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Subject:	Re: Profiling with -pg and arguments to main() - GCC 4.1.0
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Date:	Fri, 8 Dec 2006 15:54:24 -0700
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DJ Delorie <dj AT delorie DOT com> wrote on 12/08/2006 02:06:42 PM:

# > So I'm not quite sure where to go from here in debugging... ideas?
#
# Disassemble your main.o and see if the stack is getting corrupted.
# Profiling adds code to the beginning of each function to record the
# call graphs, usually with a call to _mcount.  Stepping over that and
# watching bp/sp might give some clues.

Well, I think (with the aid of a co-worker - I'm no expert in x86
assembly!) we've caught what's going on...

The first several lines of assembly set up the stack frames and then
push the EBX and ECX registers.  It then does a mov of some constant
into EDX and then calls _mcount, as you say.

It's not BP/SP that's getting corrupted, it's ECX.  The next statement
is to move ECX into EBX, which it then uses as the address of the
parameters.  (This worked before the _mcount call.)

I'm not sure where mcount lives or how to go about fixing that,
though... :)

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