Commit 6067d39522

Tristan Ross <tristan.ross@midstall.com>
2024-02-19 06:52:23
std.builtin: make atomic order fields lowercase
1 parent c260b4c
lib/compiler_rt/atomics.zig
@@ -74,7 +74,7 @@ const SpinlockTable = struct {
                         : "memory"
                     );
                 } else flag: {
-                    break :flag @atomicRmw(@TypeOf(self.v), &self.v, .Xchg, .Locked, .Acquire);
+                    break :flag @atomicRmw(@TypeOf(self.v), &self.v, .Xchg, .Locked, .acquire);
                 };
 
                 switch (flag) {
@@ -91,7 +91,7 @@ const SpinlockTable = struct {
                     : "memory"
                 );
             } else {
-                @atomicStore(@TypeOf(self.v), &self.v, .Unlocked, .Release);
+                @atomicStore(@TypeOf(self.v), &self.v, .Unlocked, .release);
             }
         }
     };
@@ -172,7 +172,7 @@ inline fn atomic_load_N(comptime T: type, src: *T, model: i32) T {
         defer sl.release();
         return src.*;
     } else {
-        return @atomicLoad(T, src, .SeqCst);
+        return @atomicLoad(T, src, .seq_cst);
     }
 }
 
@@ -203,7 +203,7 @@ inline fn atomic_store_N(comptime T: type, dst: *T, value: T, model: i32) void {
         defer sl.release();
         dst.* = value;
     } else {
-        @atomicStore(T, dst, value, .SeqCst);
+        @atomicStore(T, dst, value, .seq_cst);
     }
 }
 
@@ -239,12 +239,12 @@ fn wideUpdate(comptime T: type, ptr: *T, val: T, update: anytype) T {
 
     const mask = @as(WideAtomic, std.math.maxInt(T)) << inner_shift;
 
-    var wide_old = @atomicLoad(WideAtomic, wide_ptr, .SeqCst);
+    var wide_old = @atomicLoad(WideAtomic, wide_ptr, .seq_cst);
     while (true) {
         const old = @as(T, @truncate((wide_old & mask) >> inner_shift));
         const new = update(val, old);
         const wide_new = wide_old & ~mask | (@as(WideAtomic, new) << inner_shift);
-        if (@cmpxchgWeak(WideAtomic, wide_ptr, wide_old, wide_new, .SeqCst, .SeqCst)) |new_wide_old| {
+        if (@cmpxchgWeak(WideAtomic, wide_ptr, wide_old, wide_new, .seq_cst, .seq_cst)) |new_wide_old| {
             wide_old = new_wide_old;
         } else {
             return old;
@@ -270,7 +270,7 @@ inline fn atomic_exchange_N(comptime T: type, ptr: *T, val: T, model: i32) T {
         };
         return wideUpdate(T, ptr, val, Updater.update);
     } else {
-        return @atomicRmw(T, ptr, .Xchg, val, .SeqCst);
+        return @atomicRmw(T, ptr, .Xchg, val, .seq_cst);
     }
 }
 
@@ -315,7 +315,7 @@ inline fn atomic_compare_exchange_N(
         expected.* = value;
         return 0;
     } else {
-        if (@cmpxchgStrong(T, ptr, expected.*, desired, .SeqCst, .SeqCst)) |old_value| {
+        if (@cmpxchgStrong(T, ptr, expected.*, desired, .seq_cst, .seq_cst)) |old_value| {
             expected.* = old_value;
             return 0;
         }
@@ -373,7 +373,7 @@ inline fn fetch_op_N(comptime T: type, comptime op: std.builtin.AtomicRmwOp, ptr
         return wideUpdate(T, ptr, val, Updater.update);
     }
 
-    return @atomicRmw(T, ptr, op, val, .SeqCst);
+    return @atomicRmw(T, ptr, op, val, .seq_cst);
 }
 
 fn __atomic_fetch_add_1(ptr: *u8, val: u8, model: i32) callconv(.C) u8 {
lib/std/heap/PageAllocator.zig
@@ -30,7 +30,7 @@ fn alloc(_: *anyopaque, n: usize, log2_align: u8, ra: usize) ?[*]u8 {
         return @ptrCast(addr);
     }
 
-    const hint = @atomicLoad(@TypeOf(std.heap.next_mmap_addr_hint), &std.heap.next_mmap_addr_hint, .Unordered);
+    const hint = @atomicLoad(@TypeOf(std.heap.next_mmap_addr_hint), &std.heap.next_mmap_addr_hint, .unordered);
     const slice = os.mmap(
         hint,
         aligned_len,
@@ -41,7 +41,7 @@ fn alloc(_: *anyopaque, n: usize, log2_align: u8, ra: usize) ?[*]u8 {
     ) catch return null;
     assert(mem.isAligned(@intFromPtr(slice.ptr), mem.page_size));
     const new_hint: [*]align(mem.page_size) u8 = @alignCast(slice.ptr + aligned_len);
-    _ = @cmpxchgStrong(@TypeOf(std.heap.next_mmap_addr_hint), &std.heap.next_mmap_addr_hint, hint, new_hint, .Monotonic, .Monotonic);
+    _ = @cmpxchgStrong(@TypeOf(std.heap.next_mmap_addr_hint), &std.heap.next_mmap_addr_hint, hint, new_hint, .monotonic, .monotonic);
     return slice.ptr;
 }
 
lib/std/http/Client.zig
@@ -1642,7 +1642,7 @@ pub fn open(
 
     const host = uri.host orelse return error.UriMissingHost;
 
-    if (protocol == .tls and @atomicLoad(bool, &client.next_https_rescan_certs, .Acquire)) {
+    if (protocol == .tls and @atomicLoad(bool, &client.next_https_rescan_certs, .acquire)) {
         if (disable_tls) unreachable;
 
         client.ca_bundle_mutex.lock();
@@ -1650,7 +1650,7 @@ pub fn open(
 
         if (client.next_https_rescan_certs) {
             client.ca_bundle.rescan(client.allocator) catch return error.CertificateBundleLoadFailure;
-            @atomicStore(bool, &client.next_https_rescan_certs, false, .Release);
+            @atomicStore(bool, &client.next_https_rescan_certs, false, .release);
         }
     }
 
lib/std/os/linux/IoUring.zig
@@ -133,7 +133,7 @@ pub fn deinit(self: *IoUring) void {
 /// alternative. In Zig, we have first-class error handling... so let's use it.
 /// Matches the implementation of io_uring_get_sqe() in liburing.
 pub fn get_sqe(self: *IoUring) !*linux.io_uring_sqe {
-    const head = @atomicLoad(u32, self.sq.head, .Acquire);
+    const head = @atomicLoad(u32, self.sq.head, .acquire);
     // Remember that these head and tail offsets wrap around every four billion operations.
     // We must therefore use wrapping addition and subtraction to avoid a runtime crash.
     const next = self.sq.sqe_tail +% 1;
@@ -222,7 +222,7 @@ pub fn flush_sq(self: *IoUring) u32 {
             self.sq.sqe_head +%= 1;
         }
         // Ensure that the kernel can actually see the SQE updates when it sees the tail update.
-        @atomicStore(u32, self.sq.tail, tail, .Release);
+        @atomicStore(u32, self.sq.tail, tail, .release);
     }
     return self.sq_ready();
 }
@@ -234,7 +234,7 @@ pub fn flush_sq(self: *IoUring) u32 {
 pub fn sq_ring_needs_enter(self: *IoUring, flags: *u32) bool {
     assert(flags.* == 0);
     if ((self.flags & linux.IORING_SETUP_SQPOLL) == 0) return true;
-    if ((@atomicLoad(u32, self.sq.flags, .Unordered) & linux.IORING_SQ_NEED_WAKEUP) != 0) {
+    if ((@atomicLoad(u32, self.sq.flags, .unordered) & linux.IORING_SQ_NEED_WAKEUP) != 0) {
         flags.* |= linux.IORING_ENTER_SQ_WAKEUP;
         return true;
     }
@@ -248,14 +248,14 @@ pub fn sq_ring_needs_enter(self: *IoUring, flags: *u32) bool {
 pub fn sq_ready(self: *IoUring) u32 {
     // Always use the shared ring state (i.e. head and not sqe_head) to avoid going out of sync,
     // see https://github.com/axboe/liburing/issues/92.
-    return self.sq.sqe_tail -% @atomicLoad(u32, self.sq.head, .Acquire);
+    return self.sq.sqe_tail -% @atomicLoad(u32, self.sq.head, .acquire);
 }
 
 /// Returns the number of CQEs in the completion queue, i.e. its length.
 /// These are CQEs that the application is yet to consume.
 /// Matches the implementation of io_uring_cq_ready in liburing.
 pub fn cq_ready(self: *IoUring) u32 {
-    return @atomicLoad(u32, self.cq.tail, .Acquire) -% self.cq.head.*;
+    return @atomicLoad(u32, self.cq.tail, .acquire) -% self.cq.head.*;
 }
 
 /// Copies as many CQEs as are ready, and that can fit into the destination `cqes` slice.
@@ -313,7 +313,7 @@ pub fn copy_cqe(ring: *IoUring) !linux.io_uring_cqe {
 
 /// Matches the implementation of cq_ring_needs_flush() in liburing.
 pub fn cq_ring_needs_flush(self: *IoUring) bool {
-    return (@atomicLoad(u32, self.sq.flags, .Unordered) & linux.IORING_SQ_CQ_OVERFLOW) != 0;
+    return (@atomicLoad(u32, self.sq.flags, .unordered) & linux.IORING_SQ_CQ_OVERFLOW) != 0;
 }
 
 /// For advanced use cases only that implement custom completion queue methods.
@@ -331,7 +331,7 @@ pub fn cqe_seen(self: *IoUring, cqe: *linux.io_uring_cqe) void {
 pub fn cq_advance(self: *IoUring, count: u32) void {
     if (count > 0) {
         // Ensure the kernel only sees the new head value after the CQEs have been read.
-        @atomicStore(u32, self.cq.head, self.cq.head.* +% count, .Release);
+        @atomicStore(u32, self.cq.head, self.cq.head.* +% count, .release);
     }
 }
 
lib/std/os/linux.zig
@@ -1334,7 +1334,7 @@ const vdso_clock_gettime_ty = *align(1) const fn (i32, *timespec) callconv(.C) u
 
 pub fn clock_gettime(clk_id: i32, tp: *timespec) usize {
     if (@hasDecl(VDSO, "CGT_SYM")) {
-        const ptr = @atomicLoad(?*const anyopaque, &vdso_clock_gettime, .Unordered);
+        const ptr = @atomicLoad(?*const anyopaque, &vdso_clock_gettime, .unordered);
         if (ptr) |fn_ptr| {
             const f = @as(vdso_clock_gettime_ty, @ptrCast(fn_ptr));
             const rc = f(clk_id, tp);
@@ -1351,7 +1351,7 @@ fn init_vdso_clock_gettime(clk: i32, ts: *timespec) callconv(.C) usize {
     const ptr = @as(?*const anyopaque, @ptrFromInt(vdso.lookup(VDSO.CGT_VER, VDSO.CGT_SYM)));
     // Note that we may not have a VDSO at all, update the stub address anyway
     // so that clock_gettime will fall back on the good old (and slow) syscall
-    @atomicStore(?*const anyopaque, &vdso_clock_gettime, ptr, .Monotonic);
+    @atomicStore(?*const anyopaque, &vdso_clock_gettime, ptr, .monotonic);
     // Call into the VDSO if available
     if (ptr) |fn_ptr| {
         const f = @as(vdso_clock_gettime_ty, @ptrCast(fn_ptr));
lib/std/os/test.zig
@@ -425,7 +425,7 @@ fn start1() u8 {
 }
 
 fn start2(ctx: *i32) u8 {
-    _ = @atomicRmw(i32, ctx, AtomicRmwOp.Add, 1, AtomicOrder.SeqCst);
+    _ = @atomicRmw(i32, ctx, AtomicRmwOp.Add, 1, AtomicOrder.seq_cst);
     return 0;
 }
 
lib/std/Thread/Condition.zig
@@ -163,7 +163,7 @@ const WindowsImpl = struct {
 
         if (comptime builtin.mode == .Debug) {
             // The internal state of the DebugMutex needs to be handled here as well.
-            mutex.impl.locking_thread.store(0, .Unordered);
+            mutex.impl.locking_thread.store(0, .unordered);
         }
         const rc = os.windows.kernel32.SleepConditionVariableSRW(
             &self.condition,
@@ -173,7 +173,7 @@ const WindowsImpl = struct {
         );
         if (comptime builtin.mode == .Debug) {
             // The internal state of the DebugMutex needs to be handled here as well.
-            mutex.impl.locking_thread.store(std.Thread.getCurrentId(), .Unordered);
+            mutex.impl.locking_thread.store(std.Thread.getCurrentId(), .unordered);
         }
 
         // Return error.Timeout if we know the timeout elapsed correctly.
@@ -212,8 +212,8 @@ const FutexImpl = struct {
         // - T1: s & signals == 0 -> FUTEX_WAIT(&epoch, e) (missed the state update + the epoch change)
         //
         // Acquire barrier to ensure the epoch load happens before the state load.
-        var epoch = self.epoch.load(.Acquire);
-        var state = self.state.fetchAdd(one_waiter, .Monotonic);
+        var epoch = self.epoch.load(.acquire);
+        var state = self.state.fetchAdd(one_waiter, .monotonic);
         assert(state & waiter_mask != waiter_mask);
         state += one_waiter;
 
@@ -231,30 +231,30 @@ const FutexImpl = struct {
                         // Acquire barrier ensures code before the wake() which added the signal happens before we decrement it and return.
                         while (state & signal_mask != 0) {
                             const new_state = state - one_waiter - one_signal;
-                            state = self.state.cmpxchgWeak(state, new_state, .Acquire, .Monotonic) orelse return;
+                            state = self.state.cmpxchgWeak(state, new_state, .acquire, .monotonic) orelse return;
                         }
 
