From: Jonathan Wakely Date: Thu, 20 May 2021 15:39:06 +0000 (+0100) Subject: libstdc++: Use __builtin_unreachable for constexpr assertions [PR 100676] X-Git-Tag: releases/gcc-11.2.0~299 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=10c58754a862470484eca81623b71e6851470bb6;p=thirdparty%2Fgcc.git libstdc++: Use __builtin_unreachable for constexpr assertions [PR 100676] The current implementation of compile-time precondition checks causes compilation to fail by calling a non-constexpr function declared at block scope. This breaks the CUDA compiler, which wraps some libstdc++ headers in a pragma that declares everything as a __host__ __device__ function, but others are not wrapped and so everything is a __host__ function. The local declaration thus gets redeclared as two different types of function, which doesn't work. Just use __builtin_unreachable to make constant evaluation fail, instead of the local function declaration. Also simplify the assertion macros, which has the side effect of giving simpler compilation errors when using Clang. libstdc++-v3/ChangeLog: PR libstdc++/100676 * include/bits/c++config (__glibcxx_assert_1): Rename to ... (__glibcxx_constexpr_assert): ... this. (__glibcxx_assert_impl): Use __glibcxx_constexpr_assert. (__glibcxx_assert): Define as either __glibcxx_constexpr_assert or __glibcxx_assert_impl. (__glibcxx_assert_2): Remove * include/debug/macros.h (_GLIBCXX_DEBUG_VERIFY_AT_F): Use __glibcxx_constexpr_assert instead of __glibcxx_assert_1. * testsuite/21_strings/basic_string_view/element_access/char/back_constexpr_neg.cc: Adjust expected error. * testsuite/21_strings/basic_string_view/element_access/char/constexpr_neg.cc: Likewise. * testsuite/21_strings/basic_string_view/element_access/char/front_constexpr_neg.cc: Likewise. Likewise. * testsuite/21_strings/basic_string_view/element_access/wchar_t/back_constexpr_neg.cc: Likewise. * testsuite/21_strings/basic_string_view/element_access/wchar_t/constexpr_neg.cc: Likewise. * testsuite/21_strings/basic_string_view/element_access/wchar_t/front_constexpr_neg.cc: Likewise. * testsuite/23_containers/span/back_neg.cc: Likewise. * testsuite/23_containers/span/front_neg.cc: Likewise. * testsuite/23_containers/span/index_op_neg.cc: Likewise. (cherry picked from commit 6b42b5a8a207de5e021a2916281f46bcd60b20d2) --- diff --git a/libstdc++-v3/include/bits/c++config b/libstdc++-v3/include/bits/c++config index 72ec91949de5..9314117aed8d 100644 --- a/libstdc++-v3/include/bits/c++config +++ b/libstdc++-v3/include/bits/c++config @@ -487,6 +487,16 @@ namespace std # define _GLIBCXX_EXTERN_TEMPLATE -1 #endif + +#if __has_builtin(__builtin_is_constant_evaluated) +# define __glibcxx_constexpr_assert(cond) \ + if (__builtin_is_constant_evaluated() && !bool(cond)) \ + __builtin_unreachable() /* precondition violation detected! */ +#else +# define __glibcxx_constexpr_assert(unevaluated) +#endif + + // Assert. #if defined(_GLIBCXX_ASSERTIONS) \ || defined(_GLIBCXX_PARALLEL) || defined(_GLIBCXX_PARALLEL_ASSERTIONS) @@ -506,14 +516,19 @@ namespace std } #define __glibcxx_assert_impl(_Condition) \ if (__builtin_expect(!bool(_Condition), false)) \ + { \ + __glibcxx_constexpr_assert(_Condition); \ std::__replacement_assert(__FILE__, __LINE__, __PRETTY_FUNCTION__, \ - #_Condition) + #_Condition); \ + } #endif #if defined(_GLIBCXX_ASSERTIONS) -# define __glibcxx_assert_2(_Condition) __glibcxx_assert_impl(_Condition) +# define __glibcxx_assert(cond) \ + do { __glibcxx_assert_impl(cond); } while (false) #else -# define __glibcxx_assert_2(_Condition) +# define __glibcxx_assert(cond) \ + do { __glibcxx_constexpr_assert(cond); } while (false) #endif // Macros for race detectors. @@ -736,25 +751,6 @@ namespace std #undef _GLIBCXX_HAS_BUILTIN -#if _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED && __cplusplus >= 201402L -# 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 diff --git a/libstdc++-v3/include/debug/macros.h b/libstdc++-v3/include/debug/macros.h index 9ac52ebd09d1..9e1288cf4d92 100644 --- a/libstdc++-v3/include/debug/macros.h +++ b/libstdc++-v3/include/debug/macros.h @@ -45,8 +45,8 @@ #define _GLIBCXX_DEBUG_VERIFY_AT_F(_Cond,_ErrMsg,_File,_Line,_Func) \ do { \ - __glibcxx_assert_1(_Cond) \ - { _GLIBCXX_DEBUG_VERIFY_COND_AT(_Cond,_ErrMsg,_File,_Line,_Func); } \ + __glibcxx_constexpr_assert(_Cond); \ + _GLIBCXX_DEBUG_VERIFY_COND_AT(_Cond,_ErrMsg,_File,_Line,_Func); \ } while (false) #define _GLIBCXX_DEBUG_VERIFY_AT(_Cond,_ErrMsg,_File,_Line) \ diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/back_constexpr_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/back_constexpr_neg.cc index 0f731c9a4856..2da90bd954e2 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/back_constexpr_neg.