0x00000044, 3);
+    try test__ffssi2(0x00000045, 1);
+    try test__ffssi2(0x00000046, 2);
+    try test__ffssi2(0x00000047, 1);
+    try test__ffssi2(0x00000048, 4);
+    try test__ffssi2(0x00000049, 1);
+    try test__ffssi2(0x0000004A, 2);
+    try test__ffssi2(0x0000004B, 1);
+    try test__ffssi2(0x0000004C, 3);
+    try test__ffssi2(0x0000004D, 1);
+    try test__ffssi2(0x0000004E, 2);
+    try test__ffssi2(0x0000004F, 1);
+    try test__ffssi2(0x00000050, 5);
+    try test__ffssi2(0x00000051, 1);
+    try test__ffssi2(0x00000052, 2);
+    try test__ffssi2(0x00000053, 1);
+    try test__ffssi2(0x00000054, 3);
+    try test__ffssi2(0x00000055, 1);
+    try test__ffssi2(0x00000056, 2);
+    try test__ffssi2(0x00000057, 1);
+    try test__ffssi2(0x00000058, 4);
+    try test__ffssi2(0x00000059, 1);
+    try test__ffssi2(0x0000005A, 2);
+    try test__ffssi2(0x0000005B, 1);
+    try test__ffssi2(0x0000005C, 3);
+    try test__ffssi2(0x0000005D, 1);
+    try test__ffssi2(0x0000005E, 2);
+    try test__ffssi2(0x0000005F, 1);
+    try test__ffssi2(0x00000060, 6);
+    try test__ffssi2(0x00000061, 1);
+    try test__ffssi2(0x00000062, 2);
+    try test__ffssi2(0x00000063, 1);
+    try test__ffssi2(0x00000064, 3);
+    try test__ffssi2(0x00000065, 1);
+    try test__ffssi2(0x00000066, 2);
+    try test__ffssi2(0x00000067, 1);
+    try test__ffssi2(0x00000068, 4);
+    try test__ffssi2(0x00000069, 1);
+    try test__ffssi2(0x0000006A, 2);
+    try test__ffssi2(0x0000006B, 1);
+    try test__ffssi2(0x0000006C, 3);
+    try test__ffssi2(0x0000006D, 1);
+    try test__ffssi2(0x0000006E, 2);
+    try test__ffssi2(0x0000006F, 1);
+    try test__ffssi2(0x00000070, 5);
+    try test__ffssi2(0x00000071, 1);
+    try test__ffssi2(0x00000072, 2);
+    try test__ffssi2(0x00000073, 1);
+    try test__ffssi2(0x00000074, 3);
+    try test__ffssi2(0x00000075, 1);
+    try test__ffssi2(0x00000076, 2);
+    try test__ffssi2(0x00000077, 1);
+    try test__ffssi2(0x00000078, 4);
+    try test__ffssi2(0x00000079, 1);
+    try test__ffssi2(0x0000007A, 2);
+    try test__ffssi2(0x0000007B, 1);
+    try test__ffssi2(0x0000007C, 3);
+    try test__ffssi2(0x0000007D, 1);
+    try test__ffssi2(0x0000007E, 2);
+    try test__ffssi2(0x0000007F, 1);
+    try test__ffssi2(0x00000080, 8);
+    try test__ffssi2(0x00000081, 1);
+    try test__ffssi2(0x00000082, 2);
+    try test__ffssi2(0x00000083, 1);
+    try test__ffssi2(0x00000084, 3);
+    try test__ffssi2(0x00000085, 1);
+    try test__ffssi2(0x00000086, 2);
+    try test__ffssi2(0x00000087, 1);
+    try test__ffssi2(0x00000088, 4);
+    try test__ffssi2(0x00000089, 1);
+    try test__ffssi2(0x0000008A, 2);
+    try test__ffssi2(0x0000008B, 1);
+    try test__ffssi2(0x0000008C, 3);
+    try test__ffssi2(0x0000008D, 1);
+    try test__ffssi2(0x0000008E, 2);
+    try test__ffssi2(0x0000008F, 1);
+    try test__ffssi2(0x00000090, 5);
+    try test__ffssi2(0x00000091, 1);
+    try test__ffssi2(0x00000092, 2);
+    try test__ffssi2(0x00000093, 1);
+    try test__ffssi2(0x00000094, 3);
+    try test__ffssi2(0x00000095, 1);
+    try test__ffssi2(0x00000096, 2);
+    try test__ffssi2(0x00000097, 1);
+    try test__ffssi2(0x00000098, 4);
+    try test__ffssi2(0x00000099, 1);
+    try test__ffssi2(0x0000009A, 2);
+    try test__ffssi2(0x0000009B, 1);
+    try test__ffssi2(0x0000009C, 3);
+    try test__ffssi2(0x0000009D, 1);
+    try test__ffssi2(0x0000009E, 2);
+    try test__ffssi2(0x0000009F, 1);
+    try test__ffssi2(0x000000A0, 6);
+    try test__ffssi2(0x000000A1, 1);
+    try test__ffssi2(0x000000A2, 2);
+    try test__ffssi2(0x000000A3, 1);
+    try test__ffssi2(0x000000A4, 3);
+    try test__ffssi2(0x000000A5, 1);
+    try test__ffssi2(0x000000A6, 2);
+    try test__ffssi2(0x000000A7, 1);
+    try test__ffssi2(0x000000A8, 4);
+    try test__ffssi2(0x000000A9, 1);
+    try test__ffssi2(0x000000AA, 2);
+    try test__ffssi2(0x000000AB, 1);
+    try test__ffssi2(0x000000AC, 3);
+    try test__ffssi2(0x000000AD, 1);
+    try test__ffssi2(0x000000AE, 2);
+    try test__ffssi2(0x000000AF, 1);
+    try test__ffssi2(0x000000B0, 5);
+    try test__ffssi2(0x000000B1, 1);
+    try test__ffssi2(0x000000B2, 2);
+    try test__ffssi2(0x000000B3, 1);
+    try test__ffssi2(0x000000B4, 3);
+    try test__ffssi2(0x000000B5, 1);
+    try test__ffssi2(0x000000B6, 2);
+    try test__ffssi2(0x000000B7, 1);
+    try test__ffssi2(0x000000B8, 4);
+    try test__ffssi2(0x000000B9, 1);
+    try test__ffssi2(0x000000BA, 2);
+    try test__ffssi2(0x000000BB, 1);
+    try test__ffssi2(0x000000BC, 3);
+    try test__ffssi2(0x000000BD, 1);
+    try test__ffssi2(0x000000BE, 2);
+    try test__ffssi2(0x000000BF, 1);
+    try test__ffssi2(0x000000C0, 7);
+    try test__ffssi2(0x000000C1, 1);
+    try test__ffssi2(0x000000C2, 2);
+    try test__ffssi2(0x000000C3, 1);
+    try test__ffssi2(0x000000C4, 3);
+    try test__ffssi2(0x000000C5, 1);
+    try test__ffssi2(0x000000C6, 2);
+    try test__ffssi2(0x000000C7, 1);
+    try test__ffssi2(0x000000C8, 4);
+    try test__ffssi2(0x000000C9, 1);
+    try test__ffssi2(0x000000CA, 2);
+    try test__ffssi2(0x000000CB, 1);
+    try test__ffssi2(0x000000CC, 3);
+    try test__ffssi2(0x000000CD, 1);
+    try test__ffssi2(0x000000CE, 2);
+    try test__ffssi2(0x000000CF, 1);
+    try test__ffssi2(0x000000D0, 5);
+    try test__ffssi2(0x000000D1, 1);
+    try test__ffssi2(0x000000D2, 2);
