From 221f6d777e56517591766a582f542af92d1f19c9 Mon Sep 17 00:00:00 2001 From: Reid Kleckner Date: Mon, 8 Jul 2013 15:31:29 +0000 Subject: [PATCH] Use Clang's __has_* macros in Compiler.h to test for features When targetting Windows, clang does not define __GNUC__, and as a result we don't use our attributes with it. This leads to warnings about unused functions that are already annotated with LLVM_ATTRIBUTE_UNUSED. Rather than testing for __clang__, we can use its __has_attribute and __has_builtin macros directlty. While I'm here, conditionally define and use __GNUC_PREREQ for gcc version checks. Spelling the check out with three comparisons is verbose and error prone. Reviewers: aaron.ballman Differential Revision: http://llvm-reviews.chandlerc.com/D1080 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185831 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Support/Compiler.h | 54 +++++++++++++++++++++++++++++------------ 1 file changed, 38 insertions(+), 16 deletions(-) diff --git a/include/llvm/Support/Compiler.h b/include/llvm/Support/Compiler.h index 13d057be049..336c069c507 100644 --- a/include/llvm/Support/Compiler.h +++ b/include/llvm/Support/Compiler.h @@ -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 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 +187,35 @@ // 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. +#if __has_attribute(const) || 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 +238,7 @@ /// 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 +250,7 @@ /// 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 +292,7 @@ /// 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 +300,7 @@ /// 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 +308,10 @@ /// \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 -- 2.11.0