[Bug go/64001] gccgo: crash on stack splitting
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64001 Ian Lance Taylor changed: What|Removed |Added Status|UNCONFIRMED |WAITING Last reconfirmed||2016-02-10 Ever confirmed|0 |1
[Bug go/64001] gccgo: crash on stack splitting
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64001 --- Comment #7 from Ian Lance Taylor ian at airs dot com --- Sorry, I missed that this only happens with 4.9. Unfortunately, I was also unable to reproduce it with 4.9. I have no idea what the problem is. If you can still reproduce it, run it under strace to see what values mmap returns and make sure it returns normal values. Otherwise, the only thing I can think of is that somehow memory is being corrupted. That could be due to changes in the garbage collector. I haven't seen any other reports that suggest this, though.
[Bug go/64001] gccgo: crash on stack splitting
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64001 --- Comment #6 from Michael Hudson-Doyle michael.hudson at canonical dot com --- Which version were you using? I've never been able to reproduce it with anything newer than the 4.9 series. I'd love to know what the fix was so we can investigate backporting it...
[Bug go/64001] gccgo: crash on stack splitting
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64001 --- Comment #5 from Ian Lance Taylor ian at airs dot com --- Just a note that I have not been able to reproduce this. I ran the program from comment #1 50 times with no failures.
[Bug go/64001] gccgo: crash on stack splitting
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64001 --- Comment #4 from Michael Hudson-Doyle michael.hudson at canonical dot com --- Well, it seems to report that __morestack_segments __morestack_current_segment are always NULL for all threads. I don't understand the morestack code perfectly, but this seems a bit unlikely to actually be the case. GNU gdb (Ubuntu 7.8-1ubuntu4) 7.8.0.20141001-cvs seems like it should be new enough?
[Bug go/64001] gccgo: crash on stack splitting
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64001 --- Comment #1 from Michael Hudson-Doyle michael.hudson at canonical dot com --- Created attachment 34175 -- https://gcc.gnu.org/bugzilla/attachment.cgi?id=34175action=edit very small reproducer Well, here is a very small reproducer indeed. gccgo-go run boom.go fails ~50% of the time. Maybe it really is something to do with the https parsing code...
[Bug go/64001] gccgo: crash on stack splitting
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64001 --- Comment #2 from Michael Hudson-Doyle michael.hudson at canonical dot com --- Oh, I was wrong in my initial comment. Setting a breakpoint like this: (gdb) br *0x7971 Breakpoint 5 at 0x7971: file ../../../src/libgcc/config/i386/morestack.S, line 512. (gdb) commands Type commands for breakpoint(s) 5, one per line. End with a line saying just end. silent print $rax continue end (gdb) c (0x7971 is the instruction after the __generic_morestack call) results (eventually) in output like this: ... $202479 = 140737354018816 $202480 = 140737354022912 $202481 = 281474706301792 Program received signal SIGBUS, Bus error. __morestack () at ../../../src/libgcc/config/i386/morestack.S:529 529../../../src/libgcc/config/i386/morestack.S: No such file or directory. (gdb) p/x 281474706301792 $202482 = 0xefe1e360 So it does seem that __generic_morestack is returning junk. I can't figure out how to get gdb to show me the values of the __thread variables this is using though, so I don't know _why_ it's returning junk.
[Bug go/64001] gccgo: crash on stack splitting
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64001 --- Comment #3 from Ian Lance Taylor ian at airs dot com --- On GNU/Linux gdb can usually print TLS variables fine. It knows how to look up the value for the current thread. Make sure you are using a sufficiently new version of gdb, although I think it's been supported for a few years now.
