public inbox for gcc-cvs@sourceware.org help / color / mirror / Atom feed
From: Jason Merrill <jason@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r11-8495] c++: no clobber for C++20 destroying delete [PR91859] Date: Tue, 1 Jun 2021 15:53:27 +0000 (GMT) [thread overview] Message-ID: <20210601155327.4B7963855033@sourceware.org> (raw) https://gcc.gnu.org/g:ee3edeb01eca1cc8d7ebe777b4adb333f0c1118a commit r11-8495-gee3edeb01eca1cc8d7ebe777b4adb333f0c1118a Author: Jason Merrill <jason@redhat.com> Date: Fri May 28 17:05:23 2021 -0400 c++: no clobber for C++20 destroying delete [PR91859] Before C++20 added destroying operator delete, by the time we called operator delete for a pointer, the object would already be gone. But that isn't true for destroying delete. Since the optimizers' assumptions about operator delete are based on either DECL_IS_REPLACEABLE_OPERATOR (which already is not set) or CALL_FROM_NEW_OR_DELETE_P, let's avoid setting the latter flag in this case. PR c++/91859 gcc/ChangeLog: * tree.h (CALL_FROM_NEW_OR_DELETE_P): Adjust comment. gcc/cp/ChangeLog: * call.c (build_op_delete_call): Don't set CALL_FROM_NEW_OR_DELETE_P for destroying delete. * init.c (build_delete): Don't clobber before destroying delete. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/destroying-delete5.C: New test. Diff: --- gcc/tree.h | 2 +- gcc/cp/call.c | 4 ++- gcc/cp/init.c | 5 +++- gcc/testsuite/g++.dg/cpp2a/destroying-delete5.C | 36 +++++++++++++++++++++++++ 4 files changed, 44 insertions(+), 3 deletions(-) diff --git a/gcc/tree.h b/gcc/tree.h index f00ea2ef0af..5d85792b305 100644 --- a/gcc/tree.h +++ b/gcc/tree.h @@ -937,7 +937,7 @@ extern void omp_clause_range_check_failed (const_tree, const char *, int, /* In a CALL_EXPR, if the function being called is DECL_IS_OPERATOR_NEW_P or DECL_IS_OPERATOR_DELETE_P, true for allocator calls from C++ new or delete - expressions. */ + expressions. Not set for C++20 destroying delete operators. */ #define CALL_FROM_NEW_OR_DELETE_P(NODE) \ (CALL_EXPR_CHECK (NODE)->base.protected_flag) diff --git a/gcc/cp/call.c b/gcc/cp/call.c index cae87eae234..4c4cb5d0491 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -7211,8 +7211,10 @@ build_op_delete_call (enum tree_code code, tree addr, tree size, treat that as an implicit delete-expression. This is also called for the delete if the constructor throws in a new-expression, and for a deleting destructor (which implements a delete-expression). */ + /* But leave this flag off for destroying delete to avoid wrong + assumptions in the optimizers. */ tree call = extract_call_expr (ret); - if (TREE_CODE (call) == CALL_EXPR) + if (TREE_CODE (call) == CALL_EXPR && !destroying_delete_p (fn)) CALL_FROM_NEW_OR_DELETE_P (call) = 1; return ret; diff --git a/gcc/cp/init.c b/gcc/cp/init.c index a85f4d50750..04d495807ef 100644 --- a/gcc/cp/init.c +++ b/gcc/cp/init.c @@ -4881,7 +4881,10 @@ build_delete (location_t loc, tree otype, tree addr, complain); } - if (!destroying_delete && type_build_dtor_call (type)) + if (destroying_delete) + /* The operator delete will call the destructor. */ + expr = addr; + else if (type_build_dtor_call (type)) expr = build_dtor_call (cp_build_fold_indirect_ref (addr), auto_delete, flags, complain); else diff --git a/gcc/testsuite/g++.dg/cpp2a/destroying-delete5.C b/gcc/testsuite/g++.dg/cpp2a/destroying-delete5.C new file mode 100644 index 00000000000..553c964b9e9 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/destroying-delete5.C @@ -0,0 +1,36 @@ +// PR c++/91859 +// { dg-do run { target c++20 } } +// { dg-additional-options -O2 } + +#include <cstdlib> +#include <new> + +struct Expression { + int i = 0; + void *operator new(std::size_t); + void operator delete(Expression *, std::destroying_delete_t); +}; + +void * Expression::operator new(std::size_t sz) +{ + return std::malloc(sz); +} + +int i; + +void Expression::operator delete(Expression *p, std::destroying_delete_t) +{ + Expression * e = p; + ::i = e->i; + p->~Expression(); + std::free(p); +} + +int main() +{ + auto p = new Expression(); + p->i = 1; + delete p; + if (i != 1) + __builtin_abort(); +}
reply other threads:[~2021-06-01 15:53 UTC|newest] Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=20210601155327.4B7963855033@sourceware.org \ --to=jason@gcc.gnu.org \ --cc=gcc-cvs@gcc.gnu.org \ /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: linkBe 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).