                         // Remove the waiter we added and officially return timed out.
                         const new_state = state - one_waiter;
-                        state = self.state.cmpxchgWeak(state, new_state, .Monotonic, .Monotonic) orelse return err;
+                        state = self.state.cmpxchgWeak(state, new_state, .monotonic, .monotonic) orelse return err;
                     }
                 },
             };
 
-            epoch = self.epoch.load(.Acquire);
-            state = self.state.load(.Monotonic);
+            epoch = self.epoch.load(.acquire);
+            state = self.state.load(.monotonic);
 
             // Try to wake up by consuming a signal and decremented the waiter we added previously.
             // Acquire barrier ensures code before the wake() which added the signal happens before we decrement it and return.
             while (state & signal_mask != 0) {
                 const new_state = state - one_waiter - one_signal;
-                state = self.state.cmpxchgWeak(state, new_state, .Acquire, .Monotonic) orelse return;
+                state = self.state.cmpxchgWeak(state, new_state, .acquire, .monotonic) orelse return;
             }
         }
     }
 
     fn wake(self: *Impl, comptime notify: Notify) void {
-        var state = self.state.load(.Monotonic);
+        var state = self.state.load(.monotonic);
         while (true) {
             const waiters = (state & waiter_mask) / one_waiter;
             const signals = (state & signal_mask) / one_signal;
@@ -275,7 +275,7 @@ const FutexImpl = struct {
             // Reserve the amount of waiters to wake by incrementing the signals count.
             // Release barrier ensures code before the wake() happens before the signal it posted and consumed by the wait() threads.
             const new_state = state + (one_signal * to_wake);
-            state = self.state.cmpxchgWeak(state, new_state, .Release, .Monotonic) orelse {
+            state = self.state.cmpxchgWeak(state, new_state, .release, .monotonic) orelse {
                 // Wake up the waiting threads we reserved above by changing the epoch value.
                 // NOTE: a waiting thread could miss a wake up if *exactly* ((1<<32)-1) wake()s happen between it observing the epoch and sleeping on it.
                 // This is very unlikely due to how many precise amount of Futex.wake() calls that would be between the waiting thread's potential preemption.
@@ -288,7 +288,7 @@ const FutexImpl = struct {
                 // - T1: s = LOAD(&state)
                 // - T2: UPDATE(&state, signal) + FUTEX_WAKE(&epoch)
                 // - T1: s & signals == 0 -> FUTEX_WAIT(&epoch, e) (missed both epoch change and state change)
-                _ = self.epoch.fetchAdd(1, .Release);
+                _ = self.epoch.fetchAdd(1, .release);
                 Futex.wake(&self.epoch, to_wake);
                 return;
             };
lib/std/Thread/Futex.zig
@@ -40,7 +40,7 @@ pub fn timedWait(ptr: *const atomic.Value(u32), expect: u32, timeout_ns: u64) er
 
     // Avoid calling into the OS for no-op timeouts.
     if (timeout_ns == 0) {
-        if (ptr.load(.SeqCst) != expect) return;
+        if (ptr.load(.seq_cst) != expect) return;
         return error.Timeout;
     }
 
@@ -783,16 +783,16 @@ const PosixImpl = struct {
         // - T1: bumps pending waiters (was reordered after the ptr == expect check)
         // - T1: goes to sleep and misses both the ptr change and T2's wake up
         //
-        // SeqCst as Acquire barrier to ensure the announcement happens before the ptr check below.
-        // SeqCst as shared modification order to form a happens-before edge with the fence(.SeqCst)+load() in wake().
-        var pending = bucket.pending.fetchAdd(1, .SeqCst);
+        // seq_cst as Acquire barrier to ensure the announcement happens before the ptr check below.
+        // seq_cst as shared modification order to form a happens-before edge with the fence(.seq_cst)+load() in wake().
+        var pending = bucket.pending.fetchAdd(1, .seq_cst);
         assert(pending < std.math.maxInt(usize));
 
         // If the wait gets cancelled, remove the pending count we previously added.
         // This is done outside the mutex lock to keep the critical section short in case of contention.
         var cancelled = false;
         defer if (cancelled) {
-            pending = bucket.pending.fetchSub(1, .Monotonic);
+            pending = bucket.pending.fetchSub(1, .monotonic);
             assert(pending > 0);
         };
 
@@ -850,11 +850,11 @@ const PosixImpl = struct {
         // but the RMW operation unconditionally marks the cache-line as modified for others causing unnecessary fetching/contention.
         //
         // Instead we opt to do a full-fence + load instead which avoids taking ownership of the cache-line.
-        // fence(SeqCst) effectively converts the ptr update to SeqCst and the pending load to SeqCst: creating a Store-Load barrier.
+        // fence(seq_cst) effectively converts the ptr update to seq_cst and the pending load to seq_cst: creating a Store-Load barrier.
         //
-        // The pending count increment in wait() must also now use SeqCst for the update + this pending load
-        // to be in the same modification order as our load isn't using Release/Acquire to guarantee it.
-        bucket.pending.fence(.SeqCst);
+        // The pending count increment in wait() must also now use seq_cst for the update + this pending load
+        // to be in the same modification order as our load isn't using release/acquire to guarantee it.
+        bucket.pending.fence(.seq_cst);
         if (bucket.pending.load(.Monotonic) == 0) {
             return;
         }
@@ -912,7 +912,7 @@ test "signaling" {
         current: u32 = 0,
 
         fn hit(self: *@This()) void {
-            _ = self.value.fetchAdd(1, .Release);
+            _ = self.value.fetchAdd(1, .release);
             Futex.wake(&self.value, 1);
         }
 
@@ -921,7 +921,7 @@ test "signaling" {
                 // Wait for the value to change from hit()
                 var new_value: u32 = undefined;
                 while (true) {
-                    new_value = self.value.load(.Acquire);
+                    new_value = self.value.load(.acquire);
                     if (new_value != self.current) break;
                     Futex.wait(&self.value, self.current);
                 }
@@ -968,7 +968,7 @@ test "broadcasting" {
         fn wait(self: *@This()) !void {
             // Decrement the counter.
             // Release ensures stuff before this barrier.wait() happens before the last one.
-            const count = self.count.fetchSub(1, .Release);
+            const count = self.count.fetchSub(1, .release);
             try testing.expect(count <= num_threads);
             try testing.expect(count > 0);
 
@@ -976,15 +976,15 @@ test "broadcasting" {
             // Acquire for the last counter ensures stuff before previous barrier.wait()s happened before it.
             // Release on futex update ensures stuff before all barrier.wait()'s happens before they all return.
             if (count - 1 == 0) {
-                _ = self.count.load(.Acquire); // TODO: could be fence(Acquire) if not for TSAN
-                self.futex.store(1, .Release);
+                _ = self.count.load(.acquire); // TODO: could be fence(acquire) if not for TSAN
+                self.futex.store(1, .release);
                 Futex.wake(&self.futex, num_threads - 1);
                 return;
             }
 
             // Other threads wait until last counter wakes them up.
             // Acquire on futex synchronizes with last barrier count to ensure stuff before all barrier.wait()'s happen before us.
-            while (self.futex.load(.Acquire) == 0) {
+            while (self.futex.load(.acquire) == 0) {
                 Futex.wait(&self.futex, 0);
             }
         }
lib/std/Thread/Mutex.zig
@@ -72,23 +72,23 @@ const DebugImpl = struct {
     inline fn tryLock(self: *@This()) bool {
         const locking = self.impl.tryLock();
         if (locking) {
-            self.locking_thread.store(Thread.getCurrentId(), .Unordered);
+            self.locking_thread.store(Thread.getCurrentId(), .unordered);
         }
         return locking;
     }
 
     inline fn lock(self: *@This()) void {
         const current_id = Thread.getCurrentId();
-        if (self.locking_thread.load(.Unordered) == current_id and current_id != 0) {
+        if (self.locking_thread.load(.unordered) == current_id and current_id != 0) {
             @panic("Deadlock detected");
         }
         self.impl.lock();
-        self.locking_thread.store(current_id, .Unordered);
+        self.locking_thread.store(current_id, .unordered);
     }
 
     inline fn unlock(self: *@This()) void {
-        assert(self.locking_thread.load(.Unordered) == Thread.getCurrentId());
-        self.locking_thread.store(0, .Unordered);
+        assert(self.locking_thread.load(.unordered) == Thread.getCurrentId());
+        self.locking_thread.store(0, .unordered);
         self.impl.unlock();
     }
 };
@@ -167,12 +167,12 @@ const FutexImpl = struct {
         // - `lock bts` is smaller instruction-wise which makes it better for inlining
         if (comptime builtin.target.cpu.arch.isX86()) {
             const locked_bit = @ctz(locked);
-            return self.state.bitSet(locked_bit, .Acquire) == 0;
+            return self.state.bitSet(locked_bit, .acquire) == 0;
         }
 
         // Acquire barrier ensures grabbing the lock happens before the critical section
         // and that the previous lock holder's critical section happens before we grab the lock.
-        return self.state.cmpxchgWeak(unlocked, locked, .Acquire, .Monotonic) == null;
+        return self.state.cmpxchgWeak(unlocked, locked, .acquire, .monotonic) == null;
     }
 
     fn lockSlow(self: *@This()) void {
@@ -180,7 +180,7 @@ const FutexImpl = struct {
 
         // Avoid doing an atomic swap below if we already know the state is contended.
         // An atomic swap unconditionally stores which marks the cache-line as modified unnecessarily.
-        if (self.state.load(.Monotonic) == contended) {
+        if (self.state.load(.monotonic) == contended) {
             Futex.wait(&self.state, contended);
         }
 
@@ -193,7 +193,7 @@ const FutexImpl = struct {
         //
         // Acquire barrier ensures grabbing the lock happens before the critical section
         // and that the previous lock holder's critical section happens before we grab the lock.
-        while (self.state.swap(contended, .Acquire) != unlocked) {
+        while (self.state.swap(contended, .acquire) != unlocked) {
             Futex.wait(&self.state, contended);
         }
     }
@@ -206,7 +206,7 @@ const FutexImpl = struct {
         //
         // Release barrier ensures the critical section happens before we let go of the lock
         // and that our critical section happens before the next lock holder grabs the lock.
-        const state = self.state.swap(unlocked, .Release);
+        const state = self.state.swap(unlocked, .release);
         assert(state != unlocked);
 
         if (state == contended) {
lib/std/Thread/ResetEvent.zig
@@ -96,7 +96,7 @@ const FutexImpl = struct {
 
     fn isSet(self: *const Impl) bool {
         // Acquire barrier ensures memory accesses before set() happen before we return true.
-        return self.state.load(.Acquire) == is_set;
+        return self.state.load(.acquire) == is_set;
     }
 
     fn wait(self: *Impl, timeout: ?u64) error{Timeout}!void {
@@ -112,9 +112,9 @@ const FutexImpl = struct {
         // Try to set the state from `unset` to `waiting` to indicate
         // to the set() thread that others are blocked on the ResetEvent.
         // We avoid using any strict barriers until the end when we know the ResetEvent is set.
-        var state = self.state.load(.Monotonic);
+        var state = self.state.load(.monotonic);
         if (state == unset) {
-            state = self.state.cmpxchgStrong(state, waiting, .Monotonic, .Monotonic) orelse waiting;
+            state = self.state.cmpxchgStrong(state, waiting, .monotonic, .monotonic) orelse waiting;
         }
 
         // Wait until the ResetEvent is set since the state is waiting.
@@ -124,7 +124,7 @@ const FutexImpl = struct {
                 const wait_result = futex_deadline.wait(&self.state, waiting);
 
                 // Check if the ResetEvent was set before possibly reporting error.Timeout below.
-                state = self.state.load(.Monotonic);
+                state = self.state.load(.monotonic);
                 if (state != waiting) {
                     break;
                 }
@@ -135,25 +135,25 @@ const FutexImpl = struct {
 
         // Acquire barrier ensures memory accesses before set() happen before we return.
         assert(state == is_set);
-        self.state.fence(.Acquire);
+        self.state.fence(.acquire);
     }
 
     fn set(self: *Impl) void {
         // Quick check if the ResetEvent is already set before doing the atomic swap below.
         // set() could be getting called quite often and multiple threads calling swap() increases contention unnecessarily.
-        if (self.state.load(.Monotonic) == is_set) {
+        if (self.state.load(.monotonic) == is_set) {
             return;
         }
 
         // Mark the ResetEvent as set and unblock all waiters waiting on it if any.
         // Release barrier ensures memory accesses before set() happen before the ResetEvent is observed to be "set".
-        if (self.state.swap(is_set, .Release) == waiting) {
+        if (self.state.swap(is_set, .release) == waiting) {
             Futex.wake(&self.state, std.math.maxInt(u32));
         }
     }
 
     fn reset(self: *Impl) void {
-        self.state.store(unset, .Monotonic);
+        self.state.store(unset, .monotonic);
     }
 };
 
@@ -254,7 +254,7 @@ test "broadcast" {
         counter: std.atomic.Value(usize) = std.atomic.Value(usize).init(num_threads),
 
         fn wait(self: *@This()) void {
-            if (self.counter.fetchSub(1, .AcqRel) == 1) {
+            if (self.counter.fetchSub(1, .acq_rel) == 1) {
                 self.event.set();
             }
         }
lib/std/Thread/RwLock.zig
@@ -179,9 +179,9 @@ pub const DefaultRwLock = struct {
 
     pub fn tryLock(rwl: *DefaultRwLock) bool {
         if (rwl.mutex.tryLock()) {
-            const state = @atomicLoad(usize, &rwl.state, .SeqCst);
+            const state = @atomicLoad(usize, &rwl.state, .seq_cst);
             if (state & READER_MASK == 0) {
-                _ = @atomicRmw(usize, &rwl.state, .Or, IS_WRITING, .SeqCst);
+                _ = @atomicRmw(usize, &rwl.state, .Or, IS_WRITING, .seq_cst);
                 return true;
             }
 
