Merge remote-tracking branch 'origin/master' into stage2-zig-cc

Master branch added in the concept of library versioning being optional
to main.cpp. It will need to be re-added into this branch before merging
back into master.

20 files changed, 1572 insertions, 99 deletions

diff --git a/lib/std/build.zig b/lib/std/build.zig
index 1673737bef..30ecf98b76 100644
--- a/lib/std/build.zig
+++ b/lib/std/build.zig
@@ -258,9 +258,14 @@ pub const Builder = struct {
         }));
     }
 
-    pub fn addSharedLibrary(self: *Builder, name: []const u8, root_src: ?[]const u8, ver: Version) *LibExeObjStep {
+    pub fn addSharedLibrary(
+        self: *Builder,
+        name: []const u8,
+        root_src: ?[]const u8,
+        kind: LibExeObjStep.SharedLibKind,
+    ) *LibExeObjStep {
         const root_src_param = if (root_src) |p| @as(FileSource, .{ .path = p }) else null;
-        return LibExeObjStep.createSharedLibrary(self, name, root_src_param, ver);
+        return LibExeObjStep.createSharedLibrary(self, name, root_src_param, kind);
     }
 
     pub fn addStaticLibrary(self: *Builder, name: []const u8, root_src: ?[]const u8) *LibExeObjStep {
@@ -338,11 +343,13 @@ pub const Builder = struct {
         return TranslateCStep.create(self, source);
     }
 
-    pub fn version(self: *const Builder, major: u32, minor: u32, patch: u32) Version {
-        return Version{
-            .major = major,
-            .minor = minor,
-            .patch = patch,
+    pub fn version(self: *const Builder, major: u32, minor: u32, patch: u32) LibExeObjStep.SharedLibKind {
+        return .{
+            .versioned = .{
+                .major = major,
+                .minor = minor,
+                .patch = patch,
+            },
         };
     }
 
@@ -1048,6 +1055,7 @@ pub const Builder = struct {
             .Bin => self.exe_dir,
             .Lib => self.lib_dir,
             .Header => self.h_dir,
+            .Custom => |path| fs.path.join(self.allocator, &[_][]const u8{ self.install_path, path }) catch unreachable,
         };
         return fs.path.resolve(
             self.allocator,
@@ -1166,7 +1174,7 @@ pub const LibExeObjStep = struct {
     version_script: ?[]const u8 = null,
     out_filename: []const u8,
     is_dynamic: bool,
-    version: Version,
+    version: ?Version,
     build_mode: builtin.Mode,
     kind: Kind,
     major_only_filename: []const u8,
@@ -1212,6 +1220,8 @@ pub const LibExeObjStep = struct {
     is_linking_libc: bool = false,
     vcpkg_bin_path: ?[]const u8 = null,
 
+    /// This may be set in order to override the default install directory
+    override_dest_dir: ?InstallDir,
     installed_path: ?[]const u8,
     install_step: ?*InstallArtifactStep,
 
@@ -1268,33 +1278,41 @@ pub const LibExeObjStep = struct {
         Test,
     };
 
-    pub fn createSharedLibrary(builder: *Builder, name: []const u8, root_src: ?FileSource, ver: Version) *LibExeObjStep {
+    const SharedLibKind = union(enum) {
+        versioned: Version,
+        unversioned: void,
+    };
+
+    pub fn createSharedLibrary(builder: *Builder, name: []const u8, root_src: ?FileSource, kind: SharedLibKind) *LibExeObjStep {
         const self = builder.allocator.create(LibExeObjStep) catch unreachable;
-        self.* = initExtraArgs(builder, name, root_src, Kind.Lib, true, ver);
+        self.* = initExtraArgs(builder, name, root_src, Kind.Lib, true, switch (kind) {
+            .versioned => |ver| ver,
+            .unversioned => null,
+        });
         return self;
     }
 
     pub fn createStaticLibrary(builder: *Builder, name: []const u8, root_src: ?FileSource) *LibExeObjStep {
         const self = builder.allocator.create(LibExeObjStep) catch unreachable;
-        self.* = initExtraArgs(builder, name, root_src, Kind.Lib, false, builder.version(0, 0, 0));
+        self.* = initExtraArgs(builder, name, root_src, Kind.Lib, false, null);
         return self;
     }
 
     pub fn createObject(builder: *Builder, name: []const u8, root_src: ?FileSource) *LibExeObjStep {
         const self = builder.allocator.create(LibExeObjStep) catch unreachable;
-        self.* = initExtraArgs(builder, name, root_src, Kind.Obj, false, builder.version(0, 0, 0));
+        self.* = initExtraArgs(builder, name, root_src, Kind.Obj, false, null);
         return self;
     }
 
     pub fn createExecutable(builder: *Builder, name: []const u8, root_src: ?FileSource, is_dynamic: bool) *LibExeObjStep {
         const self = builder.allocator.create(LibExeObjStep) catch unreachable;
-        self.* = initExtraArgs(builder, name, root_src, Kind.Exe, is_dynamic, builder.version(0, 0, 0));
+        self.* = initExtraArgs(builder, name, root_src, Kind.Exe, is_dynamic, null);
         return self;
     }
 
     pub fn createTest(builder: *Builder, name: []const u8, root_src: FileSource) *LibExeObjStep {
         const self = builder.allocator.create(LibExeObjStep) catch unreachable;
-        self.* = initExtraArgs(builder, name, root_src, Kind.Test, false, builder.version(0, 0, 0));
+        self.* = initExtraArgs(builder, name, root_src, Kind.Test, false, null);
         return self;
     }
 
@@ -1304,7 +1322,7 @@ pub const LibExeObjStep = struct {
         root_src: ?FileSource,
         kind: Kind,
         is_dynamic: bool,
-        ver: Version,
+        ver: ?Version,
     ) LibExeObjStep {
         if (mem.indexOf(u8, name, "/") != null or mem.indexOf(u8, name, "\\") != null) {
             panic("invalid name: '{}'. It looks like a file path, but it is supposed to be the library or application name.", .{name});
@@ -1348,6 +1366,7 @@ pub const LibExeObjStep = struct {
             .rdynamic = false,
             .output_dir = null,
             .single_threaded = false,
+            .override_dest_dir = null,
             .installed_path = null,
             .install_step = null,
         };
@@ -1375,17 +1394,17 @@ pub const LibExeObjStep = struct {
                         self.target.staticLibSuffix(),
                     });
                     self.out_lib_filename = self.out_filename;
-                } else {
+                } else if (self.version) |version| {
                     if (self.target.isDarwin()) {
                         self.out_filename = self.builder.fmt("lib{}.{d}.{d}.{d}.dylib", .{
                             self.name,
-                            self.version.major,
-                            self.version.minor,
-                            self.version.patch,
+                            version.major,
+                            version.minor,
+                            version.patch,
                         });
                         self.major_only_filename = self.builder.fmt("lib{}.{d}.dylib", .{
                             self.name,
-                            self.version.major,
+                            version.major,
                         });
                         self.name_only_filename = self.builder.fmt("lib{}.dylib", .{self.name});
                         self.out_lib_filename = self.out_filename;
@@ -1395,14 +1414,25 @@ pub const LibExeObjStep = struct {
                     } else {
                         self.out_filename = self.builder.fmt("lib{}.so.{d}.{d}.{d}", .{
                             self.name,
-                            self.version.major,
-                            self.version.minor,
-                            self.version.patch,
+                            version.major,
+                            version.minor,
+                            version.patch,
                         });
-                        self.major_only_filename = self.builder.fmt("lib{}.so.{d}", .{ self.name, self.version.major });
+                        self.major_only_filename = self.builder.fmt("lib{}.so.{d}", .{ self.name, version.major });
                         self.name_only_filename = self.builder.fmt("lib{}.so", .{self.name});
                         self.out_lib_filename = self.out_filename;
                     }
+                } else {
+                    if (self.target.isDarwin()) {
+                        self.out_filename = self.builder.fmt("lib{}.dylib", .{self.name});
+                        self.out_lib_filename = self.out_filename;
+                    } else if (self.target.isWindows()) {
+                        self.out_filename = self.builder.fmt("{}.dll", .{self.name});
+                        self.out_lib_filename = self.builder.fmt("{}.lib", .{self.name});
+                    } else {
+                        self.out_filename = self.builder.fmt("lib{}.so", .{self.name});
+                        self.out_lib_filename = self.out_filename;
+                    }
                 }
             },
         }
@@ -2037,14 +2067,16 @@ pub const LibExeObjStep = struct {
         zig_args.append(self.name) catch unreachable;
 
         if (self.kind == Kind.Lib and self.is_dynamic) {
-            zig_args.append("--ver-major") catch unreachable;
-            zig_args.append(builder.fmt("{}", .{self.version.major})) catch unreachable;
+            if (self.version) |version| {
+                zig_args.append("--ver-major") catch unreachable;
+                zig_args.append(builder.fmt("{}", .{version.major})) catch unreachable;
 
-            zig_args.append("--ver-minor") catch unreachable;
-            zig_args.append(builder.fmt("{}", .{self.version.minor})) catch unreachable;
+                zig_args.append("--ver-minor") catch unreachable;
+                zig_args.append(builder.fmt("{}", .{version.minor})) catch unreachable;
 
-            zig_args.append("--ver-patch") catch unreachable;
-            zig_args.append(builder.fmt("{}", .{self.version.patch})) catch unreachable;
+                zig_args.append("--ver-patch") catch unreachable;
+                zig_args.append(builder.fmt("{}", .{version.patch})) catch unreachable;
+            }
         }
         if (self.is_dynamic) {
             try zig_args.append("-dynamic");
@@ -2285,7 +2317,7 @@ pub const LibExeObjStep = struct {
             }
         }
 
