Hi!
On 2025-03-24T13:38:56-0400, Jason Merrill <ja...@redhat.com> wrote:
> On 3/24/25 7:02 AM, Thomas Schwinge wrote:
>> On 2025-03-21T15:46:01+0100, I wrote:
>>> On 2025-03-19T14:25:49+0000, Jonathan Wakely <jwakely....@gmail.com> wrote:
>>>> On Wed, 19 Mar 2025 at 14:21, Marek Polacek <pola...@redhat.com> wrote:
>>>>> On Wed, Mar 19, 2025 at 12:38:31PM +0100, Thomas Schwinge wrote:
>>>>>> --- a/gcc/cp/rtti.cc
>>>>>> +++ b/gcc/cp/rtti.cc
>>>>>> @@ -198,7 +198,7 @@ throw_bad_cast (void)
>>>>>> fn = get_global_binding (name);
>>>>>> if (!fn)
>>>>>> fn = push_throw_library_fn
>>>>>> - (name, build_function_type_list (ptr_type_node, NULL_TREE));
>>>>>> + (name, build_function_type_list (void_type_node, NULL_TREE));
>>>>>> }
>>>>>>
>>>>>> return build_cxx_call (fn, 0, NULL, tf_warning_or_error);
>>>>>
>>>>> LGTM, matches what I see in abi-eh.html from the itanium-cxx-abi.
>>
>>> [...] I've now pushed to trunk branch:
>>> commit 618c42d23726be6e2086d452d6718abe5e0daca8
>>> "C++: Adjust implicit '__cxa_bad_cast' prototype to reality", [...]
>>
>> So, a similar problem exists for '__cxa_bad_typeid'. See the attached
>> "[WIP] C++: Adjust implicit '__cxa_bad_typeid' prototype to reality" for
>> what seemed to be the corresponding patch for that one. However, that
>> isn't sufficient; we run into internal errors like:
>>
>> [...]/g++.dg/rtti/typeid1.C: In function 'int main()':
>> [...]/g++.dg/rtti/typeid1.C:9:12: error: lvalue required as unary '&'
>> operand
>>
>> I got lost in the C++ front end code trying to understand how to resolve
>> this mismatch. Anyone able to advise, please?
>
> This addition seems to resolve it: [...]
Yes, thanks! OK to push the attached
"C++: Adjust implicit '__cxa_bad_typeid' prototype to reality"?
Grüße
Thomas
>From 6f8045a4976c52f49562e5e3deeeec7919100032 Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <tschwi...@baylibre.com>
Date: Wed, 19 Mar 2025 12:18:26 +0100
Subject: [PATCH] C++: Adjust implicit '__cxa_bad_typeid' prototype to reality
In 2001 Subversion r40924 (Git commit 52a11cbfcf0cfb32628b6953588b6af4037ac0b6)
"IA-64 ABI Exception Handling", '__cxa_bad_typeid' changed from
'std::type_info const &' to 'void' return type:
--- libstdc++-v3/libsupc++/exception_support.cc
+++ /dev/null
@@ -1,388 +0,0 @@
-[...]
-// Helpers for rtti. Although these don't return, we give them return types so
-// that the type system is not broken.
-[...]
-extern "C" std::type_info const &
-__cxa_bad_typeid ()
-{
- [...]
-}
-[...]
--- /dev/null
+++ libstdc++-v3/libsupc++/unwind-cxx.h
@@ -0,0 +1,163 @@
+[...]
+extern "C" void __cxa_bad_typeid ();
+[...]
--- /dev/null
+++ libstdc++-v3/libsupc++/eh_aux_runtime.cc
@@ -0,0 +1,56 @@
+[...]
+extern "C" void
+__cxa_bad_typeid ()
+{
+ [...]