+    try test__ffssi2(0x000000D3, 1);
+    try test__ffssi2(0x000000D4, 3);
+    try test__ffssi2(0x000000D5, 1);
+    try test__ffssi2(0x000000D6, 2);
+    try test__ffssi2(0x000000D7, 1);
+    try test__ffssi2(0x000000D8, 4);
+    try test__ffssi2(0x000000D9, 1);
+    try test__ffssi2(0x000000DA, 2);
+    try test__ffssi2(0x000000DB, 1);
+    try test__ffssi2(0x000000DC, 3);
+    try test__ffssi2(0x000000DD, 1);
+    try test__ffssi2(0x000000DE, 2);
+    try test__ffssi2(0x000000DF, 1);
+    try test__ffssi2(0x000000E0, 6);
+    try test__ffssi2(0x000000E1, 1);
+    try test__ffssi2(0x000000E2, 2);
+    try test__ffssi2(0x000000E3, 1);
+    try test__ffssi2(0x000000E4, 3);
+    try test__ffssi2(0x000000E5, 1);
+    try test__ffssi2(0x000000E6, 2);
+    try test__ffssi2(0x000000E7, 1);
+    try test__ffssi2(0x000000E8, 4);
+    try test__ffssi2(0x000000E9, 1);
+    try test__ffssi2(0x000000EA, 2);
+    try test__ffssi2(0x000000EB, 1);
+    try test__ffssi2(0x000000EC, 3);
+    try test__ffssi2(0x000000ED, 1);
+    try test__ffssi2(0x000000EE, 2);
+    try test__ffssi2(0x000000EF, 1);
+    try test__ffssi2(0x000000F0, 5);
+    try test__ffssi2(0x000000F1, 1);
+    try test__ffssi2(0x000000F2, 2);
+    try test__ffssi2(0x000000F3, 1);
+    try test__ffssi2(0x000000F4, 3);
+    try test__ffssi2(0x000000F5, 1);
+    try test__ffssi2(0x000000F6, 2);
+    try test__ffssi2(0x000000F7, 1);
+    try test__ffssi2(0x000000F8, 4);
+    try test__ffssi2(0x000000F9, 1);
+    try test__ffssi2(0x000000FA, 2);
+    try test__ffssi2(0x000000FB, 1);
+    try test__ffssi2(0x000000FC, 3);
+    try test__ffssi2(0x000000FD, 1);
+    try test__ffssi2(0x000000FE, 2);
+    try test__ffssi2(0x000000FF, 1);
+
+    try test__ffssi2(0x00000000, 0);
+    try test__ffssi2(0x80000000, 32);
+    try test__ffssi2(0x40000000, 31);
+    try test__ffssi2(0x20000000, 30);
+    try test__ffssi2(0x10000000, 29);
+    try test__ffssi2(0x08000000, 28);
+    try test__ffssi2(0x04000000, 27);
+    try test__ffssi2(0x02000000, 26);
+    try test__ffssi2(0x01000000, 25);
+    try test__ffssi2(0x00800000, 24);
+    try test__ffssi2(0x00400000, 23);
+    try test__ffssi2(0x00200000, 22);
+    try test__ffssi2(0x00100000, 21);
+    try test__ffssi2(0x00080000, 20);
+    try test__ffssi2(0x00040000, 19);
+    try test__ffssi2(0x00020000, 18);
+    try test__ffssi2(0x00010000, 17);
+    try test__ffssi2(0x00008000, 16);
+    try test__ffssi2(0x00004000, 15);
+    try test__ffssi2(0x00002000, 14);
+    try test__ffssi2(0x00001000, 13);
+    try test__ffssi2(0x00000800, 12);
+    try test__ffssi2(0x00000400, 11);
+    try test__ffssi2(0x00000200, 10);
+    try test__ffssi2(0x00000100, 9);
+}
lib/std/special/compiler_rt/ffsti2_test.zig
@@ -0,0 +1,391 @@
+const ffs = @import("count0bits.zig");
+const testing = @import("std").testing;
+
+fn test__ffsti2(a: u128, expected: i32) !void {
+    var x = @bitCast(i128, a);
+    var result = ffs.__ffsti2(x);
+    try testing.expectEqual(expected, result);
+}
+
+test "ffsti2" {
+    try test__ffsti2(0x00000000_00000000_00000000_00000001, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000002, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000003, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000004, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000005, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000006, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000007, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000008, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000009, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000000A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000000B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000000C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000000D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000000E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000000F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000010, 5);
+    try test__ffsti2(0x00000000_00000000_00000000_00000011, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000012, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000013, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000014, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000015, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000016, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000017, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000018, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000019, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000001A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000001B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000001C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000001D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000001E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000001F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000020, 6);