-        if (self.kind == Kind.Lib and self.is_dynamic and self.target.wantSharedLibSymLinks()) {
+        if (self.kind == Kind.Lib and self.is_dynamic and self.version != null and self.target.wantSharedLibSymLinks()) {
             try doAtomicSymLinks(builder.allocator, self.getOutputPath(), self.major_only_filename, self.name_only_filename);
         }
     }
@@ -2309,17 +2341,17 @@ pub const InstallArtifactStep = struct {
             .builder = builder,
             .step = Step.init(.InstallArtifact, builder.fmt("install {}", .{artifact.step.name}), builder.allocator, make),
             .artifact = artifact,
-            .dest_dir = switch (artifact.kind) {
+            .dest_dir = artifact.override_dest_dir orelse switch (artifact.kind) {
                 .Obj => unreachable,
                 .Test => unreachable,
-                .Exe => .Bin,
-                .Lib => .Lib,
+                .Exe => InstallDir{ .Bin = {} },
+                .Lib => InstallDir{ .Lib = {} },
             },
             .pdb_dir = if (artifact.producesPdbFile()) blk: {
                 if (artifact.kind == .Exe) {
-                    break :blk InstallDir.Bin;
+                    break :blk InstallDir{ .Bin = {} };
                 } else {
-                    break :blk InstallDir.Lib;
+                    break :blk InstallDir{ .Lib = {} };
                 }
             } else null,
             .h_dir = if (artifact.kind == .Lib and artifact.emit_h) .Header else null,
@@ -2329,8 +2361,10 @@ pub const InstallArtifactStep = struct {
 
         builder.pushInstalledFile(self.dest_dir, artifact.out_filename);
         if (self.artifact.isDynamicLibrary()) {
-            builder.pushInstalledFile(.Lib, artifact.major_only_filename);
-            builder.pushInstalledFile(.Lib, artifact.name_only_filename);
+            if (self.artifact.version != null) {
+                builder.pushInstalledFile(.Lib, artifact.major_only_filename);
+                builder.pushInstalledFile(.Lib, artifact.name_only_filename);
+            }
             if (self.artifact.target.isWindows()) {
                 builder.pushInstalledFile(.Lib, artifact.out_lib_filename);
             }
@@ -2350,7 +2384,7 @@ pub const InstallArtifactStep = struct {
 
         const full_dest_path = builder.getInstallPath(self.dest_dir, self.artifact.out_filename);
         try builder.updateFile(self.artifact.getOutputPath(), full_dest_path);
-        if (self.artifact.isDynamicLibrary() and self.artifact.target.wantSharedLibSymLinks()) {
+        if (self.artifact.isDynamicLibrary() and self.artifact.version != null and self.artifact.target.wantSharedLibSymLinks()) {
             try doAtomicSymLinks(builder.allocator, full_dest_path, self.artifact.major_only_filename, self.artifact.name_only_filename);
         }
         if (self.pdb_dir) |pdb_dir| {
@@ -2615,11 +2649,13 @@ const VcpkgRootStatus = enum {
 
 pub const VcpkgLinkage = std.builtin.LinkMode;
 
-pub const InstallDir = enum {
-    Prefix,
-    Lib,
-    Bin,
-    Header,
+pub const InstallDir = union(enum) {
+    Prefix: void,
+    Lib: void,
+    Bin: void,
+    Header: void,
+    /// A path relative to the prefix
+    Custom: []const u8,
 };
 
 pub const InstalledFile = struct {
diff --git a/lib/std/c.zig b/lib/std/c.zig
index 1b3f403ab5..aa50fff90e 100644
--- a/lib/std/c.zig
+++ b/lib/std/c.zig
@@ -132,8 +132,6 @@ pub usingnamespace switch (builtin.os.tag) {
     },
 };
 
-pub extern "c" fn setreuid(ruid: c_uint, euid: c_uint) c_int;
-pub extern "c" fn setregid(rgid: c_uint, egid: c_uint) c_int;
 pub extern "c" fn rmdir(path: [*:0]const u8) c_int;
 pub extern "c" fn getenv(name: [*:0]const u8) ?[*:0]u8;
 pub extern "c" fn sysctl(name: [*]const c_int, namelen: c_uint, oldp: ?*c_void, oldlenp: ?*usize, newp: ?*c_void, newlen: usize) c_int;
@@ -237,8 +235,15 @@ pub usingnamespace switch (builtin.os.tag) {
 
 pub extern "c" fn kill(pid: pid_t, sig: c_int) c_int;
 pub extern "c" fn getdirentries(fd: fd_t, buf_ptr: [*]u8, nbytes: usize, basep: *i64) isize;
-pub extern "c" fn setgid(ruid: c_uint, euid: c_uint) c_int;
-pub extern "c" fn setuid(uid: c_uint) c_int;
+
+pub extern "c" fn setuid(uid: uid_t) c_int;
+pub extern "c" fn setgid(gid: gid_t) c_int;
+pub extern "c" fn seteuid(euid: uid_t) c_int;
+pub extern "c" fn setegid(egid: gid_t) c_int;
+pub extern "c" fn setreuid(ruid: uid_t, euid: uid_t) c_int;
+pub extern "c" fn setregid(rgid: gid_t, egid: gid_t) c_int;
+pub extern "c" fn setresuid(ruid: uid_t, euid: uid_t, suid: uid_t) c_int;
+pub extern "c" fn setresgid(rgid: gid_t, egid: gid_t, sgid: gid_t) c_int;
 
 pub extern "c" fn aligned_alloc(alignment: usize, size: usize) ?*c_void;
 pub extern "c" fn malloc(usize) ?*c_void;
@@ -335,3 +340,5 @@ pub extern "c" fn sync() void;
 pub extern "c" fn syncfs(fd: c_int) c_int;
 pub extern "c" fn fsync(fd: c_int) c_int;
 pub extern "c" fn fdatasync(fd: c_int) c_int;
+
+pub extern "c" fn prctl(option: c_int, ...) c_int;
diff --git a/lib/std/compress.zig b/lib/std/compress.zig
index 5518f807df..95f496021e 100644
--- a/lib/std/compress.zig
+++ b/lib/std/compress.zig
@@ -6,8 +6,10 @@
 const std = @import("std.zig");
 
 pub const deflate = @import("compress/deflate.zig");
+pub const gzip = @import("compress/gzip.zig");
 pub const zlib = @import("compress/zlib.zig");
 
 test "" {
+    _ = gzip;
     _ = zlib;
 }
diff --git a/lib/std/compress/deflate.zig b/lib/std/compress/deflate.zig
index bad23349e8..9fe96cacb7 100644
--- a/lib/std/compress/deflate.zig
+++ b/lib/std/compress/deflate.zig
@@ -21,48 +21,121 @@ const MAXDCODES = 30;
 const MAXCODES = MAXLCODES + MAXDCODES;
 const FIXLCODES = 288;
 
+// The maximum length of a Huffman code's prefix we can decode using the fast
+// path. The factor 9 is inherited from Zlib, tweaking the value showed little
+// or no changes in the profiler output.
+const PREFIX_LUT_BITS = 9;
+
 const Huffman = struct {
+    // Number of codes for each possible length
     count: [MAXBITS + 1]u16,
+    // Mapping between codes and symbols
     symbol: [MAXCODES]u16,
 
-    fn construct(self: *Huffman, length: []const u16) !void {
+    // The decoding process uses a trick explained by Mark Adler in [1].
+    // We basically precompute for a fixed number of codes (0 <= x <= 2^N-1)
+    // the symbol and the effective code length we'd get if the decoder was run
+    // on the given N-bit sequence.
+    // A code with length 0 means the sequence is not a valid prefix for this
+    // canonical Huffman code and we have to decode it using a slower method.
+    //
+    // [1] https://github.com/madler/zlib/blob/v1.2.11/doc/algorithm.txt#L58
+    prefix_lut: [1 << PREFIX_LUT_BITS]u16,
+    prefix_lut_len: [1 << PREFIX_LUT_BITS]u16,
+    // The following info refer to the codes of length PREFIX_LUT_BITS+1 and are
+    // used to bootstrap the bit-by-bit reading method if the fast-path fails.
+    last_code: u16,
+    last_index: u16,
+
+    fn construct(self: *Huffman, code_length: []const u16) !void {
         for (self.count) |*val| {
             val.* = 0;
         }
 
-        for (length) |val| {
-            self.count[val] += 1;
+        for (code_length) |len| {
+            self.count[len] += 1;
         }
 
-        if (self.count[0] == length.len)
+        // All zero.
+        if (self.count[0] == code_length.len)
             return;
 
         var left: isize = 1;
         for (self.count[1..]) |val| {
+            // Each added bit doubles the amount of codes.
             left *= 2;
+            // Make sure the number of codes with this length isn't too high.
             left -= @as(isize, @bitCast(i16, val));
             if (left < 0)
                 return error.InvalidTree;
         }
 
-        var offs: [MAXBITS + 1]u16 = undefined;
+        // Compute the offset of the first symbol represented by a code of a
+        // given length in the symbol table, together with the first canonical
+        // Huffman code for that length.
+        var offset: [MAXBITS + 1]u16 = undefined;
+        var codes: [MAXBITS + 1]u16 = undefined;
         {
+            offset[1] = 0;
+            codes[1] = 0;
             var len: usize = 1;
-            offs[1] = 0;
             while (len < MAXBITS) : (len += 1) {
-                offs[len + 1] = offs[len] + self.count[len];
+                offset[len + 1] = offset[len] + self.count[len];
+                codes[len + 1] = (codes[len] + self.count[len]) << 1;
             }
         }
 
-        for (length) |val, symbol| {
-            if (val != 0) {
-                self.symbol[offs[val]] = @truncate(u16, symbol);
-                offs[val] += 1;
+        self.prefix_lut_len = mem.zeroes(@TypeOf(self.prefix_lut_len));
+
+        for (code_length) |len, symbol| {
+            if (len != 0) {
+                // Fill the symbol table.
+                // The symbols are assigned sequentially for each length.
+                self.symbol[offset[len]] = @truncate(u16, symbol);
+                // Track the last assigned offset
+                offset[len] += 1;
+            }
+
+            if (len == 0 or len > PREFIX_LUT_BITS)
+                continue;
+
+            // Given a Huffman code of length N we have to massage it so
+            // that it becomes an index in the lookup table.
+            // The bit order is reversed as the fast path reads the bit
+            // sequence MSB to LSB using an &, the order is flipped wrt the
+            // one obtained by reading bit-by-bit.
+            // The codes are prefix-free, if the prefix matches we can
+            // safely ignore the trail bits. We do so by replicating the
+            // symbol info for each combination of the trailing bits.
+            const bits_to_fill = @intCast(u5, PREFIX_LUT_BITS - len);
+            const rev_code = bitReverse(codes[len], len);
+            // Track the last used code, but only for lengths < PREFIX_LUT_BITS
+            codes[len] += 1;
+
+            var j: usize = 0;
+            while (j < @as(usize, 1) << bits_to_fill) : (j += 1) {
+                const index = rev_code | (j << @intCast(u5, len));
+                assert(self.prefix_lut_len[index] == 0);
+                self.prefix_lut[index] = @truncate(u16, symbol);
+                self.prefix_lut_len[index] = @truncate(u16, len);
             }
         }
+
+        self.last_code = codes[PREFIX_LUT_BITS + 1];
+        self.last_index = offset[PREFIX_LUT_BITS + 1] - self.count[PREFIX_LUT_BITS + 1];
     }
 };
 
+// Reverse bit-by-bit a N-bit value
+fn bitReverse(x: usize, N: usize) usize {
+    var tmp: usize = 0;
+    var i: usize = 0;
+    while (i < N) : (i += 1) {
+        tmp |= ((x >> @intCast(u5, i)) & 1) << @intCast(u5, N - i - 1);
+    }
+    return tmp;
+}
+
 pub fn InflateStream(comptime ReaderType: type) type {
     return struct {
         const Self = @This();
@@ -83,7 +156,7 @@ pub fn InflateStream(comptime ReaderType: type) type {
         };
         pub const Reader = io.Reader(*Self, Error, read);
 
