Author: mgorny Date: Mon Jan 9 14:54:20 2017 New Revision: 291477 URL: http://llvm.org/viewvc/llvm-project?rev=291477&view=rev Log: [Frontend] Correct values of ATOMIC_*_LOCK_FREE to match builtin
Correct the logic used to set ATOMIC_*_LOCK_FREE preprocessor macros not to rely on the ABI alignment of types. Instead, just assume all those types are aligned correctly by default since clang uses safe alignment for _Atomic types even if the underlying types are aligned to a lower boundary by default. For example, the 'long long' and 'double' types on x86 are aligned to 32-bit boundary by default. However, '_Atomic long long' and '_Atomic double' are aligned to 64-bit boundary, therefore satisfying the requirements of lock-free atomic operations. This fixes PR #19355 by correcting the value of __GCC_ATOMIC_LLONG_LOCK_FREE on x86, and therefore also fixing the assumption made in libc++ tests. This also fixes PR #30581 by applying a consistent logic between the functions used to implement both interfaces. Differential Revision: https://reviews.llvm.org/D28213 Modified: cfe/trunk/lib/Frontend/InitPreprocessor.cpp cfe/trunk/test/Sema/atomic-ops.c Modified: cfe/trunk/lib/Frontend/InitPreprocessor.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/InitPreprocessor.cpp?rev=291477&r1=291476&r2=291477&view=diff ============================================================================== --- cfe/trunk/lib/Frontend/InitPreprocessor.cpp (original) +++ cfe/trunk/lib/Frontend/InitPreprocessor.cpp Mon Jan 9 14:54:20 2017 @@ -286,12 +286,12 @@ static void DefineFastIntType(unsigned T /// Get the value the ATOMIC_*_LOCK_FREE macro should have for a type with /// the specified properties. -static const char *getLockFreeValue(unsigned TypeWidth, unsigned TypeAlign, - unsigned InlineWidth) { +static const char *getLockFreeValue(unsigned TypeWidth, unsigned InlineWidth) { // Fully-aligned, power-of-2 sizes no larger than the inline // width will be inlined as lock-free operations. - if (TypeWidth == TypeAlign && (TypeWidth & (TypeWidth - 1)) == 0 && - TypeWidth <= InlineWidth) + // Note: we do not need to check alignment since _Atomic(T) is always + // appropriately-aligned in clang. + if ((TypeWidth & (TypeWidth - 1)) == 0 && TypeWidth <= InlineWidth) return "2"; // "always lock free" // We cannot be certain what operations the lib calls might be // able to implement as lock-free on future processors. @@ -881,7 +881,6 @@ static void InitializePredefinedMacros(c #define DEFINE_LOCK_FREE_MACRO(TYPE, Type) \ Builder.defineMacro("__GCC_ATOMIC_" #TYPE "_LOCK_FREE", \ getLockFreeValue(TI.get##Type##Width(), \ - TI.get##Type##Align(), \ InlineWidthBits)); DEFINE_LOCK_FREE_MACRO(BOOL, Bool); DEFINE_LOCK_FREE_MACRO(CHAR, Char); @@ -894,7 +893,6 @@ static void InitializePredefinedMacros(c DEFINE_LOCK_FREE_MACRO(LLONG, LongLong); Builder.defineMacro("__GCC_ATOMIC_POINTER_LOCK_FREE", getLockFreeValue(TI.getPointerWidth(0), - TI.getPointerAlign(0), InlineWidthBits)); #undef DEFINE_LOCK_FREE_MACRO } Modified: cfe/trunk/test/Sema/atomic-ops.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/atomic-ops.c?rev=291477&r1=291476&r2=291477&view=diff ============================================================================== --- cfe/trunk/test/Sema/atomic-ops.c (original) +++ cfe/trunk/test/Sema/atomic-ops.c Mon Jan 9 14:54:20 2017 @@ -14,11 +14,7 @@ _Static_assert(__GCC_ATOMIC_WCHAR_T_LOCK _Static_assert(__GCC_ATOMIC_SHORT_LOCK_FREE == 2, ""); _Static_assert(__GCC_ATOMIC_INT_LOCK_FREE == 2, ""); _Static_assert(__GCC_ATOMIC_LONG_LOCK_FREE == 2, ""); -#ifdef __i386__ -_Static_assert(__GCC_ATOMIC_LLONG_LOCK_FREE == 1, ""); -#else _Static_assert(__GCC_ATOMIC_LLONG_LOCK_FREE == 2, ""); -#endif _Static_assert(__GCC_ATOMIC_POINTER_LOCK_FREE == 2, ""); _Static_assert(__c11_atomic_is_lock_free(1), ""); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
