Middle-end folks: any thoughts about how best to make the change described in
the last paragraph below?
Library folks: any thoughts on the changes to __cxa_call_terminate?
-- 8< --
[except.handle]/7 says that when we enter std::terminate due to a throw,
that is considered an active handler. We already implemented that properly
for the case of not finding a handler (__cxa_throw calls __cxa_begin_catch
before std::terminate) and the case of finding a callsite with no landing
pad (the personality function calls __cxa_call_terminate which calls
__cxa_begin_catch), but for the case of a throw in a try/catch in a noexcept
function, we were emitting a cleanup that calls std::terminate directly
without ever calling __cxa_begin_catch to handle the exception.
A straightforward way to fix this seems to be calling __cxa_call_terminate
instead. However, that requires exporting it from libstdc++, which we have
not previously done. Despite the name, it isn't actually part of the ABI
standard. Nor is __cxa_call_unexpected, as far as I can tell, but that one
is also used by clang. For this case they use __clang_call_terminate; it
seems reasonable to me for us to stick with __cxa_call_terminate.
I also change __cxa_call_terminate to take void* for simplicity in the front
end (and consistency with __cxa_call_unexpected) but that isn't necessary if
it's undesirable for some reason.
This patch does not fix the issue that representing the noexcept as a
cleanup is wrong, and confuses the handler search; since it looks like a
cleanup in the EH tables, the unwinder keeps looking until it finds the
catch in main(), which it should never have gotten to. Without the
try/catch in main, the unwinder would reach the end of the stack and say no
handler was found. The noexcept is a handler, and should be treated as one,
as it is when the landing pad is omitted.
The best fix for that issue seems to me to be to represent an
ERT_MUST_NOT_THROW after an ERT_TRY in an action list as though it were an
ERT_ALLOWED_EXCEPTIONS (since indeed it is an exception-specification). The
actual code generation shouldn't need to change (apart from the change made
by this patch), only the action table entry.
PR c++/97720
gcc/cp/ChangeLog:
* cp-tree.h (enum cp_tree_index): Add CPTI_CALL_TERMINATE_FN.
(call_terminate_fn): New macro.
* cp-gimplify.cc (gimplify_must_not_throw_expr): Use it.
* except.cc (init_exception_processing): Set it.
(cp_protect_cleanup_actions): Return it.
gcc/ChangeLog:
* tree-eh.cc (lower_resx): Pass the exception pointer to the
failure_decl.
* except.h: Tweak comment.
libstdc++-v3/ChangeLog:
* libsupc++/eh_call.cc (__cxa_call_terminate): Take void*.
* config/abi/pre/gnu.ver: Add it.
gcc/testsuite/ChangeLog:
* g++.dg/eh/terminate2.C: New test.
---
gcc/cp/cp-tree.h | 2 ++
gcc/except.h | 2 +-
gcc/cp/cp-gimplify.cc | 2 +-
gcc/cp/except.cc | 5 ++++-
gcc/testsuite/g++.dg/eh/terminate2.C | 30 ++++++++++++++++++++++++++++
gcc/tree-eh.cc | 16 ++++++++++++++-
libstdc++-v3/libsupc++/eh_call.cc | 4 +++-
libstdc++-v3/config/abi/pre/gnu.ver | 7 +++++++
8 files changed, 63 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/eh/terminate2.C
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index a1b882f11fe..a8465a988b5 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -217,6 +217,7 @@ enum cp_tree_index
definitions. */
CPTI_ALIGN_TYPE,
CPTI_TERMINATE_FN,
+ CPTI_CALL_TERMINATE_FN,
CPTI_CALL_UNEXPECTED_FN,
/* These are lazily inited. */
@@ -358,6 +359,7 @@ extern GTY(()) tree cp_global_trees[CPTI_MAX];
/* Exception handling function declarations. */
#define terminate_fn cp_global_trees[CPTI_TERMINATE_FN]
#define call_unexpected_fn cp_global_trees[CPTI_CALL_UNEXPECTED_FN]
+#define call_terminate_fn cp_global_trees[CPTI_CALL_TERMINATE_FN]
#define get_exception_ptr_fn
cp_global_trees[CPTI_GET_EXCEPTION_PTR_FN]
#define begin_catch_fn
cp_global_trees[CPTI_BEGIN_CATCH_FN]
#define end_catch_fn cp_global_trees[CPTI_END_CATCH_FN]
diff --git a/gcc/except.h b/gcc/except.h
index 5ecdbc0d1dc..378a9e4cb77 100644
--- a/gcc/except.h
+++ b/gcc/except.h
@@ -155,7 +155,7 @@ struct GTY(()) eh_region_d
struct eh_region_u_must_not_throw {
/* A function decl to be invoked if this region is actually reachable
from within the function, rather than implementable from the runtime.