-        bit_reader: io.BitReader(.Little, ReaderType),
+        inner_reader: ReaderType,
 
         // True if the decoder met the end of the compressed stream, no further
         // data can be decompressed
@@ -135,7 +208,7 @@ pub fn InflateStream(comptime ReaderType: type) type {
 
             // Insert a single byte into the window.
             // Assumes there's enough space.
-            fn appendUnsafe(self: *WSelf, value: u8) void {
+            inline fn appendUnsafe(self: *WSelf, value: u8) void {
                 self.buf[self.wi] = value;
                 self.wi = (self.wi + 1) & (self.buf.len - 1);
                 self.el += 1;
@@ -180,7 +253,7 @@ pub fn InflateStream(comptime ReaderType: type) type {
                 // of the window memory for the non-overlapping case.
                 var i: usize = 0;
                 while (i < N) : (i += 1) {
-                    const index = (self.wi -% distance) % self.buf.len;
+                    const index = (self.wi -% distance) & (self.buf.len - 1);
                     self.appendUnsafe(self.buf[index]);
                 }
 
@@ -196,13 +269,36 @@ pub fn InflateStream(comptime ReaderType: type) type {
         hdist: *Huffman,
         hlen: *Huffman,
 
+        // Temporary buffer for the bitstream, only bits 0..`bits_left` are
+        // considered valid.
+        bits: u32,
+        bits_left: usize,
+
+        fn peekBits(self: *Self, bits: usize) !u32 {
+            while (self.bits_left < bits) {
+                const byte = try self.inner_reader.readByte();
+                self.bits |= @as(u32, byte) << @intCast(u5, self.bits_left);
+                self.bits_left += 8;
+            }
+            return self.bits & ((@as(u32, 1) << @intCast(u5, bits)) - 1);
+        }
+        fn readBits(self: *Self, bits: usize) !u32 {
+            const val = self.peekBits(bits);
+            self.discardBits(bits);
+            return val;
+        }
+        fn discardBits(self: *Self, bits: usize) void {
+            self.bits >>= @intCast(u5, bits);
+            self.bits_left -= bits;
+        }
+
         fn stored(self: *Self) !void {
             // Discard the remaining bits, the lenght field is always
             // byte-aligned (and so is the data)
-            self.bit_reader.alignToByte();
+            self.discardBits(self.bits_left);
 
-            const length = (try self.bit_reader.readBitsNoEof(u16, 16));
-            const length_cpl = (try self.bit_reader.readBitsNoEof(u16, 16));
+            const length = try self.inner_reader.readIntLittle(u16);
+            const length_cpl = try self.inner_reader.readIntLittle(u16);
 
             if (length != ~length_cpl)
                 return error.InvalidStoredSize;
@@ -237,11 +333,11 @@ pub fn InflateStream(comptime ReaderType: type) type {
 
         fn dynamic(self: *Self) !void {
             // Number of length codes
-            const nlen = (try self.bit_reader.readBitsNoEof(usize, 5)) + 257;
+            const nlen = (try self.readBits(5)) + 257;
             // Number of distance codes
-            const ndist = (try self.bit_reader.readBitsNoEof(usize, 5)) + 1;
+            const ndist = (try self.readBits(5)) + 1;
             // Number of code length codes
-            const ncode = (try self.bit_reader.readBitsNoEof(usize, 4)) + 4;
+            const ncode = (try self.readBits(4)) + 4;
 
             if (nlen > MAXLCODES or ndist > MAXDCODES)
                 return error.BadCounts;
@@ -259,7 +355,7 @@ pub fn InflateStream(comptime ReaderType: type) type {
 
                 // Read the code lengths, missing ones are left as zero
                 for (ORDER[0..ncode]) |val| {
-                    lengths[val] = try self.bit_reader.readBitsNoEof(u16, 3);
+                    lengths[val] = @intCast(u16, try self.readBits(3));
                 }
 
                 try lencode.construct(lengths[0..]);
@@ -284,7 +380,7 @@ pub fn InflateStream(comptime ReaderType: type) type {
                         if (i == 0) return error.NoLastLength;
 
                         const last_length = lengths[i - 1];
-                        const repeat = 3 + (try self.bit_reader.readBitsNoEof(usize, 2));
+                        const repeat = 3 + (try self.readBits(2));
                         const last_index = i + repeat;
                         while (i < last_index) : (i += 1) {
                             lengths[i] = last_length;
@@ -292,11 +388,11 @@ pub fn InflateStream(comptime ReaderType: type) type {
                     },
                     17 => {
                         // repeat zero 3..10 times
-                        i += 3 + (try self.bit_reader.readBitsNoEof(usize, 3));
+                        i += 3 + (try self.readBits(3));
                     },
                     18 => {
                         // repeat zero 11..138 times
-                        i += 11 + (try self.bit_reader.readBitsNoEof(usize, 7));
+                        i += 11 + (try self.readBits(7));
                     },
                     else => return error.InvalidSymbol,
                 }
@@ -359,11 +455,11 @@ pub fn InflateStream(comptime ReaderType: type) type {
                         // Length/distance pair
                         const length_symbol = symbol - 257;
                         const length = LENS[length_symbol] +
-                            try self.bit_reader.readBitsNoEof(u16, LEXT[length_symbol]);
+                            @intCast(u16, try self.readBits(LEXT[length_symbol]));
 
                         const distance_symbol = try self.decode(distcode);
                         const distance = DISTS[distance_symbol] +
-                            try self.bit_reader.readBitsNoEof(u16, DEXT[distance_symbol]);
+                            @intCast(u16, try self.readBits(DEXT[distance_symbol]));
 
                         if (distance > self.window.buf.len)
                             return error.InvalidDistance;
@@ -385,13 +481,29 @@ pub fn InflateStream(comptime ReaderType: type) type {
         }
 
         fn decode(self: *Self, h: *Huffman) !u16 {
-            var len: usize = 1;
-            var code: usize = 0;
-            var first: usize = 0;
-            var index: usize = 0;
+            // Fast path, read some bits and hope they're prefixes of some code
+            const prefix = try self.peekBits(PREFIX_LUT_BITS);
+            if (h.prefix_lut_len[prefix] != 0) {
+                self.discardBits(h.prefix_lut_len[prefix]);
+                return h.prefix_lut[prefix];
+            }
+
+            // The sequence we've read is not a prefix of any code of length <=
+            // PREFIX_LUT_BITS, keep decoding it using a slower method
+            self.discardBits(PREFIX_LUT_BITS);
+
+            // Speed up the decoding by starting from the first code length
+            // that's not covered by the table
+            var len: usize = PREFIX_LUT_BITS + 1;
+            var first: usize = h.last_code;
+            var index: usize = h.last_index;
+
+            // Reverse the prefix so that the LSB becomes the MSB and make space
+            // for the next bit
+            var code = bitReverse(prefix, PREFIX_LUT_BITS + 1);
 
             while (len <= MAXBITS) : (len += 1) {
-                code |= try self.bit_reader.readBitsNoEof(usize, 1);
+                code |= try self.readBits(1);
                 const count = h.count[len];
                 if (code < first + count)
                     return h.symbol[index + (code - first)];
@@ -411,8 +523,8 @@ pub fn InflateStream(comptime ReaderType: type) type {
                         // The compressed stream is done
                         if (self.seen_eos) return;
 
-                        const last = try self.bit_reader.readBitsNoEof(u1, 1);
-                        const kind = try self.bit_reader.readBitsNoEof(u2, 2);
+                        const last = @intCast(u1, try self.readBits(1));
+                        const kind = @intCast(u2, try self.readBits(2));
 
                         self.seen_eos = last != 0;
 
@@ -439,7 +551,7 @@ pub fn InflateStream(comptime ReaderType: type) type {
                         var i: usize = 0;
                         while (i < N) : (i += 1) {
                             var tmp: [1]u8 = undefined;
-                            if ((try self.bit_reader.read(&tmp)) != 1) {
+                            if ((try self.inner_reader.read(&tmp)) != 1) {
                                 // Unexpected end of stream, keep this error
                                 // consistent with the use of readBitsNoEof
                                 return error.EndOfStream;
@@ -478,12 +590,14 @@ pub fn InflateStream(comptime ReaderType: type) type {
             assert(math.isPowerOfTwo(window_slice.len));
 
             return Self{
-                .bit_reader = io.bitReader(.Little, source),
+                .inner_reader = source,
                 .window = .{ .buf = window_slice },
                 .seen_eos = false,
                 .state = .DecodeBlockHeader,
                 .hdist = undefined,
                 .hlen = undefined,
+                .bits = 0,
+                .bits_left = 0,
             };
         }
 