@@ -192,34 +192,34 @@ pub const DefaultRwLock = struct {
     }
 
     pub fn lock(rwl: *DefaultRwLock) void {
-        _ = @atomicRmw(usize, &rwl.state, .Add, WRITER, .SeqCst);
+        _ = @atomicRmw(usize, &rwl.state, .Add, WRITER, .seq_cst);
         rwl.mutex.lock();
 
-        const state = @atomicRmw(usize, &rwl.state, .Add, IS_WRITING -% WRITER, .SeqCst);
+        const state = @atomicRmw(usize, &rwl.state, .Add, IS_WRITING -% WRITER, .seq_cst);
         if (state & READER_MASK != 0)
             rwl.semaphore.wait();
     }
 
     pub fn unlock(rwl: *DefaultRwLock) void {
-        _ = @atomicRmw(usize, &rwl.state, .And, ~IS_WRITING, .SeqCst);
+        _ = @atomicRmw(usize, &rwl.state, .And, ~IS_WRITING, .seq_cst);
         rwl.mutex.unlock();
     }
 
     pub fn tryLockShared(rwl: *DefaultRwLock) bool {
-        const state = @atomicLoad(usize, &rwl.state, .SeqCst);
+        const state = @atomicLoad(usize, &rwl.state, .seq_cst);
         if (state & (IS_WRITING | WRITER_MASK) == 0) {
             _ = @cmpxchgStrong(
                 usize,
                 &rwl.state,
                 state,
                 state + READER,
-                .SeqCst,
-                .SeqCst,
+                .seq_cst,
+                .seq_cst,
             ) orelse return true;
         }
 
         if (rwl.mutex.tryLock()) {
-            _ = @atomicRmw(usize, &rwl.state, .Add, READER, .SeqCst);
+            _ = @atomicRmw(usize, &rwl.state, .Add, READER, .seq_cst);
             rwl.mutex.unlock();
             return true;
         }
@@ -228,25 +228,25 @@ pub const DefaultRwLock = struct {
     }
 
     pub fn lockShared(rwl: *DefaultRwLock) void {
-        var state = @atomicLoad(usize, &rwl.state, .SeqCst);
+        var state = @atomicLoad(usize, &rwl.state, .seq_cst);
         while (state & (IS_WRITING | WRITER_MASK) == 0) {
             state = @cmpxchgWeak(
                 usize,
                 &rwl.state,
                 state,
                 state + READER,
-                .SeqCst,
-                .SeqCst,
+                .seq_cst,
+                .seq_cst,
             ) orelse return;
         }
 
         rwl.mutex.lock();
-        _ = @atomicRmw(usize, &rwl.state, .Add, READER, .SeqCst);
+        _ = @atomicRmw(usize, &rwl.state, .Add, READER, .seq_cst);
         rwl.mutex.unlock();
     }
 
     pub fn unlockShared(rwl: *DefaultRwLock) void {
-        const state = @atomicRmw(usize, &rwl.state, .Sub, READER, .SeqCst);
+        const state = @atomicRmw(usize, &rwl.state, .Sub, READER, .seq_cst);
 
         if ((state & READER_MASK == READER) and (state & IS_WRITING != 0))
             rwl.semaphore.post();
@@ -318,12 +318,12 @@ test "concurrent access" {
                 self.rwl.lockShared();
                 defer self.rwl.unlockShared();
 
-                if (self.writes >= num_writes or self.reads.load(.Unordered) >= num_reads)
+                if (self.writes >= num_writes or self.reads.load(.unordered) >= num_reads)
                     break;
 
                 try self.check();
 
-                _ = self.reads.fetchAdd(1, .Monotonic);
+                _ = self.reads.fetchAdd(1, .monotonic);
             }
         }
 
lib/std/Thread/WaitGroup.zig
@@ -10,22 +10,22 @@ state: std.atomic.Value(usize) = std.atomic.Value(usize).init(0),
 event: std.Thread.ResetEvent = .{},
 
 pub fn start(self: *WaitGroup) void {
-    const state = self.state.fetchAdd(one_pending, .Monotonic);
+    const state = self.state.fetchAdd(one_pending, .monotonic);
     assert((state / one_pending) < (std.math.maxInt(usize) / one_pending));
 }
 
 pub fn finish(self: *WaitGroup) void {
-    const state = self.state.fetchSub(one_pending, .Release);
+    const state = self.state.fetchSub(one_pending, .release);
     assert((state / one_pending) > 0);
 
     if (state == (one_pending | is_waiting)) {
-        self.state.fence(.Acquire);
+        self.state.fence(.acquire);
         self.event.set();
     }
 }
 
 pub fn wait(self: *WaitGroup) void {
-    const state = self.state.fetchAdd(is_waiting, .Acquire);
+    const state = self.state.fetchAdd(is_waiting, .acquire);
     assert(state & is_waiting == 0);
 
     if ((state / one_pending) > 0) {
@@ -34,12 +34,12 @@ pub fn wait(self: *WaitGroup) void {
 }
 
 pub fn reset(self: *WaitGroup) void {
-    self.state.store(0, .Monotonic);
+    self.state.store(0, .monotonic);
     self.event.reset();
 }
 
 pub fn isDone(wg: *WaitGroup) bool {
-    const state = wg.state.load(.Acquire);
+    const state = wg.state.load(.acquire);
     assert(state & is_waiting == 0);
 
     return (state / one_pending) == 0;
lib/std/atomic.zig
@@ -23,10 +23,10 @@ pub fn Value(comptime T: type) type {
 
                 const addr: *anyopaque = self;
                 return switch (order) {
-                    .Unordered, .Monotonic => @compileError(@tagName(order) ++ " only applies to atomic loads and stores"),
-                    .Acquire => tsan.__tsan_acquire(addr),
-                    .Release => tsan.__tsan_release(addr),
-                    .AcqRel, .SeqCst => {
+                    .unordered, .monotonic => @compileError(@tagName(order) ++ " only applies to atomic loads and stores"),
+                    .acquire => tsan.__tsan_acquire(addr),
+                    .release => tsan.__tsan_release(addr),
+                    .acq_rel, .seq_cst => {
                         tsan.__tsan_acquire(addr);
                         tsan.__tsan_release(addr);
                     },
@@ -149,20 +149,20 @@ test Value {
 
         fn ref(rc: *RefCount) void {
             // No ordering necessary; just updating a counter.
-            _ = rc.count.fetchAdd(1, .Monotonic);
+            _ = rc.count.fetchAdd(1, .monotonic);
         }
 
         fn unref(rc: *RefCount) void {
             // Release ensures code before unref() happens-before the
             // count is decremented as dropFn could be called by then.
-            if (rc.count.fetchSub(1, .Release) == 1) {
-                // Acquire ensures count decrement and code before
+            if (rc.count.fetchSub(1, .release) == 1) {
+                // acquire ensures count decrement and code before
                 // previous unrefs()s happens-before we call dropFn
                 // below.
                 // Another alternative is to use .AcqRel on the
                 // fetchSub count decrement but it's extra barrier in
                 // possibly hot path.
-                rc.count.fence(.Acquire);
+                rc.count.fence(.acquire);
                 (rc.dropFn)(rc);
             }
         }
@@ -182,118 +182,118 @@ test Value {
 
 test "Value.swap" {
     var x = Value(usize).init(5);
-    try testing.expectEqual(@as(usize, 5), x.swap(10, .SeqCst));
-    try testing.expectEqual(@as(usize, 10), x.load(.SeqCst));
+    try testing.expectEqual(@as(usize, 5), x.swap(10, .seq_cst));
+    try testing.expectEqual(@as(usize, 10), x.load(.seq_cst));
 
     const E = enum(usize) { a, b, c };
     var y = Value(E).init(.c);
-    try testing.expectEqual(E.c, y.swap(.a, .SeqCst));
-    try testing.expectEqual(E.a, y.load(.SeqCst));
+    try testing.expectEqual(E.c, y.swap(.a, .seq_cst));
+    try testing.expectEqual(E.a, y.load(.seq_cst));
 
     var z = Value(f32).init(5.0);
-    try testing.expectEqual(@as(f32, 5.0), z.swap(10.0, .SeqCst));
-    try testing.expectEqual(@as(f32, 10.0), z.load(.SeqCst));
+    try testing.expectEqual(@as(f32, 5.0), z.swap(10.0, .seq_cst));
+    try testing.expectEqual(@as(f32, 10.0), z.load(.seq_cst));
 
     var a = Value(bool).init(false);
-    try testing.expectEqual(false, a.swap(true, .SeqCst));
-    try testing.expectEqual(true, a.load(.SeqCst));
+    try testing.expectEqual(false, a.swap(true, .seq_cst));
+    try testing.expectEqual(true, a.load(.seq_cst));
 
     var b = Value(?*u8).init(null);
-    try testing.expectEqual(@as(?*u8, null), b.swap(@as(?*u8, @ptrFromInt(@alignOf(u8))), .SeqCst));
-    try testing.expectEqual(@as(?*u8, @ptrFromInt(@alignOf(u8))), b.load(.SeqCst));
+    try testing.expectEqual(@as(?*u8, null), b.swap(@as(?*u8, @ptrFromInt(@alignOf(u8))), .seq_cst));
+    try testing.expectEqual(@as(?*u8, @ptrFromInt(@alignOf(u8))), b.load(.seq_cst));
 }
 
 test "Value.store" {
     var x = Value(usize).init(5);
-    x.store(10, .SeqCst);
-    try testing.expectEqual(@as(usize, 10), x.load(.SeqCst));
+    x.store(10, .seq_cst);
+    try testing.expectEqual(@as(usize, 10), x.load(.seq_cst));
 }
 
 test "Value.cmpxchgWeak" {
     var x = Value(usize).init(0);
 
-    try testing.expectEqual(@as(?usize, 0), x.cmpxchgWeak(1, 0, .SeqCst, .SeqCst));
-    try testing.expectEqual(@as(usize, 0), x.load(.SeqCst));
+    try testing.expectEqual(@as(?usize, 0), x.cmpxchgWeak(1, 0, .seq_cst, .seq_cst));
+    try testing.expectEqual(@as(usize, 0), x.load(.seq_cst));
 
-    while (x.cmpxchgWeak(0, 1, .SeqCst, .SeqCst)) |_| {}
-    try testing.expectEqual(@as(usize, 1), x.load(.SeqCst));
+    while (x.cmpxchgWeak(0, 1, .seq_cst, .seq_cst)) |_| {}
+    try testing.expectEqual(@as(usize, 1), x.load(.seq_cst));
 
-    while (x.cmpxchgWeak(1, 0, .SeqCst, .SeqCst)) |_| {}
-    try testing.expectEqual(@as(usize, 0), x.load(.SeqCst));
+    while (x.cmpxchgWeak(1, 0, .seq_cst, .seq_cst)) |_| {}
+    try testing.expectEqual(@as(usize, 0), x.load(.seq_cst));
 }
 
 test "Value.cmpxchgStrong" {
     var x = Value(usize).init(0);
-    try testing.expectEqual(@as(?usize, 0), x.cmpxchgStrong(1, 0, .SeqCst, .SeqCst));
-    try testing.expectEqual(@as(usize, 0), x.load(.SeqCst));
-    try testing.expectEqual(@as(?usize, null), x.cmpxchgStrong(0, 1, .SeqCst, .SeqCst));
-    try testing.expectEqual(@as(usize, 1), x.load(.SeqCst));
-    try testing.expectEqual(@as(?usize, null), x.cmpxchgStrong(1, 0, .SeqCst, .SeqCst));
-    try testing.expectEqual(@as(usize, 0), x.load(.SeqCst));
+    try testing.expectEqual(@as(?usize, 0), x.cmpxchgStrong(1, 0, .seq_cst, .seq_cst));
+    try testing.expectEqual(@as(usize, 0), x.load(.seq_cst));
+    try testing.expectEqual(@as(?usize, null), x.cmpxchgStrong(0, 1, .seq_cst, .seq_cst));
+    try testing.expectEqual(@as(usize, 1), x.load(.seq_cst));
+    try testing.expectEqual(@as(?usize, null), x.cmpxchgStrong(1, 0, .seq_cst, .seq_cst));
+    try testing.expectEqual(@as(usize, 0), x.load(.seq_cst));
 }
 
 test "Value.fetchAdd" {
     var x = Value(usize).init(5);
-    try testing.expectEqual(@as(usize, 5), x.fetchAdd(5, .SeqCst));
-    try testing.expectEqual(@as(usize, 10), x.load(.SeqCst));
-    try testing.expectEqual(@as(usize, 10), x.fetchAdd(std.math.maxInt(usize), .SeqCst));
-    try testing.expectEqual(@as(usize, 9), x.load(.SeqCst));
+    try testing.expectEqual(@as(usize, 5), x.fetchAdd(5, .seq_cst));
+    try testing.expectEqual(@as(usize, 10), x.load(.seq_cst));
+    try testing.expectEqual(@as(usize, 10), x.fetchAdd(std.math.maxInt(usize), .seq_cst));
+    try testing.expectEqual(@as(usize, 9), x.load(.seq_cst));
 }
 
