Some improvements to the handling of C11 atomic types:
- Add atomic-to/from-nonatomic cast types
- Emit atomic operations for arithmetic on atomic types
- Emit non-atomic stores for initialisation of atomic types, but atomic stores and loads for every other store / load
- Add a __atomic_init() intrinsic which does a non-atomic store to an _Atomic() type. This is needed for the corresponding C11 stdatomic.h function.
- Enables the relevant __has_feature() checks. The feature isn't 100% complete yet, but it's done enough that we want people testing it.
Still to do:
- Make the arithmetic operations on atomic types (e.g. Atomic(int) foo = 1; foo++;) use the correct LLVM intrinsic if one exists, not a loop with a cmpxchg.
- Add a signal fence builtin
- Properly set the fenv state in atomic operations on floating point values
- Correctly handle things like _Atomic(_Complex double) which are too large for an atomic cmpxchg on some platforms (this requires working out what 'correctly' means in this context)
- Fix the many remaining corner cases
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148242 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/atomic_ops.c b/test/CodeGen/atomic_ops.c
new file mode 100644
index 0000000..9a18c9e
--- /dev/null
+++ b/test/CodeGen/atomic_ops.c
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s
+
+void foo(void)
+{
+ _Atomic(int) i = 0;
+ // Check that multiply / divides on atomics produce a cmpxchg loop
+ i *= 2; // CHECK: cmpxchg
+ i /= 2; // CHECK: cmpxchg
+ // These should be emitting atomicrmw instructions, but they aren't yet
+ i += 2; // CHECK: cmpxchg
+ i -= 2; // CHECK: cmpxchg
+ i++; // CHECK: cmpxchg
+ i--; // CHECK: cmpxchg
+}