http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52179
--- Comment #7 from Jack Howarth <howarth at nitro dot med.uc.edu> 2012-02-11 01:10:48 UTC --- Interestingly, aslr randomizes the gdb crash log. For instance... # gdb ./gctest (gdb) break mark.c:361 Breakpoint 1 at 0x20c49ba5e20a81: file ../../../gcc-4.7-20120209/boehm-gc/mark.c, line 361. (gdb) r Starting program: /sw/src/fink.build/gcc47-4.7.0-1/darwin_objdir/x86_64-apple-darwin11.3.0/boehm-gc/testsuite/.libs/gctest Reading symbols for shared libraries + done Reading symbols for shared libraries ++++........................ done Breakpoint 1, GC_mark_some (cold_gc_frame=0x7fff6624b64c "\001") at ../../../gcc-4.7-20120209/boehm-gc/mark.c:361 361 MARK_FROM_MARK_STACK(); (gdb) c 106 Will ignore next 105 crossings of breakpoint 1. Continuing. Breakpoint 1, GC_mark_some (cold_gc_frame=0x7fff6624b64c "\001") at ../../../gcc-4.7-20120209/boehm-gc/mark.c:361 361 MARK_FROM_MARK_STACK(); (gdb) break mark.c:759 Breakpoint 2 at 0x1066722ac: file ../../../gcc-4.7-20120209/boehm-gc/mark.c, line 759. (gdb) c 3000 Will ignore next 2999 crossings of breakpoint 1. Continuing. Breakpoint 2, GC_mark_from (mark_stack_top=0x106716000, mark_stack=0x106716000, mark_stack_limit=0x106726000) at ../../../gcc-4.7-20120209/boehm-gc/mark.c:759 759 deferred = *limit; (gdb) c 1000 Will ignore next 999 crossings of breakpoint 2. Continuing. Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address: 0x00007fff662d03d8 GC_mark_from (mark_stack_top=0x106716000, mark_stack=0x106716000, mark_stack_limit=0x106726000) at ../../../gcc-4.7-20120209/boehm-gc/mark.c:759 759 deferred = *limit; vs # gdb ./gctest GNU gdb 6.3.50-20050815 (Apple version gdb-1708) (Thu Nov 3 21:59:02 UTC 2011) Copyright 2004 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "x86_64-apple-darwin"...Reading symbols for shared libraries .... done (gdb) set disable-aslr off (gdb) break mark.c:361 Breakpoint 1 at 0x20c49ba5e20a81: file ../../../gcc-4.7-20120209/boehm-gc/mark.c, line 361. (gdb) r Starting program: /sw/src/fink.build/gcc47-4.7.0-1/darwin_objdir/x86_64-apple-darwin11.3.0/boehm-gc/testsuite/.libs/gctest Reading symbols for shared libraries + done Reading symbols for shared libraries ++++........................ done Breakpoint 1, GC_mark_some (cold_gc_frame=0x7fff605eb64c "\001") at ../../../gcc-4.7-20120209/boehm-gc/mark.c:361 361 MARK_FROM_MARK_STACK(); (gdb) c 106 Will ignore next 105 crossings of breakpoint 1. Continuing. Breakpoint 1, GC_mark_some (cold_gc_frame=0x7fff605eb64c "\001") at ../../../gcc-4.7-20120209/boehm-gc/mark.c:361 361 MARK_FROM_MARK_STACK(); (gdb) break mark.c:759 Breakpoint 2 at 0x100a112ac: file ../../../gcc-4.7-20120209/boehm-gc/mark.c, line 759. (gdb) c 4000 Will ignore next 3999 crossings of breakpoint 1. Continuing. Breakpoint 2, GC_mark_from (mark_stack_top=0x100abb000, mark_stack=0x100abb000, mark_stack_limit=0x100acb000) at ../../../gcc-4.7-20120209/boehm-gc/mark.c:759 759 deferred = *limit; (gdb) where the second attempt crosses the same number of breakpoints on mark.c:759 without crashing as in the first try.