+    try test__ffsti2(0x00000000_00000000_00000000_00000021, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000022, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000023, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000024, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000025, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000026, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000027, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000028, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000029, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000002A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000002B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000002C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000002D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000002E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000002F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000030, 5);
+    try test__ffsti2(0x00000000_00000000_00000000_00000031, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000032, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000033, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000034, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000035, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000036, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000037, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000038, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000039, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000003A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000003B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000003C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000003D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000003E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000003F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000040, 7);
+    try test__ffsti2(0x00000000_00000000_00000000_00000041, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000042, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000043, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000044, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000045, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000046, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000047, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000048, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000049, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000004A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000004B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000004C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000004D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000004E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000004F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000050, 5);
+    try test__ffsti2(0x00000000_00000000_00000000_00000051, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000052, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000053, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000054, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000055, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000056, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000057, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000058, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000059, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000005A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000005B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000005C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000005D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000005E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000005F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000060, 6);
+    try test__ffsti2(0x00000000_00000000_00000000_00000061, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000062, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000063, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000064, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000065, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000066, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000067, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000068, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000069, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000006A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000006B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000006C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000006D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000006E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000006F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000070, 5);
+    try test__ffsti2(0x00000000_00000000_00000000_00000071, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000072, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000073, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000074, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000075, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000076, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000077, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000078, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000079, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000007A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000007B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000007C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000007D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000007E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000007F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000080, 8);