 test "Value.fetchSub" {
     var x = Value(usize).init(5);
-    try testing.expectEqual(@as(usize, 5), x.fetchSub(5, .SeqCst));
-    try testing.expectEqual(@as(usize, 0), x.load(.SeqCst));
-    try testing.expectEqual(@as(usize, 0), x.fetchSub(1, .SeqCst));
-    try testing.expectEqual(@as(usize, std.math.maxInt(usize)), x.load(.SeqCst));
+    try testing.expectEqual(@as(usize, 5), x.fetchSub(5, .seq_cst));
+    try testing.expectEqual(@as(usize, 0), x.load(.seq_cst));
+    try testing.expectEqual(@as(usize, 0), x.fetchSub(1, .seq_cst));
+    try testing.expectEqual(@as(usize, std.math.maxInt(usize)), x.load(.seq_cst));
 }
 
 test "Value.fetchMin" {
     var x = Value(usize).init(5);
-    try testing.expectEqual(@as(usize, 5), x.fetchMin(0, .SeqCst));
-    try testing.expectEqual(@as(usize, 0), x.load(.SeqCst));
-    try testing.expectEqual(@as(usize, 0), x.fetchMin(10, .SeqCst));
-    try testing.expectEqual(@as(usize, 0), x.load(.SeqCst));
+    try testing.expectEqual(@as(usize, 5), x.fetchMin(0, .seq_cst));
+    try testing.expectEqual(@as(usize, 0), x.load(.seq_cst));
+    try testing.expectEqual(@as(usize, 0), x.fetchMin(10, .seq_cst));
+    try testing.expectEqual(@as(usize, 0), x.load(.seq_cst));
 }
 
 test "Value.fetchMax" {
     var x = Value(usize).init(5);
-    try testing.expectEqual(@as(usize, 5), x.fetchMax(10, .SeqCst));
-    try testing.expectEqual(@as(usize, 10), x.load(.SeqCst));
-    try testing.expectEqual(@as(usize, 10), x.fetchMax(5, .SeqCst));
-    try testing.expectEqual(@as(usize, 10), x.load(.SeqCst));
+    try testing.expectEqual(@as(usize, 5), x.fetchMax(10, .seq_cst));
+    try testing.expectEqual(@as(usize, 10), x.load(.seq_cst));
+    try testing.expectEqual(@as(usize, 10), x.fetchMax(5, .seq_cst));
+    try testing.expectEqual(@as(usize, 10), x.load(.seq_cst));
 }
 
 test "Value.fetchAnd" {
     var x = Value(usize).init(0b11);
-    try testing.expectEqual(@as(usize, 0b11), x.fetchAnd(0b10, .SeqCst));
-    try testing.expectEqual(@as(usize, 0b10), x.load(.SeqCst));
-    try testing.expectEqual(@as(usize, 0b10), x.fetchAnd(0b00, .SeqCst));
-    try testing.expectEqual(@as(usize, 0b00), x.load(.SeqCst));
+    try testing.expectEqual(@as(usize, 0b11), x.fetchAnd(0b10, .seq_cst));
+    try testing.expectEqual(@as(usize, 0b10), x.load(.seq_cst));
+    try testing.expectEqual(@as(usize, 0b10), x.fetchAnd(0b00, .seq_cst));
+    try testing.expectEqual(@as(usize, 0b00), x.load(.seq_cst));
 }
 
 test "Value.fetchNand" {
     var x = Value(usize).init(0b11);
-    try testing.expectEqual(@as(usize, 0b11), x.fetchNand(0b10, .SeqCst));
-    try testing.expectEqual(~@as(usize, 0b10), x.load(.SeqCst));
-    try testing.expectEqual(~@as(usize, 0b10), x.fetchNand(0b00, .SeqCst));
-    try testing.expectEqual(~@as(usize, 0b00), x.load(.SeqCst));
+    try testing.expectEqual(@as(usize, 0b11), x.fetchNand(0b10, .seq_cst));
+    try testing.expectEqual(~@as(usize, 0b10), x.load(.seq_cst));
+    try testing.expectEqual(~@as(usize, 0b10), x.fetchNand(0b00, .seq_cst));
+    try testing.expectEqual(~@as(usize, 0b00), x.load(.seq_cst));
 }
 
 test "Value.fetchOr" {
     var x = Value(usize).init(0b11);
-    try testing.expectEqual(@as(usize, 0b11), x.fetchOr(0b100, .SeqCst));
-    try testing.expectEqual(@as(usize, 0b111), x.load(.SeqCst));
-    try testing.expectEqual(@as(usize, 0b111), x.fetchOr(0b010, .SeqCst));
-    try testing.expectEqual(@as(usize, 0b111), x.load(.SeqCst));
+    try testing.expectEqual(@as(usize, 0b11), x.fetchOr(0b100, .seq_cst));
+    try testing.expectEqual(@as(usize, 0b111), x.load(.seq_cst));
+    try testing.expectEqual(@as(usize, 0b111), x.fetchOr(0b010, .seq_cst));
+    try testing.expectEqual(@as(usize, 0b111), x.load(.seq_cst));
 }
 
 test "Value.fetchXor" {
     var x = Value(usize).init(0b11);
-    try testing.expectEqual(@as(usize, 0b11), x.fetchXor(0b10, .SeqCst));
-    try testing.expectEqual(@as(usize, 0b01), x.load(.SeqCst));
-    try testing.expectEqual(@as(usize, 0b01), x.fetchXor(0b01, .SeqCst));
-    try testing.expectEqual(@as(usize, 0b00), x.load(.SeqCst));
+    try testing.expectEqual(@as(usize, 0b11), x.fetchXor(0b10, .seq_cst));
+    try testing.expectEqual(@as(usize, 0b01), x.load(.seq_cst));
+    try testing.expectEqual(@as(usize, 0b01), x.fetchXor(0b01, .seq_cst));
+    try testing.expectEqual(@as(usize, 0b00), x.load(.seq_cst));
 }
 
 test "Value.bitSet" {
@@ -304,19 +304,19 @@ test "Value.bitSet" {
         const mask = @as(usize, 1) << bit;
 
         // setting the bit should change the bit
-        try testing.expect(x.load(.SeqCst) & mask == 0);
-        try testing.expectEqual(@as(u1, 0), x.bitSet(bit, .SeqCst));
-        try testing.expect(x.load(.SeqCst) & mask != 0);
+        try testing.expect(x.load(.seq_cst) & mask == 0);
+        try testing.expectEqual(@as(u1, 0), x.bitSet(bit, .seq_cst));
+        try testing.expect(x.load(.seq_cst) & mask != 0);
 
         // setting it again shouldn't change the bit
-        try testing.expectEqual(@as(u1, 1), x.bitSet(bit, .SeqCst));
-        try testing.expect(x.load(.SeqCst) & mask != 0);
+        try testing.expectEqual(@as(u1, 1), x.bitSet(bit, .seq_cst));
+        try testing.expect(x.load(.seq_cst) & mask != 0);
 
         // all the previous bits should have not changed (still be set)
         for (0..bit_index) |prev_bit_index| {
             const prev_bit = @as(std.math.Log2Int(usize), @intCast(prev_bit_index));
             const prev_mask = @as(usize, 1) << prev_bit;
-            try testing.expect(x.load(.SeqCst) & prev_mask != 0);
+            try testing.expect(x.load(.seq_cst) & prev_mask != 0);
         }
     }
 }
@@ -330,19 +330,19 @@ test "Value.bitReset" {
         x.raw |= mask;
 
         // unsetting the bit should change the bit
-        try testing.expect(x.load(.SeqCst) & mask != 0);
-        try testing.expectEqual(@as(u1, 1), x.bitReset(bit, .SeqCst));
-        try testing.expect(x.load(.SeqCst) & mask == 0);
+        try testing.expect(x.load(.seq_cst) & mask != 0);
+        try testing.expectEqual(@as(u1, 1), x.bitReset(bit, .seq_cst));
+        try testing.expect(x.load(.seq_cst) & mask == 0);
 
         // unsetting it again shouldn't change the bit
-        try testing.expectEqual(@as(u1, 0), x.bitReset(bit, .SeqCst));
-        try testing.expect(x.load(.SeqCst) & mask == 0);
+        try testing.expectEqual(@as(u1, 0), x.bitReset(bit, .seq_cst));
+        try testing.expect(x.load(.seq_cst) & mask == 0);
 
         // all the previous bits should have not changed (still be reset)
         for (0..bit_index) |prev_bit_index| {
             const prev_bit = @as(std.math.Log2Int(usize), @intCast(prev_bit_index));
             const prev_mask = @as(usize, 1) << prev_bit;
-            try testing.expect(x.load(.SeqCst) & prev_mask == 0);
+            try testing.expect(x.load(.seq_cst) & prev_mask == 0);
         }
     }
 }
@@ -355,19 +355,19 @@ test "Value.bitToggle" {
         const mask = @as(usize, 1) << bit;
 
         // toggling the bit should change the bit
-        try testing.expect(x.load(.SeqCst) & mask == 0);
-        try testing.expectEqual(@as(u1, 0), x.bitToggle(bit, .SeqCst));
-        try testing.expect(x.load(.SeqCst) & mask != 0);
+        try testing.expect(x.load(.seq_cst) & mask == 0);
+        try testing.expectEqual(@as(u1, 0), x.bitToggle(bit, .seq_cst));
+        try testing.expect(x.load(.seq_cst) & mask != 0);
 
         // toggling it again *should* change the bit
-        try testing.expectEqual(@as(u1, 1), x.bitToggle(bit, .SeqCst));
-        try testing.expect(x.load(.SeqCst) & mask == 0);
+        try testing.expectEqual(@as(u1, 1), x.bitToggle(bit, .seq_cst));
+        try testing.expect(x.load(.seq_cst) & mask == 0);
 
         // all the previous bits should have not changed (still be toggled back)
         for (0..bit_index) |prev_bit_index| {
             const prev_bit = @as(std.math.Log2Int(usize), @intCast(prev_bit_index));
             const prev_mask = @as(usize, 1) << prev_bit;
-            try testing.expect(x.load(.SeqCst) & prev_mask == 0);
+            try testing.expect(x.load(.seq_cst) & prev_mask == 0);
         }
     }
 }
lib/std/builtin.zig
@@ -81,12 +81,12 @@ pub const SymbolVisibility = enum {
 /// This data structure is used by the Zig language code generation and
 /// therefore must be kept in sync with the compiler implementation.
 pub const AtomicOrder = enum {
-    Unordered,
-    Monotonic,
-    Acquire,
-    Release,
-    AcqRel,
-    SeqCst,
+    unordered,
+    monotonic,
+    acquire,
+    release,
+    acq_rel,
+    seq_cst,
 };
 
 /// This data structure is used by the Zig language code generation and
lib/std/child_process.zig
@@ -1420,7 +1420,7 @@ fn windowsMakeAsyncPipe(rd: *?windows.HANDLE, wr: *?windows.HANDLE, sattr: *cons
         const pipe_path = std.fmt.bufPrintZ(
             &tmp_buf,
             "\\\\.\\pipe\\zig-childprocess-{d}-{d}",
-            .{ windows.kernel32.GetCurrentProcessId(), pipe_name_counter.fetchAdd(1, .Monotonic) },
+            .{ windows.kernel32.GetCurrentProcessId(), pipe_name_counter.fetchAdd(1, .monotonic) },
         ) catch unreachable;
         const len = std.unicode.wtf8ToWtf16Le(&tmp_bufw, pipe_path) catch unreachable;
         tmp_bufw[len] = 0;
lib/std/debug.zig
@@ -461,7 +461,7 @@ pub fn panicImpl(trace: ?*const std.builtin.StackTrace, first_trace_addr: ?usize
         0 => {
             panic_stage = 1;
 
-            _ = panicking.fetchAdd(1, .SeqCst);
+            _ = panicking.fetchAdd(1, .seq_cst);
 
             // Make sure to release the mutex when done
             {
@@ -503,7 +503,7 @@ pub fn panicImpl(trace: ?*const std.builtin.StackTrace, first_trace_addr: ?usize
 
 /// Must be called only after adding 1 to `panicking`. There are three callsites.
 fn waitForOtherThreadToFinishPanicking() void {
-    if (panicking.fetchSub(1, .SeqCst) != 1) {
+    if (panicking.fetchSub(1, .seq_cst) != 1) {
         // Another thread is panicking, wait for the last one to finish
         // and call abort()
         if (builtin.single_threaded) unreachable;
@@ -2587,7 +2587,7 @@ fn handleSegfaultPosix(sig: i32, info: *const os.siginfo_t, ctx_ptr: ?*const any
     nosuspend switch (panic_stage) {
         0 => {
             panic_stage = 1;
-            _ = panicking.fetchAdd(1, .SeqCst);
+            _ = panicking.fetchAdd(1, .seq_cst);
 
             {
                 panic_mutex.lock();
@@ -2663,7 +2663,7 @@ fn handleSegfaultWindowsExtra(
         nosuspend switch (panic_stage) {
             0 => {
                 panic_stage = 1;
-                _ = panicking.fetchAdd(1, .SeqCst);
+                _ = panicking.fetchAdd(1, .seq_cst);
 
