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llvm-project/clang/test/CodeGen/atomic_ops.c

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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 llvm-svn: 148242
2012-01-17 01:27:18 +08:00
// 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
}