diff --git a/lib/std/compress/gzip.zig b/lib/std/compress/gzip.zig
new file mode 100644
index 0000000000..aad1731393
--- /dev/null
+++ b/lib/std/compress/gzip.zig
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2015-2020 Zig Contributors
+// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
+// The MIT license requires this copyright notice to be included in all copies
+// and substantial portions of the software.
+//
+// Decompressor for GZIP data streams (RFC1952)
+
+const std = @import("std");
+const io = std.io;
+const fs = std.fs;
+const testing = std.testing;
+const mem = std.mem;
+const deflate = std.compress.deflate;
+
+// Flags for the FLG field in the header
+const FTEXT = 1 << 0;
+const FHCRC = 1 << 1;
+const FEXTRA = 1 << 2;
+const FNAME = 1 << 3;
+const FCOMMENT = 1 << 4;
+
+pub fn GzipStream(comptime ReaderType: type) type {
+    return struct {
+        const Self = @This();
+
+        pub const Error = ReaderType.Error ||
+            deflate.InflateStream(ReaderType).Error ||
+            error{ CorruptedData, WrongChecksum };
+        pub const Reader = io.Reader(*Self, Error, read);
+
+        allocator: *mem.Allocator,
+        inflater: deflate.InflateStream(ReaderType),
+        in_reader: ReaderType,
+        hasher: std.hash.Crc32,
+        window_slice: []u8,
+        read_amt: usize,
+
+        info: struct {
+            filename: ?[]const u8,
+            comment: ?[]const u8,
+            modification_time: u32,
+        },
+
+        fn init(allocator: *mem.Allocator, source: ReaderType) !Self {
+            // gzip header format is specified in RFC1952
+            const header = try source.readBytesNoEof(10);
+
+            // Check the ID1/ID2 fields
+            if (header[0] != 0x1f or header[1] != 0x8b)
+                return error.BadHeader;
+
+            const CM = header[2];
+            // The CM field must be 8 to indicate the use of DEFLATE
+            if (CM != 8) return error.InvalidCompression;
+            // Flags
+            const FLG = header[3];
+            // Modification time, as a Unix timestamp.
+            // If zero there's no timestamp available.
+            const MTIME = mem.readIntLittle(u32, header[4..8]);
+            // Extra flags
+            const XFL = header[8];
+            // Operating system where the compression took place
+            const OS = header[9];
+
+            if (FLG & FEXTRA != 0) {
+                // Skip the extra data, we could read and expose it to the user
+                // if somebody needs it.
+                const len = try source.readIntLittle(u16);
+                try source.skipBytes(len, .{});
+            }
+
+            var filename: ?[]const u8 = null;
+            if (FLG & FNAME != 0) {
+                filename = try source.readUntilDelimiterAlloc(
+                    allocator,
+                    0,
+                    std.math.maxInt(usize),
+                );
+            }
+            errdefer if (filename) |p| allocator.free(p);
+
+            var comment: ?[]const u8 = null;
+            if (FLG & FCOMMENT != 0) {
+                comment = try source.readUntilDelimiterAlloc(
+                    allocator,
+                    0,
+                    std.math.maxInt(usize),
+                );
+            }
+            errdefer if (comment) |p| allocator.free(p);
+
+            if (FLG & FHCRC != 0) {
+                // TODO: Evaluate and check the header checksum. The stdlib has
+                // no CRC16 yet :(
+                _ = try source.readIntLittle(u16);
+            }
+
+            // The RFC doesn't say anything about the DEFLATE window size to be
+            // used, default to 32K.
+            var window_slice = try allocator.alloc(u8, 32 * 1024);
+
+            return Self{
+                .allocator = allocator,
+                .inflater = deflate.inflateStream(source, window_slice),
+                .in_reader = source,
+                .hasher = std.hash.Crc32.init(),
+                .window_slice = window_slice,
+                .info = .{
+                    .filename = filename,
+                    .comment = comment,
+                    .modification_time = MTIME,
+                },
+                .read_amt = 0,
+            };
+        }
+
+        pub fn deinit(self: *Self) void {
+            self.allocator.free(self.window_slice);
+            if (self.info.filename) |filename|
+                self.allocator.free(filename);
+            if (self.info.comment) |comment|
+                self.allocator.free(comment);
+        }
+
+        // Implements the io.Reader interface
+        pub fn read(self: *Self, buffer: []u8) Error!usize {
+            if (buffer.len == 0)
+                return 0;
+
+            // Read from the compressed stream and update the computed checksum
+            const r = try self.inflater.read(buffer);
+            if (r != 0) {
+                self.hasher.update(buffer[0..r]);
+                self.read_amt += r;
+                return r;
+            }
+
+            // We've reached the end of stream, check if the checksum matches
+            const hash = try self.in_reader.readIntLittle(u32);
+            if (hash != self.hasher.final())
+                return error.WrongChecksum;
+
+            // The ISIZE field is the size of the uncompressed input modulo 2^32
+            const input_size = try self.in_reader.readIntLittle(u32);
+            if (self.read_amt & 0xffffffff != input_size)
+                return error.CorruptedData;
+
+            return 0;
+        }
+
+        pub fn reader(self: *Self) Reader {
+            return .{ .context = self };
+        }
+    };
+}
+
+pub fn gzipStream(allocator: *mem.Allocator, reader: anytype) !GzipStream(@TypeOf(reader)) {
+    return GzipStream(@TypeOf(reader)).init(allocator, reader);
+}
+
+fn testReader(data: []const u8, comptime expected: []const u8) !void {
+    var in_stream = io.fixedBufferStream(data);
+
+    var gzip_stream = try gzipStream(testing.allocator, in_stream.reader());
+    defer gzip_stream.deinit();
+
+    // Read and decompress the whole file
+    const buf = try gzip_stream.reader().readAllAlloc(testing.allocator, std.math.maxInt(usize));
+    defer testing.allocator.free(buf);
+    // Calculate its SHA256 hash and check it against the reference
+    var hash: [32]u8 = undefined;
+    std.crypto.hash.sha2.Sha256.hash(buf, hash[0..], .{});
+
+    assertEqual(expected, &hash);
+}
+
+// Assert `expected` == `input` where `input` is a bytestring.
+pub fn assertEqual(comptime expected: []const u8, input: []const u8) void {
+    var expected_bytes: [expected.len / 2]u8 = undefined;
+    for (expected_bytes) |*r, i| {
+        r.* = std.fmt.parseInt(u8, expected[2 * i .. 2 * i + 2], 16) catch unreachable;
+    }
+
+    testing.expectEqualSlices(u8, &expected_bytes, input);
+}
+
+// All the test cases are obtained by compressing the RFC1952 text
+//
+// https://tools.ietf.org/rfc/rfc1952.txt length=25037 bytes
+// SHA256=164ef0897b4cbec63abf1b57f069f3599bd0fb7c72c2a4dee21bd7e03ec9af67
+test "compressed data" {
+    try testReader(
+        @embedFile("rfc1952.txt.gz"),
+        "164ef0897b4cbec63abf1b57f069f3599bd0fb7c72c2a4dee21bd7e03ec9af67",
+    );
+}
+
+test "sanity checks" {
+    // Truncated header
+    testing.expectError(
+        error.EndOfStream,
+        testReader(&[_]u8{ 0x1f, 0x8B }, ""),
+    );
+    // Wrong CM
+    testing.expectError(
+        error.InvalidCompression,
+        testReader(&[_]u8{
+            0x1f, 0x8b, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x03,
+        }, ""),
+    );
+    // Wrong checksum
+    testing.expectError(
+        error.WrongChecksum,
+        testReader(&[_]u8{
+            0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x03, 0x03, 0x00, 0x00, 0x00, 0x00, 0x01,
+            0x00, 0x00, 0x00, 0x00,
+        }, ""),
+    );
+    // Truncated checksum
+    testing.expectError(
+        error.EndOfStream,
+        testReader(&[_]u8{
+            0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x03, 0x03, 0x00, 0x00, 0x00, 0x00,
+        }, ""),
+    );
+    // Wrong initial size
+    testing.expectError(
+        error.CorruptedData,
+        testReader(&[_]u8{
+            0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x03, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x01,
+        }, ""),
+    );
+    // Truncated initial size field
+    testing.expectError(
+        error.EndOfStream,
+        testReader(&[_]u8{
+            0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x03, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00,
+        }, ""),
+    );
+}
diff --git a/lib/std/compress/rfc1952.txt.gz b/lib/std/compress/rfc1952.txt.gz
new file mode 100644
index 0000000000..be43b90a79
--- /dev/null
+++ b/lib/std/compress/rfc1952.txt.gz
diff --git a/lib/std/event/loop.zig b/lib/std/event/loop.zig
index b34ad8c940..2600b337b3 100644
--- a/lib/std/event/loop.zig
+++ b/lib/std/event/loop.zig
@@ -112,7 +112,8 @@ pub const Loop = struct {
     /// have the correct pointer value.
     /// https://github.com/ziglang/zig/issues/2761 and https://github.com/ziglang/zig/issues/2765
     pub fn init(self: *Loop) !void {
-        if (builtin.single_threaded) {
+        if (builtin.single_threaded
+            or (@hasDecl(root, "event_loop_mode") and root.event_loop_mode == .single_threaded)) {
             return self.initSingleThreaded();
         } else {
             return self.initMultiThreaded();
diff --git a/lib/std/fs/file.zig b/lib/std/fs/file.zig
index ef1b501ec3..73babf5fa2 100644
--- a/lib/std/fs/file.zig
+++ b/lib/std/fs/file.zig
@@ -728,7 +728,7 @@ pub const File = struct {
         }
         var i: usize = 0;
         while (i < trailers.len) {
-            while (amt >= headers[i].iov_len) {
+            while (amt >= trailers[i].iov_len) {
                 amt -= trailers[i].iov_len;
                 i += 1;
                 if (i >= trailers.len) return;
@@ -740,14 +740,16 @@ pub const File = struct {
     }
 
     pub const Reader = io.Reader(File, ReadError, read);
+
     /// Deprecated: use `Reader`
     pub const InStream = Reader;
 
-    pub fn reader(file: File) io.Reader(File, ReadError, read) {
+    pub fn reader(file: File) Reader {
         return .{ .context = file };
     }
+
     /// Deprecated: use `reader`
-    pub fn inStream(file: File) io.InStream(File, ReadError, read) {
+    pub fn inStream(file: File) Reader {
         return .{ .context = file };
     }
 
diff --git a/lib/std/os.zig b/lib/std/os.zig
index 181bf4930d..91365c81dd 100644
--- a/lib/std/os.zig
+++ b/lib/std/os.zig
@@ -2515,9 +2515,9 @@ pub fn readlinkatZ(dirfd: fd_t, file_path: [*:0]const u8, out_buffer: []u8) Read
 pub const SetEidError = error{
     InvalidUserId,
     PermissionDenied,
-};
+} || UnexpectedError;
 
-pub const SetIdError = error{ResourceLimitReached} || SetEidError || UnexpectedError;
+pub const SetIdError = error{ResourceLimitReached} || SetEidError;
 
 pub fn setuid(uid: uid_t) SetIdError!void {
     switch (errno(system.setuid(uid))) {
@@ -5418,3 +5418,42 @@ pub fn fdatasync(fd: fd_t) SyncError!void {
         else => |err| return std.os.unexpectedErrno(err),
     }
 }
+
+pub const PrctlError = error{
+    /// Can only occur with PR_SET_SECCOMP/SECCOMP_MODE_FILTER or
+    /// PR_SET_MM/PR_SET_MM_EXE_FILE
+    AccessDenied,
+    /// Can only occur with PR_SET_MM/PR_SET_MM_EXE_FILE
+    InvalidFileDescriptor,
+    InvalidAddress,
+    /// Can only occur with PR_SET_SPECULATION_CTRL, PR_MPX_ENABLE_MANAGEMENT,
+    /// or PR_MPX_DISABLE_MANAGEMENT
+    UnsupportedFeature,
+    /// Can only occur wih PR_SET_FP_MODE
+    OperationNotSupported,
+    PermissionDenied,
+} || UnexpectedError;
+
+pub fn prctl(option: i32, args: anytype) PrctlError!u31 {
+    if (@typeInfo(@TypeOf(args)) != .Struct)
+        @compileError("Expected tuple or struct argument, found " ++ @typeName(@TypeOf(args)));
+    if (args.len > 4)
+        @compileError("prctl takes a maximum of 4 optional arguments");
+
+    var buf: [4]usize = undefined;
+    inline for (args) |arg, i| buf[i] = arg;
+
+    const rc = system.prctl(option, buf[0], buf[1], buf[2], buf[3]);
+    switch (errno(rc)) {
+        0 => return @intCast(u31, rc),
+        EACCES => return error.AccessDenied,
+        EBADF => return error.InvalidFileDescriptor,
+        EFAULT => return error.InvalidAddress,
+        EINVAL => unreachable,
+        ENODEV, ENXIO => return error.UnsupportedFeature,
+        EOPNOTSUPP => return error.OperationNotSupported,
+        EPERM, EBUSY => return error.PermissionDenied,
+        ERANGE => unreachable,
+        else => |err| return std.os.unexpectedErrno(err),
+    }
+}
diff --git a/lib/std/os/bits/linux.zig b/lib/std/os/bits/linux.zig
index cec8833dfe..df31bc32fd 100644
--- a/lib/std/os/bits/linux.zig
+++ b/lib/std/os/bits/linux.zig
@@ -20,10 +20,13 @@ pub usingnamespace switch (builtin.arch) {
     .arm => @import("linux/arm-eabi.zig"),
     .riscv64 => @import("linux/riscv64.zig"),
     .mips, .mipsel => @import("linux/mips.zig"),
+    .powerpc64, .powerpc64le => @import("linux/powerpc64.zig"),
     else => struct {},
 };
 