                 {
                     panic_mutex.lock();
lib/std/heap.zig
@@ -303,11 +303,11 @@ pub const HeapAllocator = switch (builtin.os.tag) {
 
             const ptr_align = @as(usize, 1) << @as(Allocator.Log2Align, @intCast(log2_ptr_align));
             const amt = n + ptr_align - 1 + @sizeOf(usize);
-            const optional_heap_handle = @atomicLoad(?HeapHandle, &self.heap_handle, .SeqCst);
+            const optional_heap_handle = @atomicLoad(?HeapHandle, &self.heap_handle, .seq_cst);
             const heap_handle = optional_heap_handle orelse blk: {
                 const options = if (builtin.single_threaded) os.windows.HEAP_NO_SERIALIZE else 0;
                 const hh = os.windows.kernel32.HeapCreate(options, amt, 0) orelse return null;
-                const other_hh = @cmpxchgStrong(?HeapHandle, &self.heap_handle, null, hh, .SeqCst, .SeqCst) orelse break :blk hh;
+                const other_hh = @cmpxchgStrong(?HeapHandle, &self.heap_handle, null, hh, .seq_cst, .seq_cst) orelse break :blk hh;
                 os.windows.HeapDestroy(hh);
                 break :blk other_hh.?; // can't be null because of the cmpxchg
             };
@@ -482,13 +482,13 @@ pub const FixedBufferAllocator = struct {
         const self: *FixedBufferAllocator = @ptrCast(@alignCast(ctx));
         _ = ra;
         const ptr_align = @as(usize, 1) << @as(Allocator.Log2Align, @intCast(log2_ptr_align));
-        var end_index = @atomicLoad(usize, &self.end_index, .SeqCst);
+        var end_index = @atomicLoad(usize, &self.end_index, .seq_cst);
         while (true) {
             const adjust_off = mem.alignPointerOffset(self.buffer.ptr + end_index, ptr_align) orelse return null;
             const adjusted_index = end_index + adjust_off;
             const new_end_index = adjusted_index + n;
             if (new_end_index > self.buffer.len) return null;
-            end_index = @cmpxchgWeak(usize, &self.end_index, end_index, new_end_index, .SeqCst, .SeqCst) orelse
+            end_index = @cmpxchgWeak(usize, &self.end_index, end_index, new_end_index, .seq_cst, .seq_cst) orelse
                 return self.buffer[adjusted_index..new_end_index].ptr;
         }
     }
lib/std/once.zig
@@ -17,7 +17,7 @@ pub fn Once(comptime f: fn () void) type {
         /// first time.
         /// The invocations are thread-safe.
         pub fn call(self: *@This()) void {
-            if (@atomicLoad(bool, &self.done, .Acquire))
+            if (@atomicLoad(bool, &self.done, .acquire))
                 return;
 
             return self.callSlow();
@@ -32,7 +32,7 @@ pub fn Once(comptime f: fn () void) type {
             // The first thread to acquire the mutex gets to run the initializer
             if (!self.done) {
                 f();
-                @atomicStore(bool, &self.done, true, .Release);
+                @atomicStore(bool, &self.done, true, .release);
             }
         }
     };
lib/std/os.zig
@@ -436,7 +436,7 @@ fn fchmodat1(dirfd: fd_t, path: []const u8, mode: mode_t, flags: u32) FChmodAtEr
 fn fchmodat2(dirfd: fd_t, path: []const u8, mode: mode_t, flags: u32) FChmodAtError!void {
     const path_c = try toPosixPath(path);
     const use_fchmodat2 = (builtin.os.isAtLeast(.linux, .{ .major = 6, .minor = 6, .patch = 0 }) orelse false) and
-        has_fchmodat2_syscall.load(.Monotonic);
+        has_fchmodat2_syscall.load(.monotonic);
     while (use_fchmodat2) {
         // Later on this should be changed to `system.fchmodat2`
         // when the musl/glibc add a wrapper.
@@ -458,7 +458,7 @@ fn fchmodat2(dirfd: fd_t, path: []const u8, mode: mode_t, flags: u32) FChmodAtEr
             .ROFS => return error.ReadOnlyFileSystem,
 
             .NOSYS => { // Use fallback.
-                has_fchmodat2_syscall.store(false, .Monotonic);
+                has_fchmodat2_syscall.store(false, .monotonic);
                 break;
             },
             else => |err| return unexpectedErrno(err),
@@ -729,7 +729,7 @@ pub fn abort() noreturn {
             const global = struct {
                 var abort_entered: bool = false;
             };
-            while (@cmpxchgWeak(bool, &global.abort_entered, false, true, .SeqCst, .SeqCst)) |_| {}
+            while (@cmpxchgWeak(bool, &global.abort_entered, false, true, .seq_cst, .seq_cst)) |_| {}
         }
 
         // Install default handler so that the tkill below will terminate.
@@ -6809,7 +6809,7 @@ pub fn copy_file_range(fd_in: fd_t, off_in: u64, fd_out: fd_t, off_out: u64, len
     if ((comptime builtin.os.isAtLeast(.freebsd, .{ .major = 13, .minor = 0, .patch = 0 }) orelse false) or
         ((comptime builtin.os.isAtLeast(.linux, .{ .major = 4, .minor = 5, .patch = 0 }) orelse false and
         std.c.versionCheck(.{ .major = 2, .minor = 27, .patch = 0 })) and
-        has_copy_file_range_syscall.load(.Monotonic)))
+        has_copy_file_range_syscall.load(.monotonic)))
     {
         var off_in_copy: i64 = @bitCast(off_in);
         var off_out_copy: i64 = @bitCast(off_out);
@@ -6844,7 +6844,7 @@ pub fn copy_file_range(fd_in: fd_t, off_in: u64, fd_out: fd_t, off_out: u64, len
                     .TXTBSY => return error.SwapFile,
                     .XDEV => break, // support for cross-filesystem copy added in Linux 5.3, use fallback
                     .NOSYS => { // syscall added in Linux 4.5, use fallback
-                        has_copy_file_range_syscall.store(false, .Monotonic);
+                        has_copy_file_range_syscall.store(false, .monotonic);
                         break;
                     },
                     else => |err| return unexpectedErrno(err),
lib/std/Progress.zig
@@ -95,9 +95,9 @@ pub const Node = struct {
     /// This is the same as calling `start` and then `end` on the returned `Node`. Thread-safe.
     pub fn completeOne(self: *Node) void {
         if (self.parent) |parent| {
-            @atomicStore(?*Node, &parent.recently_updated_child, self, .Release);
+            @atomicStore(?*Node, &parent.recently_updated_child, self, .release);
         }
-        _ = @atomicRmw(usize, &self.unprotected_completed_items, .Add, 1, .Monotonic);
+        _ = @atomicRmw(usize, &self.unprotected_completed_items, .Add, 1, .monotonic);
         self.context.maybeRefresh();
     }
 
@@ -108,7 +108,7 @@ pub const Node = struct {
             {
                 self.context.update_mutex.lock();
                 defer self.context.update_mutex.unlock();
-                _ = @cmpxchgStrong(?*Node, &parent.recently_updated_child, self, null, .Monotonic, .Monotonic);
+                _ = @cmpxchgStrong(?*Node, &parent.recently_updated_child, self, null, .monotonic, .monotonic);
             }
             parent.completeOne();
         } else {
@@ -122,7 +122,7 @@ pub const Node = struct {
     /// Tell the parent node that this node is actively being worked on. Thread-safe.
     pub fn activate(self: *Node) void {
         if (self.parent) |parent| {
-            @atomicStore(?*Node, &parent.recently_updated_child, self, .Release);
+            @atomicStore(?*Node, &parent.recently_updated_child, self, .release);
             self.context.maybeRefresh();
         }
     }
@@ -134,9 +134,9 @@ pub const Node = struct {
         defer progress.update_mutex.unlock();
         self.name = name;
         if (self.parent) |parent| {
-            @atomicStore(?*Node, &parent.recently_updated_child, self, .Release);
+            @atomicStore(?*Node, &parent.recently_updated_child, self, .release);
             if (parent.parent) |grand_parent| {
-                @atomicStore(?*Node, &grand_parent.recently_updated_child, parent, .Release);
+                @atomicStore(?*Node, &grand_parent.recently_updated_child, parent, .release);
             }
             if (progress.timer) |*timer| progress.maybeRefreshWithHeldLock(timer);
         }
@@ -149,9 +149,9 @@ pub const Node = struct {
         defer progress.update_mutex.unlock();
         self.unit = unit;
         if (self.parent) |parent| {
-            @atomicStore(?*Node, &parent.recently_updated_child, self, .Release);
+            @atomicStore(?*Node, &parent.recently_updated_child, self, .release);
             if (parent.parent) |grand_parent| {
-                @atomicStore(?*Node, &grand_parent.recently_updated_child, parent, .Release);
+                @atomicStore(?*Node, &grand_parent.recently_updated_child, parent, .release);
             }
             if (progress.timer) |*timer| progress.maybeRefreshWithHeldLock(timer);
         }
@@ -159,12 +159,12 @@ pub const Node = struct {
 
     /// Thread-safe. 0 means unknown.
     pub fn setEstimatedTotalItems(self: *Node, count: usize) void {
-        @atomicStore(usize, &self.unprotected_estimated_total_items, count, .Monotonic);
+        @atomicStore(usize, &self.unprotected_estimated_total_items, count, .monotonic);
     }
 
     /// Thread-safe.
     pub fn setCompletedItems(self: *Node, completed_items: usize) void {
-        @atomicStore(usize, &self.unprotected_completed_items, completed_items, .Monotonic);
+        @atomicStore(usize, &self.unprotected_completed_items, completed_items, .monotonic);
     }
 };
 
@@ -313,8 +313,8 @@ fn refreshWithHeldLock(self: *Progress) void {
                 self.bufWrite(&end, "... ", .{});
             }
             need_ellipse = false;
-            const eti = @atomicLoad(usize, &node.unprotected_estimated_total_items, .Monotonic);
-            const completed_items = @atomicLoad(usize, &node.unprotected_completed_items, .Monotonic);
+            const eti = @atomicLoad(usize, &node.unprotected_estimated_total_items, .monotonic);
+            const completed_items = @atomicLoad(usize, &node.unprotected_completed_items, .monotonic);
             const current_item = completed_items + 1;
             if (node.name.len != 0 or eti > 0) {
                 if (node.name.len != 0) {
@@ -331,7 +331,7 @@ fn refreshWithHeldLock(self: *Progress) void {
                     need_ellipse = false;
                 }
             }
-            maybe_node = @atomicLoad(?*Node, &node.recently_updated_child, .Acquire);
+            maybe_node = @atomicLoad(?*Node, &node.recently_updated_child, .acquire);
         }
         if (need_ellipse) {
             self.bufWrite(&end, "... ", .{});
lib/std/Thread.zig
@@ -510,7 +510,7 @@ const WindowsThreadImpl = struct {
 
             fn entryFn(raw_ptr: windows.PVOID) callconv(.C) windows.DWORD {
                 const self: *@This() = @ptrCast(@alignCast(raw_ptr));
-                defer switch (self.thread.completion.swap(.completed, .SeqCst)) {
+                defer switch (self.thread.completion.swap(.completed, .seq_cst)) {
                     .running => {},
                     .completed => unreachable,
                     .detached => self.thread.free(),
@@ -563,7 +563,7 @@ const WindowsThreadImpl = struct {
 
     fn detach(self: Impl) void {
         windows.CloseHandle(self.thread.thread_handle);
-        switch (self.thread.completion.swap(.detached, .SeqCst)) {
+        switch (self.thread.completion.swap(.detached, .seq_cst)) {
             .running => {},
             .completed => self.thread.free(),
             .detached => unreachable,
@@ -573,7 +573,7 @@ const WindowsThreadImpl = struct {
     fn join(self: Impl) void {
         windows.WaitForSingleObjectEx(self.thread.thread_handle, windows.INFINITE, false) catch unreachable;
         windows.CloseHandle(self.thread.thread_handle);
-        assert(self.thread.completion.load(.SeqCst) == .completed);
+        assert(self.thread.completion.load(.seq_cst) == .completed);
         self.thread.free();
     }
 };
@@ -780,11 +780,11 @@ const WasiThreadImpl = struct {
     }
 
     fn getHandle(self: Impl) ThreadHandle {
-        return self.thread.tid.load(.SeqCst);
+        return self.thread.tid.load(.seq_cst);
     }
 
     fn detach(self: Impl) void {
-        switch (self.thread.state.swap(.detached, .SeqCst)) {
+        switch (self.thread.state.swap(.detached, .seq_cst)) {
             .running => {},
             .completed => self.join(),
             .detached => unreachable,
@@ -801,7 +801,7 @@ const WasiThreadImpl = struct {
 
         var spin: u8 = 10;
         while (true) {
-            const tid = self.thread.tid.load(.SeqCst);
+            const tid = self.thread.tid.load(.seq_cst);
             if (tid == 0) {
                 break;
             }
@@ -901,7 +901,7 @@ const WasiThreadImpl = struct {
         if (tid < 0) {
             return error.SystemResources;
         }
-        instance.thread.tid.store(tid, .SeqCst);
+        instance.thread.tid.store(tid, .seq_cst);
 
         return .{ .thread = &instance.thread };
     }
@@ -914,12 +914,12 @@ const WasiThreadImpl = struct {
         }
         __set_stack_pointer(arg.thread.memory.ptr + arg.stack_offset);
         __wasm_init_tls(arg.thread.memory.ptr + arg.tls_offset);
-        @atomicStore(u32, &WasiThreadImpl.tls_thread_id, @intCast(tid), .SeqCst);
+        @atomicStore(u32, &WasiThreadImpl.tls_thread_id, @intCast(tid), .seq_cst);
 
         // Finished bootstrapping, call user's procedure.
         arg.call_back(arg.raw_ptr);
 
