From: Bryce McKinlay <mckinlay@redhat.com>
To: Ranjit Mathew <rmathew@gmail.com>
Cc: java-patches@gcc.gnu.org
Subject: Re: [MinGW] RFA: Make Stack Traces Work for Interpreted Code on Windows
Date: Tue, 11 Jul 2006 17:59:00 -0000 [thread overview]
Message-ID: <44B3E70F.4070009@redhat.com> (raw)
In-Reply-To: <e8qhm9$gh7$1@sea.gmane.org>
Hi Ranjit,
Ranjit Mathew wrote:
> When run under the interpreter, an exception-throwing programme
> crashes the interpreter on Windows since JvRunMain() does not
> occur in the call stack and we once again roam the wilderness of
> arbitrary EBP values.
>
> The fix was to change fallback_backtrace() in
> "sysdep/i386/backtrace.h" to stop on _Jv_RunMain() instead since
> this does occur in both interpreted and natively-executed call
> stacks. (Since this function is overloaded, I needed to use an
> interim variable with the appropriate cast to tell the compiler
> which of these function variants to pick up.)
>
Only the main thread will have JvRunMain on the stack - you probably
also need to look for the thread-start routine to handle other threads.
Note that even then there are some situations (invocation API) where
neither _Jv_RunMain or _Jv_ThreadStart will be on the stack.
> fallback_backtrace() also does not correctly handle unwinding
> through interpreted code. The fix was as simple as copying the
> relevant bits of code from _Jv_StackTrace::Unwind_TraceFn() and
> adjusting it a little bit.
>
This part of the patch is a bit awkward - duplicating the
interpreter-specific code is fragile and will make maintenance more
difficult. Couldn't we instead have fallback_backtrace call the real
UnwindTraceFn? I believe _Unwind_context is an opaque type, so it should
be possible to have fallback_backtrace pass its own data there.
> (I note that under the interpreter we do
> not get line numbers for the innermost call frame, even on Linux.
> I haven't investigated this issue yet.)
>
Hmm. There shouldn't be any problems here (on Linux) - do you have a
test case?
Bryce
next prev parent reply other threads:[~2006-07-11 17:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-09 9:19 Ranjit Mathew
2006-07-11 17:59 ` Bryce McKinlay [this message]
2006-07-11 18:34 ` Ranjit Mathew
2006-07-11 21:34 ` Bryce McKinlay
2006-07-12 17:28 ` Ranjit Mathew
2006-07-12 20:05 ` Bryce McKinlay
2006-07-14 17:26 ` Ranjit Mathew
2006-07-12 20:10 ` Bryce McKinlay
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