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/back_constexpr_neg.cc @@ -32,4 +32,4 @@ back() static_assert(back() != 'a'); // { dg-error "non-constant condition" } // { dg-prune-output "in 'constexpr' expansion" } -// { dg-prune-output "failed_assertion" } +// { dg-prune-output "unreachable" } diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/constexpr_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/constexpr_neg.cc index 5dd206f1a296..844b62277c5f 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/constexpr_neg.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/constexpr_neg.cc @@ -31,4 +31,4 @@ test() static_assert(test() == 0); // { dg-error "non-constant condition" } // { dg-prune-output "in 'constexpr' expansion" } -// { dg-prune-output "failed_assertion" } +// { dg-prune-output "unreachable" } diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/front_constexpr_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/front_constexpr_neg.cc index 9c846116bb92..d6dceb61a34c 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/front_constexpr_neg.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/char/front_constexpr_neg.cc @@ -32,4 +32,4 @@ front() static_assert(front() != 'a'); // { dg-error "non-constant condition" } // { dg-prune-output "in 'constexpr' expansion" } -// { dg-prune-output "failed_assertion" } +// { dg-prune-output "unreachable" } diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/back_constexpr_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/back_constexpr_neg.cc index 26d2d4da54b2..798e1a4074de 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/back_constexpr_neg.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/back_constexpr_neg.cc @@ -32,4 +32,4 @@ back() static_assert(back() != L'a'); // { dg-error "non-constant condition" } // { dg-prune-output "in 'constexpr' expansion" } -// { dg-prune-output "failed_assertion" } +// { dg-prune-output "unreachable" } diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/constexpr_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/constexpr_neg.cc index c853dada7dc7..0e22b766b3de 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/constexpr_neg.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/constexpr_neg.cc @@ -31,4 +31,4 @@ test() static_assert(test() == 0); // { dg-error "non-constant condition" } // { dg-prune-output "in 'constexpr' expansion" } -// { dg-prune-output "failed_assertion" } +// { dg-prune-output "unreachable" } diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/front_constexpr_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/front_constexpr_neg.cc index fdcabd7363d2..f49774a0bdd4 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/front_constexpr_neg.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/element_access/wchar_t/front_constexpr_neg.cc @@ -32,4 +32,4 @@ front() static_assert(front() != L'a'); // { dg-error "non-constant condition" } // { dg-prune-output "in 'constexpr' expansion" } -// { dg-prune-output "failed_assertion" } +// { dg-prune-output "unreachable" } diff --git a/libstdc++-v3/testsuite/23_containers/span/back_neg.cc b/libstdc++-v3/testsuite/23_containers/span/back_neg.cc index 0289ece7a50a..ce00aa8868f0 100644 --- a/libstdc++-v3/testsuite/23_containers/span/back_neg.cc +++ b/libstdc++-v3/testsuite/23_containers/span/back_neg.cc @@ -31,5 +31,5 @@ test01(bool b) static_assert(test01(false)); static_assert(test01(true)); // { dg-error "non-constant" } -// { dg-error "assert" "" { target *-*-* } 0 } +// { dg-error "unreachable" "" { target *-*-* } 0 } // { dg-prune-output "in 'constexpr' expansion" } diff --git a/libstdc++-v3/testsuite/23_containers/span/front_neg.cc b/libstdc++-v3/testsuite/23_containers/span/front_neg.cc index dfad9f8a5428..a6efc7dd8363 100644 --- a/libstdc++-v3/testsuite/23_containers/span/front_neg.cc +++ b/libstdc++-v3/testsuite/23_containers/span/front_neg.cc @@ -31,5 +31,5 @@ test01(bool b) static_assert(test01(false)); static_assert(test01(true)); // { dg-error "non-constant" } -// { dg-error "assert" "" { target *-*-* } 0 } +// { dg-error "unreachable" "" { target *-*-* } 0 } // { dg-prune-output "in 'constexpr' expansion" } diff --git a/libstdc++-v3/testsuite/23_containers/span/index_op_neg.cc b/libstdc++-v3/testsuite/23_containers/span/index_op_neg.cc index 378ae05e0ea2..2dce639819c7 100644 --- a/libstdc++-v3/testsuite/23_containers/span/index_op_neg.cc +++ b/libstdc++-v3/testsuite/23_containers/span/index_op_neg.cc @@ -31,5 +31,5 @@ test01(bool b) static_assert(test01(false)); static_assert(test01(true)); // { dg-error "non-constant" } -// { dg-error "assert" "" { target *-*-* } 0 } +// { dg-error "unreachable" "" { target *-*-* } 0 } // { dg-prune-output "in 'constexpr' expansion" }