Hi Jason, Jason Merrill <ja...@redhat.com> writes:
> On 12/10/22 08:13, Arsen Arsenović wrote: >> If the mangler is relied on, functions with extern "C" on them emit multiple >> definitions of the same name. > > But doing it here interferes with lazy mangling. How about appending the > suffix into write_mangled_name instead of write_encoding? The demangler > already expects "clone" suffixes at the end of the mangled name. Ah, sorry. I'm not well versed in the mangler code, so I didn't realize (frankly, I was initially surprised when I saw that DECL_ASSEMBLER_NAME was set that early, but went with it). That makes sense. How about this? Tested on x86_64-pc-linux-gnu via check-g++.
From 2a2d98e94bdd7a8d7f862b2accda849927e4509e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Arsen=20Arsenovi=C4=87?= <ar...@aarsen.me> Date: Thu, 15 Dec 2022 18:56:59 +0100 Subject: [PATCH v2] c++: Mangle contracts in write_mangled_name unconditionally This fixes contract-checked extern "C" functions. gcc/cp/ChangeLog: * mangle.cc (write_encoding): Move contract pre/post function mangling from here... (write_mangled_name): ... to here, and make it happen always. gcc/testsuite/ChangeLog: * g++.dg/contracts/contracts-externC.C: New test. --- gcc/cp/mangle.cc | 14 +++++++------- .../g++.dg/contracts/contracts-externC.C | 19 +++++++++++++++++++ 2 files changed, 26 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/g++.dg/contracts/contracts-externC.C diff --git a/gcc/cp/mangle.cc b/gcc/cp/mangle.cc index e363ef35b9f..074cf27ec7a 100644 --- a/gcc/cp/mangle.cc +++ b/gcc/cp/mangle.cc @@ -798,6 +798,13 @@ write_mangled_name (const tree decl, bool top_level) write_string ("_Z"); write_encoding (decl); } + + /* If this is the pre/post function for a guarded function, append + .pre/post, like something from create_virtual_clone. */ + if (DECL_IS_PRE_FN_P (decl)) + write_string (".pre"); + else if (DECL_IS_POST_FN_P (decl)) + write_string (".post"); } /* Returns true if the return type of DECL is part of its signature, and @@ -856,13 +863,6 @@ write_encoding (const tree decl) mangle_return_type_p (decl), d); - /* If this is the pre/post function for a guarded function, append - .pre/post, like something from create_virtual_clone. */ - if (DECL_IS_PRE_FN_P (decl)) - write_string (".pre"); - else if (DECL_IS_POST_FN_P (decl)) - write_string (".post"); - /* If this is a coroutine helper, then append an appropriate string to identify which. */ if (tree ramp = DECL_RAMP_FN (decl)) diff --git a/gcc/testsuite/g++.dg/contracts/contracts-externC.C b/gcc/testsuite/g++.dg/contracts/contracts-externC.C new file mode 100644 index 00000000000..873056b742b --- /dev/null +++ b/gcc/testsuite/g++.dg/contracts/contracts-externC.C @@ -0,0 +1,19 @@ +// simple check to ensure we don't emit a function with the same name twice, +// when wrapping functions in pre- and postconditions. +// { dg-do link } +// { dg-options "-std=c++2a -fcontracts -fcontract-continuation-mode=on" } + +volatile int x = 10; + +extern "C" void +f () + [[ pre: x < 10 ]] +{ +} + +int +main () + [[ post: x > 10 ]] +{ + f(); +} -- 2.39.0
I did run c++filt (afaik, it uses the libiberty demangler) on this revision, and I got: .type f(int) [clone .pre], @function f(int) [clone .pre]: out of ``void f(int x) [[ pre: x > 10 ]] {}'', which seems to match your description. If I understand this right, write_xxx corresponds to xxx in the Itanium ABI mangling BNF, in which case, I believe I have the correct spot here. In that case, a similar change should happen for coroutines; I think Iain was working on that. Thanks, have a great day. -- Arsen Arsenović
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