[llvm] r185831 - Use Clang's __has_* macros in Compiler.h to test for features

Mon Jul 8 09:55:03 PDT 2013

That failed:
http://lab.llvm.org:8013/builders/clang-x86_64-darwin11-nobootstrap-RAincremental/builds/4081/steps/make/logs/stdio

It looks like this was a clang bug (rdar://10253857) fixed in r161767.

Probably the best workaround is just to check for __clang__.

On Mon, Jul 8, 2013 at 12:39 PM, Reid Kleckner <rnk at google.com> wrote:

> Prospective fix in r185833.
>
> I can't reproduce the bot problem locally when building clang with a
> ~month-old clang.  Is there anything special about that bot?  Is it
> building with a clang from XCode, maybe?
>
> I also didn't receive any mail or IRC notifications about the failure.  Is
> that a known issue?
>
>
> On Mon, Jul 8, 2013 at 12:08 PM, David Dean <david_dean at apple.com> wrote:
>
>> This commit has broken some of the buildbots:
>>
>>
>> http://lab.llvm.org:8013/builders/clang-x86_64-darwin11-nobootstrap-RAincremental/builds/4079
>>
>> /Users/buildslave/zorg/buildbot/smooshlab/slave-0.8/build.clang-x86_64-darwin11-nobootstrap-RAincremental/llvm/include/llvm/Support/Compiler.h:204:5:
>> error: builtin feature check macro requires a parenthesized identifier
>> #if __has_attribute(const) || defined(__GNUC__)
>>     ^
>> /Users/buildslave/zorg/buildbot/smooshlab/slave-0.8/build.clang-x86_64-darwin11-nobootstrap-RAincremental/llvm/include/llvm/Support/Compiler.h:204:26:
>> error: expected end of line in preprocessor expression
>>
>> Please fix or revert as soon as you can.
>>
>> On 8 Jul 2013, at 8:31 AM, Reid Kleckner <reid at kleckner.net> wrote:
>>
>> > Author: rnk
>> > Date: Mon Jul  8 10:31:29 2013
>> > New Revision: 185831
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=185831&view=rev
>> > Log:
>> > 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
>> >
>> > 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=185831&r1=185830&r2=185831&view=diff
>> >
>> ==============================================================================
>> > --- llvm/trunk/include/llvm/Support/Compiler.h (original)
>> > +++ llvm/trunk/include/llvm/Support/Compiler.h Mon Jul  8 10:31:29 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 +187,35 @@
>> > // 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
>> >
>> >
>> > _______________________________________________
>> > llvm-commits mailing list
>> > llvm-commits at cs.uiuc.edu
>> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>
>> -David
>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>
>
>
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