From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-1.mimecast.com (us-smtp-2.mimecast.com [205.139.110.61]) by sourceware.org (Postfix) with ESMTP id 45B9B38618B8 for ; Wed, 26 Aug 2020 16:48:14 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 45B9B38618B8 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-400-yrbdyFw9NYCm7uG5dRAUgQ-1; Wed, 26 Aug 2020 12:48:11 -0400 X-MC-Unique: yrbdyFw9NYCm7uG5dRAUgQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9C9671005504; Wed, 26 Aug 2020 16:48:10 +0000 (UTC) Received: from localhost (unknown [10.33.36.61]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4A85560CC0; Wed, 26 Aug 2020 16:48:10 +0000 (UTC) Date: Wed, 26 Aug 2020 17:48:09 +0100 From: Jonathan Wakely To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: [PATCH] libstdc++: Add compile-time checks to__glibcxx_assert [PR 71960] Message-ID: <20200826164809.GA942310@redhat.com> MIME-Version: 1.0 X-Clacks-Overhead: GNU Terry Pratchett X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Type: multipart/mixed; boundary="1yeeQ81UyVL57Vl7" Content-Disposition: inline X-Spam-Status: No, score=-14.4 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 26 Aug 2020 16:48:15 -0000 --1yeeQ81UyVL57Vl7 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit This change evaluates __glibcxx_assert checks unconditionally when a function is being constant evaluated (when std::is_constant_evaluated() is true). If the check fails, compilation will fail with an error. If the function isn't being constant evaluated, the normal runtime check will be done if enabled by _GLIBCXX_ASSERTIONS or _GLIBCXX_DEBUG, the same as before. Tangentially, the __glibcxx_assert and _GLIBCXX_PARALLEL_ASSERT macros are changed to expand to 'do { } while (false)' when assertions are disabled, instead of expanding to nothing. This avoids -Wempty-body warnings when a disabled assertion is used in an 'if' or 'else' statement e.g. if constexpr (/* precondition is testable */) __glibcxx_assert(precondition); a.C:9:27: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body] 9 | __glibcxx_assert(precondition); | ^ libstdc++-v3/ChangeLog: PR libstdc++/71960 * include/bits/c++config (__glibcxx_assert_impl): Remove do-while so that uses of the macro need to add it. (__glibcxx_assert): Rename macro for runtime assertions to __glibcxx_assert_2. (__glibcxx_assert_1): Define macro for constexpr assertions. (__glibcxx_assert): Define macro for constexpr and runtime assertions. * include/bits/range_access.h (ranges::advance): Remove redundant precondition checks during constant evaluation. * include/parallel/base.h (_GLIBCXX_PARALLEL_ASSERT): Always use do-while in macro expansion. * include/std/ranges (iota_view::iota_view(W, B)): Remove redundant braces. Not yet committed. Tested powerpc64le-linux, normal and debug modes. Thoughts? --1yeeQ81UyVL57Vl7 Content-Type: text/plain; charset=utf-8 Content-Disposition: attachment; filename="patch.txt" Content-Transfer-Encoding: 8bit commit 4e71993e73cabcba16d23f43c0d000778e812884 Author: Jonathan Wakely Date: Wed Aug 26 17:45:36 2020 libstdc++: Add compile-time checks to__glibcxx_assert [PR 71960] This change evaluates __glibcxx_assert checks unconditionally when a function is being constant evaluated (when std::is_constant_evaluated() is true). If the check fails, compilation will fail with an error. If the function isn't being constant evaluated, the normal runtime check will be done if enabled by _GLIBCXX_ASSERTIONS or _GLIBCXX_DEBUG, the same as before. Tangentially, the __glibcxx_assert and _GLIBCXX_PARALLEL_ASSERT macros are changed to expand to 'do { } while (false)' when assertions are disabled, instead of expanding to nothing. This avoids -Wempty-body warnings when a disabled assertion is used in an 'if' or 'else' statement e.g. if constexpr (/* precondition is testable */) __glibcxx_assert(precondition); a.C:9:27: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body] 9 | __glibcxx_assert(precondition); | ^ libstdc++-v3/ChangeLog: PR libstdc++/71960 * include/bits/c++config (__glibcxx_assert_impl): Remove do-while so that uses of the macro need to add it. (__glibcxx_assert): Rename macro for runtime assertions to __glibcxx_assert_2. (__glibcxx_assert_1): Define macro for constexpr assertions. (__glibcxx_assert): Define macro for constexpr and runtime assertions. * include/bits/range_access.h (ranges::advance): Remove redundant precondition checks during constant evaluation. * include/parallel/base.h (_GLIBCXX_PARALLEL_ASSERT): Always use do-while in macro expansion. * include/std/ranges (iota_view::iota_view(W, B)): Remove redundant braces. diff --git a/libstdc++-v3/include/bits/c++config b/libstdc++-v3/include/bits/c++config index de28acea6b7..badf9d01a04 100644 --- a/libstdc++-v3/include/bits/c++config +++ b/libstdc++-v3/include/bits/c++config @@ -477,19 +477,16 @@ namespace std __builtin_abort(); } } -#define __glibcxx_assert_impl(_Condition) \ - do \ - { \ - if (! (_Condition)) \ - std::__replacement_assert(__FILE__, __LINE__, __PRETTY_FUNCTION__, \ - #_Condition); \ - } while (false) +#define __glibcxx_assert_impl(_Condition) \ + if (!bool(_Condition)) \ + std::__replacement_assert(__FILE__, __LINE__, __PRETTY_FUNCTION__, \ + #_Condition) #endif #if defined(_GLIBCXX_ASSERTIONS) -# define __glibcxx_assert(_Condition) __glibcxx_assert_impl(_Condition) +# define __glibcxx_assert_2(_Condition) __glibcxx_assert_impl(_Condition) #else -# define __glibcxx_assert(_Condition) +# define __glibcxx_assert_2(_Condition) #endif // Macros for race detectors. @@ -683,6 +680,26 @@ namespace std # endif #endif // GCC +#if _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED +# define __glibcxx_assert_1(_Condition) \ + if (__builtin_is_constant_evaluated()) \ + { \ + void __failed_assertion(); \ + if (!bool(_Condition)) \ + __failed_assertion(); \ + } \ + else +#else +# define __glibcxx_assert_1(_Condition) +#endif + +# define __glibcxx_assert(_Condition) \ + do { \ + __glibcxx_assert_1(_Condition) \ + { __glibcxx_assert_2(_Condition); } \ + } while (false) + + // PSTL configuration #if __cplusplus >= 201703L diff --git a/libstdc++-v3/include/bits/range_access.h b/libstdc++-v3/include/bits/range_access.h index bafced31ea8..5c5b2fe0c6c 100644 --- a/libstdc++-v3/include/bits/range_access.h +++ b/libstdc++-v3/include/bits/range_access.h @@ -987,10 +987,7 @@ namespace ranges } else { -#ifdef __cpp_lib_is_constant_evaluated - if (std::is_constant_evaluated() && __n < 0) - throw "attempt to decrement a non-bidirectional iterator"; -#endif + // cannot decrement a non-bidirectional iterator __glibcxx_assert(__n >= 0); while (__n-- > 0) ++__it; @@ -1065,10 +1062,7 @@ namespace ranges } else { -#ifdef __cpp_lib_is_constant_evaluated - if (std::is_constant_evaluated() && __n < 0) - throw "attempt to decrement a non-bidirectional iterator"; -#endif + // cannot decrement a non-bidirectional iterator __glibcxx_assert(__n >= 0); return __n; } diff --git a/libstdc++-v3/include/parallel/base.h b/libstdc++-v3/include/parallel/base.h index 0d1c2644e8f..973a2dcd514 100644 --- a/libstdc++-v3/include/parallel/base.h +++ b/libstdc++-v3/include/parallel/base.h @@ -420,9 +420,10 @@ namespace __gnu_parallel } #if _GLIBCXX_PARALLEL_ASSERTIONS && defined(__glibcxx_assert_impl) -#define _GLIBCXX_PARALLEL_ASSERT(_Condition) __glibcxx_assert_impl(_Condition) +# define _GLIBCXX_PARALLEL_ASSERT(_Condition) \ + do { __glibcxx_assert_impl(_Condition); } while (false) #else -#define _GLIBCXX_PARALLEL_ASSERT(_Condition) +# define _GLIBCXX_PARALLEL_ASSERT(_Condition) do { } while (false) #endif } //namespace __gnu_parallel diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index 9d22b138082..7d135536b0c 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -860,9 +860,7 @@ namespace ranges : _M_value(__value), _M_bound(__bound) { if constexpr (totally_ordered_with<_Winc, _Bound>) - { - __glibcxx_assert( bool(__value <= __bound) ); - } + __glibcxx_assert( bool(__value <= __bound) ); } constexpr _Iterator --1yeeQ81UyVL57Vl7--