- The normal way for this to happen is for there to be a CLEANUP region
+ The normal way for this to happen is for there to be a TRY region
contained within this MUST_NOT_THROW region. Note that if the
runtime handles the MUST_NOT_THROW region, we have no control over
what termination function is called; it will be decided by the
diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index 216a6231d6f..853b1e44236 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -343,7 +343,7 @@ gimplify_must_not_throw_expr (tree *expr_p, gimple_seq
*pre_p)
gimple *mnt;
gimplify_and_add (body, &try_);
- mnt = gimple_build_eh_must_not_throw (terminate_fn);
+ mnt = gimple_build_eh_must_not_throw (call_terminate_fn);
gimple_seq_add_stmt_without_update (&catch_, mnt);
mnt = gimple_build_try (try_, catch_, GIMPLE_TRY_CATCH);
diff --git a/gcc/cp/except.cc b/gcc/cp/except.cc
index 91a5e049860..b04eb00d220 100644
--- a/gcc/cp/except.cc
+++ b/gcc/cp/except.cc
@@ -64,6 +64,9 @@ init_exception_processing (void)
tmp = build_function_type_list (void_type_node, ptr_type_node, NULL_TREE);
call_unexpected_fn
= push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
+ call_terminate_fn
+ = push_library_fn (get_identifier ("__cxa_call_terminate"), tmp, NULL_TREE,
+ ECF_NORETURN | ECF_COLD | ECF_NOTHROW);
}
/* Returns an expression to be executed if an unhandled exception is
@@ -76,7 +79,7 @@ cp_protect_cleanup_actions (void)
When the destruction of an object during stack unwinding exits
using an exception ... void terminate(); is called. */
- return terminate_fn;
+ return call_terminate_fn;
}
static tree
diff --git a/gcc/testsuite/g++.dg/eh/terminate2.C
b/gcc/testsuite/g++.dg/eh/terminate2.C
new file mode 100644
index 00000000000..1c69dab95f8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/eh/terminate2.C
@@ -0,0 +1,30 @@
+// PR c++/97720
+// { dg-do run }
+
+// Test that there is an active exception when we reach the terminate handler.
+
+#include <exception>
+#include <cstdlib>
+
+void bad_guy() throw() {
+ try { throw 0; }
+ catch (float) { }
+ // Don't catch int.
+}
+
+void level1() {
+ bad_guy();
+ throw "dead code";
+}
+
+void my_term()
+{
+ try { throw; }
+ catch(...) { std::exit(0); }
+}
+
+int main() {
+ std::set_terminate (my_term);
+ try { level1(); }
+ catch (int) { }
+}
diff --git a/gcc/tree-eh.cc b/gcc/tree-eh.cc
index 934209d205f..e8ceff36cc6 100644
--- a/gcc/tree-eh.cc
+++ b/gcc/tree-eh.cc
@@ -3382,8 +3382,22 @@ lower_resx (basic_block bb, gresx *stmt,
lab = gimple_block_label (new_bb);
gsi2 = gsi_start_bb (new_bb);
+ /* Handle failure fns that expect either no arguments or the
+ exception pointer. */
fn = dst_r->u.must_not_throw.failure_decl;
- x = gimple_build_call (fn, 0);
+ if (TYPE_ARG_TYPES (TREE_TYPE (fn)) != void_list_node)
+ {
+ tree epfn = builtin_decl_implicit (BUILT_IN_EH_POINTER);
+ src_nr = build_int_cst (integer_type_node, src_r->index);
+ x = gimple_build_call (epfn, 1, src_nr);
+ tree var = create_tmp_var (ptr_type_node);
+ var = make_ssa_name (var, x);
+ gimple_call_set_lhs (x, var);
+ gsi_insert_after (&gsi2, x, GSI_CONTINUE_LINKING);
+ x = gimple_build_call (fn, 1, var);
+ }
+ else
+ x = gimple_build_call (fn, 0);
gimple_set_location (x, dst_r->u.must_not_throw.failure_loc);
gsi_insert_after (&gsi2, x, GSI_CONTINUE_LINKING);
diff --git a/libstdc++-v3/libsupc++/eh_call.cc b/libstdc++-v3/libsupc++/eh_call.cc
index 3cfc71a4ef1..2bec4e83a7d 100644
--- a/libstdc++-v3/libsupc++/eh_call.cc
+++ b/libstdc++-v3/libsupc++/eh_call.cc
@@ -36,8 +36,10 @@ using namespace __cxxabiv1;
// terminate.
extern "C" void
-__cxa_call_terminate(_Unwind_Exception* ue_header) throw ()
+__cxa_call_terminate(void* ue_header_in) throw ()
{
+ _Unwind_Exception* ue_header
+ = reinterpret_cast<_Unwind_Exception*>(ue_header_in);
if (ue_header)
{
diff --git a/libstdc++-v3/config/abi/pre/gnu.ver
b/libstdc++-v3/config/abi/pre/gnu.ver
index 768cd4a4a6c..a2e5f3b4e74 100644
--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -2841,6 +2841,13 @@ CXXABI_1.3.14 {
} CXXABI_1.3.13;
+CXXABI_1.3.15 {
+
+ global:
+ __cxa_call_terminate;
+
+} CXXABI_1.3.14;
+
# Symbols in the support library (libsupc++) supporting transactional memory.
CXXABI_TM_1 {
base-commit: 2738955004256c2e9753364d78a7be340323b74b