+    try test__ffsti2(0x00000000_00000000_00000000_00000081, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000082, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000083, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000084, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000085, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000086, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000087, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000088, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000089, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000008A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000008B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000008C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000008D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000008E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000008F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000090, 5);
+    try test__ffsti2(0x00000000_00000000_00000000_00000091, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000092, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000093, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000094, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_00000095, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000096, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_00000097, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_00000098, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_00000099, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000009A, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000009B, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000009C, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_0000009D, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_0000009E, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_0000009F, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A0, 6);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A1, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A2, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A3, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A4, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A5, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A6, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A7, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A8, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_000000A9, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000AA, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000AB, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000AC, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000AD, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000AE, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000AF, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B0, 5);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B1, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B2, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B3, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B4, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B5, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B6, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B7, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B8, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_000000B9, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000BA, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000BB, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000BC, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000BD, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000BE, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000BF, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C0, 7);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C1, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C2, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C3, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C4, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C5, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C6, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C7, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C8, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_000000C9, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000CA, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000CB, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000CC, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000CD, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000CE, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000CF, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D0, 5);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D1, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D2, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D3, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D4, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D5, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D6, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D7, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D8, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_000000D9, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000DA, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000DB, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000DC, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000DD, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000DE, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000DF, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E0, 6);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E1, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E2, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E3, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E4, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E5, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E6, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E7, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E8, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_000000E9, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000EA, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000EB, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000EC, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000ED, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000EE, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000EF, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F0, 5);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F1, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F2, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F3, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F4, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F5, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F6, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F7, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F8, 4);
+    try test__ffsti2(0x00000000_00000000_00000000_000000F9, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000FA, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000FB, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000FC, 3);
+    try test__ffsti2(0x00000000_00000000_00000000_000000FD, 1);
+    try test__ffsti2(0x00000000_00000000_00000000_000000FE, 2);
+    try test__ffsti2(0x00000000_00000000_00000000_000000FF, 1);
+
+    try test__ffsti2(0x00000000_00000000_00000000_00000000, 0);
+    try test__ffsti2(0x80000000_00000000_00000000_00000000, 128);
+    try test__ffsti2(0x40000000_00000000_00000000_00000000, 127);
+    try test__ffsti2(0x20000000_00000000_00000000_00000000, 126);
+    try test__ffsti2(0x10000000_00000000_00000000_00000000, 125);
+    try test__ffsti2(0x08000000_00000000_00000000_00000000, 124);
+    try test__ffsti2(0x04000000_00000000_00000000_00000000, 123);
+    try test__ffsti2(0x02000000_00000000_00000000_00000000, 122);
+    try test__ffsti2(0x01000000_00000000_00000000_00000000, 121);
+    try test__ffsti2(0x00800000_00000000_00000000_00000000, 120);
+    try test__ffsti2(0x00400000_00000000_00000000_00000000, 119);
+    try test__ffsti2(0x00200000_00000000_00000000_00000000, 118);
+    try test__ffsti2(0x00100000_00000000_00000000_00000000, 117);
+    try test__ffsti2(0x00080000_00000000_00000000_00000000, 116);
+    try test__ffsti2(0x00040000_00000000_00000000_00000000, 115);
+    try test__ffsti2(0x00020000_00000000_00000000_00000000, 114);
+    try test__ffsti2(0x00010000_00000000_00000000_00000000, 113);
+    try test__ffsti2(0x00008000_00000000_00000000_00000000, 112);
+    try test__ffsti2(0x00004000_00000000_00000000_00000000, 111);
+    try test__ffsti2(0x00002000_00000000_00000000_00000000, 110);
+    try test__ffsti2(0x00001000_00000000_00000000_00000000, 109);
+    try test__ffsti2(0x00000800_00000000_00000000_00000000, 108);
+    try test__ffsti2(0x00000400_00000000_00000000_00000000, 107);
+    try test__ffsti2(0x00000200_00000000_00000000_00000000, 106);
+    try test__ffsti2(0x00000100_00000000_00000000_00000000, 105);
+    try test__ffsti2(0x00000080_00000000_00000000_00000000, 104);
+    try test__ffsti2(0x00000040_00000000_00000000_00000000, 103);
+    try test__ffsti2(0x00000020_00000000_00000000_00000000, 102);
+    try test__ffsti2(0x00000010_00000000_00000000_00000000, 101);
+    try test__ffsti2(0x00000008_00000000_00000000_00000000, 100);
+    try test__ffsti2(0x00000004_00000000_00000000_00000000, 99);
+    try test__ffsti2(0x00000002_00000000_00000000_00000000, 98);
+    try test__ffsti2(0x00000001_00000000_00000000_00000000, 97);
+
+    try test__ffsti2(0x00000000_80000000_00000000_00000000, 96);
+    try test__ffsti2(0x00000000_40000000_00000000_00000000, 95);
+    try test__ffsti2(0x00000000_20000000_00000000_00000000, 94);
+    try test__ffsti2(0x00000000_10000000_00000000_00000000, 93);
+    try test__ffsti2(0x00000000_08000000_00000000_00000000, 92);
+    try test__ffsti2(0x00000000_04000000_00000000_00000000, 91);
+    try test__ffsti2(0x00000000_02000000_00000000_00000000, 90);
+    try test__ffsti2(0x00000000_01000000_00000000_00000000, 89);
+    try test__ffsti2(0x00000000_00800000_00000000_00000000, 88);
+    try test__ffsti2(0x00000000_00400000_00000000_00000000, 87);
+    try test__ffsti2(0x00000000_00200000_00000000_00000000, 86);
+    try test__ffsti2(0x00000000_00100000_00000000_00000000, 85);
+    try test__ffsti2(0x00000000_00080000_00000000_00000000, 84);
+    try test__ffsti2(0x00000000_00040000_00000000_00000000, 83);
+    try test__ffsti2(0x00000000_00020000_00000000_00000000, 82);
+    try test__ffsti2(0x00000000_00010000_00000000_00000000, 81);
+    try test__ffsti2(0x00000000_00008000_00000000_00000000, 80);
+    try test__ffsti2(0x00000000_00004000_00000000_00000000, 79);
+    try test__ffsti2(0x00000000_00002000_00000000_00000000, 78);
