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Re: windows gdb.exe, setting breakpoints before debugging cause extremely slow loading


On 3:59, asmwarrior wrote:
Hi, all, I'm a windows gdb user, I have used both official MinGW gdb.exe and gdb.exe build myself.

I found that when I set a breakpoint before loading or after loading has much different result.
I use GDB.exe under Codeblocks, here is the debugger log when I try to debug something:
----------------------------------------------------------------------------


Situation works badly:

I just set breakpoint before I start "run" the debugee

>>>>>>cb_gdb:
> break "E:/code/cb/cc_branch/src/plugins/codecompletion/parser/parserthread.cpp:471"
No source file named E:/code/cb/cc_branch/src/plugins/codecompletion/parser/parserthread.cpp.
Breakpoint 1 ("E:/code/cb/cc_branch/src/plugins/codecompletion/parser/parserthread.cpp:471) pending.
>>>>>>cb_gdb:
> run


Now, it will take about 1 and a half minutes to start the debugee.

----------------------------------------------------------------------------

But If I do *not* set any breakpoint before running, then ,the loading stage is quite fast(about 10 second), after that I can still set breakpoint and all the breakpoint works fine.

Not only me find the problem, see the message posted in Codeblocks forum by One of Codeblocks developers Pecan:
http://forums.codeblocks.org/index.php/topic,12951.msg87332.html#msg87332


Does this a gdb bug?

Thanks

asmwarrior(ollydbg from codeblocks forum)



I personally think there is something wrong with "pending breakpoint" when we load a shared dll library.

As my initial guess, When after loading some new shared libraries, gdb need to check if the pending breakpoint can be set to the new libraries. if Yes, then the these breakpoint can translated from "pending breakpoint" to "real breakpoint".

return to my problem:
I guess there are some recursive search algorithm for pending breakpoints after some new shared library debug information is loaded.


Can some one give me a direction that how does gdb treat with "pending breakpoint" after loading some new shared libraries?
I have read the gdb source "breakpoint.c" there:


struct breakpoint *b

if b->loc is NULL, which means it is a pending breakpoint. So, where and when will be this pointer member filled.

Thanks

asmwarrior





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