https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60406
--- Comment #23 from Dominik Vogt <vogt at linux dot vnet.ibm.com> ---
Regarding the new patch:
1) We need to call __builtin_extract_return_address(retaddr) in
__go_set_defer_retaddr() too. (On s390 (31 bit) this is necessary to remove
the most significant bit of the address which indicates the addressing mode.)
I.e.
--snip--
- g->defer->__retaddr = retaddr;
+ g->defer->__retaddr = __builtin_extract_return_addr (retaddr);
--snip--
2) The new patch does not compile for me:
--
In file included from ../../../libgo/runtime/go-check-interface.c:8:0:
../../../libgo/runtime/go-panic.h:43:13: error: conflicting types for
‘__go_makefunc_can_recover’
extern void __go_makefunc_can_recover (void *retaddr);
^
In file included from ../../../libgo/runtime/go-check-interface.c:7:0:
../../../libgo/runtime/runtime.h:845:9: note: previous declaration of
‘__go_makefunc_can_recover’ was here
void __go_makefunc_can_recover (const void *);
^
--
In runtime.h, __go_makefunc_can_recover still has a "const" argument:
--snip--
-void __go_makefunc_can_recover (const void *);
+void __go_makefunc_can_recover (void *);
--snip--
3) Couldn't this be written more efficiently by passing a flag?
+ /* If we are called from __go_makefunc_can_recover, then we need to
+ look one level higher. */
+ if (locs[0].function.len > 0
+ && __builtin_strcmp ((const char *) locs[0].function.str,
+ "__go_makefunc_can_recover") == 0)
E.g.
_Bool __go_can_recover (void *retaddr, _Bool called_by_makefunc_can_recover)
{
...
if (called_by_makefunc_can_recover)
{ do something }
else
{ do something else }
...
}
4) With the suggested changes from 1 and 2 above:
s390x (64 bit):
* PASS: test/recover.go
* the test from #4 in my earlier posting works as expected
* my private defer/recover/panic testsuite works as expected
s390 (31 bit):
* PASS: test/recover.go
* the test from #4 in my earlier posting works as expected
* my private defer/recover/panic testsuite works as expected
5) I find the assumption in the loop at the end of __go_can_recover() that if a
caller's name begins with "__go_" that means the panic can be recovered, a bit
hairy. Even if it is with the current libgo, an unrelated change elsewhere
could break this logic.