+    try test__ffsti2(0x00000000_00001000_00000000_00000000, 77);
+    try test__ffsti2(0x00000000_00000800_00000000_00000000, 76);
+    try test__ffsti2(0x00000000_00000400_00000000_00000000, 75);
+    try test__ffsti2(0x00000000_00000200_00000000_00000000, 74);
+    try test__ffsti2(0x00000000_00000100_00000000_00000000, 73);
+    try test__ffsti2(0x00000000_00000080_00000000_00000000, 72);
+    try test__ffsti2(0x00000000_00000040_00000000_00000000, 71);
+    try test__ffsti2(0x00000000_00000020_00000000_00000000, 70);
+    try test__ffsti2(0x00000000_00000010_00000000_00000000, 69);
+    try test__ffsti2(0x00000000_00000008_00000000_00000000, 68);
+    try test__ffsti2(0x00000000_00000004_00000000_00000000, 67);
+    try test__ffsti2(0x00000000_00000002_00000000_00000000, 66);
+    try test__ffsti2(0x00000000_00000001_00000000_00000000, 65);
+
+    try test__ffsti2(0x00000000_00000000_80000000_00000000, 64);
+    try test__ffsti2(0x00000000_00000000_40000000_00000000, 63);
+    try test__ffsti2(0x00000000_00000000_20000000_00000000, 62);
+    try test__ffsti2(0x00000000_00000000_10000000_00000000, 61);
+    try test__ffsti2(0x00000000_00000000_08000000_00000000, 60);
+    try test__ffsti2(0x00000000_00000000_04000000_00000000, 59);
+    try test__ffsti2(0x00000000_00000000_02000000_00000000, 58);
+    try test__ffsti2(0x00000000_00000000_01000000_00000000, 57);
+    try test__ffsti2(0x00000000_00000000_00800000_00000000, 56);
+    try test__ffsti2(0x00000000_00000000_00400000_00000000, 55);
+    try test__ffsti2(0x00000000_00000000_00200000_00000000, 54);
+    try test__ffsti2(0x00000000_00000000_00100000_00000000, 53);
+    try test__ffsti2(0x00000000_00000000_00080000_00000000, 52);
+    try test__ffsti2(0x00000000_00000000_00040000_00000000, 51);
+    try test__ffsti2(0x00000000_00000000_00020000_00000000, 50);
+    try test__ffsti2(0x00000000_00000000_00010000_00000000, 49);
+    try test__ffsti2(0x00000000_00000000_00008000_00000000, 48);
+    try test__ffsti2(0x00000000_00000000_00004000_00000000, 47);
+    try test__ffsti2(0x00000000_00000000_00002000_00000000, 46);
+    try test__ffsti2(0x00000000_00000000_00001000_00000000, 45);
+    try test__ffsti2(0x00000000_00000000_00000800_00000000, 44);
+    try test__ffsti2(0x00000000_00000000_00000400_00000000, 43);
+    try test__ffsti2(0x00000000_00000000_00000200_00000000, 42);
+    try test__ffsti2(0x00000000_00000000_00000100_00000000, 41);
+    try test__ffsti2(0x00000000_00000000_00000080_00000000, 40);
+    try test__ffsti2(0x00000000_00000000_00000040_00000000, 39);
+    try test__ffsti2(0x00000000_00000000_00000020_00000000, 38);
+    try test__ffsti2(0x00000000_00000000_00000010_00000000, 37);
+    try test__ffsti2(0x00000000_00000000_00000008_00000000, 36);
+    try test__ffsti2(0x00000000_00000000_00000004_00000000, 35);
+    try test__ffsti2(0x00000000_00000000_00000002_00000000, 34);
+    try test__ffsti2(0x00000000_00000000_00000001_00000000, 33);
+
+    try test__ffsti2(0x00000000_00000000_00000000_80000000, 32);
+    try test__ffsti2(0x00000000_00000000_00000000_40000000, 31);
+    try test__ffsti2(0x00000000_00000000_00000000_20000000, 30);
+    try test__ffsti2(0x00000000_00000000_00000000_10000000, 29);
+    try test__ffsti2(0x00000000_00000000_00000000_08000000, 28);
+    try test__ffsti2(0x00000000_00000000_00000000_04000000, 27);
+    try test__ffsti2(0x00000000_00000000_00000000_02000000, 26);
+    try test__ffsti2(0x00000000_00000000_00000000_01000000, 25);
+    try test__ffsti2(0x00000000_00000000_00000000_00800000, 24);
+    try test__ffsti2(0x00000000_00000000_00000000_00400000, 23);
+    try test__ffsti2(0x00000000_00000000_00000000_00200000, 22);
+    try test__ffsti2(0x00000000_00000000_00000000_00100000, 21);
+    try test__ffsti2(0x00000000_00000000_00000000_00080000, 20);
+    try test__ffsti2(0x00000000_00000000_00000000_00040000, 19);
+    try test__ffsti2(0x00000000_00000000_00000000_00020000, 18);
+    try test__ffsti2(0x00000000_00000000_00000000_00010000, 17);
+    try test__ffsti2(0x00000000_00000000_00000000_00008000, 16);
+    try test__ffsti2(0x00000000_00000000_00000000_00004000, 15);
+    try test__ffsti2(0x00000000_00000000_00000000_00002000, 14);
+    try test__ffsti2(0x00000000_00000000_00000000_00001000, 13);
+    try test__ffsti2(0x00000000_00000000_00000000_00000800, 12);
+    try test__ffsti2(0x00000000_00000000_00000000_00000400, 11);
+    try test__ffsti2(0x00000000_00000000_00000000_00000200, 10);
+    try test__ffsti2(0x00000000_00000000_00000000_00000100, 9);
+}
lib/std/special/compiler_rt.zig
@@ -244,6 +244,12 @@ comptime {
         @export(__ctzdi2, .{ .name = "__ctzdi2", .linkage = linkage });
         const __ctzti2 = @import("compiler_rt/count0bits.zig").__ctzti2;
         @export(__ctzti2, .{ .name = "__ctzti2", .linkage = linkage });
+        const __ffssi2 = @import("compiler_rt/count0bits.zig").__ffssi2;
+        @export(__ffssi2, .{ .name = "__ffssi2", .linkage = linkage });
+        const __ffsdi2 = @import("compiler_rt/count0bits.zig").__ffsdi2;
+        @export(__ffsdi2, .{ .name = "__ffsdi2", .linkage = linkage });
+        const __ffsti2 = @import("compiler_rt/count0bits.zig").__ffsti2;
+        @export(__ffsti2, .{ .name = "__ffsti2", .linkage = linkage });
 
         const __paritysi2 = @import("compiler_rt/parity.zig").__paritysi2;
         @export(__paritysi2, .{ .name = "__paritysi2", .linkage = linkage });