Pushed to trunk.
On Thu, 27 Jun 2024 at 10:01, Jonathan Wakely <jwak...@redhat.com> wrote:
>
> As I commented in the PR, I think it would be nice if the compiler
> accepted C++11 alignof in C++98 mode when -faligned-new is used. But
> even if G++ added that, we'd need Clang to use it, and then wait a few
> releases for that new Clang support to be in widespread use.
>
> So let's just disable the extended alignment support in allocators.
> Using -std=c++98 -faligned-new seems like a silly combination anyway.
>
> Tested x86_64-linux.
>
> -- >8 --
>
> When -faligned-new (or Clang's -faligned-allocation) is used our
> allocators try to support extended alignments, gated on the
> __cpp_aligned_new macro. However, because they use alignof(_Tp) which is
> not a keyword in C++98 mode, using -std=c++98 -faligned-new results in
> errors from <memory> and other headers.
>
> We could change them to use __alignof__ instead of alignof, but that
> would potentially alter the result of the conditions, because e.g.
> alignof(long long) != __alignof__(long long) on some targets. That's
> probably not an issue for any types with extended alignment, so maybe it
> would be a safe change.
>
> For now, it seems acceptable to just disable the extended alignment
> support in C++98 mode, so that -faligned-new enables std::align_val_t
> and the corresponding operator new overloads, but doesn't affect
> std::allocator, __gnu_cxx::__bitmap_allocator etc.
>
> libstdc++-v3/ChangeLog:
>
> PR libstdc++/104395
> * include/bits/new_allocator.h: Disable extended alignment
> support in C++98 mode.
> * include/bits/stl_tempbuf.h: Likewise.
> * include/ext/bitmap_allocator.h: Likewise.
> * include/ext/malloc_allocator.h: Likewise.
> * include/ext/mt_allocator.h: Likewise.
> * include/ext/pool_allocator.h: Likewise.
> * testsuite/ext/104395.cc: New test.
> ---
> libstdc++-v3/include/bits/new_allocator.h | 4 ++--
> libstdc++-v3/include/bits/stl_tempbuf.h | 6 +++---
> libstdc++-v3/include/ext/bitmap_allocator.h | 4 ++--
> libstdc++-v3/include/ext/malloc_allocator.h | 2 +-
> libstdc++-v3/include/ext/mt_allocator.h | 4 ++--
> libstdc++-v3/include/ext/pool_allocator.h | 4 ++--
> libstdc++-v3/testsuite/ext/104395.cc | 8 ++++++++
> 7 files changed, 20 insertions(+), 12 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/ext/104395.cc
>
> diff --git a/libstdc++-v3/include/bits/new_allocator.h
> b/libstdc++-v3/include/bits/new_allocator.h
> index 0e90c8819ac..5dcdee11c4d 100644
> --- a/libstdc++-v3/include/bits/new_allocator.h
> +++ b/libstdc++-v3/include/bits/new_allocator.h
> @@ -140,7 +140,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> std::__throw_bad_alloc();
> }
>
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> {
> std::align_val_t __al = std::align_val_t(alignof(_Tp));
> @@ -161,7 +161,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> # define _GLIBCXX_SIZED_DEALLOC(p, n) (p)
> #endif
>
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> {
> _GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n),
> diff --git a/libstdc++-v3/include/bits/stl_tempbuf.h
> b/libstdc++-v3/include/bits/stl_tempbuf.h
> index 759c4937744..0f267054613 100644
> --- a/libstdc++-v3/include/bits/stl_tempbuf.h
> +++ b/libstdc++-v3/include/bits/stl_tempbuf.h
> @@ -85,7 +85,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> if (__builtin_expect(size_t(__len) > (size_t(-1) / sizeof(_Tp)), 0))
> return 0;
>
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> return (_Tp*) _GLIBCXX_OPERATOR_NEW(__len * sizeof(_Tp),
> align_val_t(alignof(_Tp)),
> @@ -107,7 +107,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> # define _GLIBCXX_SIZED_DEALLOC(T, p, n) (p)
> #endif
>
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> {
> _GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(_Tp, __p, __len),
> @@ -168,7 +168,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> inline void
> return_temporary_buffer(_Tp* __p)
> {
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> _GLIBCXX_OPERATOR_DELETE(__p, align_val_t(alignof(_Tp)));
> else
> diff --git a/libstdc++-v3/include/ext/bitmap_allocator.h
> b/libstdc++-v3/include/ext/bitmap_allocator.h
> index ef2ee13187b..45b2283ca30 100644
> --- a/libstdc++-v3/include/ext/bitmap_allocator.h
> +++ b/libstdc++-v3/include/ext/bitmap_allocator.h
> @@ -1017,7 +1017,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> if (__n > this->max_size())
> std::__throw_bad_alloc();
>
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> if (alignof(value_type) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> {
> const size_type __b = __n * sizeof(value_type);
> @@ -1044,7 +1044,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> if (__builtin_expect(__p != 0, true))
> {
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> // Types with extended alignment are handled by operator delete.