-        switch (arg.thread.state.swap(.completed, .SeqCst)) {
+        switch (arg.thread.state.swap(.completed, .seq_cst)) {
             .running => {
                 // reset the Thread ID
                 asm volatile (
@@ -1191,7 +1191,7 @@ const LinuxThreadImpl = struct {
 
             fn entryFn(raw_arg: usize) callconv(.C) u8 {
                 const self = @as(*@This(), @ptrFromInt(raw_arg));
-                defer switch (self.thread.completion.swap(.completed, .SeqCst)) {
+                defer switch (self.thread.completion.swap(.completed, .seq_cst)) {
                     .running => {},
                     .completed => unreachable,
                     .detached => self.thread.freeAndExit(),
@@ -1311,7 +1311,7 @@ const LinuxThreadImpl = struct {
     }
 
     fn detach(self: Impl) void {
-        switch (self.thread.completion.swap(.detached, .SeqCst)) {
+        switch (self.thread.completion.swap(.detached, .seq_cst)) {
             .running => {},
             .completed => self.join(),
             .detached => unreachable,
@@ -1323,7 +1323,7 @@ const LinuxThreadImpl = struct {
 
         var spin: u8 = 10;
         while (true) {
-            const tid = self.thread.child_tid.load(.SeqCst);
+            const tid = self.thread.child_tid.load(.seq_cst);
             if (tid == 0) {
                 break;
             }
lib/build_runner.zig
@@ -892,10 +892,10 @@ fn workerMakeOneStep(
     // then we return without doing the step, relying on another worker to
     // queue this step up again when dependencies are met.
     for (s.dependencies.items) |dep| {
-        switch (@atomicLoad(Step.State, &dep.state, .SeqCst)) {
+        switch (@atomicLoad(Step.State, &dep.state, .seq_cst)) {
             .success, .skipped => continue,
             .failure, .dependency_failure, .skipped_oom => {
-                @atomicStore(Step.State, &s.state, .dependency_failure, .SeqCst);
+                @atomicStore(Step.State, &s.state, .dependency_failure, .seq_cst);
                 return;
             },
             .precheck_done, .running => {
@@ -929,7 +929,7 @@ fn workerMakeOneStep(
         s.state = .running;
     } else {
         // Avoid running steps twice.
-        if (@cmpxchgStrong(Step.State, &s.state, .precheck_done, .running, .SeqCst, .SeqCst) != null) {
+        if (@cmpxchgStrong(Step.State, &s.state, .precheck_done, .running, .seq_cst, .seq_cst) != null) {
             // Another worker got the job.
             return;
         }
@@ -956,13 +956,13 @@ fn workerMakeOneStep(
 
     handle_result: {
         if (make_result) |_| {
-            @atomicStore(Step.State, &s.state, .success, .SeqCst);
+            @atomicStore(Step.State, &s.state, .success, .seq_cst);
         } else |err| switch (err) {
             error.MakeFailed => {
-                @atomicStore(Step.State, &s.state, .failure, .SeqCst);
+                @atomicStore(Step.State, &s.state, .failure, .seq_cst);
                 break :handle_result;
             },
-            error.MakeSkipped => @atomicStore(Step.State, &s.state, .skipped, .SeqCst),
+            error.MakeSkipped => @atomicStore(Step.State, &s.state, .skipped, .seq_cst),
         }
 
         // Successful completion of a step, so we queue up its dependants as well.
src/arch/aarch64/CodeGen.zig
@@ -815,10 +815,10 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .call_never_tail   => try self.airCall(inst, .never_tail),
             .call_never_inline => try self.airCall(inst, .never_inline),
 
-            .atomic_store_unordered => try self.airAtomicStore(inst, .Unordered),
-            .atomic_store_monotonic => try self.airAtomicStore(inst, .Monotonic),
-            .atomic_store_release   => try self.airAtomicStore(inst, .Release),
-            .atomic_store_seq_cst   => try self.airAtomicStore(inst, .SeqCst),
+            .atomic_store_unordered => try self.airAtomicStore(inst, .unordered),
+            .atomic_store_monotonic => try self.airAtomicStore(inst, .monotonic),
+            .atomic_store_release   => try self.airAtomicStore(inst, .release),
+            .atomic_store_seq_cst   => try self.airAtomicStore(inst, .seq_cst),
 
             .struct_field_ptr_index_0 => try self.airStructFieldPtrIndex(inst, 0),
             .struct_field_ptr_index_1 => try self.airStructFieldPtrIndex(inst, 1),
src/arch/arm/CodeGen.zig
@@ -801,10 +801,10 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .call_never_tail   => try self.airCall(inst, .never_tail),
             .call_never_inline => try self.airCall(inst, .never_inline),
 
-            .atomic_store_unordered => try self.airAtomicStore(inst, .Unordered),
-            .atomic_store_monotonic => try self.airAtomicStore(inst, .Monotonic),
-            .atomic_store_release   => try self.airAtomicStore(inst, .Release),
-            .atomic_store_seq_cst   => try self.airAtomicStore(inst, .SeqCst),
+            .atomic_store_unordered => try self.airAtomicStore(inst, .unordered),
+            .atomic_store_monotonic => try self.airAtomicStore(inst, .monotonic),
+            .atomic_store_release   => try self.airAtomicStore(inst, .release),
+            .atomic_store_seq_cst   => try self.airAtomicStore(inst, .seq_cst),
 
             .struct_field_ptr_index_0 => try self.airStructFieldPtrIndex(inst, 0),
             .struct_field_ptr_index_1 => try self.airStructFieldPtrIndex(inst, 1),
src/arch/riscv64/CodeGen.zig
@@ -634,10 +634,10 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .call_never_tail   => try self.airCall(inst, .never_tail),
             .call_never_inline => try self.airCall(inst, .never_inline),
 
-            .atomic_store_unordered => try self.airAtomicStore(inst, .Unordered),
-            .atomic_store_monotonic => try self.airAtomicStore(inst, .Monotonic),
-            .atomic_store_release   => try self.airAtomicStore(inst, .Release),
-            .atomic_store_seq_cst   => try self.airAtomicStore(inst, .SeqCst),
+            .atomic_store_unordered => try self.airAtomicStore(inst, .unordered),
+            .atomic_store_monotonic => try self.airAtomicStore(inst, .monotonic),
+            .atomic_store_release   => try self.airAtomicStore(inst, .release),
+            .atomic_store_seq_cst   => try self.airAtomicStore(inst, .seq_cst),
 
             .struct_field_ptr_index_0 => try self.airStructFieldPtrIndex(inst, 0),
             .struct_field_ptr_index_1 => try self.airStructFieldPtrIndex(inst, 1),
src/arch/x86_64/CodeGen.zig
@@ -2111,10 +2111,10 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .call_never_tail   => try self.airCall(inst, .never_tail),
             .call_never_inline => try self.airCall(inst, .never_inline),
 
-            .atomic_store_unordered => try self.airAtomicStore(inst, .Unordered),
-            .atomic_store_monotonic => try self.airAtomicStore(inst, .Monotonic),
-            .atomic_store_release   => try self.airAtomicStore(inst, .Release),
-            .atomic_store_seq_cst   => try self.airAtomicStore(inst, .SeqCst),
+            .atomic_store_unordered => try self.airAtomicStore(inst, .unordered),
+            .atomic_store_monotonic => try self.airAtomicStore(inst, .monotonic),
+            .atomic_store_release   => try self.airAtomicStore(inst, .release),
+            .atomic_store_seq_cst   => try self.airAtomicStore(inst, .seq_cst),
 
             .struct_field_ptr_index_0 => try self.airStructFieldPtrIndex(inst, 0),
             .struct_field_ptr_index_1 => try self.airStructFieldPtrIndex(inst, 1),
@@ -11977,9 +11977,9 @@ fn airFrameAddress(self: *Self, inst: Air.Inst.Index) !void {
 fn airFence(self: *Self, inst: Air.Inst.Index) !void {
     const order = self.air.instructions.items(.data)[@intFromEnum(inst)].fence;
     switch (order) {
-        .Unordered, .Monotonic => unreachable,
-        .Acquire, .Release, .AcqRel => {},
-        .SeqCst => try self.asmOpOnly(.{ ._, .mfence }),
+        .unordered, .monotonic => unreachable,
+        .acquire, .release, .acq_rel => {},
+        .seq_cst => try self.asmOpOnly(.{ ._, .mfence }),
     }
     self.finishAirBookkeeping();
 }
@@ -15747,9 +15747,9 @@ fn atomicOp(
                 .Xor => .xor,
                 else => unreachable,
             } else switch (order) {
-                .Unordered, .Monotonic, .Release, .AcqRel => .mov,
-                .Acquire => unreachable,
-                .SeqCst => .xchg,
+                .unordered, .monotonic, .release, .acq_rel => .mov,
+                .acquire => unreachable,
+                .seq_cst => .xchg,
             };
 
             const dst_reg = try self.register_manager.allocReg(null, abi.RegisterClass.gp);
src/codegen/llvm/bitcode_writer.zig
@@ -415,8 +415,8 @@ fn BufType(comptime T: type, comptime min_len: usize) type {
         .Enum => |info| info.tag_type,
         .Bool => u1,
         .Struct => |info| switch (info.layout) {
-            .Auto, .Extern => @compileError("Unsupported type: " ++ @typeName(T)),
-            .Packed => std.meta.Int(.unsigned, @bitSizeOf(T)),
+            .auto, .@"extern" => @compileError("Unsupported type: " ++ @typeName(T)),
+            .@"packed" => std.meta.Int(.unsigned, @bitSizeOf(T)),
         },
         else => @compileError("Unsupported type: " ++ @typeName(T)),
     })));
src/codegen/llvm/Builder.zig
@@ -8398,7 +8398,7 @@ pub const Metadata = enum(u32) {
             fmt_str = fmt_str ++ ")\n";
 
             var fmt_args: @Type(.{ .Struct = .{
-                .layout = .Auto,
+                .layout = .auto,
                 .fields = &fields,
                 .decls = &.{},
                 .is_tuple = false,
src/codegen/c.zig
@@ -3278,10 +3278,10 @@ fn genBodyInner(f: *Function, body: []const Air.Inst.Index) error{ AnalysisFail,
 
             .int_from_ptr => try airIntFromPtr(f, inst),
 
-            .atomic_store_unordered => try airAtomicStore(f, inst, toMemoryOrder(.Unordered)),
-            .atomic_store_monotonic => try airAtomicStore(f, inst, toMemoryOrder(.Monotonic)),
-            .atomic_store_release   => try airAtomicStore(f, inst, toMemoryOrder(.Release)),
-            .atomic_store_seq_cst   => try airAtomicStore(f, inst, toMemoryOrder(.SeqCst)),
+            .atomic_store_unordered => try airAtomicStore(f, inst, toMemoryOrder(.unordered)),
+            .atomic_store_monotonic => try airAtomicStore(f, inst, toMemoryOrder(.monotonic)),
+            .atomic_store_release   => try airAtomicStore(f, inst, toMemoryOrder(.release)),
+            .atomic_store_seq_cst   => try airAtomicStore(f, inst, toMemoryOrder(.seq_cst)),
 
             .struct_field_ptr_index_0 => try airStructFieldPtrIndex(f, inst, 0),
             .struct_field_ptr_index_1 => try airStructFieldPtrIndex(f, inst, 1),
@@ -7482,11 +7482,11 @@ fn airCVaCopy(f: *Function, inst: Air.Inst.Index) !CValue {
 fn toMemoryOrder(order: std.builtin.AtomicOrder) [:0]const u8 {
     return switch (order) {
         // Note: unordered is actually even less atomic than relaxed
-        .Unordered, .Monotonic => "zig_memory_order_relaxed",
-        .Acquire => "zig_memory_order_acquire",
-        .Release => "zig_memory_order_release",
-        .AcqRel => "zig_memory_order_acq_rel",
-        .SeqCst => "zig_memory_order_seq_cst",
+        .unordered, .monotonic => "zig_memory_order_relaxed",
+        .acquire => "zig_memory_order_acquire",
+        .release => "zig_memory_order_release",
+        .acq_rel => "zig_memory_order_acq_rel",
+        .seq_cst => "zig_memory_order_seq_cst",
     };
 }
 
src/codegen/llvm.zig
@@ -1278,7 +1278,7 @@ pub const Object = struct {
 
         const reloc_mode: llvm.RelocMode = if (pic)
             .PIC
-        else if (self.module.comp.config.link_mode == .Dynamic)
+        else if (self.module.comp.config.link_mode == .dynamic)
             llvm.RelocMode.DynamicNoPIC
         else
             .Static;
@@ -10801,12 +10801,12 @@ pub const FuncGen = struct {
 
 fn toLlvmAtomicOrdering(atomic_order: std.builtin.AtomicOrder) Builder.AtomicOrdering {
     return switch (atomic_order) {
-        .Unordered => .unordered,
-        .Monotonic => .monotonic,
-        .Acquire => .acquire,
-        .Release => .release,
-        .AcqRel => .acq_rel,
-        .SeqCst => .seq_cst,
+        .unordered => .unordered,
+        .monotonic => .monotonic,
+        .acquire => .acquire,
+        .release => .release,
+        .acq_rel => .acq_rel,
+        .seq_cst => .seq_cst,
     };
 }
 
src/crash_report.zig
@@ -376,7 +376,7 @@ const PanicSwitch = struct {
         };
         state.* = new_state;
 
-        _ = panicking.fetchAdd(1, .SeqCst);
+        _ = panicking.fetchAdd(1, .seq_cst);
 
         state.recover_stage = .release_ref_count;
 
@@ -458,7 +458,7 @@ const PanicSwitch = struct {
     noinline fn releaseRefCount(state: *volatile PanicState) noreturn {
         state.recover_stage = .abort;
 
