[llvm] r185850 - Reland "Use Clang's __has_* macros in Compiler.h ..." with fixes
Reid Kleckner
reid at kleckner.net
Mon Jul 8 12:06:25 PDT 2013
Author: rnk
Date: Mon Jul 8 14:06:25 2013
New Revision: 185850
URL: http://llvm.org/viewvc/llvm-project?rev=185850&view=rev
Log:
Reland "Use Clang's __has_* macros in Compiler.h ..." with fixes
This reverts r185841 and relands r185831 without using
__has_attribute(const).
Clang prior to r161767 (between 3.1 and 3.2) does not accept
__has_attribute(const) due to rdar://10253857. __const and __const__
are both keyword aliases of const, so they don't work either.
I was able to repro the buildbot failure using clang 3.1 and this patch
fixes it. Various important versions of XCode use clang 2.9-ish, so
this workaround is necessary.
Modified:
llvm/trunk/include/llvm/Support/Compiler.h
Modified: llvm/trunk/include/llvm/Support/Compiler.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Compiler.h?rev=185850&r1=185849&r2=185850&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/Compiler.h (original)
+++ llvm/trunk/include/llvm/Support/Compiler.h Mon Jul 8 14:06:25 2013
@@ -21,6 +21,25 @@
# define __has_feature(x) 0
#endif
+#ifndef __has_attribute
+# define __has_attribute(x) 0
+#endif
+
+#ifndef __has_builtin
+# define __has_builtin(x) 0
+#endif
+
+/// \macro __GNUC_PREREQ
+/// \brief Defines __GNUC_PREREQ if glibc's features.h isn't available.
+#ifndef __GNUC_PREREQ
+# if defined(__GNUC__) && defined(__GNUC_MINOR__)
+# define __GNUC_PREREQ(maj, min) \
+ ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
+# else
+# define __GNUC_PREREQ(maj, min) 0
+# endif
+#endif
+
/// \brief Does the compiler support r-value references?
/// This implies that <utility> provides the one-argument std::move; it
/// does not imply the existence of any other C++ library features.
@@ -146,13 +165,15 @@
/// into a shared library, then the class should be private to the library and
/// not accessible from outside it. Can also be used to mark variables and
/// functions, making them private to any shared library they are linked into.
-#if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
+/// On PE/COFF targets, library visibility is the default, so this isn't needed.
+#if (__has_attribute(visibility) || __GNUC_PREREQ(4, 0)) && \
+ !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32)
#define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
#else
#define LLVM_LIBRARY_VISIBILITY
#endif
-#if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
+#if __has_attribute(used) || __GNUC_PREREQ(3, 1)
#define LLVM_ATTRIBUTE_USED __attribute__((__used__))
#else
#define LLVM_ATTRIBUTE_USED
@@ -166,31 +187,37 @@
// more portable solution:
// (void)unused_var_name;
// Prefer cast-to-void wherever it is sufficient.
-#if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
+#if __has_attribute(unused) || __GNUC_PREREQ(3, 1)
#define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
#else
#define LLVM_ATTRIBUTE_UNUSED
#endif
-#if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
+// FIXME: Provide this for PE/COFF targets.
+#if (__has_attribute(weak) || __GNUC_PREREQ(4, 0)) && \
+ (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32))
#define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
#else
#define LLVM_ATTRIBUTE_WEAK
#endif
-#ifdef __GNUC__ // aka 'CONST' but following LLVM Conventions.
+// Prior to clang 3.2, clang did not accept any spelling of
+// __has_attribute(const), so assume it is supported.
+#if defined(__clang__) || defined(__GNUC__)
+// aka 'CONST' but following LLVM Conventions.
#define LLVM_READNONE __attribute__((__const__))
#else
#define LLVM_READNONE
#endif
-#ifdef __GNUC__ // aka 'PURE' but following LLVM Conventions.
+#if __has_attribute(pure) || defined(__GNUC__)
+// aka 'PURE' but following LLVM Conventions.
#define LLVM_READONLY __attribute__((__pure__))
#else
#define LLVM_READONLY
#endif
-#if (__GNUC__ >= 4)
+#if __has_builtin(__builtin_expect) || __GNUC_PREREQ(4, 0)
#define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
#define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
#else
@@ -213,7 +240,7 @@
/// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
/// mark a method "not for inlining".
-#if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
+#if __has_attribute(noinline) || __GNUC_PREREQ(3, 4)
#define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
#elif defined(_MSC_VER)
#define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
@@ -225,7 +252,7 @@
/// so, mark a method "always inline" because it is performance sensitive. GCC
/// 3.4 supported this but is buggy in various cases and produces unimplemented
/// errors, just use it in GCC 4.0 and later.
-#if __GNUC__ > 3
+#if __has_attribute(always_inline) || __GNUC_PREREQ(4, 0)
#define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline))
#elif defined(_MSC_VER)
#define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
@@ -267,8 +294,7 @@
/// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
/// to an expression which states that it is undefined behavior for the
/// compiler to reach this point. Otherwise is not defined.
-#if defined(__clang__) || (__GNUC__ > 4) \
- || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
+#if __has_builtin(__builtin_unreachable) || __GNUC_PREREQ(4, 5)
# define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
#elif defined(_MSC_VER)
# define LLVM_BUILTIN_UNREACHABLE __assume(false)
@@ -276,8 +302,7 @@
/// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
/// which causes the program to exit abnormally.
-#if defined(__clang__) || (__GNUC__ > 4) \
- || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
+#if __has_builtin(__builtin_trap) || __GNUC_PREREQ(4, 3)
# define LLVM_BUILTIN_TRAP __builtin_trap()
#else
# define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0
@@ -285,11 +310,10 @@
/// \macro LLVM_ASSUME_ALIGNED
/// \brief Returns a pointer with an assumed alignment.
-#if !defined(__clang__) && ((__GNUC__ > 4) \
- || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7))
-// FIXME: Enable on clang when it supports it.
+#if __has_builtin(__builtin_assume_aligned) && __GNUC_PREREQ(4, 7)
# define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
#elif defined(LLVM_BUILTIN_UNREACHABLE)
+// As of today, clang does not support __builtin_assume_aligned.
# define LLVM_ASSUME_ALIGNED(p, a) \
(((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p)))
#else
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