+}
The implicit prototype in the C++ front end however wasn't likewise adjusted,
and so for nvptx we generate code for 'std::type_info const &' return type:
// BEGIN GLOBAL FUNCTION DECL: __cxa_bad_typeid
.extern .func (.param .u64 %value_out) __cxa_bad_typeid;
{
.param .u64 %value_in;
call (%value_in),__cxa_bad_typeid;
trap;
// (noreturn)
exit;
// (noreturn)
ld.param.u64 %r39,[%value_in];
}
..., which is in conflict with the library code with 'void' return type:
// BEGIN GLOBAL FUNCTION DECL: __cxa_bad_typeid
.visible .func __cxa_bad_typeid;
// BEGIN GLOBAL FUNCTION DEF: __cxa_bad_typeid
.visible .func __cxa_bad_typeid
{
[...]
}
..., and we thus get execution test FAILs for 'g++.dg/rtti/typeid11.C', for
example:
error : Prototype doesn't match for '__cxa_bad_typeid' in 'input file 4 at offset 22204', first defined in 'input file 4 at offset 22204'
nvptx-run: cuLinkAddData failed: unknown error (CUDA_ERROR_UNKNOWN, 999)
With this patched, we get the expected:
// BEGIN GLOBAL FUNCTION DECL: __cxa_bad_typeid
-.extern .func (.param .u64 %value_out) __cxa_bad_typeid;
+.extern .func __cxa_bad_typeid;
{
-.param .u64 %value_in;
-call (%value_in),__cxa_bad_typeid;
+call __cxa_bad_typeid;
trap;
// (noreturn)
exit;
// (noreturn)
-ld.param.u64 %r39,[%value_in];
}
..., and execution test PASSes for a few test cases.
gcc/cp/
* rtti.cc (throw_bad_typeid): Adjust implicit '__cxa_bad_typeid'
prototype to reality. Adjust all users.
Co-authored-by: Jason Merrill <ja...@redhat.com>
---
gcc/cp/rtti.cc | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)
diff --git a/gcc/cp/rtti.cc b/gcc/cp/rtti.cc
index 158b5ba13979..353996206f5c 100644
--- a/gcc/cp/rtti.cc
+++ b/gcc/cp/rtti.cc
@@ -204,8 +204,7 @@ throw_bad_cast (void)
return build_cxx_call (fn, 0, NULL, tf_warning_or_error);
}
-/* Return an expression for "__cxa_bad_typeid()". The expression
- returned is an lvalue of type "const std::type_info". */
+/* See 'libstdc++-v3/libsupc++/eh_aux_runtime.cc' for '__cxa_bad_typeid'. */
static tree
throw_bad_typeid (void)
@@ -216,11 +215,8 @@ throw_bad_typeid (void)
tree name = get_identifier ("__cxa_bad_typeid");
fn = get_global_binding (name);
if (!fn)
- {
- tree t = build_reference_type (const_type_info_type_node);
- t = build_function_type_list (t, NULL_TREE);
- fn = push_throw_library_fn (name, t);
- }
+ fn = push_throw_library_fn
+ (name, build_function_type_list (void_type_node, NULL_TREE));
}
return build_cxx_call (fn, 0, NULL, tf_warning_or_error);
@@ -259,7 +255,7 @@ get_void_tinfo_ptr (tree type)
otherwise return the static type of the expression. */
static tree
-get_tinfo_decl_dynamic (tree exp, tsubst_flags_t complain)
+get_tinfo_ptr_dynamic (tree exp, tsubst_flags_t complain)
{
tree type;
tree t;
@@ -299,7 +295,7 @@ get_tinfo_decl_dynamic (tree exp, tsubst_flags_t complain)
/* Otherwise return the type_info for the static type of the expr. */
t = get_tinfo_ptr (type);
- return cp_build_fold_indirect_ref (t);
+ return t;
}
static bool
@@ -369,7 +365,7 @@ build_typeid (tree exp, tsubst_flags_t complain)
exp = cp_build_fold_indirect_ref (exp);
}
- exp = get_tinfo_decl_dynamic (exp, complain);
+ exp = get_tinfo_ptr_dynamic (exp, complain);
if (exp == error_mark_node)
return error_mark_node;
@@ -383,7 +379,7 @@ build_typeid (tree exp, tsubst_flags_t complain)
else
mark_type_use (initial_expr);
- return exp;
+ return cp_build_fold_indirect_ref (exp);
}
/* Generate the NTBS name of a type. If MARK_PRIVATE, put a '*' in front so that
--
2.34.1