 pub usingnamespace @import("linux/netlink.zig");
+pub usingnamespace @import("linux/prctl.zig");
+pub usingnamespace @import("linux/securebits.zig");
 
 const is_mips = builtin.arch.isMIPS();
 
diff --git a/lib/std/os/bits/linux/powerpc64.zig b/lib/std/os/bits/linux/powerpc64.zig
new file mode 100644
index 0000000000..adc6c87c1a
--- /dev/null
+++ b/lib/std/os/bits/linux/powerpc64.zig
@@ -0,0 +1,602 @@
+const std = @import("../../../std.zig");
+const linux = std.os.linux;
+const socklen_t = linux.socklen_t;
+const iovec = linux.iovec;
+const iovec_const = linux.iovec_const;
+const uid_t = linux.uid_t;
+const gid_t = linux.gid_t;
+const pid_t = linux.pid_t;
+const stack_t = linux.stack_t;
+const sigset_t = linux.sigset_t;
+pub const SYS = extern enum(usize) {
+    restart_syscall = 0,
+    exit = 1,
+    fork = 2,
+    read = 3,
+    write = 4,
+    open = 5,
+    close = 6,
+    waitpid = 7,
+    creat = 8,
+    link = 9,
+    unlink = 10,
+    execve = 11,
+    chdir = 12,
+    time = 13,
+    mknod = 14,
+    chmod = 15,
+    lchown = 16,
+    @"break" = 17,
+    oldstat = 18,
+    lseek = 19,
+    getpid = 20,
+    mount = 21,
+    umount = 22,
+    setuid = 23,
+    getuid = 24,
+    stime = 25,
+    ptrace = 26,
+    alarm = 27,
+    oldfstat = 28,
+    pause = 29,
+    utime = 30,
+    stty = 31,
+    gtty = 32,
+    access = 33,
+    nice = 34,
+    ftime = 35,
+    sync = 36,
+    kill = 37,
+    rename = 38,
+    mkdir = 39,
+    rmdir = 40,
+    dup = 41,
+    pipe = 42,
+    times = 43,
+    prof = 44,
+    brk = 45,
+    setgid = 46,
+    getgid = 47,
+    signal = 48,
+    geteuid = 49,
+    getegid = 50,
+    acct = 51,
+    umount2 = 52,
+    lock = 53,
+    ioctl = 54,
+    fcntl = 55,
+    mpx = 56,
+    setpgid = 57,
+    ulimit = 58,
+    oldolduname = 59,
+    umask = 60,
+    chroot = 61,
+    ustat = 62,
+    dup2 = 63,
+    getppid = 64,
+    getpgrp = 65,
+    setsid = 66,
+    sigaction = 67,
+    sgetmask = 68,
+    ssetmask = 69,
+    setreuid = 70,
+    setregid = 71,
+    sigsuspend = 72,
+    sigpending = 73,
+    sethostname = 74,
+    setrlimit = 75,
+    getrlimit = 76,
+    getrusage = 77,
+    gettimeofday = 78,
+    settimeofday = 79,
+    getgroups = 80,
+    setgroups = 81,
+    select = 82,
+    symlink = 83,
+    oldlstat = 84,
+    readlink = 85,
+    uselib = 86,
+    swapon = 87,
+    reboot = 88,
+    readdir = 89,
+    mmap = 90,
+    munmap = 91,
+    truncate = 92,
+    ftruncate = 93,
+    fchmod = 94,
+    fchown = 95,
+    getpriority = 96,
+    setpriority = 97,
+    profil = 98,
+    statfs = 99,
+    fstatfs = 100,
+    ioperm = 101,
+    socketcall = 102,
+    syslog = 103,
+    setitimer = 104,
+    getitimer = 105,
+    stat = 106,
+    lstat = 107,
+    fstat = 108,
+    olduname = 109,
+    iopl = 110,
+    vhangup = 111,
+    idle = 112,
+    vm86 = 113,
+    wait4 = 114,
+    swapoff = 115,
+    sysinfo = 116,
+    ipc = 117,
+    fsync = 118,
+    sigreturn = 119,
+    clone = 120,
+    setdomainname = 121,
+    uname = 122,
+    modify_ldt = 123,
+    adjtimex = 124,
+    mprotect = 125,
+    sigprocmask = 126,
+    create_module = 127,
+    init_module = 128,
+    delete_module = 129,
+    get_kernel_syms = 130,
+    quotactl = 131,
+    getpgid = 132,
+    fchdir = 133,
+    bdflush = 134,
+    sysfs = 135,
+    personality = 136,
+    afs_syscall = 137,
+    setfsuid = 138,
+    setfsgid = 139,
+    _llseek = 140,
+    getdents = 141,
+    _newselect = 142,
+    flock = 143,
+    msync = 144,
+    readv = 145,
+    writev = 146,
+    getsid = 147,
+    fdatasync = 148,
+    _sysctl = 149,
+    mlock = 150,
+    munlock = 151,
+    mlockall = 152,
+    munlockall = 153,
+    sched_setparam = 154,
+    sched_getparam = 155,
+    sched_setscheduler = 156,
+    sched_getscheduler = 157,
+    sched_yield = 158,
+    sched_get_priority_max = 159,
+    sched_get_priority_min = 160,
+    sched_rr_get_interval = 161,
+    nanosleep = 162,
+    mremap = 163,
+    setresuid = 164,
+    getresuid = 165,
+    query_module = 166,
+    poll = 167,
+    nfsservctl = 168,
+    setresgid = 169,
+    getresgid = 170,
+    prctl = 171,
+    rt_sigreturn = 172,
+    rt_sigaction = 173,
+    rt_sigprocmask = 174,
+    rt_sigpending = 175,
+    rt_sigtimedwait = 176,
+    rt_sigqueueinfo = 177,
+    rt_sigsuspend = 178,
+    pread64 = 179,
+    pwrite64 = 180,
+    chown = 181,
+    getcwd = 182,
+    capget = 183,
+    capset = 184,
+    sigaltstack = 185,
+    sendfile = 186,
+    getpmsg = 187,
+    putpmsg = 188,
+    vfork = 189,
+    ugetrlimit = 190,
+    readahead = 191,
+    pciconfig_read = 198,
+    pciconfig_write = 199,
+    pciconfig_iobase = 200,
+    multiplexer = 201,
+    getdents64 = 202,
+    pivot_root = 203,
+    madvise = 205,
+    mincore = 206,
+    gettid = 207,
+    tkill = 208,
+    setxattr = 209,
+    lsetxattr = 210,
+    fsetxattr = 211,
+    getxattr = 212,
+    lgetxattr = 213,
+    fgetxattr = 214,
+    listxattr = 215,
+    llistxattr = 216,
+    flistxattr = 217,
+    removexattr = 218,
+    lremovexattr = 219,
+    fremovexattr = 220,
+    futex = 221,
+    sched_setaffinity = 222,
+    sched_getaffinity = 223,
+    tuxcall = 225,
+    io_setup = 227,
+    io_destroy = 228,
+    io_getevents = 229,
+    io_submit = 230,
+    io_cancel = 231,
+    set_tid_address = 232,
+    fadvise64 = 233,
+    exit_group = 234,
+    lookup_dcookie = 235,
+    epoll_create = 236,
+    epoll_ctl = 237,
+    epoll_wait = 238,
+    remap_file_pages = 239,
+    timer_create = 240,
+    timer_settime = 241,
+    timer_gettime = 242,
+    timer_getoverrun = 243,
+    timer_delete = 244,
+    clock_settime = 245,
+    clock_gettime = 246,
+    clock_getres = 247,
+    clock_nanosleep = 248,
+    swapcontext = 249,
+    tgkill = 250,
+    utimes = 251,
+    statfs64 = 252,
+    fstatfs64 = 253,
+    rtas = 255,
+    sys_debug_setcontext = 256,
+    migrate_pages = 258,
+    mbind = 259,
+    get_mempolicy = 260,
+    set_mempolicy = 261,
+    mq_open = 262,
+    mq_unlink = 263,
+    mq_timedsend = 264,
+    mq_timedreceive = 265,
+    mq_notify = 266,
+    mq_getsetattr = 267,
+    kexec_load = 268,
+    add_key = 269,
+    request_key = 270,
+    keyctl = 271,
+    waitid = 272,
+    ioprio_set = 273,
+    ioprio_get = 274,
+    inotify_init = 275,
+    inotify_add_watch = 276,
+    inotify_rm_watch = 277,
+    spu_run = 278,
+    spu_create = 279,
+    pselect6 = 280,
+    ppoll = 281,
+    unshare = 282,
+    splice = 283,
+    tee = 284,
+    vmsplice = 285,
+    openat = 286,
+    mkdirat = 287,
+    mknodat = 288,
+    fchownat = 289,
+    futimesat = 290,
+    newfstatat = 291,
+    unlinkat = 292,
+    renameat = 293,
+    linkat = 294,
+    symlinkat = 295,
+    readlinkat = 296,
+    fchmodat = 297,
+    faccessat = 298,
+    get_robust_list = 299,
+    set_robust_list = 300,
+    move_pages = 301,
+    getcpu = 302,
+    epoll_pwait = 303,
+    utimensat = 304,
+    signalfd = 305,
+    timerfd_create = 306,
+    eventfd = 307,
+    sync_file_range2 = 308,
+    fallocate = 309,
+    subpage_prot = 310,
+    timerfd_settime = 311,
+    timerfd_gettime = 312,
+    signalfd4 = 313,
+    eventfd2 = 314,
+    epoll_create1 = 315,
+    dup3 = 316,
+    pipe2 = 317,
+    inotify_init1 = 318,
+    perf_event_open = 319,
+    preadv = 320,
+    pwritev = 321,
+    rt_tgsigqueueinfo = 322,
+    fanotify_init = 323,
+    fanotify_mark = 324,
+    prlimit64 = 325,
+    socket = 326,
+    bind = 327,
+    connect = 328,
+    listen = 329,
+    accept = 330,
+    getsockname = 331,
+    getpeername = 332,
+    socketpair = 333,
+    send = 334,
+    sendto = 335,
+    recv = 336,
+    recvfrom = 337,
+    shutdown = 338,
+    setsockopt = 339,
+    getsockopt = 340,
+    sendmsg = 341,
+    recvmsg = 342,
+    recvmmsg = 343,
+    accept4 = 344,
+    name_to_handle_at = 345,
+    open_by_handle_at = 346,
+    clock_adjtime = 347,
+    syncfs = 348,
+    sendmmsg = 349,
+    setns = 350,
+    process_vm_readv = 351,
+    process_vm_writev = 352,
+    finit_module = 353,
+    kcmp = 354,
+    sched_setattr = 355,
+    sched_getattr = 356,
+    renameat2 = 357,
+    seccomp = 358,
+    getrandom = 359,
+    memfd_create = 360,
+    bpf = 361,
+    execveat = 362,
+    switch_endian = 363,
+    userfaultfd = 364,
+    membarrier = 365,
+    mlock2 = 378,
+    copy_file_range = 379,
+    preadv2 = 380,
+    pwritev2 = 381,
+    kexec_file_load = 382,
+    statx = 383,
+    pkey_alloc = 384,
+    pkey_free = 385,
+    pkey_mprotect = 386,
+    rseq = 387,
+    io_pgetevents = 388,
+    semtimedop = 392,
+    semget = 393,
+    semctl = 394,
+    shmget = 395,
+    shmctl = 396,
+    shmat = 397,
+    shmdt = 398,
+    msgget = 399,
+    msgsnd = 400,
+    msgrcv = 401,
+    msgctl = 402,
+    pidfd_send_signal = 424,
+    io_uring_setup = 425,
+    io_uring_enter = 426,
+    io_uring_register = 427,
+    open_tree = 428,
+    move_mount = 429,
+    fsopen = 430,
+    fsconfig = 431,
+    fsmount = 432,
+    fspick = 433,
+    pidfd_open = 434,
+    clone3 = 435,
+    openat2 = 437,
+    pidfd_getfd = 438,
+
+    _,
+};
+
+pub const O_CREAT = 0o100;
+pub const O_EXCL = 0o200;
+pub const O_NOCTTY = 0o400;
+pub const O_TRUNC = 0o1000;
+pub const O_APPEND = 0o2000;
+pub const O_NONBLOCK = 0o4000;
+pub const O_DSYNC = 0o10000;
+pub const O_SYNC = 0o4010000;
+pub const O_RSYNC = 0o4010000;
+pub const O_DIRECTORY = 0o40000;
+pub const O_NOFOLLOW = 0o100000;
+pub const O_CLOEXEC = 0o2000000;
+
+pub const O_ASYNC = 0o20000;
+pub const O_DIRECT = 0o400000;
+pub const O_LARGEFILE = 0o200000;
+pub const O_NOATIME = 0o1000000;
+pub const O_PATH = 0o10000000;
+pub const O_TMPFILE = 0o20200000;
+pub const O_NDELAY = O_NONBLOCK;
+
+pub const F_DUPFD = 0;
+pub const F_GETFD = 1;
+pub const F_SETFD = 2;
+pub const F_GETFL = 3;
+pub const F_SETFL = 4;
+
+pub const F_SETOWN = 8;
+pub const F_GETOWN = 9;
+pub const F_SETSIG = 10;
+pub const F_GETSIG = 11;
+
+pub const F_GETLK = 5;
+pub const F_SETLK = 6;
+pub const F_SETLKW = 7;
+
+pub const F_RDLCK = 0;
+pub const F_WRLCK = 1;
+pub const F_UNLCK = 2;
+
+pub const LOCK_SH = 1;
+pub const LOCK_EX = 2;
+pub const LOCK_UN = 8;
+pub const LOCK_NB = 4;
+
+pub const F_SETOWN_EX = 15;
+pub const F_GETOWN_EX = 16;
+
+pub const F_GETOWNER_UIDS = 17;
+
+/// stack-like segment
+pub const MAP_GROWSDOWN = 0x0100;
+
+/// ETXTBSY
