From: Patrick O'Neill <patrick@rivosinc.com>
To: Jakub Jelinek <jakub@redhat.com>
Cc: gcc-patches@gcc.gnu.org, rguenther@suse.de, jwakely@redhat.com
Subject: Re: [PATCH] vec.h: Guard most of static assertions for GCC >= 5
Date: Sat, 30 Sep 2023 12:30:05 -0700 [thread overview]
Message-ID: <2803cc5e-054a-8e81-37a2-05dbdec95422@rivosinc.com> (raw)
In-Reply-To: <ZRaqA3UNB9SShxiF@tucnak>
Hi Jakub,
A follow-up commit of yours (9d249b7e31e) is causing bootstrap failures
for riscv*-*-* targets.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111649
Patrick
On 9/29/23 03:42, Jakub Jelinek wrote:
> Hi!
>
> As reported by Jonathan on IRC, my vec.h patch broke build with GCC 4.8.x
> or 4.9.x as system compiler, e.g. on CFarm.
> The problem is that while all of
> std::is_trivially_{destructible,copyable,default_constructible} traits
> are in C++, only std::is_trivially_destructible has been implemented in GCC
> 4.8, the latter two were added only in GCC 5.
> Only std::is_trivially_destructible is the really important one though,
> which is used to decide what pop returns and whether to invoke the
> destructors or not. The rest are solely used in static_asserts and as such
> I think it is acceptable if we don't assert those when built with GCC 4.8
> or 4.9, anybody doing bootstrap from those system compilers or doing builds
> with newer GCC will catch that.
>
> So, the following patch guards those for 5+.
> If we switch to C++14 later on and start requiring newer version of system
> GCC as well (do we require GCC >= 5 which claims the last C++14 language
> features, or what provides all C++14 library features, or GCC >= 6 which
> uses -std=c++14 by default?), this patch then can be reverted.
>
> Ok for trunk?
>
> 2023-09-29 Jakub Jelinek <jakub@redhat.com>
>
> * vec.h (quick_insert, ordered_remove, unordered_remove,
> block_remove, qsort, sort, stablesort, quick_grow): Guard
> std::is_trivially_{copyable,default_constructible} and
> vec_detail::is_trivially_copyable_or_pair static assertions
> with GCC_VERSION >= 5000.
> (vec_detail::is_trivially_copyable_or_pair): Guard definition
> with GCC_VERSION >= 5000.
>
> --- gcc/vec.h.jj 2023-09-29 10:59:09.830551963 +0200
> +++ gcc/vec.h 2023-09-29 12:29:32.676428677 +0200
> @@ -1086,7 +1086,12 @@ vec<T, A, vl_embed>::quick_insert (unsig
> {
> gcc_checking_assert (length () < allocated ());
> gcc_checking_assert (ix <= length ());
> +#if GCC_VERSION >= 5000
> + /* GCC 4.8 and 4.9 only implement std::is_trivially_destructible,
> + but not std::is_trivially_copyable nor
> + std::is_trivially_default_constructible. */
> static_assert (std::is_trivially_copyable <T>::value, "");
> +#endif
> T *slot = &address ()[ix];
> memmove (slot + 1, slot, (m_vecpfx.m_num++ - ix) * sizeof (T));
> *slot = obj;
> @@ -1102,7 +1107,9 @@ inline void
> vec<T, A, vl_embed>::ordered_remove (unsigned ix)
> {
> gcc_checking_assert (ix < length ());
> +#if GCC_VERSION >= 5000
> static_assert (std::is_trivially_copyable <T>::value, "");
> +#endif
> T *slot = &address ()[ix];
> memmove (slot, slot + 1, (--m_vecpfx.m_num - ix) * sizeof (T));
> }
> @@ -1150,7 +1157,9 @@ inline void
> vec<T, A, vl_embed>::unordered_remove (unsigned ix)
> {
> gcc_checking_assert (ix < length ());
> +#if GCC_VERSION >= 5000
> static_assert (std::is_trivially_copyable <T>::value, "");
> +#endif
> T *p = address ();
> p[ix] = p[--m_vecpfx.m_num];
> }
> @@ -1164,13 +1173,16 @@ inline void
> vec<T, A, vl_embed>::block_remove (unsigned ix, unsigned len)
> {
> gcc_checking_assert (ix + len <= length ());
> +#if GCC_VERSION >= 5000
> static_assert (std::is_trivially_copyable <T>::value, "");
> +#endif
> T *slot = &address ()[ix];
> m_vecpfx.m_num -= len;
> memmove (slot, slot + len, (m_vecpfx.m_num - ix) * sizeof (T));
> }
>
>
> +#if GCC_VERSION >= 5000
> namespace vec_detail
> {
> /* gcc_{qsort,qsort_r,stablesort_r} implementation under the hood
> @@ -1189,6 +1201,7 @@ namespace vec_detail
> : std::integral_constant<bool, std::is_trivially_copyable<T>::value
> && std::is_trivially_copyable<U>::value> { };
> }
> +#endif
>
> /* Sort the contents of this vector with qsort. CMP is the comparison
> function to pass to qsort. */
> @@ -1197,7 +1210,9 @@ template<typename T, typename A>
> inline void
> vec<T, A, vl_embed>::qsort (int (*cmp) (const void *, const void *))
> {
> +#if GCC_VERSION >= 5000
> static_assert (vec_detail::is_trivially_copyable_or_pair <T>::value, "");
> +#endif
> if (length () > 1)
> gcc_qsort (address (), length (), sizeof (T), cmp);
> }
> @@ -1210,7 +1225,9 @@ inline void
> vec<T, A, vl_embed>::sort (int (*cmp) (const void *, const void *, void *),
> void *data)
> {
> +#if GCC_VERSION >= 5000
> static_assert (vec_detail::is_trivially_copyable_or_pair <T>::value, "");
> +#endif
> if (length () > 1)
> gcc_sort_r (address (), length (), sizeof (T), cmp, data);
> }
> @@ -1223,7 +1240,9 @@ inline void
> vec<T, A, vl_embed>::stablesort (int (*cmp) (const void *, const void *,
> void *), void *data)
> {
> +#if GCC_VERSION >= 5000
> static_assert (vec_detail::is_trivially_copyable_or_pair <T>::value, "");
> +#endif
> if (length () > 1)
> gcc_stablesort_r (address (), length (), sizeof (T), cmp, data);
> }
> @@ -1396,7 +1415,9 @@ inline void
> vec<T, A, vl_embed>::quick_grow (unsigned len)
> {
> gcc_checking_assert (length () <= len && len <= m_vecpfx.m_alloc);
> +#if GCC_VERSION >= 5000
> // static_assert (std::is_trivially_default_constructible <T>::value, "");
> +#endif
> m_vecpfx.m_num = len;
> }
>
>
> Jakub
>
prev parent reply other threads:[~2023-09-30 19:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-29 10:42 Jakub Jelinek
2023-09-29 12:40 ` Richard Biener
2023-09-30 19:30 ` Patrick O'Neill [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2803cc5e-054a-8e81-37a2-05dbdec95422@rivosinc.com \
--to=patrick@rivosinc.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=jakub@redhat.com \
--cc=jwakely@redhat.com \
--cc=rguenther@suse.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).