> if (alignof(value_type) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> {
> diff --git a/libstdc++-v3/include/ext/malloc_allocator.h
> b/libstdc++-v3/include/ext/malloc_allocator.h
> index b0a87b62d5a..36513780925 100644
> --- a/libstdc++-v3/include/ext/malloc_allocator.h
> +++ b/libstdc++-v3/include/ext/malloc_allocator.h
> @@ -120,7 +120,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> }
>
> _Tp* __ret = 0;
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> #if __cplusplus > 201402L && _GLIBCXX_HAVE_ALIGNED_ALLOC
> if (alignof(_Tp) > alignof(std::max_align_t))
> {
> diff --git a/libstdc++-v3/include/ext/mt_allocator.h
> b/libstdc++-v3/include/ext/mt_allocator.h
> index 0b0bf8dc5f7..77f7dcd2762 100644
> --- a/libstdc++-v3/include/ext/mt_allocator.h
> +++ b/libstdc++-v3/include/ext/mt_allocator.h
> @@ -693,7 +693,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> if (__n > this->max_size())
> std::__throw_bad_alloc();
>
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> // Types with extended alignment are handled by operator new/delete.
> if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> {
> @@ -748,7 +748,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> if (__builtin_expect(__p != 0, true))
> {
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> // Types with extended alignment are handled by operator new/delete.
> if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> {
> diff --git a/libstdc++-v3/include/ext/pool_allocator.h
> b/libstdc++-v3/include/ext/pool_allocator.h
> index 13895b2f71a..679b4b3d276 100644
> --- a/libstdc++-v3/include/ext/pool_allocator.h
> +++ b/libstdc++-v3/include/ext/pool_allocator.h
> @@ -224,7 +224,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> const size_t __bytes = __n * sizeof(_Tp);
>
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> {
> std::align_val_t __al = std::align_val_t(alignof(_Tp));
> @@ -272,7 +272,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> using std::size_t;
> if (__builtin_expect(__n != 0 && __p != 0, true))
> {
> -#if __cpp_aligned_new
> +#if __cpp_aligned_new && __cplusplus >= 201103L
> if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
> {
> ::operator delete(__p, std::align_val_t(alignof(_Tp)));
> diff --git a/libstdc++-v3/testsuite/ext/104395.cc
> b/libstdc++-v3/testsuite/ext/104395.cc
> new file mode 100644
> index 00000000000..252c40c9698
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/ext/104395.cc
> @@ -0,0 +1,8 @@
> +// { dg-options "-std=gnu++98 -faligned-new" }
> +// { dg-do compile }
> +#include <ext/memory>
> +#include <ext/bitmap_allocator.h>
> +#include <ext/mt_allocator.h>
> +#include <ext/malloc_allocator.h>
> +#include <ext/new_allocator.h>
> +#include <ext/pool_allocator.h>
> --
> 2.45.2
>