+pub const MAP_DENYWRITE = 0x0800;
+
+/// mark it as an executable
+pub const MAP_EXECUTABLE = 0x1000;
+
+/// pages are locked
+pub const MAP_LOCKED = 0x0080;
+
+/// don't check for reservations
+pub const MAP_NORESERVE = 0x0040;
+
+pub const VDSO_CGT_SYM = "__kernel_clock_gettime";
+pub const VDSO_CGT_VER = "LINUX_2.6.15";
+
+pub const Flock = extern struct {
+    l_type: i16,
+    l_whence: i16,
+    l_start: off_t,
+    l_len: off_t,
+    l_pid: pid_t,
+    __unused: [4]u8,
+};
+
+pub const msghdr = extern struct {
+    msg_name: ?*sockaddr,
+    msg_namelen: socklen_t,
+    msg_iov: [*]iovec,
+    msg_iovlen: usize,
+    msg_control: ?*c_void,
+    msg_controllen: usize,
+    msg_flags: i32,
+};
+
+pub const msghdr_const = extern struct {
+    msg_name: ?*const sockaddr,
+    msg_namelen: socklen_t,
+    msg_iov: [*]iovec_const,
+    msg_iovlen: usize,
+    msg_control: ?*c_void,
+    msg_controllen: usize,
+    msg_flags: i32,
+};
+
+pub const blksize_t = i64;
+pub const nlink_t = u64;
+pub const time_t = i64;
+pub const mode_t = u32;
+pub const off_t = i64;
+pub const ino_t = u64;
+pub const dev_t = u64;
+pub const blkcnt_t = i64;
+
+/// Renamed to Stat to not conflict with the stat function.
+/// atime, mtime, and ctime have functions to return `timespec`,
+/// because although this is a POSIX API, the layout and names of
+/// the structs are inconsistent across operating systems, and
+/// in C, macros are used to hide the differences. Here we use
+/// methods to accomplish this.
+pub const Stat = extern struct {
+    dev: dev_t,
+    ino: ino_t,
+    nlink: nlink_t,
+    mode: mode_t,
+    uid: uid_t,
+    gid: gid_t,
+    rdev: dev_t,
+    size: off_t,
+    blksize: blksize_t,
+    blocks: blkcnt_t,
+    atim: timespec,
+    mtim: timespec,
+    ctim: timespec,
+    __unused: [3]u64,
+
+    pub fn atime(self: Stat) timespec {
+        return self.atim;
+    }
+
+    pub fn mtime(self: Stat) timespec {
+        return self.mtim;
+    }
+
+    pub fn ctime(self: Stat) timespec {
+        return self.ctim;
+    }
+};
+
+pub const timespec = extern struct {
+    tv_sec: time_t,
+    tv_nsec: isize,
+};
+
+pub const timeval = extern struct {
+    tv_sec: isize,
+    tv_usec: isize,
+};
+
+pub const timezone = extern struct {
+    tz_minuteswest: i32,
+    tz_dsttime: i32,
+};
+
+pub const greg_t = u64;
+pub const gregset_t = [48]greg_t;
+pub const fpregset_t = [33]f64;
+
+/// The position of the vscr register depends on endianness.
+/// On C, macros are used to change vscr_word's offset to
+/// account for this. Here we'll just define vscr_word_le
+/// and vscr_word_be. Code must take care to use the correct one.
+pub const vrregset = extern struct {
+    vrregs: [32][4]u32 align(16),
+    vscr_word_le: u32,
+    _pad1: [2]u32,
+    vscr_word_be: u32,
+    vrsave: u32,
+    _pad2: [3]u32,
+};
+pub const vrregset_t = vrregset;
+
+pub const mcontext_t = extern struct {
+    __unused: [4]u64,
+    signal: i32,
+    _pad0: i32,
+    handler: u64,
+    oldmask: u64,
+    regs: ?*c_void,
+    gp_regs: gregset_t,
+    fp_regs: fpregset_t,
+    v_regs: *vrregset_t,
+    vmx_reserve: [34 + 34 + 32 + 1]i64,
+};
+
+pub const ucontext_t = extern struct {
+    flags: u32,
+    link: *ucontext_t,
+    stack: stack_t,
+    sigmask: sigset_t,
+    mcontext: mcontext_t,
+};
+
+pub const Elf_Symndx = u32;
diff --git a/lib/std/os/bits/linux/prctl.zig b/lib/std/os/bits/linux/prctl.zig
new file mode 100644
index 0000000000..7fa9969af4
--- /dev/null
+++ b/lib/std/os/bits/linux/prctl.zig
@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2015-2020 Zig Contributors
+// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
+// The MIT license requires this copyright notice to be included in all copies
+// and substantial portions of the software.
+
+pub const PR_SET_PDEATHSIG = 1;
+pub const PR_GET_PDEATHSIG = 2;
+
+pub const PR_GET_DUMPABLE = 3;
+pub const PR_SET_DUMPABLE = 4;
+
+pub const PR_GET_UNALIGN = 5;
+pub const PR_SET_UNALIGN = 6;
+pub const PR_UNALIGN_NOPRINT = 1;
+pub const PR_UNALIGN_SIGBUS = 2;
+
+pub const PR_GET_KEEPCAPS = 7;
+pub const PR_SET_KEEPCAPS = 8;
+
+pub const PR_GET_FPEMU = 9;
+pub const PR_SET_FPEMU = 10;
+pub const PR_FPEMU_NOPRINT = 1;
+pub const PR_FPEMU_SIGFPE = 2;
+
+pub const PR_GET_FPEXC = 11;
+pub const PR_SET_FPEXC = 12;
+pub const PR_FP_EXC_SW_ENABLE = 0x80;
+pub const PR_FP_EXC_DIV = 0x010000;
+pub const PR_FP_EXC_OVF = 0x020000;
+pub const PR_FP_EXC_UND = 0x040000;
+pub const PR_FP_EXC_RES = 0x080000;
+pub const PR_FP_EXC_INV = 0x100000;
+pub const PR_FP_EXC_DISABLED = 0;
+pub const PR_FP_EXC_NONRECOV = 1;
+pub const PR_FP_EXC_ASYNC = 2;
+pub const PR_FP_EXC_PRECISE = 3;
+
+pub const PR_GET_TIMING = 13;
+pub const PR_SET_TIMING = 14;
+pub const PR_TIMING_STATISTICAL = 0;
+pub const PR_TIMING_TIMESTAMP = 1;
+
+pub const PR_SET_NAME = 15;
+pub const PR_GET_NAME = 16;
+
+pub const PR_GET_ENDIAN = 19;
+pub const PR_SET_ENDIAN = 20;
+pub const PR_ENDIAN_BIG = 0;
+pub const PR_ENDIAN_LITTLE = 1;
+pub const PR_ENDIAN_PPC_LITTLE = 2;
+
+pub const PR_GET_SECCOMP = 21;
+pub const PR_SET_SECCOMP = 22;
+
+pub const PR_CAPBSET_READ = 23;
+pub const PR_CAPBSET_DROP = 24;
+
+pub const PR_GET_TSC = 25;
+pub const PR_SET_TSC = 26;
+pub const PR_TSC_ENABLE = 1;
+pub const PR_TSC_SIGSEGV = 2;
+
+pub const PR_GET_SECUREBITS = 27;
+pub const PR_SET_SECUREBITS = 28;
+
+pub const PR_SET_TIMERSLACK = 29;
+pub const PR_GET_TIMERSLACK = 30;
+
+pub const PR_TASK_PERF_EVENTS_DISABLE = 31;
+pub const PR_TASK_PERF_EVENTS_ENABLE = 32;
+
+pub const PR_MCE_KILL = 33;
+pub const PR_MCE_KILL_CLEAR = 0;
+pub const PR_MCE_KILL_SET = 1;
+
+pub const PR_MCE_KILL_LATE = 0;
+pub const PR_MCE_KILL_EARLY = 1;
+pub const PR_MCE_KILL_DEFAULT = 2;
+
+pub const PR_MCE_KILL_GET = 34;
+
+pub const PR_SET_MM = 35;
+pub const PR_SET_MM_START_CODE = 1;
+pub const PR_SET_MM_END_CODE = 2;
+pub const PR_SET_MM_START_DATA = 3;
+pub const PR_SET_MM_END_DATA = 4;
+pub const PR_SET_MM_START_STACK = 5;
+pub const PR_SET_MM_START_BRK = 6;
+pub const PR_SET_MM_BRK = 7;
+pub const PR_SET_MM_ARG_START = 8;
+pub const PR_SET_MM_ARG_END = 9;
+pub const PR_SET_MM_ENV_START = 10;
+pub const PR_SET_MM_ENV_END = 11;
+pub const PR_SET_MM_AUXV = 12;
+pub const PR_SET_MM_EXE_FILE = 13;
+pub const PR_SET_MM_MAP = 14;
+pub const PR_SET_MM_MAP_SIZE = 15;
+
+pub const prctl_mm_map = extern struct {
+    start_code: u64,
+    end_code: u64,
+    start_data: u64,
+    end_data: u64,
+    start_brk: u64,
+    brk: u64,
+    start_stack: u64,
+    arg_start: u64,
+    arg_end: u64,
+    env_start: u64,
+    env_end: u64,
+    auxv: *u64,
+    auxv_size: u32,
+    exe_fd: u32,
+};
+
+pub const PR_SET_PTRACER = 0x59616d61;
+pub const PR_SET_PTRACER_ANY = std.math.maxInt(c_ulong);
+
+pub const PR_SET_CHILD_SUBREAPER = 36;
+pub const PR_GET_CHILD_SUBREAPER = 37;
+
+pub const PR_SET_NO_NEW_PRIVS = 38;
+pub const PR_GET_NO_NEW_PRIVS = 39;
+
+pub const PR_GET_TID_ADDRESS = 40;
+
+pub const PR_SET_THP_DISABLE = 41;
+pub const PR_GET_THP_DISABLE = 42;
+
+pub const PR_MPX_ENABLE_MANAGEMENT = 43;
+pub const PR_MPX_DISABLE_MANAGEMENT = 44;
+
+pub const PR_SET_FP_MODE = 45;
+pub const PR_GET_FP_MODE = 46;
+pub const PR_FP_MODE_FR = 1 << 0;
+pub const PR_FP_MODE_FRE = 1 << 1;
+
+pub const PR_CAP_AMBIENT = 47;
+pub const PR_CAP_AMBIENT_IS_SET = 1;
+pub const PR_CAP_AMBIENT_RAISE = 2;
+pub const PR_CAP_AMBIENT_LOWER = 3;
+pub const PR_CAP_AMBIENT_CLEAR_ALL = 4;
+
+pub const PR_SVE_SET_VL = 50;
+pub const PR_SVE_SET_VL_ONEXEC = 1 << 18;
+pub const PR_SVE_GET_VL = 51;
+pub const PR_SVE_VL_LEN_MASK = 0xffff;
+pub const PR_SVE_VL_INHERIT = 1 << 17;
+
+pub const PR_GET_SPECULATION_CTRL = 52;
+pub const PR_SET_SPECULATION_CTRL = 53;
+pub const PR_SPEC_STORE_BYPASS = 0;
+pub const PR_SPEC_NOT_AFFECTED = 0;
+pub const PR_SPEC_PRCTL = 1 << 0;
+pub const PR_SPEC_ENABLE = 1 << 1;
+pub const PR_SPEC_DISABLE = 1 << 2;
+pub const PR_SPEC_FORCE_DISABLE = 1 << 3;
diff --git a/lib/std/os/bits/linux/securebits.zig b/lib/std/os/bits/linux/securebits.zig
new file mode 100644
index 0000000000..0086a694d9
--- /dev/null
+++ b/lib/std/os/bits/linux/securebits.zig
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2015-2020 Zig Contributors
+// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
+// The MIT license requires this copyright notice to be included in all copies
+// and substantial portions of the software.
+
+fn issecure_mask(comptime x: comptime_int) comptime_int {
+    return 1 << x;
+}
+
+pub const SECUREBITS_DEFAULT = 0x00000000;
+
+pub const SECURE_NOROOT = 0;
+pub const SECURE_NOROOT_LOCKED = 1;
+
+pub const SECBIT_NOROOT = issecure_mask(SECURE_NOROOT);
+pub const SECBIT_NOROOT_LOCKED = issecure_mask(SECURE_NOROOT_LOCKED);
+
+pub const SECURE_NO_SETUID_FIXUP = 2;
+pub const SECURE_NO_SETUID_FIXUP_LOCKED = 3;
+
+pub const SECBIT_NO_SETUID_FIXUP = issecure_mask(SECURE_NO_SETUID_FIXUP);
+pub const SECBIT_NO_SETUID_FIXUP_LOCKED = issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED);
+
+pub const SECURE_KEEP_CAPS = 4;
+pub const SECURE_KEEP_CAPS_LOCKED = 5;
+
+pub const SECBIT_KEEP_CAPS = issecure_mask(SECURE_KEEP_CAPS);
+pub const SECBIT_KEEP_CAPS_LOCKED = issecure_mask(SECURE_KEEP_CAPS_LOCKED);
+
+pub const SECURE_NO_CAP_AMBIENT_RAISE = 6;
+pub const SECURE_NO_CAP_AMBIENT_RAISE_LOCKED = 7;
+
+pub const SECBIT_NO_CAP_AMBIENT_RAISE = issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE);
+pub const SECBIT_NO_CAP_AMBIENT_RAISE_LOCKED = issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE_LOCKED);
+
+pub const SECURE_ALL_BITS = issecure_mask(SECURE_NOROOT) |
+    issecure_mask(SECURE_NO_SETUID_FIXUP) |
+    issecure_mask(SECURE_KEEP_CAPS) |
+    issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE);
+pub const SECURE_ALL_LOCKS = SECURE_ALL_BITS << 1;
diff --git a/lib/std/os/linux.zig b/lib/std/os/linux.zig
index 8f697fb967..50d1e4ae78 100644
--- a/lib/std/os/linux.zig
+++ b/lib/std/os/linux.zig
@@ -25,6 +25,7 @@ pub usingnamespace switch (builtin.arch) {
     .arm => @import("linux/arm-eabi.zig"),
     .riscv64 => @import("linux/riscv64.zig"),
     .mips, .mipsel => @import("linux/mips.zig"),
+    .powerpc64, .powerpc64le => @import("linux/powerpc64.zig"),
     else => struct {},
 };
 pub usingnamespace @import("bits.zig");
@@ -1258,6 +1259,10 @@ pub fn fdatasync(fd: fd_t) usize {
     return syscall1(.fdatasync, @bitCast(usize, @as(isize, fd)));
 }
 
