On 3/24/25 7:02 AM, Thomas Schwinge wrote:
Hi!
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:
In 2001 Subversion r40924 (Git commit 52a11cbfcf0cfb32628b6953588b6af4037ac0b6)
"IA-64 ABI Exception Handling", '__cxa_bad_cast' changed from 'void *' 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" void *
-__cxa_bad_cast ()
-{
- [...]
-}
-[...]
--- /dev/null
+++ libstdc++-v3/libsupc++/unwind-cxx.h
@@ -0,0 +1,163 @@
+[...]
+extern "C" void __cxa_bad_cast ();
+[...]
--- /dev/null
+++ libstdc++-v3/libsupc++/eh_aux_runtime.cc
@@ -0,0 +1,56 @@
+[...]
+extern "C" void
+__cxa_bad_cast ()
+{
+ [...]
+}
+[...]
The implicit prototype in the C++ front end however wasn't likewise adjusted,
and so for nvptx we generate code for 'void *' return type:
// BEGIN GLOBAL FUNCTION DECL: __cxa_bad_cast
.extern .func (.param .u64 %value_out) __cxa_bad_cast;
{
.param .u64 %value_in;
call (%value_in),__cxa_bad_cast;
trap;
// (noreturn)
exit;
// (noreturn)
ld.param.u64 %r30,[%value_in];
}
..., which is in conflict with the library code with 'void' return type:
// BEGIN GLOBAL FUNCTION DECL: __cxa_bad_cast
.visible .func __cxa_bad_cast;
// BEGIN GLOBAL FUNCTION DEF: __cxa_bad_cast
.visible .func __cxa_bad_cast
{
[...]
}
..., and we thus get execution test FAIL for 'g++.dg/rtti/dyncast2.C':
error : Prototype doesn't match for '__cxa_bad_cast' in 'input file 7 at
offset 51437', first defined in 'input file 7 at offset 51437'
nvptx-run: cuLinkAddData failed: device kernel image is invalid
(CUDA_ERROR_INVALID_SOURCE, 300)
With this patched, we get the expected: [...]
--- 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:
From f70662ddca467079cdb2bd3c8144d164e94a6268 Mon Sep 17 00:00:00 2001
From: Jason Merrill <ja...@redhat.com>
Date: Mon, 24 Mar 2025 13:32:55 -0400
Subject: [PATCH] ptr
---
gcc/cp/rtti.cc | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/gcc/cp/rtti.cc b/gcc/cp/rtti.cc
index a55b8611cda..353996206f5 100644
--- a/gcc/cp/rtti.cc
+++ b/gcc/cp/rtti.cc
@@ -255,7 +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;
@@ -295,7 +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
@@ -365,7 +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;
@@ -379,7 +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
--
2.49.0
