[PATCH] D123080: [compiler-rt builtins] Assert that atomic.c can be compiled correctly.

[Eli Friedman via Phabricator via llvm-commits]

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The spinlock requires that lock-free operations are available; otherwise, the implementation just calls itself. As discussed in D120026 <https://reviews.llvm.org/D120026>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D123080

Files:
  compiler-rt/lib/builtins/atomic.c


Index: compiler-rt/lib/builtins/atomic.c
===================================================================
--- compiler-rt/lib/builtins/atomic.c
+++ compiler-rt/lib/builtins/atomic.c
@@ -92,6 +92,8 @@
 static Lock locks[SPINLOCK_COUNT]; // initialized to OS_SPINLOCK_INIT which is 0
 
 #else
+_Static_assert(__atomic_always_lock_free(sizeof(uintptr_t), 0),
+               "Implementation assumes lock-free pointer-size cmpxchg");
 typedef _Atomic(uintptr_t) Lock;
 /// Unlock a lock.  This is a release operation.
 __inline static void unlock(Lock *l) {


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