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Implement the missing pieces needed to support libstdc++4.7's <atomic>:

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__atomic_test_and_set, __atomic_clear, plus a pile of undocumented __GCC_*
predefined macros.

Implement library fallback for __atomic_is_lock_free and
__c11_atomic_is_lock_free, and implement __atomic_always_lock_free.

Contrary to their documentation, GCC's __atomic_fetch_add family don't
multiply the operand by sizeof(T) when operating on a pointer type.
libstdc++ relies on this quirk. Remove this handling for all but the
__c11_atomic_fetch_add and __c11_atomic_fetch_sub builtins.

Contrary to their documentation, __atomic_test_and_set and __atomic_clear
take a first argument of type 'volatile void *', not 'void *' or 'bool *',
and __atomic_is_lock_free and __atomic_always_lock_free have an argument
of type 'const volatile void *', not 'void *'.

With this change, libstdc++4.7's <atomic> passes libc++'s atomic test suite,
except for a couple of libstdc++ bugs and some cases where libc++'s test
suite tests for properties which implementations have latitude to vary.

llvm-svn: 154640
This commit is contained in:
Richard Smith
2012-04-13 00:45:38 +00:00
parent 18104239b4
commit 01ba47d7b6
7 changed files with 375 additions and 46 deletions
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40
clang/lib/Frontend/InitPreprocessor.cpp
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@@ -202,6 +202,20 @@ static void DefineExactWidthIntType(TargetInfo::IntType Ty,
ConstSuffix);
}
/// 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) {
// 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)
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.
return "1"; // "sometimes lock free"
}
/// \brief Add definitions required for a smooth interaction between
/// Objective-C++ automated reference counting and libstdc++ (4.2).
static void AddObjCXXARCLibstdcxxDefines(const LangOptions &LangOpts,
@@ -521,6 +535,32 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
else
Builder.defineMacro("__GNUC_STDC_INLINE__");
// The value written by __atomic_test_and_set.
// FIXME: This is target-dependent.
Builder.defineMacro("__GCC_ATOMIC_TEST_AND_SET_TRUEVAL", "1");
// Used by libstdc++ to implement ATOMIC_<foo>_LOCK_FREE.
unsigned InlineWidthBits = TI.getMaxAtomicInlineWidth();
#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);
DEFINE_LOCK_FREE_MACRO(CHAR16_T, Char16);
DEFINE_LOCK_FREE_MACRO(CHAR32_T, Char32);
DEFINE_LOCK_FREE_MACRO(WCHAR_T, WChar);
DEFINE_LOCK_FREE_MACRO(SHORT, Short);
DEFINE_LOCK_FREE_MACRO(INT, Int);
DEFINE_LOCK_FREE_MACRO(LONG, Long);
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
if (LangOpts.NoInlineDefine)
Builder.defineMacro("__NO_INLINE__");