1const std = @import("../std.zig");
 2const builtin = @import("builtin");
 3const math = std.math;
 4const meta = std.meta;
 5const expect = std.testing.expect;
 6
 7pub fn isNan(x: anytype) bool {
 8    return x != x;
 9}
10
11/// TODO: LLVM is known to miscompile on some architectures to quiet NaN -
12///       this is tracked by https://github.com/ziglang/zig/issues/14366
13pub fn isSignalNan(x: anytype) bool {
14    const T = @TypeOf(x);
15    const U = meta.Int(.unsigned, @bitSizeOf(T));
16    const quiet_signal_bit_mask = 1 << (math.floatFractionalBits(T) - 1);
17    return isNan(x) and (@as(U, @bitCast(x)) & quiet_signal_bit_mask == 0);
18}
19
20test isNan {
21    inline for ([_]type{ f16, f32, f64, f80, f128, c_longdouble }) |T| {
22        try expect(isNan(math.nan(T)));
23        try expect(isNan(-math.nan(T)));
24        try expect(isNan(math.snan(T)));
25        try expect(!isNan(@as(T, 1.0)));
26        try expect(!isNan(@as(T, math.inf(T))));
27    }
28}
29
30test isSignalNan {
31    if (builtin.zig_backend == .stage2_x86_64 and builtin.object_format == .coff and builtin.abi != .gnu) return error.SkipZigTest;
32
33    inline for ([_]type{ f16, f32, f64, f80, f128, c_longdouble }) |T| {
34        // TODO: Signalling NaN values get converted to quiet NaN values in
35        //       some cases where they shouldn't such that this can fail.
36        //       See https://github.com/ziglang/zig/issues/14366
37        if (!builtin.cpu.arch.isArm() and
38            !builtin.cpu.arch.isAARCH64() and
39            builtin.cpu.arch != .hexagon and
40            !builtin.cpu.arch.isMIPS32() and
41            !builtin.cpu.arch.isPowerPC() and
42            builtin.zig_backend != .stage2_c)
43        {
44            try expect(isSignalNan(math.snan(T)));
45        }
46        try expect(!isSignalNan(math.nan(T)));
47        try expect(!isSignalNan(@as(T, 1.0)));
48        try expect(!isSignalNan(math.inf(T)));
49    }
50}