-        if (panicking.fetchSub(1, .SeqCst) != 1) {
+        if (panicking.fetchSub(1, .seq_cst) != 1) {
             // Another thread is panicking, wait for the last one to finish
             // and call abort()
 
src/main.zig
@@ -4145,8 +4145,8 @@ fn progressThread(progress: *std.Progress, server: *const Server, reset: *std.Th
                     buf.appendSlice("... ") catch {};
                 }
                 need_ellipse = false;
-                const eti = @atomicLoad(usize, &node.unprotected_estimated_total_items, .Monotonic);
-                const completed_items = @atomicLoad(usize, &node.unprotected_completed_items, .Monotonic);
+                const eti = @atomicLoad(usize, &node.unprotected_estimated_total_items, .monotonic);
+                const completed_items = @atomicLoad(usize, &node.unprotected_completed_items, .monotonic);
                 const current_item = completed_items + 1;
                 if (node.name.len != 0 or eti > 0) {
                     if (node.name.len != 0) {
@@ -4163,7 +4163,7 @@ fn progressThread(progress: *std.Progress, server: *const Server, reset: *std.Th
                         need_ellipse = false;
                     }
                 }
-                maybe_node = @atomicLoad(?*std.Progress.Node, &node.recently_updated_child, .Acquire);
+                maybe_node = @atomicLoad(?*std.Progress.Node, &node.recently_updated_child, .acquire);
             }
         }
 
src/print_air.zig
@@ -303,10 +303,10 @@ const Writer = struct {
             .fence => try w.writeFence(s, inst),
             .atomic_load => try w.writeAtomicLoad(s, inst),
             .prefetch => try w.writePrefetch(s, inst),
-            .atomic_store_unordered => try w.writeAtomicStore(s, inst, .Unordered),
-            .atomic_store_monotonic => try w.writeAtomicStore(s, inst, .Monotonic),
-            .atomic_store_release => try w.writeAtomicStore(s, inst, .Release),
-            .atomic_store_seq_cst => try w.writeAtomicStore(s, inst, .SeqCst),
+            .atomic_store_unordered => try w.writeAtomicStore(s, inst, .unordered),
+            .atomic_store_monotonic => try w.writeAtomicStore(s, inst, .monotonic),
+            .atomic_store_release => try w.writeAtomicStore(s, inst, .release),
+            .atomic_store_seq_cst => try w.writeAtomicStore(s, inst, .seq_cst),
             .atomic_rmw => try w.writeAtomicRmw(s, inst),
             .field_parent_ptr => try w.writeFieldParentPtr(s, inst),
             .wasm_memory_size => try w.writeWasmMemorySize(s, inst),
src/Sema.zig
@@ -6450,8 +6450,8 @@ fn zirFence(sema: *Sema, block: *Block, extended: Zir.Inst.Extended.InstData) Co
         .needed_comptime_reason = "atomic order of @fence must be comptime-known",
     });
 
-    if (@intFromEnum(order) < @intFromEnum(std.builtin.AtomicOrder.Acquire)) {
-        return sema.fail(block, order_src, "atomic ordering must be Acquire or stricter", .{});
+    if (@intFromEnum(order) < @intFromEnum(std.builtin.AtomicOrder.acquire)) {
+        return sema.fail(block, order_src, "atomic ordering must be acquire or stricter", .{});
     }
 
     _ = try block.addInst(.{
@@ -23894,17 +23894,17 @@ fn zirCmpxchg(
         .needed_comptime_reason = "atomic order of cmpxchg failure must be comptime-known",
     });
 
-    if (@intFromEnum(success_order) < @intFromEnum(std.builtin.AtomicOrder.Monotonic)) {
-        return sema.fail(block, success_order_src, "success atomic ordering must be Monotonic or stricter", .{});
+    if (@intFromEnum(success_order) < @intFromEnum(std.builtin.AtomicOrder.monotonic)) {
+        return sema.fail(block, success_order_src, "success atomic ordering must be monotonic or stricter", .{});
     }
-    if (@intFromEnum(failure_order) < @intFromEnum(std.builtin.AtomicOrder.Monotonic)) {
-        return sema.fail(block, failure_order_src, "failure atomic ordering must be Monotonic or stricter", .{});
+    if (@intFromEnum(failure_order) < @intFromEnum(std.builtin.AtomicOrder.monotonic)) {
+        return sema.fail(block, failure_order_src, "failure atomic ordering must be monotonic or stricter", .{});
     }
     if (@intFromEnum(failure_order) > @intFromEnum(success_order)) {
         return sema.fail(block, failure_order_src, "failure atomic ordering must be no stricter than success", .{});
     }
-    if (failure_order == .Release or failure_order == .AcqRel) {
-        return sema.fail(block, failure_order_src, "failure atomic ordering must not be Release or AcqRel", .{});
+    if (failure_order == .release or failure_order == .acq_rel) {
+        return sema.fail(block, failure_order_src, "failure atomic ordering must not be release or acq_rel", .{});
     }
 
     const result_ty = try mod.optionalType(elem_ty.toIntern());
@@ -24346,11 +24346,11 @@ fn zirAtomicLoad(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!
     });
 
     switch (order) {
-        .Release, .AcqRel => {
+        .release, .acq_rel => {
             return sema.fail(
                 block,
                 order_src,
-                "@atomicLoad atomic ordering must not be Release or AcqRel",
+                "@atomicLoad atomic ordering must not be release or acq_rel",
                 .{},
             );
         },
@@ -24412,8 +24412,8 @@ fn zirAtomicRmw(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!A
         .needed_comptime_reason = "atomic order of @atomicRmW must be comptime-known",
     });
 
-    if (order == .Unordered) {
-        return sema.fail(block, order_src, "@atomicRmw atomic ordering must not be Unordered", .{});
+    if (order == .unordered) {
+        return sema.fail(block, order_src, "@atomicRmw atomic ordering must not be unordered", .{});
     }
 
     // special case zero bit types
@@ -24482,18 +24482,18 @@ fn zirAtomicStore(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError
     });
 
     const air_tag: Air.Inst.Tag = switch (order) {
-        .Acquire, .AcqRel => {
+        .acquire, .acq_rel => {
             return sema.fail(
                 block,
                 order_src,
-                "@atomicStore atomic ordering must not be Acquire or AcqRel",
+                "@atomicStore atomic ordering must not be acquire or acq_rel",
                 .{},
             );
         },
-        .Unordered => .atomic_store_unordered,
-        .Monotonic => .atomic_store_monotonic,
-        .Release => .atomic_store_release,
-        .SeqCst => .atomic_store_seq_cst,
+        .unordered => .atomic_store_unordered,
+        .monotonic => .atomic_store_monotonic,
+        .release => .atomic_store_release,
+        .seq_cst => .atomic_store_seq_cst,
     };
 
     return sema.storePtr2(block, src, ptr, ptr_src, operand, operand_src, air_tag);
test/behavior/atomics.zig
@@ -22,18 +22,18 @@ test "cmpxchg" {
 
 fn testCmpxchg() !void {
     var x: i32 = 1234;
-    if (@cmpxchgWeak(i32, &x, 99, 5678, .SeqCst, .SeqCst)) |x1| {
+    if (@cmpxchgWeak(i32, &x, 99, 5678, .seq_cst, .seq_cst)) |x1| {
         try expect(x1 == 1234);
     } else {
         @panic("cmpxchg should have failed");
     }
 
-    while (@cmpxchgWeak(i32, &x, 1234, 5678, .SeqCst, .SeqCst)) |x1| {
+    while (@cmpxchgWeak(i32, &x, 1234, 5678, .seq_cst, .seq_cst)) |x1| {
         try expect(x1 == 1234);
     }
     try expect(x == 5678);
 
-    try expect(@cmpxchgStrong(i32, &x, 5678, 42, .SeqCst, .SeqCst) == null);
+    try expect(@cmpxchgStrong(i32, &x, 5678, 42, .seq_cst, .seq_cst) == null);
     try expect(x == 42);
 }
 
@@ -43,7 +43,7 @@ test "fence" {
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
 
     var x: i32 = 1234;
-    @fence(.SeqCst);
+    @fence(.seq_cst);
     x = 5678;
 }
 
@@ -60,18 +60,18 @@ test "atomicrmw and atomicload" {
 }
 
 fn testAtomicRmw(ptr: *u8) !void {
-    const prev_value = @atomicRmw(u8, ptr, .Xchg, 42, .SeqCst);
+    const prev_value = @atomicRmw(u8, ptr, .Xchg, 42, .seq_cst);
     try expect(prev_value == 200);
     comptime {
         var x: i32 = 1234;
         const y: i32 = 12345;
-        try expect(@atomicLoad(i32, &x, .SeqCst) == 1234);
-        try expect(@atomicLoad(i32, &y, .SeqCst) == 12345);
+        try expect(@atomicLoad(i32, &x, .seq_cst) == 1234);
+        try expect(@atomicLoad(i32, &y, .seq_cst) == 12345);
     }
 }
 
 fn testAtomicLoad(ptr: *u8) !void {
-    const x = @atomicLoad(u8, ptr, .SeqCst);
+    const x = @atomicLoad(u8, ptr, .seq_cst);
     try expect(x == 42);
 }
 
@@ -85,18 +85,18 @@ test "cmpxchg with ptr" {
     var data2: i32 = 5678;
     var data3: i32 = 9101;
     var x: *i32 = &data1;
-    if (@cmpxchgWeak(*i32, &x, &data2, &data3, .SeqCst, .SeqCst)) |x1| {
+    if (@cmpxchgWeak(*i32, &x, &data2, &data3, .seq_cst, .seq_cst)) |x1| {
         try expect(x1 == &data1);
     } else {
         @panic("cmpxchg should have failed");
     }
 
-    while (@cmpxchgWeak(*i32, &x, &data1, &data3, .SeqCst, .SeqCst)) |x1| {
+    while (@cmpxchgWeak(*i32, &x, &data1, &data3, .seq_cst, .seq_cst)) |x1| {
         try expect(x1 == &data1);
     }
     try expect(x == &data3);
 
-    try expect(@cmpxchgStrong(*i32, &x, &data3, &data2, .SeqCst, .SeqCst) == null);
+    try expect(@cmpxchgStrong(*i32, &x, &data3, &data2, .seq_cst, .seq_cst) == null);
     try expect(x == &data2);
 }
 
@@ -108,7 +108,7 @@ test "cmpxchg with ignored result" {
 
     var x: i32 = 1234;
 
-    _ = @cmpxchgStrong(i32, &x, 1234, 5678, .Monotonic, .Monotonic);
+    _ = @cmpxchgStrong(i32, &x, 1234, 5678, .monotonic, .monotonic);
 
     try expect(5678 == x);
 }
@@ -127,18 +127,18 @@ test "128-bit cmpxchg" {
 
 fn test_u128_cmpxchg() !void {
     var x: u128 align(16) = 1234;
-    if (@cmpxchgWeak(u128, &x, 99, 5678, .SeqCst, .SeqCst)) |x1| {
+    if (@cmpxchgWeak(u128, &x, 99, 5678, .seq_cst, .seq_cst)) |x1| {
         try expect(x1 == 1234);
     } else {
         @panic("cmpxchg should have failed");
     }
 
-    while (@cmpxchgWeak(u128, &x, 1234, 5678, .SeqCst, .SeqCst)) |x1| {
+    while (@cmpxchgWeak(u128, &x, 1234, 5678, .seq_cst, .seq_cst)) |x1| {
         try expect(x1 == 1234);
     }
     try expect(x == 5678);
 
-    try expect(@cmpxchgStrong(u128, &x, 5678, 42, .SeqCst, .SeqCst) == null);
+    try expect(@cmpxchgStrong(u128, &x, 5678, 42, .seq_cst, .seq_cst) == null);
     try expect(x == 42);
 }
 
@@ -155,7 +155,7 @@ test "cmpxchg on a global variable" {
         return error.SkipZigTest;
     }
 
-    _ = @cmpxchgWeak(u32, &a_global_variable, 1234, 42, .Acquire, .Monotonic);
+    _ = @cmpxchgWeak(u32, &a_global_variable, 1234, 42, .acquire, .monotonic);
     try expect(a_global_variable == 42);
 }
 
@@ -168,12 +168,12 @@ test "atomic load and rmw with enum" {
     const Value = enum(u8) { a, b, c };
     var x = Value.a;
 
-    try expect(@atomicLoad(Value, &x, .SeqCst) != .b);
+    try expect(@atomicLoad(Value, &x, .seq_cst) != .b);
 
-    _ = @atomicRmw(Value, &x, .Xchg, .c, .SeqCst);
-    try expect(@atomicLoad(Value, &x, .SeqCst) == .c);
-    try expect(@atomicLoad(Value, &x, .SeqCst) != .a);
-    try expect(@atomicLoad(Value, &x, .SeqCst) != .b);
+    _ = @atomicRmw(Value, &x, .Xchg, .c, .seq_cst);
+    try expect(@atomicLoad(Value, &x, .seq_cst) == .c);
+    try expect(@atomicLoad(Value, &x, .seq_cst) != .a);
+    try expect(@atomicLoad(Value, &x, .seq_cst) != .b);
 }
 
 test "atomic store" {
@@ -183,10 +183,10 @@ test "atomic store" {
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
 
     var x: u32 = 0;
-    @atomicStore(u32, &x, 1, .SeqCst);
-    try expect(@atomicLoad(u32, &x, .SeqCst) == 1);
-    @atomicStore(u32, &x, 12345678, .SeqCst);
-    try expect(@atomicLoad(u32, &x, .SeqCst) == 12345678);
+    @atomicStore(u32, &x, 1, .seq_cst);
+    try expect(@atomicLoad(u32, &x, .seq_cst) == 1);
+    @atomicStore(u32, &x, 12345678, .seq_cst);
+    try expect(@atomicLoad(u32, &x, .seq_cst) == 12345678);
 }
 
 test "atomic store comptime" {
@@ -201,10 +201,10 @@ test "atomic store comptime" {
 
 fn testAtomicStore() !void {
     var x: u32 = 0;
-    @atomicStore(u32, &x, 1, .SeqCst);
-    try expect(@atomicLoad(u32, &x, .SeqCst) == 1);
-    @atomicStore(u32, &x, 12345678, .SeqCst);
-    try expect(@atomicLoad(u32, &x, .SeqCst) == 12345678);
+    @atomicStore(u32, &x, 1, .seq_cst);
+    try expect(@atomicLoad(u32, &x, .seq_cst) == 1);
+    @atomicStore(u32, &x, 12345678, .seq_cst);
+    try expect(@atomicLoad(u32, &x, .seq_cst) == 12345678);
 }
 
 test "atomicrmw with floats" {
@@ -224,15 +224,15 @@ test "atomicrmw with floats" {
 fn testAtomicRmwFloat() !void {
     var x: f32 = 0;
     try expect(x == 0);
-    _ = @atomicRmw(f32, &x, .Xchg, 1, .SeqCst);
+    _ = @atomicRmw(f32, &x, .Xchg, 1, .seq_cst);
     try expect(x == 1);
-    _ = @atomicRmw(f32, &x, .Add, 5, .SeqCst);
+    _ = @atomicRmw(f32, &x, .Add, 5, .seq_cst);
     try expect(x == 6);
-    _ = @atomicRmw(f32, &x, .Sub, 2, .SeqCst);
+    _ = @atomicRmw(f32, &x, .Sub, 2, .seq_cst);
     try expect(x == 4);
-    _ = @atomicRmw(f32, &x, .Max, 13, .SeqCst);
+    _ = @atomicRmw(f32, &x, .Max, 13, .seq_cst);
     try expect(x == 13);
-    _ = @atomicRmw(f32, &x, .Min, 42, .SeqCst);
+    _ = @atomicRmw(f32, &x, .Min, 42, .seq_cst);
     try expect(x == 13);
 }
 