+pub fn prctl(option: i32, arg2: usize, arg3: usize, arg4: usize, arg5: usize) usize {
+    return syscall5(.prctl, @bitCast(usize, @as(isize, option)), arg2, arg3, arg4, arg5);
+}
+
 test "" {
     if (builtin.os.tag == .linux) {
         _ = @import("linux/test.zig");
diff --git a/lib/std/os/linux/powerpc64.zig b/lib/std/os/linux/powerpc64.zig
new file mode 100644
index 0000000000..337a6aa30a
--- /dev/null
+++ b/lib/std/os/linux/powerpc64.zig
@@ -0,0 +1,127 @@
+usingnamespace @import("../bits.zig");
+
+pub fn syscall0(number: SYS) usize {
+    return asm volatile (
+        \\ sc
+        \\ bns+ 1f
+        \\ neg 3, 3
+        \\ 1:
+        : [ret] "={r3}" (-> usize)
+        : [number] "{r0}" (@enumToInt(number))
+        : "memory", "cr0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12"
+    );
+}
+
+pub fn syscall1(number: SYS, arg1: usize) usize {
+    return asm volatile (
+        \\ sc
+        \\ bns+ 1f
+        \\ neg 3, 3
+        \\ 1:
+        : [ret] "={r3}" (-> usize)
+        : [number] "{r0}" (@enumToInt(number)),
+          [arg1] "{r3}" (arg1)
+        : "memory", "cr0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12"
+    );
+}
+
+pub fn syscall2(number: SYS, arg1: usize, arg2: usize) usize {
+    return asm volatile (
+        \\ sc
+        \\ bns+ 1f
+        \\ neg 3, 3
+        \\ 1:
+        : [ret] "={r3}" (-> usize)
+        : [number] "{r0}" (@enumToInt(number)),
+          [arg1] "{r3}" (arg1),
+          [arg2] "{r4}" (arg2)
+        : "memory", "cr0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12"
+    );
+}
+
+pub fn syscall3(number: SYS, arg1: usize, arg2: usize, arg3: usize) usize {
+    return asm volatile (
+        \\ sc
+        \\ bns+ 1f
+        \\ neg 3, 3
+        \\ 1:
+        : [ret] "={r3}" (-> usize)
+        : [number] "{r0}" (@enumToInt(number)),
+          [arg1] "{r3}" (arg1),
+          [arg2] "{r4}" (arg2),
+          [arg3] "{r5}" (arg3)
+        : "memory", "cr0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12"
+    );
+}
+
+pub fn syscall4(number: SYS, arg1: usize, arg2: usize, arg3: usize, arg4: usize) usize {
+    return asm volatile (
+        \\ sc
+        \\ bns+ 1f
+        \\ neg 3, 3
+        \\ 1:
+        : [ret] "={r3}" (-> usize)
+        : [number] "{r0}" (@enumToInt(number)),
+          [arg1] "{r3}" (arg1),
+          [arg2] "{r4}" (arg2),
+          [arg3] "{r5}" (arg3),
+          [arg4] "{r6}" (arg4)
+        : "memory", "cr0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12"
+    );
+}
+
+pub fn syscall5(number: SYS, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) usize {
+    return asm volatile (
+        \\ sc
+        \\ bns+ 1f
+        \\ neg 3, 3
+        \\ 1:
+        : [ret] "={r3}" (-> usize)
+        : [number] "{r0}" (@enumToInt(number)),
+          [arg1] "{r3}" (arg1),
+          [arg2] "{r4}" (arg2),
+          [arg3] "{r5}" (arg3),
+          [arg4] "{r6}" (arg4),
+          [arg5] "{r7}" (arg5)
+        : "memory", "cr0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12"
+    );
+}
+
+pub fn syscall6(
+    number: SYS,
+    arg1: usize,
+    arg2: usize,
+    arg3: usize,
+    arg4: usize,
+    arg5: usize,
+    arg6: usize,
+) usize {
+    return asm volatile (
+        \\ sc
+        \\ bns+ 1f
+        \\ neg 3, 3
+        \\ 1:
+        : [ret] "={r3}" (-> usize)
+        : [number] "{r0}" (@enumToInt(number)),
+          [arg1] "{r3}" (arg1),
+          [arg2] "{r4}" (arg2),
+          [arg3] "{r5}" (arg3),
+          [arg4] "{r6}" (arg4),
+          [arg5] "{r7}" (arg5),
+          [arg6] "{r8}" (arg6)
+        : "memory", "cr0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12"
+    );
+}
+
+/// This matches the libc clone function.
+pub extern fn clone(func: fn (arg: usize) callconv(.C) u8, stack: usize, flags: usize, arg: usize, ptid: *i32, tls: usize, ctid: *i32) usize;
+
+pub const restore = restore_rt;
+
+pub fn restore_rt() callconv(.Naked) void {
+    return asm volatile ("sc"
+        :
+        : [number] "{r0}" (@enumToInt(SYS.rt_sigreturn))
+        : "memory", "cr0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12"
+    );
+}
diff --git a/lib/std/os/linux/tls.zig b/lib/std/os/linux/tls.zig
index b10dae14d7..0330a4e410 100644
--- a/lib/std/os/linux/tls.zig
+++ b/lib/std/os/linux/tls.zig
@@ -53,7 +53,7 @@ const TLSVariant = enum {
 };
 
