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

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index 76962e4dd7a..73efb4d5762 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -626,12 +626,14 @@ static bool HasFeature(const Preprocessor &PP, const IdentifierInfo *II) {
            .Case("arc_cf_code_audited", true)
            // C11 features
            .Case("c_alignas", LangOpts.C11)
+           .Case("c_atomic", LangOpts.C11)
            .Case("c_generic_selections", LangOpts.C11)
            .Case("c_static_assert", LangOpts.C11)
            // C++0x features
            .Case("cxx_access_control_sfinae", LangOpts.CPlusPlus0x)
            .Case("cxx_alias_templates", LangOpts.CPlusPlus0x)
            .Case("cxx_alignas", LangOpts.CPlusPlus0x)
+           .Case("cxx_atomic", LangOpts.CPlusPlus0x)
            .Case("cxx_attributes", LangOpts.CPlusPlus0x)
            .Case("cxx_auto_type", LangOpts.CPlusPlus0x)
          //.Case("cxx_constexpr", false);
@@ -724,9 +726,11 @@ static bool HasExtension(const Preprocessor &PP, const IdentifierInfo *II) {
   return llvm::StringSwitch<bool>(II->getName())
            // C11 features supported by other languages as extensions.
            .Case("c_alignas", true)
+           .Case("c_atomic", true)
            .Case("c_generic_selections", true)
            .Case("c_static_assert", true)
            // C++0x features supported by other languages as extensions.
+           .Case("cxx_atomic", LangOpts.CPlusPlus)
            .Case("cxx_deleted_functions", LangOpts.CPlusPlus)
            .Case("cxx_explicit_conversions", LangOpts.CPlusPlus)
            .Case("cxx_inline_namespaces", LangOpts.CPlusPlus)