@@ -266,46 +266,46 @@ fn testAtomicRmwInt(comptime signedness: std.builtin.Signedness, comptime N: usi
     const int = std.meta.Int(signedness, N);
 
     var x: int = 1;
-    var res = @atomicRmw(int, &x, .Xchg, 3, .SeqCst);
+    var res = @atomicRmw(int, &x, .Xchg, 3, .seq_cst);
     try expect(x == 3 and res == 1);
 
-    res = @atomicRmw(int, &x, .Add, 3, .SeqCst);
+    res = @atomicRmw(int, &x, .Add, 3, .seq_cst);
     var y: int = 3;
     try expect(res == y);
     y = y + 3;
     try expect(x == y);
 
-    res = @atomicRmw(int, &x, .Sub, 1, .SeqCst);
+    res = @atomicRmw(int, &x, .Sub, 1, .seq_cst);
     try expect(res == y);
     y = y - 1;
     try expect(x == y);
 
-    res = @atomicRmw(int, &x, .And, 4, .SeqCst);
+    res = @atomicRmw(int, &x, .And, 4, .seq_cst);
     try expect(res == y);
     y = y & 4;
     try expect(x == y);
 
-    res = @atomicRmw(int, &x, .Nand, 4, .SeqCst);
+    res = @atomicRmw(int, &x, .Nand, 4, .seq_cst);
     try expect(res == y);
     y = ~(y & 4);
     try expect(x == y);
 
-    res = @atomicRmw(int, &x, .Or, 6, .SeqCst);
+    res = @atomicRmw(int, &x, .Or, 6, .seq_cst);
     try expect(res == y);
     y = y | 6;
     try expect(x == y);
 
-    res = @atomicRmw(int, &x, .Xor, 2, .SeqCst);
+    res = @atomicRmw(int, &x, .Xor, 2, .seq_cst);
     try expect(res == y);
     y = y ^ 2;
     try expect(x == y);
 
-    res = @atomicRmw(int, &x, .Max, 1, .SeqCst);
+    res = @atomicRmw(int, &x, .Max, 1, .seq_cst);
     try expect(res == y);
     y = @max(y, 1);
     try expect(x == y);
 
-    res = @atomicRmw(int, &x, .Min, 1, .SeqCst);
+    res = @atomicRmw(int, &x, .Min, 1, .seq_cst);
     try expect(res == y);
     y = @min(y, 1);
     try expect(x == y);
@@ -333,53 +333,53 @@ fn testAtomicRmwInt128(comptime signedness: std.builtin.Signedness) !void {
     const replacement: int = 0x00000000_00000005_00000000_00000003;
 
     var x: int align(16) = initial;
-    var res = @atomicRmw(int, &x, .Xchg, replacement, .SeqCst);
+    var res = @atomicRmw(int, &x, .Xchg, replacement, .seq_cst);
     try expect(x == replacement and res == initial);
 
     var operator: int = 0x00000001_00000000_20000000_00000000;
-    res = @atomicRmw(int, &x, .Add, operator, .SeqCst);
+    res = @atomicRmw(int, &x, .Add, operator, .seq_cst);
     var y: int = replacement;
     try expect(res == y);
     y = y + operator;
     try expect(x == y);
 
     operator = 0x00000000_10000000_00000000_20000000;
-    res = @atomicRmw(int, &x, .Sub, operator, .SeqCst);
+    res = @atomicRmw(int, &x, .Sub, operator, .seq_cst);
     try expect(res == y);
     y = y - operator;
     try expect(x == y);
 
     operator = 0x12345678_87654321_12345678_87654321;
-    res = @atomicRmw(int, &x, .And, operator, .SeqCst);
+    res = @atomicRmw(int, &x, .And, operator, .seq_cst);
     try expect(res == y);
     y = y & operator;
     try expect(x == y);
 
     operator = 0x00000000_10000000_00000000_20000000;
-    res = @atomicRmw(int, &x, .Nand, operator, .SeqCst);
+    res = @atomicRmw(int, &x, .Nand, operator, .seq_cst);
     try expect(res == y);
     y = ~(y & operator);
     try expect(x == y);
 
     operator = 0x12340000_56780000_67890000_98760000;
-    res = @atomicRmw(int, &x, .Or, operator, .SeqCst);
+    res = @atomicRmw(int, &x, .Or, operator, .seq_cst);
     try expect(res == y);
     y = y | operator;
     try expect(x == y);
 
     operator = 0x0a0b0c0d_0e0f0102_03040506_0708090a;
-    res = @atomicRmw(int, &x, .Xor, operator, .SeqCst);
+    res = @atomicRmw(int, &x, .Xor, operator, .seq_cst);
     try expect(res == y);
     y = y ^ operator;
     try expect(x == y);
 
     operator = 0x00000000_10000000_00000000_20000000;
-    res = @atomicRmw(int, &x, .Max, operator, .SeqCst);
+    res = @atomicRmw(int, &x, .Max, operator, .seq_cst);
     try expect(res == y);
     y = @max(y, operator);
     try expect(x == y);
 
-    res = @atomicRmw(int, &x, .Min, operator, .SeqCst);
+    res = @atomicRmw(int, &x, .Min, operator, .seq_cst);
     try expect(res == y);
     y = @min(y, operator);
     try expect(x == y);
@@ -405,13 +405,13 @@ test "atomics with different types" {
 
 fn testAtomicsWithType(comptime T: type, a: T, b: T) !void {
     var x: T = b;
-    @atomicStore(T, &x, a, .SeqCst);
+    @atomicStore(T, &x, a, .seq_cst);
     try expect(x == a);
-    try expect(@atomicLoad(T, &x, .SeqCst) == a);
-    try expect(@atomicRmw(T, &x, .Xchg, b, .SeqCst) == a);
-    try expect(@cmpxchgStrong(T, &x, b, a, .SeqCst, .SeqCst) == null);
+    try expect(@atomicLoad(T, &x, .seq_cst) == a);
+    try expect(@atomicRmw(T, &x, .Xchg, b, .seq_cst) == a);
+    try expect(@cmpxchgStrong(T, &x, b, a, .seq_cst, .seq_cst) == null);
     if (@sizeOf(T) != 0)
-        try expect(@cmpxchgStrong(T, &x, b, a, .SeqCst, .SeqCst).? == a);
+        try expect(@cmpxchgStrong(T, &x, b, a, .seq_cst, .seq_cst).? == a);
 }
 
 test "return @atomicStore, using it as a void value" {
@@ -425,12 +425,12 @@ test "return @atomicStore, using it as a void value" {
             value: usize,
 
             pub fn store(self: *A, value: usize) void {
-                return @atomicStore(usize, &self.value, value, .Unordered);
+                return @atomicStore(usize, &self.value, value, .unordered);
             }
 
             pub fn store2(self: *A, value: usize) void {
                 return switch (value) {
-                    else => @atomicStore(usize, &self.value, value, .Unordered),
+                    else => @atomicStore(usize, &self.value, value, .unordered),
                 };
             }
         };
test/behavior/builtin_functions_returning_void_or_noreturn.zig
@@ -14,10 +14,10 @@ test {
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
 
     var val: u8 = undefined;
-    try testing.expectEqual({}, @atomicStore(u8, &val, 0, .Unordered));
+    try testing.expectEqual({}, @atomicStore(u8, &val, 0, .unordered));
     try testing.expectEqual(void, @TypeOf(@breakpoint()));
     try testing.expectEqual({}, @export(x, .{ .name = "x" }));
-    try testing.expectEqual({}, @fence(.Acquire));
+    try testing.expectEqual({}, @fence(.acquire));
     try testing.expectEqual({}, @memcpy(@as([*]u8, @ptrFromInt(1))[0..0], @as([*]u8, @ptrFromInt(1))[0..0]));
     try testing.expectEqual({}, @memset(@as([*]u8, @ptrFromInt(1))[0..0], undefined));
     try testing.expectEqual(noreturn, @TypeOf(if (true) @panic("") else {}));
test/cases/compile_errors/atomic_orderings_of_atomicStore_Acquire_or_AcqRel.zig
@@ -1,10 +1,10 @@
 export fn entry() void {
     var x: u32 = 0;
-    @atomicStore(u32, &x, 1, .Acquire);
+    @atomicStore(u32, &x, 1, .acquire);
 }
 
 // error
 // backend=stage2
 // target=native
 //
-// :3:31: error: @atomicStore atomic ordering must not be Acquire or AcqRel
+// :3:31: error: @atomicStore atomic ordering must not be acquire or acq_rel
test/cases/compile_errors/atomic_orderings_of_cmpxchg-failure_stricter_than_success.zig
@@ -1,7 +1,7 @@
 const AtomicOrder = @import("std").builtin.AtomicOrder;
 export fn f() void {
     var x: i32 = 1234;
-    while (!@cmpxchgWeak(i32, &x, 1234, 5678, AtomicOrder.Monotonic, AtomicOrder.SeqCst)) {}
+    while (!@cmpxchgWeak(i32, &x, 1234, 5678, AtomicOrder.monotonic, AtomicOrder.seq_cst)) {}
 }
 
 // error
test/cases/compile_errors/atomic_orderings_of_cmpxchg-success_Monotonic_or_stricter.zig
@@ -1,11 +1,11 @@
 const AtomicOrder = @import("std").builtin.AtomicOrder;
 export fn f() void {
     var x: i32 = 1234;
-    while (!@cmpxchgWeak(i32, &x, 1234, 5678, AtomicOrder.Unordered, AtomicOrder.Unordered)) {}
+    while (!@cmpxchgWeak(i32, &x, 1234, 5678, AtomicOrder.unordered, AtomicOrder.unordered)) {}
 }
 
 // error
 // backend=stage2
 // target=native
 //
-// :4:58: error: success atomic ordering must be Monotonic or stricter
+// :4:58: error: success atomic ordering must be monotonic or stricter
test/cases/compile_errors/atomic_orderings_of_fence_Acquire_or_stricter.zig
@@ -1,9 +1,9 @@
 export fn entry() void {
-    @fence(.Monotonic);
+    @fence(.monotonic);
 }
 
 // error
 // backend=stage2
 // target=native
 //
-// :2:13: error: atomic ordering must be Acquire or stricter
+// :2:13: error: atomic ordering must be acquire or stricter
test/cases/compile_errors/atomicrmw_with_bool_op_not_.Xchg.zig
@@ -1,6 +1,6 @@
 export fn entry() void {
     var x = false;
-    _ = @atomicRmw(bool, &x, .Add, true, .SeqCst);
+    _ = @atomicRmw(bool, &x, .Add, true, .seq_cst);
 }
 
 // error
test/cases/compile_errors/atomicrmw_with_enum_op_not_.Xchg.zig
@@ -6,7 +6,7 @@ export fn entry() void {
         d,
     };
     var x: E = .a;
-    _ = @atomicRmw(E, &x, .Add, .b, .SeqCst);
+    _ = @atomicRmw(E, &x, .Add, .b, .seq_cst);
 }
 
 // error
test/cases/compile_errors/atomicrmw_with_float_op_not_.Xchg_.Add_.Sub_.Max_or_.Min.zig
@@ -1,6 +1,6 @@
 export fn entry() void {
     var x: f32 = 0;
-    _ = @atomicRmw(f32, &x, .And, 2, .SeqCst);
+    _ = @atomicRmw(f32, &x, .And, 2, .seq_cst);
 }
 
 // error
test/cases/compile_errors/cmpxchg_with_float.zig
@@ -1,6 +1,6 @@
 export fn entry() void {
     var x: f32 = 0;
-    _ = @cmpxchgWeak(f32, &x, 1, 2, .SeqCst, .SeqCst);
+    _ = @cmpxchgWeak(f32, &x, 1, 2, .seq_cst, .seq_cst);
 }
 
 // error
test/cases/compile_errors/passing_a_not-aligned-enough_pointer_to_cmpxchg.zig
@@ -1,7 +1,7 @@
 const AtomicOrder = @import("std").builtin.AtomicOrder;
 export fn entry() bool {
     var x: i32 align(1) = 1234;
-    while (!@cmpxchgWeak(i32, &x, 1234, 5678, AtomicOrder.SeqCst, AtomicOrder.SeqCst)) {}
+    while (!@cmpxchgWeak(i32, &x, 1234, 5678, AtomicOrder.seq_cst, AtomicOrder.seq_cst)) {}
     return x == 5678;
 }