From 310055e7b481eb86318dc75dcf67f4091e395757 Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Thu, 17 Sep 2015 16:46:04 +0100 Subject: [PATCH] Handle alignment in __atomic_is_lock_free gcc: 2015-09-17 Richard Henderson PR libstdc++/65913 * builtins.c (fold_builtin_atomic_always_lock_free): Handle fake pointers that encode the alignment of the object. libstdc++-v3: 2015-09-17 Jonathan Wakely PR libstdc++/65913 * include/bits/atomic_base.h (__atomic_base<_TTp>::is_lock_free(), __atomic_base<_PTp*>::is_lock_free()): Call the built-in with the immediate pointer value, not a variable. * include/std/atomic (atomic::is_lock_free()): Likewise. * testsuite/29_atomics/atomic/65913.cc: New. From-SVN: r227878 --- gcc/ChangeLog | 6 +++ gcc/builtins.c | 16 +++++++- libstdc++-v3/ChangeLog | 7 ++++ libstdc++-v3/include/bits/atomic_base.h | 20 +++++----- libstdc++-v3/include/std/atomic | 8 ++-- .../testsuite/29_atomics/atomic/65913.cc | 39 +++++++++++++++++++ 6 files changed, 80 insertions(+), 16 deletions(-) create mode 100644 libstdc++-v3/testsuite/29_atomics/atomic/65913.cc diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 64664541f31..1e9cf70182f 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2015-09-17 Richard Henderson + + PR libstdc++/65913 + * builtins.c (fold_builtin_atomic_always_lock_free): Handle fake + pointers that encode the alignment of the object. + 2015-09-17 Eric Botcazou PR rtl-optimization/66790 diff --git a/gcc/builtins.c b/gcc/builtins.c index d79372cf268..aeec1708759 100644 --- a/gcc/builtins.c +++ b/gcc/builtins.c @@ -5635,8 +5635,20 @@ fold_builtin_atomic_always_lock_free (tree arg0, tree arg1) mode = mode_for_size (size, MODE_INT, 0); mode_align = GET_MODE_ALIGNMENT (mode); - if (TREE_CODE (arg1) == INTEGER_CST && INTVAL (expand_normal (arg1)) == 0) - type_align = mode_align; + if (TREE_CODE (arg1) == INTEGER_CST) + { + unsigned HOST_WIDE_INT val = UINTVAL (expand_normal (arg1)); + + /* Either this argument is null, or it's a fake pointer encoding + the alignment of the object. */ + val = val & -val; + val *= BITS_PER_UNIT; + + if (val == 0 || mode_align < val) + type_align = mode_align; + else + type_align = val; + } else { tree ttype = TREE_TYPE (arg1); diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index fd1ed22cb93..a1b0c3545f8 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,12 @@ 2015-09-17 Jonathan Wakely + PR libstdc++/65913 + * include/bits/atomic_base.h (__atomic_base<_TTp>::is_lock_free(), + __atomic_base<_PTp*>::is_lock_free()): Call the built-in with the + immediate pointer value, not a variable. + * include/std/atomic (atomic::is_lock_free()): Likewise. + * testsuite/29_atomics/atomic/65913.cc: New. + * testsuite/experimental/filesystem/operations/canonical.cc: Remove non-deterministic part of the test. diff --git a/libstdc++-v3/include/bits/atomic_base.h b/libstdc++-v3/include/bits/atomic_base.h index 79769cf46d8..75a7ca7731a 100644 --- a/libstdc++-v3/include/bits/atomic_base.h +++ b/libstdc++-v3/include/bits/atomic_base.h @@ -350,17 +350,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION bool is_lock_free() const noexcept { - // Produce a fake, minimally aligned pointer. - void *__a = reinterpret_cast(-__alignof(_M_i)); - return __atomic_is_lock_free(sizeof(_M_i), __a); + // Use a fake, minimally aligned pointer. + return __atomic_is_lock_free(sizeof(_M_i), + reinterpret_cast(-__alignof(_M_i))); } bool is_lock_free() const volatile noexcept { - // Produce a fake, minimally aligned pointer. - void *__a = reinterpret_cast(-__alignof(_M_i)); - return __atomic_is_lock_free(sizeof(_M_i), __a); + // Use a fake, minimally aligned pointer. + return __atomic_is_lock_free(sizeof(_M_i), + reinterpret_cast(-__alignof(_M_i))); } _GLIBCXX_ALWAYS_INLINE void @@ -666,16 +666,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION is_lock_free() const noexcept { // Produce a fake, minimally aligned pointer. - void *__a = reinterpret_cast(-__alignof(_M_p)); - return __atomic_is_lock_free(sizeof(_M_p), __a); + return __atomic_is_lock_free(sizeof(_M_p), + reinterpret_cast(-__alignof(_M_p))); } bool is_lock_free() const volatile noexcept { // Produce a fake, minimally aligned pointer. - void *__a = reinterpret_cast(-__alignof(_M_p)); - return __atomic_is_lock_free(sizeof(_M_p), __a); + return __atomic_is_lock_free(sizeof(_M_p), + reinterpret_cast(-__alignof(_M_p))); } _GLIBCXX_ALWAYS_INLINE void diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic index 125e37a2838..cdd1f0b992d 100644 --- a/libstdc++-v3/include/std/atomic +++ b/libstdc++-v3/include/std/atomic @@ -208,16 +208,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION is_lock_free() const noexcept { // Produce a fake, minimally aligned pointer. - void *__a = reinterpret_cast(-__alignof(_M_i)); - return __atomic_is_lock_free(sizeof(_M_i), __a); + return __atomic_is_lock_free(sizeof(_M_i), + reinterpret_cast(-__alignof(_M_i))); } bool is_lock_free() const volatile noexcept { // Produce a fake, minimally aligned pointer. - void *__a = reinterpret_cast(-__alignof(_M_i)); - return __atomic_is_lock_free(sizeof(_M_i), __a); + return __atomic_is_lock_free(sizeof(_M_i), + reinterpret_cast(-__alignof(_M_i))); } void diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/65913.cc b/libstdc++-v3/testsuite/29_atomics/atomic/65913.cc new file mode 100644 index 00000000000..dbdd9cf7db6 --- /dev/null +++ b/libstdc++-v3/testsuite/29_atomics/atomic/65913.cc @@ -0,0 +1,39 @@ +// Copyright (C) 2015 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// . + +// { dg-do run { target x86_64-*-linux* powerpc*-*-linux* } } +// { dg-options "-std=gnu++11 -O0" } + +#include +#include + +// PR libstdc++/65913 + +void +test01() +{ + struct Int { int i; }; + VERIFY( std::atomic{}.is_lock_free() ); + VERIFY( std::atomic{}.is_lock_free() ); + VERIFY( std::atomic{}.is_lock_free() ); +} + +int +main() +{ + test01(); +} -- 2.30.2