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rust.godbolt.org | ||
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gcc.godbolt.org
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| | | | | Compiler Explorer is an interactive online compiler which shows the assembly output of compiled C++, Rust, Go (and many more) code. | |
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sdowney.org
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| | | | | A Possible Technique constexpr bool g(int lhs, int rhs) { auto& op = partial_eq; return op.ne(lhs, rhs); } Compiler Explorer with Supporting Code A trait is defined as a template var... | |
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zig.godbolt.org
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| | | | | const std = @import("std"); const testing = std.testing; const utfValidator = struct { const State = enum(u6) { ok, one, two, three, fail, }; fn step(char: u8, state: State) State { return switch (state) { .ok => switch (char) { 0x00...0x7f => .ok, 0xc0...0xdf => .one, 0xe0...0xef => .two, 0xf0...0xf7 => .three, else => .fail, }, .one => switch (char) { 0x80...0xbf => .ok, else => .fail, }, .two => switch (char) { 0x80...0xbf => .one, else => .fail, }, .three => switch (char) { 0x80...0xbf => .two, else => .fail, }, .fail => .fail, }; } }; fn pext(val: u64, mask: u64) callconv(.Inline) u64 { return asm("pext %[m],%[v],%[r]":[r] "=r" (-> u64) : [v] "r" (val), [m] "r" (mask)); } pub fn is_utf8(data: []const u8) bool { const table1 = comptime init: { var tmp = [_]u32{0} ** 256; @setEvalBranchQuota(5000); for (&tmp, 0..) |*e, i| { for (@typeInfo(utfValidator.State).Enum.fields) |f| { e.* |= (5 * @as(u32, @enumToInt(utfValidator.step(i, @intToEnum(utfValidator.State, f.value))))) << (f.value * 5); } } break :init tmp; }; const table2 = comptime init: { var tmp = [_]u32{0} ** 1024; @setEvalBranchQuota(50000); for (&tmp, 0..) |*e, i| { for (@typeInfo(utfValidator.State).Enum.fields) |f| { var s = @intToEnum(utfValidator.State, f.value); s = utfValidator.step((i & 0x01f) << 3, s); s = utfValidator.step((i & 0x3e0) >> 2, s); e.* |= (5 * @as(u32, @enumToInt(s))) << (f.value * 5); } } break :init tmp; }; var state: u32 = 0; if (data.len < 16) { for (data) |w| { state = table1[w] >> @truncate(u5, state); } return @intToEnum(utfValidator.State, @truncate(u5, state) / 5) == .ok; } var dp = data.ptr; const ep = dp + data.len; // Process first few bytes one-by-one to align the pointer to 4 bytes. const extra = @ptrToInt(dp) & 7; if (extra != 0) for (0..8-extra) |_| { state = table1[dp[0]] >> @truncate(u5, state); dp += 1; }; var wp = @ptrCast([*]const u64, @alignCast(8, dp)); const unroll = 4; while (@ptrToInt(wp+unroll) < @ptrToInt(ep)) { inline for (wp, 0..unroll) |w, _| { state = table2[pext(w, 0x000000000000f8f8)] >> @truncate(u5, state); state = table2[pext(w, 0x00000000f8f80000)] >> @truncate(u5, state); state = table2[pext(w, 0x0000f8f800000000)] >> @truncate(u5, state); state = table2[pext(w, 0xf8f8000000000000)] >> @truncate(u5, state); } wp += unroll; } dp = @ptrCast([*]const u8, wp); while (dp != ep) { state = table1[dp[0]] >> @truncate(u5, state); dp += 1; } return @intToEnum(utfValidator.State, @truncate(u5, state) / 5) == .ok; } pub fn main() !void { const str = "a random string to valida\xffte"; const str2 = "asdasda"; std.debug.print("{}\n", .{@call(.never_inline, is_utf8, .{str})}); std.debug.print("{}\n", .{@call(.never_inline, is_utf8, .{str2})}); } | |
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atomicbird.com
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| | | or, how to accidentally break Swift initialization rules. Today Im going to talk about optionals. Swift optionals. And also another kind of optional. And how you might break the ironclad rules of Swift without realizing it until its too late. What is an optional anyway? It depends who you ask. Swift will give you one answer, but Core Data has other ideas. So what happens when you bring them together? | ||
