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

4 files changed, 46 insertions, 0 deletions

diff --git a/clang/test/CodeGen/atomic_init.c b/clang/test/CodeGen/atomic_init.c
new file mode 100644
index 00000000000..243eb602cb1
--- /dev/null
+++ b/clang/test/CodeGen/atomic_init.c
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s
+
+// Check that no atomic operations are used in any initialisation of _Atomic
+// types.  
+
+_Atomic(int) i = 42;
+
+void foo()
+{
+  _Atomic(int) j = 12; // CHECK: store 
+                       // CHECK-NOT: atomic
+  __atomic_init(&j, 42); // CHECK: store 
+                         // CHECK-NOT: atomic
+}
diff --git a/clang/test/CodeGen/atomic_ops.c b/clang/test/CodeGen/atomic_ops.c
new file mode 100644
index 00000000000..9a18c9e9449
--- /dev/null
+++ b/clang/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
+}
diff --git a/clang/test/Lexer/has_feature_c1x.c b/clang/test/Lexer/has_feature_c1x.c
index a502f16ce3f..c9a5f56ddf3 100644
--- a/clang/test/Lexer/has_feature_c1x.c
+++ b/clang/test/Lexer/has_feature_c1x.c
@@ -1,6 +1,15 @@
 // RUN: %clang_cc1 -E -std=c1x %s -o - | FileCheck --check-prefix=CHECK-1X %s
 // RUN: %clang_cc1 -E %s -o - | FileCheck --check-prefix=CHECK-NO-1X %s
 
+#if __has_feature(c_atomic)
+int has_atomic();
+#else
+int no_atomic();
+#endif
+
+// CHECK-1X: has_atomic
+// CHECK-NO-1X: no_atomic
+
 #if __has_feature(c_static_assert)
 int has_static_assert();
 #else
diff --git a/clang/test/Lexer/has_feature_cxx0x.cpp b/clang/test/Lexer/has_feature_cxx0x.cpp
index a22cf64c205..f02f1031add 100644
--- a/clang/test/Lexer/has_feature_cxx0x.cpp
+++ b/clang/test/Lexer/has_feature_cxx0x.cpp
@@ -1,6 +1,15 @@
 // RUN: %clang_cc1 -E -std=c++11 %s -o - | FileCheck --check-prefix=CHECK-0X %s
 // RUN: %clang_cc1 -E %s -o - | FileCheck --check-prefix=CHECK-NO-0X %s
 
+#if __has_feature(cxx_atomic)
+int has_atomic();
+#else
+int no_atomic();
+#endif
+
+// CHECK-0X: has_atomic
+// CHECK-NO-0X: no_atomic
+
 #if __has_feature(cxx_lambdas)
 int has_lambdas();
 #else