 const tls_variant = switch (builtin.arch) {
-    .arm, .armeb, .aarch64, .aarch64_be, .riscv32, .riscv64, .mips, .mipsel => TLSVariant.VariantI,
+    .arm, .armeb, .aarch64, .aarch64_be, .riscv32, .riscv64, .mips, .mipsel, .powerpc, .powerpc64, .powerpc64le => TLSVariant.VariantI,
     .x86_64, .i386 => TLSVariant.VariantII,
     else => @compileError("undefined tls_variant for this architecture"),
 };
@@ -77,12 +77,12 @@ const tls_tp_points_past_tcb = switch (builtin.arch) {
 // make the generated code more efficient
 
 const tls_tp_offset = switch (builtin.arch) {
-    .mips, .mipsel => 0x7000,
+    .mips, .mipsel, .powerpc, .powerpc64, .powerpc64le => 0x7000,
     else => 0,
 };
 
 const tls_dtv_offset = switch (builtin.arch) {
-    .mips, .mipsel => 0x8000,
+    .mips, .mipsel, .powerpc, .powerpc64, .powerpc64le => 0x8000,
     .riscv32, .riscv64 => 0x800,
     else => 0,
 };
@@ -165,6 +165,13 @@ pub fn setThreadPointer(addr: usize) void {
             const rc = std.os.linux.syscall1(.set_thread_area, addr);
             assert(rc == 0);
         },
+        .powerpc, .powerpc64, .powerpc64le => {
+            asm volatile (
+                \\ mr 13, %[addr]
+                :
+                : [addr] "r" (addr)
+            );
+        },
         else => @compileError("Unsupported architecture"),
     }
 }
diff --git a/lib/std/priority_queue.zig b/lib/std/priority_queue.zig
index 1c0d230d4d..b9be9b70bf 100644
--- a/lib/std/priority_queue.zig
+++ b/lib/std/priority_queue.zig
@@ -195,7 +195,7 @@ pub fn PriorityQueue(comptime T: type) type {
             count: usize,
 
             pub fn next(it: *Iterator) ?T {
-                if (it.count > it.queue.len - 1) return null;
+                if (it.count >= it.queue.len) return null;
                 const out = it.count;
                 it.count += 1;
                 return it.queue.items[out];
@@ -428,3 +428,12 @@ test "std.PriorityQueue: remove at index" {
     expectEqual(queue.remove(), 3);
     expectEqual(queue.removeOrNull(), null);
 }
+
+test "std.PriorityQueue: iterator while empty" {
+    var queue = PQ.init(testing.allocator, lessThan);
+    defer queue.deinit();
+
+    var it = queue.iterator();
+
+    expectEqual(it.next(), null);
+}
diff --git a/lib/std/process.zig b/lib/std/process.zig
index 9cb571714c..2813d8cbab 100644
--- a/lib/std/process.zig
+++ b/lib/std/process.zig
@@ -593,8 +593,10 @@ pub fn getUserInfo(name: []const u8) !UserInfo {
 /// TODO this reads /etc/passwd. But sometimes the user/id mapping is in something else
 /// like NIS, AD, etc. See `man nss` or look at an strace for `id myuser`.
 pub fn posixGetUserInfo(name: []const u8) !UserInfo {
-    var reader = try io.Reader.open("/etc/passwd", null);
-    defer reader.close();
+    const file = try std.fs.openFileAbsolute("/etc/passwd", .{});
+    defer file.close();
+
+    const reader = file.reader();
 
     const State = enum {
         Start,
@@ -650,8 +652,8 @@ pub fn posixGetUserInfo(name: []const u8) !UserInfo {
                             '0'...'9' => byte - '0',
                             else => return error.CorruptPasswordFile,
                         };
-                        if (@mulWithOverflow(u32, uid, 10, *uid)) return error.CorruptPasswordFile;
-                        if (@addWithOverflow(u32, uid, digit, *uid)) return error.CorruptPasswordFile;
+                        if (@mulWithOverflow(u32, uid, 10, &uid)) return error.CorruptPasswordFile;
+                        if (@addWithOverflow(u32, uid, digit, &uid)) return error.CorruptPasswordFile;
                     },
                 },
                 .ReadGroupId => switch (byte) {
@@ -666,8 +668,8 @@ pub fn posixGetUserInfo(name: []const u8) !UserInfo {
                             '0'...'9' => byte - '0',
                             else => return error.CorruptPasswordFile,
                         };
-                        if (@mulWithOverflow(u32, gid, 10, *gid)) return error.CorruptPasswordFile;
-                        if (@addWithOverflow(u32, gid, digit, *gid)) return error.CorruptPasswordFile;
+                        if (@mulWithOverflow(u32, gid, 10, &gid)) return error.CorruptPasswordFile;
+                        if (@addWithOverflow(u32, gid, digit, &gid)) return error.CorruptPasswordFile;
                     },
                 },
             }
diff --git a/lib/std/special/c.zig b/lib/std/special/c.zig
index ce8d1c29cc..53f7e1738d 100644
--- a/lib/std/special/c.zig
+++ b/lib/std/special/c.zig
@@ -394,6 +394,61 @@ fn clone() callconv(.Naked) void {
                 \\  syscall
             );
         },
+
+        .powerpc64, .powerpc64le => {
+            asm volatile (
+                \\  # store non-volatile regs r30, r31 on stack in order to put our
+                \\  # start func and its arg there
+                \\  stwu 30, -16(1)
+                \\  stw 31, 4(1)
+                \\  # save r3 (func) into r30, and r6(arg) into r31
+                \\  mr 30, 3
+                \\  mr 31, 6
+                \\  # create initial stack frame for new thread
+                \\  clrrwi 4, 4, 4
+                \\  li 0, 0
+                \\  stwu 0, -16(4)
+                \\  #move c into first arg
+                \\  mr 3, 5
+                \\  mr 5, 7
+                \\  mr 6, 8
+                \\  mr 7, 9
+                \\  # move syscall number into r0
+                \\  li 0, 120
+                \\  sc
+
+                \\  # check for syscall error
+                \\  bns+ 1f # jump to label 1 if no summary overflow.
+                \\  #else
+                \\  neg 3, 3 #negate the result (errno)
+                \\1:
+                \\  # compare sc result with 0
+                \\  cmpwi cr7, 3, 0
+
+                \\  # if not 0, jump to end
+                \\  bne cr7, 2f
+
+                \\  #else: we're the child
+                \\  #call funcptr: move arg (d) into r3
+                \\  mr 3, 31
+                \\  #move r30 (funcptr) into CTR reg
+                \\  mtctr 30
+                \\  # call CTR reg
+                \\  bctrl
+                \\  # mov SYS_exit into r0 (the exit param is already in r3)
+                \\  li 0, 1
+                \\  sc
+
+                \\2:
+                \\  # restore stack
+                \\  lwz 30, 0(1)
+                \\  lwz 31, 4(1)
+                \\  addi 1, 1, 16
+
+                \\  blr
+            );
+        },
+
         else => @compileError("Implement clone() for this arch."),
     }
 }
diff --git a/lib/std/start.zig b/lib/std/start.zig
index c65cd08981..aea31a1531 100644
--- a/lib/std/start.zig
+++ b/lib/std/start.zig
@@ -121,6 +121,21 @@ fn _start() callconv(.Naked) noreturn {
                 : [argc] "=r" (-> [*]usize)
             );
         },
+        .powerpc64le => {
+            // Before returning the stack pointer, we have to set up a backchain
+            // and a few other registers required by the ELFv2 ABI.
+            // TODO: Support powerpc64 (big endian) on ELFv2.
+            starting_stack_ptr = asm (
+                \\ mr 4, 1
+                \\ subi 1, 1, 32
+                \\ li 5, 0
+                \\ std 5, 0(1)
+                \\ mr %[argc], 4
+                : [argc] "=r" (-> [*]usize)
+                :
+                : "r4", "r5"
+            );
+        },
         else => @compileError("unsupported arch"),
     }
     // If LLVM inlines stack variables into _start, they will overwrite