stage2: implement `@atomicRmw` and `@atomicLoad`

 * langref: add some more "see also" links for atomics
 * Add the following AIR instructions
   - atomic_load
   - atomic_store_unordered
   - atomic_store_monotonic
   - atomic_store_release
   - atomic_store_seq_cst
   - atomic_rmw
 * Implement those AIR instructions in LLVM and C backends.
 * AstGen: make the `ty` result locations for `@atomicRmw`, `@atomicLoad`,
   and `@atomicStore` be `coerced_ty` to avoid unnecessary ZIR
   instructions when Sema will be doing the coercions redundantly.
 * Sema for `@atomicLoad` and `@atomicRmw` is done, however Sema for
   `@atomicStore` is not yet implemented.
   - comptime eval for `@atomicRmw` is not yet implemented.
 * Sema: flesh out `coerceInMemoryAllowed` a little bit more. It can now
   handle pointers.

1 files changed, 51 insertions, 6 deletions

diff --git a/src/link/C/zig.h b/src/link/C/zig.h
index 28d6f2dd17..e19a138c1b 100644
--- a/src/link/C/zig.h
+++ b/src/link/C/zig.h
@@ -62,16 +62,61 @@
 
 #if __STDC_VERSION__ >= 201112L && !defined(__STDC_NO_ATOMICS__)
 #include <stdatomic.h>
-#define zig_cmpxchg_strong(obj, expected, desired, succ, fail) atomic_compare_exchange_strong_explicit(obj, expected, desired, succ, fail)
-#define zig_cmpxchg_weak(obj, expected, desired, succ, fail) atomic_compare_exchange_weak_explicit(obj, expected, desired, succ, fail)
+#define zig_cmpxchg_strong(obj, expected, desired, succ, fail) atomic_compare_exchange_strong_explicit(obj, &(expected), desired, succ, fail)
+#define zig_cmpxchg_weak  (obj, expected, desired, succ, fail) atomic_compare_exchange_weak_explicit  (obj, &(expected), desired, succ, fail)
+#define zig_atomicrmw_xchg(obj, arg, order) atomic_exchange_explicit  (obj, arg, order)
+#define zig_atomicrmw_add (obj, arg, order) atomic_fetch_add_explicit (obj, arg, order)
+#define zig_atomicrmw_sub (obj, arg, order) atomic_fetch_sub_explicit (obj, arg, order)
+#define zig_atomicrmw_or  (obj, arg, order) atomic_fetch_or_explicit  (obj, arg, order)
+#define zig_atomicrmw_xor (obj, arg, order) atomic_fetch_xor_explicit (obj, arg, order)
+#define zig_atomicrmw_and (obj, arg, order) atomic_fetch_and_explicit (obj, arg, order)
+#define zig_atomicrmw_nand(obj, arg, order) atomic_fetch_nand_explicit(obj, arg, order)
+#define zig_atomicrmw_min (obj, arg, order) atomic_fetch_min_explicit (obj, arg, order)
+#define zig_atomicrmw_max (obj, arg, order) atomic_fetch_max_explicit (obj, arg, order)
+#define zig_atomic_store  (obj, arg, order) atomic_store_explicit     (obj, arg, order)
+#define zig_atomic_load   (obj,      order) atomic_load_explicit      (obj,      order)
 #define zig_fence(order) atomic_thread_fence(order)
 #elif __GNUC__
-#define zig_cmpxchg_strong(obj, expected, desired, succ, fail) __sync_val_compare_and_swap(obj, expected, desired)
-#define zig_cmpxchg_weak(obj, expected, desired, succ, fail) __sync_val_compare_and_swap(obj, expected, desired)
-#define zig_fence(order) __sync_synchronize(order)
+#define memory_order_relaxed __ATOMIC_RELAXED
+#define memory_order_consume __ATOMIC_CONSUME
+#define memory_order_acquire __ATOMIC_ACQUIRE
+#define memory_order_release __ATOMIC_RELEASE
+#define memory_order_acq_rel __ATOMIC_ACQ_REL
+#define memory_order_seq_cst __ATOMIC_SEQ_CST
+#define zig_cmpxchg_strong(obj, expected, desired, succ, fail) __atomic_compare_exchange_n(obj, &(expected), desired, false, succ, fail)
+#define zig_cmpxchg_weak  (obj, expected, desired, succ, fail) __atomic_compare_exchange_n(obj, &(expected), desired, true , succ, fail)
+#define zig_atomicrmw_xchg(obj, arg, order) __atomic_exchange_n(obj, arg, order)
+#define zig_atomicrmw_add (obj, arg, order) __atomic_fetch_add (obj, arg, order)
+#define zig_atomicrmw_sub (obj, arg, order) __atomic_fetch_sub (obj, arg, order)
+#define zig_atomicrmw_or  (obj, arg, order) __atomic_fetch_or  (obj, arg, order)
+#define zig_atomicrmw_xor (obj, arg, order) __atomic_fetch_xor (obj, arg, order)
+#define zig_atomicrmw_and (obj, arg, order) __atomic_fetch_and (obj, arg, order)
+#define zig_atomicrmw_nand(obj, arg, order) __atomic_fetch_nand(obj, arg, order)
+#define zig_atomicrmw_min (obj, arg, order) __atomic_fetch_min (obj, arg, order)
+#define zig_atomicrmw_max (obj, arg, order) __atomic_fetch_max (obj, arg, order)
+#define zig_atomic_store  (obj, arg, order) __atomic_store     (obj, arg, order)
+#define zig_atomic_load   (obj,      order) __atomic_load      (obj,      order)
+#define zig_fence(order) __atomic_thread_fence(order)
 #else
+#define memory_order_relaxed 0
+#define memory_order_consume 1
+#define memory_order_acquire 2
+#define memory_order_release 3
+#define memory_order_acq_rel 4
+#define memory_order_seq_cst 5
 #define zig_cmpxchg_strong(obj, expected, desired, succ, fail) zig_unimplemented()
-#define zig_cmpxchg_weak(obj, expected, desired, succ, fail) zig_unimplemented()
+#define zig_cmpxchg_weak  (obj, expected, desired, succ, fail) zig_unimplemented()
+#define zig_atomicrmw_xchg(obj, arg, order) zig_unimplemented()
+#define zig_atomicrmw_add (obj, arg, order) zig_unimplemented()
+#define zig_atomicrmw_sub (obj, arg, order) zig_unimplemented()
+#define zig_atomicrmw_or  (obj, arg, order) zig_unimplemented()
+#define zig_atomicrmw_xor (obj, arg, order) zig_unimplemented()
+#define zig_atomicrmw_and (obj, arg, order) zig_unimplemented()
+#define zig_atomicrmw_nand(obj, arg, order) zig_unimplemented()
+#define zig_atomicrmw_min (obj, arg, order) zig_unimplemented()
+#define zig_atomicrmw_max (obj, arg, order) zig_unimplemented()
+#define zig_atomic_store  (obj, arg, order) zig_unimplemented()
+#define zig_atomic_load   (obj,      order) zig_unimplemented()
 #define zig_fence(order) zig_unimplemented()
 #endif